Process for modifying a polymer recyclate

Abstract

This invention relates to a method for modifying post-consumer recycled polypropylene-based polyolefin compositions. The invention also relates to modified polyolefin compositions obtained by this method, and articles comprising the modified polyolefin compositions.

Description

Technical Field

[0001] This invention relates to a method for modifying post-consumer recycled polypropylene-based polyolefin compositions. The invention also relates to a modified polyolefin composition obtained by this method, and articles comprising the modified polyolefin composition. Background Technology

[0002] The challenges of managing accumulated plastic waste and the environmental problems it causes have garnered widespread attention from the public and professionals. Therefore, the recycling of plastic materials has become an important issue, as plastic waste can be transformed into resources for new plastic products. Thus, recycling and reusing plastic materials can achieve a combination of environmental and economic benefits.

[0003] Although plastic recycling began in the mid-1990s, and collection systems have been implemented to more specifically collect and separate plastic materials from other household waste, the reuse of plastic materials derived from plastic waste remains limited. So-called post-consumer recycled (PCR) plastic materials typically consist of a mixture of different plastics and several contaminating materials. These mixtures usually require extensive mechanical recycling (i.e., material sorting and washing) before further processing or use. The methods employed are generally limited to using relatively homogeneous plastic materials with low contaminant content. Furthermore, these methods often fail to produce recycled plastic materials with the desired properties for a wide range of applications.

[0004] However, there is a general need for further modification methods for waste plastic materials, especially post-consumer recycled plastic materials.

[0005] Polyolefins are the primary plastic material in post-consumer recycled materials. Therefore, there is an urgent need to provide methods for modifying polyolefins in post-consumer recycled plastic materials. These methods should be highly tolerant to propylene polymer to ethylene polymer ratios and should further be tolerant to the presence of non-polyolefin plastic materials and other contaminants present in post-consumer recycled plastic materials.

[0006] Several properties are important for the use of recycled polyolefins. These properties particularly relate to the rheological and mechanical properties of recycled polyolefins, which enable them to be processed and used in the preparation of new articles. Therefore, there is a particular need for methods of modifying polyolefins to impart these properties to the modified polyolefins.

[0007] The rheological and mechanical properties of recycled polyolefins can be modified by treating them with free radicals and by controlling the introduction of long-chain branching. For example, rheological properties can be altered by adding peroxides and optional other reagents. European patent application EP3757152A1 discloses a method for preparing controlled rheologically modified mixed plastic-polyethylene blends from waste streams, with a melt flow rate of 0.1 to 0.45 g / 10 min (ISO 1133, 2.16 kg load, 190 °C), wherein the mixed plastic-polyethylene reactant blend is melt-blended with a peroxide.

[0008] While peroxides are widely used in the polyolefin industry to optimize the molecular weight of polyolefins, particularly polypropylene, the degradation products generated by the peroxide reaction are a drawback. In particular, a significant increase in volatile organic compounds (VOCs) and semi-volatile organic "fog" (FOG) compounds has been observed, negatively impacting taste and odor. These compounds are sometimes associated with health problems. Furthermore, high levels of emitted VOCs can create explosive atmospheres, making polymer handling difficult.

[0009] Therefore, there is a need for methods to further modify waste plastic materials, which provide the necessary rheological and mechanical properties for the recycling of polyolefins, while having low levels of volatile and semi-volatile organic compounds. Summary of the Invention

[0010] The purpose of this invention is to provide a method for solving the above-mentioned problems and to provide a corresponding modified polyolefin.

[0011] Therefore, the present invention provides a method for modifying post-consumer recycled polyolefin compositions, comprising the following steps: (A) Provides a post-consumer recycled polyolefin composition, wherein, by FTIR spectroscopy, based on the total weight of the post-consumer recycled polyolefin composition, the post-consumer recycled polyolefin composition comprises... (a) at least 50 wt% of one or more propylene (co)polymer components, and (b) Up to 50 wt% of one or more ethylene (co)polymer components; (B) Add a free radical initiator to the post-consumer recycled polyolefin composition, and optionally mix the free radical initiator and the post-consumer recycled polyolefin composition to form a first mixture (1); (C) Optionally, a twofold unsaturated hydrocarbon compound having the general formula (1) is added. (1) CH2=CH-(R)-CH=CH2, R may or may not be present. If present, R is an aliphatic hydrocarbon group or an aromatic hydrocarbon group containing 1 to 6 carbon atoms. The double unsaturated hydrocarbon compound, the free radical initiator and the post-consumer recycled polyolefin composition are mixed to form a second mixture (2). (D) Extruding the first mixture (1) or the second mixture (2) to obtain an extruded polyolefin composition; (E) Contacting the extruded polyolefin composition with a solvent; and (F) Remove the solvent to obtain a modified polyolefin composition.

[0012] This method can modify post-consumer recycled polyolefin compositions to provide modified polyolefin compositions, such as modified polyolefin compositions with uniform molecular weight, achieved by a narrow molecular weight distribution (MWD) or by introducing long-chain branching, while also having low content of volatile organic compounds (VOCs) and semi-volatile organic "fog" (FOG) compounds.

[0013] The present invention also provides a modified polyolefin composition obtained by the method, and articles comprising the modified polyolefin composition. Attached Figure Description

[0014] Figure 1 The content of low-boiling-point compounds (LBS) in the embodiments of the present invention and the comparative embodiments is shown.

[0015] Figure 2 The contents of the high-boiling-point compound (HBS) in the embodiments of the present invention and the comparative embodiments are shown.

[0016] Figure 3 a shows the molecular weight distribution (MWD, denoted as dW / dlog(M)) of PCR1 and P2.

[0017] Figure 3 b shows the radius of gyration (denoted as log Rg) along the molecular weight (log(M)) as predicted for a fully linear polymer.

[0018] Figure 4 The molecular weight distribution (MWD, denoted as dW / dlog(M)) of PCR2 and P5 or P6 is shown.

[0019] Figure 5 The correlation between the ethylene content of the crystalline fractions in recycled and virgin polyolefins and the ethylene content in the polymer is shown. Detailed Implementation

[0020] The present invention provides a method for modifying post-consumer recycled polyolefin compositions to obtain polyolefins with a more uniform structure and thus improved rheological properties.

[0021] The term “post-consumer recycled waste” here refers to an item that has completed at least its first use cycle (or life cycle), i.e., has fulfilled its first purpose. The term “virgin” here refers to newly produced materials and / or items that have not yet been recycled before their first use. The term “recycled” as used here refers to materials that have been reprocessed from “recycled waste”.

[0022] This method uses a post-consumer recycled (PCR) polyolefin composition containing a high polypropylene content and modifies its structure to alter its rheological properties.

[0023] Reactions with free radical initiators typically shift the structure of post-consumer recycled polyolefin compositions toward lower molecular weight (Mw) and narrower molecular weight distribution (MWD). Consequently, this step increases the melt flow rate.

[0024] Optional reactions with unsaturated hydrocarbon compounds, occurring concurrently with a free radical initiator, allow for the controlled introduction of long-chain branching into post-consumer recycled polyolefin compositions. This can also influence rheological properties by reducing the melt flow rate of the final product. Furthermore, long-chain branching imparts improved mechanical properties to the polyolefin, such as stiffness and toughness. Following the final extraction step, the resulting polyolefin exhibits lower levels of volatile and semi-volatile organic compounds. This facilitates the handling of the composition during the production of new products. The modified polymer can be used in a wider range of applications, particularly those with stringent requirements for odor and taste.

[0025] Step (A) - Providing a post-consumer recycled (PCR) polyolefin composition In step (A) of the method of the present invention, a post-consumer recycled polyolefin composition is provided.

[0026] According to the present invention, a post-consumer recycled (PCR) polyolefin composition refers to a composition containing polyolefins obtained from consumer waste. Therefore, post-consumer recycled polyolefins have completed at least one first use cycle (or life cycle), i.e., they have fulfilled their first purpose. Post-consumer recycled polyolefins differ from virgin polyolefins, i.e., newly produced material that has not yet been recycled. Post-consumer recycled polyolefins also differ from industrial waste, i.e., manufacturing waste, which typically does not reach consumers.

[0027] Virgin materials and used and / or recycled materials (e.g., mechanically recycled polymers) can be easily distinguished by the presence of contaminants such as limonene, fatty acids, paper and / or wood, or often based on their ash content. Polyolefins (e.g., blends of polypropylene and polyethylene) can also be further distinguished in terms of material origin by the presence of non-polyolefin polymers such as polystyrene and / or polyamides.

[0028] The method of this invention is applicable to compositions comprising a wide range of propylene polymer to ethylene polymer ratios. Based on the total weight of the post-consumer recycled polyolefin composition, as determined by Fourier transform infrared (FTIR) spectroscopy, the post-consumer recycled polyolefin composition comprises: (a) at least 50 wt% of one or more propylene (co)polymer components, and (b) Up to 50 wt% of one or more ethylene (co)polymer components.

[0029] The content of one or more ethylene (co)polymer components in the post-consumer recycled polyolefin composition can range from 0 wt% to 50 wt%. In particular, based on the total weight of the post-consumer recycled polyolefin composition, the content of one or more ethylene (co)polymer components in the post-consumer recycled polyolefin composition can be determined by FTIR spectroscopy to be at least 1 wt% (i.e., 1 wt% to 50 wt%).

[0030] Post-consumer recycled polyolefin compositions may comprise a mixture (e.g., polymer blends) of one or more propylene (co)polymer components and one or more ethylene (co)polymer components.

[0031] Since the contents of propylene (co)polymer and ethylene (co)polymer cannot be directly determined, the weight content is determined by calibrated equivalent ratio of isotactic polypropylene (iPP) homopolymer and high-density polyethylene (HDPE) using the FTIR method described herein.

[0032] In one embodiment, the post-consumer recycled polyolefin composition comprises, based on the total weight of the composition, as determined by FTIR spectroscopy: (a) 50 wt% to 98 wt%, preferably 52 wt% to 96 wt%, more preferably 53 wt% to 95 wt% of one or more propylene (co)polymer components, and (b) 2 wt% to 50 wt%, preferably 4 wt% to 48 wt%, more preferably 5 wt% to 47 wt% of one or more ethylene (co)polymer components.

[0033] The (co)polymer component preferably has a high degree of crystallinity as defined below. However, in post-consumer recycled polyolefin compositions, a copolymer component with less crystallinity or amorphousness may also be present.

[0034] Preferably, the post-consumer recycled polyolefin composition comprises a crystalline fraction (CF) as determined by Crystex analysis as described herein, in an amount ranging from 75 wt% to 98 wt% based on the total weight of the post-consumer recycled polyolefin composition. A less crystalline or amorphous copolymer component constitutes the majority of the soluble fraction (SF) as determined by Crystex analysis as described herein, in an amount ranging from 2 wt% to 25 wt% based on the total weight of the post-consumer recycled polyolefin composition.

[0035] The post-consumer recycled polyolefin composition may further include an ethylene content (C2(CF)) of the crystal fraction determined by FTIR during the Crystex analysis described herein, based on the total weight of the crystal fraction of the post-consumer recycled polyolefin composition, in the range of 3 wt% to 60 wt%, preferably 5 wt% to 55 wt%, more preferably 6 wt% to 50 wt%.

[0036] The post-consumer recycled polyolefin composition may also contain an ethylene content (C2(SF)) of the soluble portion, which is determined by FTIR during the Crystex analysis described herein, based on the total weight of the soluble portion of the post-consumer recycled polyolefin composition, and is 20 wt% to 50 wt%, preferably 23 wt% to 47 wt%, more preferably 25 wt% to 45 wt%.

[0037] Propylene (co)polymer component According to the present invention, "propylene (co)polymer component" refers to propylene homopolymer component and / or propylene copolymer component, and includes mixtures thereof.

[0038] The term "propylene homopolymer" refers to a propylene polymer, which is quantitatively determined based on the total weight of the propylene polymer. 13 C1H nuclear magnetic resonance (NMR) spectroscopy analysis revealed that the polymer contains at least 99.0 wt% propylene monomer units, preferably at least 99.5 wt% propylene monomer units, and more preferably at least 99.8 wt% propylene monomer units. In one embodiment, only propylene monomer units are detectable in the propylene homopolymer.

[0039] Based on its crystal structure, propylene homopolymers may exist in isotactic, synisotactic, or atactic forms.

[0040] Preferably, the propylene homopolymer has high crystallinity. Preferably, the propylene homopolymer is an isotactic propylene homopolymer, i.e., a propylene homopolymer with a five-membered isotactic structure, and is reported as a percentage of the isotactic pentad (mmmm) sequence relative to all pentad sequences, through quantitative analysis. 13 The percentage of C{1H} NMR spectroscopy determination is 95% to 98%, preferably 95.5% to 98%, and more preferably 96% to 97.5%.

[0041] The term "propylene copolymer" refers to a propylene polymer that typically comprises propylene monomer units and other comonomer units, preferably ethylene comonomer units and / or one or more α-olefin comonomer units having 4 to 10 carbon atoms, most preferably ethylene comonomer units. Preferably, by quantitative... 13 C{ 1 H-NMR spectroscopy determination, based on the total weight of the propylene copolymer, shows that the content of propylene monomer units in the propylene copolymer is at least 70 wt%, or by quantitative analysis. 13 C{ 1 H-NMR spectroscopy determination, based on a total molar content of 70 mol% for the propylene copolymer.

[0042] Preferably, the propylene copolymer is an isotactic propylene copolymer, i.e., a propylene copolymer with a five-membered isotactic structure, and is reported as a percentage of isotactic pentad (mmmm) sequences relative to all pentad sequences, through quantitative analysis. 13 The percentage of C{1H} NMR spectroscopy determination is 95% to 98%, preferably 95.5% to 98%, and more preferably 96% to 97.5%.

[0043] In one embodiment of the invention, at least one propylene (co)polymer component is an isotactic propylene homopolymer. In another embodiment of the invention, at least one propylene (co)polymer component is an isotactic propylene copolymer of propylene and a comonomer selected from ethylene and / or one or more α-olefins having 4 to 10 carbon atoms, preferably ethylene, wherein the copolymer is quantitatively... 13 C{ 1 H-NMR spectroscopy analysis showed that the copolymer preferably contains 0.1 mol% to 27 mol%, more preferably 0.1 mol% to 20 mol% of comonomer.

[0044] Ethylene (co)polymer component According to the present invention, the ethylene (co)polymer component refers to the ethylene homopolymer component and the ethylene copolymer component, as well as combinations thereof, such as copolymers or blends.

[0045] The term "ethylene homopolymer" refers to ethylene polymers, measured quantitatively based on the total weight of the ethylene polymer. 13 C{ 1 ¹H-NMR spectroscopy analysis revealed that the ethylene polymer contains at least 99.0 wt% ethylene monomer units, preferably at least 99.5 wt% ethylene monomer units, and more preferably at least 99.8 wt% ethylene monomer units. In one embodiment, only ethylene monomer units are detectable in the ethylene homopolymer.

[0046] The term "ethylene copolymer" refers to an ethylene polymer that typically comprises ethylene monomer units and other comonomer units, preferably one or more α-olefin comonomer units having 4 to 10 carbon atoms. Preferably, the total weight of the ethylene copolymer is used to determine the composition by quantitative analysis. 13 C{ 1 H-NMR spectroscopy analysis showed that the ethylene monomer unit content in the ethylene copolymer was at least 70 wt%, or by quantitative analysis... 13 C{ 1 H-NMR spectroscopy determination, based on a total molar amount of 75 mol of ethylene copolymer.

[0047] Preferably, the enthalpy of melting of the fully crystalline ethylene polymer is determined by differential scanning calorimetry (DSC) and assumed to be 293 J / g, indicating that the ethylene (co)polymer has a high crystallinity of at least 40%.

[0048] In one embodiment of the invention, at least one ethylene (co)polymer component is an ethylene homopolymer having a crystallinity of 40% to 90%, said crystallinity being determined by differential scanning calorimetry (DSC) and assuming a melting enthalpy of 293 J / g for a fully crystalline ethylene polymer. In another embodiment of the invention, said at least one ethylene (co)polymer component is an ethylene copolymer of ethylene and one or more comonomers selected from α-olefins having 4 to 10 carbon atoms, wherein said crystallinity is determined by quantitative... 13 C { 1 H NMR spectroscopy determined that the copolymer preferably contains 0.1 mol% to 20 mol% of comonomer, more preferably 0.1 mol% to 15 mol% of comonomer, and the determination was performed by differential scanning calorimetry (DSC), assuming that the melting enthalpy of the fully crystalline ethylene polymer is 293 J / g and its crystallinity is 40% to 90%.

[0049] Preferably, as determined by Fourier transform infrared (FTIR) spectroscopy, the post-consumer recycled polyolefin composition comprises 0 wt% to 1 wt% of a non-polyolefin polymer by weight of the total post-consumer recycled polyolefin composition. More preferably, polyamide (PA) and / or polystyrene (PS) polymers are undetectable by FTIR spectroscopy in the post-consumer recycled polyolefin composition. Further preferably, PET and / or PVC are undetectable by FTIR spectroscopy in the post-consumer recycled polyolefin composition. Most preferably, any one of PA, PS, PET, and PVC is undetectable by FTIR spectroscopy in the post-consumer recycled polyolefin composition.

[0050] There are several methods to distinguish post-consumer recycled polyolefin compositions used as starting materials in the methods of this invention from virgin polyolefins. For example, the presence of contaminating compounds in post-consumer recycled polyolefin compositions can be considered a distinguishing feature.

[0051] In some embodiments, based on the total weight of the post-consumer recycled polyolefin composition, the post-consumer recycled polyolefin composition used in the method of the present invention comprises one or more of the following components. (c) Limonene, determined by solid-phase microextraction (HS-SPME-GC-MS), having a content of 0.1 ppm to 100 ppm, preferably 0.1 ppm to 50 ppm, more preferably 0.1 ppm to 20 ppm, and most preferably 0.1 ppm to 5 ppm; (d) Fatty acids, determined by solid-phase microextraction (HS-SPME-GC-MS), have a content of 0.1 ppm to 100 ppm, preferably 0.1 ppm to 50 ppm, more preferably 0.1 ppm to 20 ppm, and most preferably 0.1 ppm to 5 ppm; (e) A non-polyolefin polymer, as determined by FTIR spectroscopy, having a content of 0.1 wt% to 10 wt%, preferably 0.1 wt% to 5 wt%, more preferably 0.1 wt% to 3 wt%; in particular, polystyrene having a content of 0.1 wt% to 3 wt%, and / or polyamide having a content of 0.1 wt% to 3 wt%. (f) Other components, in a content of 0.1 wt% to 10 wt%, preferably 0.1 wt% to 5 wt%, more preferably 0.1 wt% to 3 wt%, selected from talc, chalk, carbon, calcium stearate, titanium dioxide, pigments, metals, glass, paper, wood and combinations thereof, as determined as described below (the content of talc and chalk is preferably determined by TGA).

[0052] In some embodiments, the post-consumer recycled polyolefin composition contains at least 0.1 ppm of limonene.

[0053] In some embodiments, the sum of component a), b), and at least one of c) to f) (preferably c)) accounts for 100 wt% of the post-consumer recycled polyolefin composition.

[0054] The post-consumer recycled polyolefin composition may also contain less than 3.0 wt% of residual ash, preferably 0.5 wt% to 2.7 wt% of residual ash, more preferably 0.7 wt% to 2.5 wt% of residual ash, measured according to the ISO 3451-1 (1997) standard.

[0055] The method of the present invention is tolerant to the above-specified components within the specified amounts, and the modified polyolefin composition obtained by this method has excellent quality and can meet the requirements for subsequent recycling.

[0056] The post-consumer recycled polyolefin composition can also be or alternatively differentiated from virgin polyolefin by the ethylene content (C2(CF)) of the crystalline fraction (CF). In particular, post-consumer recycled polyolefin compositions containing a high content of polypropylene can be identified by this method. In addition, if the post-consumer recycled polyolefin composition is prepared by using a dissolution or extraction method and contains a high-purity polyolefin composition with only a small amount of contaminants, it can still be differentiated from virgin polyolefin by this measurement method.

[0057] Therefore, the ethylene content (C2(CF)) of the crystalline fraction (CF) determined by Crystex analysis as described herein is in the range of [C2 - 3.4] wt% to [C2 - 0.2] wt% of the total weight of the crystalline fraction of the post-consumer recycled polyolefin composition, more preferably in the range of [C2 - 3.0] wt% to [C2 - 0.6] wt%, and most preferably in the range of [C2 - 2.4] wt% to [C2 - 1.2] wt%. C2 herein represents the ethylene content value of the corresponding polymer determined by Crystex analysis as described herein, in weight percentage.

[0058] In other words, based on the total weight of the crystalline fraction in the post-consumer recycled polyolefin composition, the ethylene content (C2(CF)) of the crystalline fraction (CF) in weight percentage is preferably [-3,4 + C2] < C2(CF) < [-0,2 + C2], more preferably [-3,0 + C2] < C2(CF) < [-0,6 + C2], and most preferably [-2,4 + C2] < C2(CF) < [-1,2 + C2].

[0059] From Figure 5As can be seen, the correlation between the ethylene content of the crystalline fraction and the ethylene content of the polymer sample differs between recycled polyolefins (SbR) and virgin polyolefins. "Heco PP" is an abbreviation for multiphase propylene copolymer. "HomoPP" is an abbreviation for propylene homopolymer. "RaHe Co PP" is an abbreviation for random multiphase propylene copolymer.

[0060] The melt flow rate MFR2(1) of the post-consumer recycled polyolefin composition (i.e., the initial melt flow rate at the start of the method), determined according to ISO 1133 at a load of 2.16 kg and a temperature of 230 °C, is from 1.0 g / 10 min to 100 g / 10 min, preferably from 2.0 g / 10 min to 80 g / 10 min, and more preferably from 3.0 g / 10 min to 60 g / 10 min. As described below, the melt flow rate is generally varied by applying step (B) and optional step (C).

[0061] Post-consumer recycled polyolefin compositions can generally be present in particulate form, with no limitation on their geometry, as long as they have sufficient surface area for reaction in steps (B) and (C). However, preferably, the post-consumer recycled polyolefin compositions are present in granular form, with a median thickness T50 determined by direct caliper measurement of 0.5 mm to 5.0 mm, preferably 0.8 mm to 3.5 mm. These granules are preferably cylindrical or lenticular, with a median diameter D50 determined by optical analysis using a high-speed camera of 2.0 mm to 5.0 mm, preferably 2.5 mm to 4.5 mm.

[0062] The post-consumer recycled polyolefin compositions required by this invention can be prepared from pre-compositions based on post-consumer recyclables having other contents or forms. For example, post-consumer polymer waste can be treated by various mechanical (e.g., sorting), washing, or chemical (e.g., dissolving) methods to obtain the post-consumer recycled polyolefin compositions used in the methods of this invention.

[0063] Specifically, post-consumer recycled polyolefin compositions can be prepared to the desired size and morphology by extrusion at 180°C to 300°C, preferably 200°C to 280°C, in a single-screw or twin-screw extruder, preferably a co-rotating twin-screw extruder, followed by a suitable granulation process in which the pellet thickness and diameter are determined. Suitable granulation processes include underwater granulation, water ring granulation, and strand granulation, wherein strand granulation involves solidifying one or more melt strands in a water bath and then cutting the strands into pellets. In all cases, the pellet diameter is determined by the die diameter, and the pellet length is determined by the cutting frequency during the granulation process.

[0064] Generally, the post-consumer recycled polyolefin composition provided in step (A) means that the composition is ready for use. This post-consumer recycled polyolefin composition can be provided by placing the composition in a reactor and then adding other components thereto. However, the composition can also be added to the reactor simultaneously during the addition process in step (B).

[0065] Typically, the post-consumption recycled polyolefin composition of step (A) can be provided at temperatures ranging from -20°C to 90°C, for example from 15°C to 90°C, and particularly from 15°C to 25°C.

[0066] Optionally, the post-consumption recycled polyolefin composition of step (A) can be melted before step (B), for example at a melting temperature of 180°C to 300°C, preferably 200°C to 280°C.

[0067] Step (B) – Adding a free radical initiator In step (B) of the method of the present invention, a free radical initiator is added to the post-consumer recycled polyolefin composition, and optionally, the components are mixed to form a mixture (1).

[0068] Preferably, the amount of free radical initiator added is 0.01 wt% to 1.50 wt%, more preferably 0.02 wt% to 1.20 wt%, and most preferably 0.03 wt% to 1.00 wt%, based on the total weight of the post-consumer recycled polyolefin composition.

[0069] The free radical initiator can be selected from any free radical initiator suitable for the viscosity reduction reaction of propylene polymers. Preferably, the free radical initiator is a carbon-carbon free radical compound, an azo compound, a stable nitroxyl compound, a sterically hindered N-acyl compound, or a peroxide compound. The peroxide compound is preferably selected from acyl peroxides, alkyl peroxides, hydroperoxides, peresters, peroxycarbonates, and combinations thereof.

[0070] In a preferred embodiment, the free radical initiator is tert-butyl peroxyisopropyl carbonate.

[0071] Free radical initiators are preferably added to post-consumer recycled polyolefin compositions in liquid form. Since most free radical initiators are solid compounds, they can be dissolved in a liquid before addition.

[0072] After the free radical initiator is added to the post-consumer recycled polyolefin composition, the components are preferably mixed to form a mixture (1). The mixing process is preferably carried out with the components in contact for at least 2 minutes, more preferably 5 to 30 minutes, and even more preferably 8 to 25 minutes, to achieve relatively uniform absorption of the free radical initiator by the post-consumer recycled polyolefin composition.

[0073] In a preferred embodiment, the addition in step (B) is carried out in a flow-through reactor, such as a horizontal mixer with a paddle agitator, preferably in continuous mode. The post-consumer recycled polyolefin and the free radical initiator can be added to the flow-through reactor in a parallel flow. Preferably, the flow-through reactor is a horizontal flow-through reactor, and the components can be conveyed within the reactor via conveyor paddles. In this way, the free radical initiator is absorbed very efficiently with the post-consumer recycled polyolefin.

[0074] However, other reactors can be used, in which, for example, a free radical initiator is added after the post-consumer recycled polyolefin composition has been placed into the reactor.

[0075] Step (B) is preferably carried out at a temperature range of 20°C to 90°C, more preferably in the range of 40°C to 80°C. Alternatively, if the post-consumer recycled polyolefin composition in step (A) has been melted prior to step (B), then step (B) can be carried out at a higher temperature, such as 180°C to 300°C, or, for example, 200°C to 280°C.

[0076] Depending on the subsequent processing method, and especially whether step (C) is applied, step (B) may use different temperatures. For example, if step (C) is not used, step (B) may use a higher temperature.

[0077] In some embodiments of this method, if step (C) is used subsequently, it must be ensured that the method does not involve a viscosity-reducing reaction, i.e., that no intermediate product is allowed to react with a free radical initiator in the absence of a double-unsaturated hydrocarbon compound.

[0078] If step (C) is used, it is preferable to continue after step (B). In some embodiments, steps (B) and (C) can be performed simultaneously by adding a free radical initiator and a double unsaturated hydrocarbon compound (e.g., in the form of a masterbatch). In these embodiments, only one mixture (mixture (2)) is formed.

[0079] Without step (C), the method of the present invention typically increases the melt flow rate of post-consumer recycled polyolefin compositions. Without being theoretically limited, it is assumed that the polypropylene chains in the post-consumer recycled polyolefin compositions undergo major breakage, resulting in a narrower molecular weight distribution (MWD) and an increased melt flow rate (MFR).

[0080] Preferably, the second melt flow rate MFR2(B) of the modified polyolefin composition (i.e., the melt flow rate of the final modified polyolefin composition obtained by performing only step (B) without performing step (C)) is 20 g / 10 min to 300 g / 10 min, more preferably 30 g / 10 min to 270 g / 10 min, as determined according to ISO 1133 under conditions of 2.16 kg load and 230 °C.

[0081] Preferably, the modified polyolefin composition prepared by using step (B) without using step (C) has a uniform molecular weight, which can be observed by a narrowed molecular weight distribution (MWD), determined according to GPC methods and expressed as a ratio of weight-average molecular weight (Mw) to number-average molecular weight (Mn). Compared with post-consumer recycled polyolefin compositions, the ratio Mw / Mn, also known as polydispersity, in the modified polyolefin composition (after treatment in step (B)) is preferably reduced, preferably by at least 10%, more preferably by at least 15%. Figure 4 This shows the corresponding changes in polydispersity.

[0082] Step (C) - Adding a double-unsaturated hydrocarbon compound Step (C) is an optional step in the method of the present invention. Therefore, if step (C) is present, a double-unsaturated hydrocarbon compound having the general formula (1) is added in step (C): (1) CH2=CH-(R)-CH=CH2, R may or may not be present. If present, R is an aliphatic or aromatic hydrocarbon group containing 1 to 6 carbon atoms. These components are then mixed to form a mixture (2).

[0083] Preferably, based on the total weight of the post-consumer recycled polyolefin composition, the amount of the double unsaturated hydrocarbon compound having the general formula (1) added is 0.05 wt% to 0.5 wt%, more preferably 0.08 wt% to 0.45 wt%, and most preferably 0.10 wt% to 0.40 wt%.

[0084] Formula (1) includes formulas (1a) and (1b): (1a)CH2= CH-CH = CH2 (1b) CH2=CH-R-CH=CH2, In formula (1b), R is an aliphatic hydrocarbon group or an aromatic hydrocarbon group containing 1 to 6 carbon atoms.

[0085] In a preferred embodiment, the double unsaturated hydrocarbon compound of formula (1) is 1,3-butadiene (i.e., R is not present in formula (1)).

[0086] In other embodiments, the residue R in the double unsaturated hydrocarbon compound of formula (1) is selected from methylene, ethylene, propylene, n-butylene, tert-butylene, n-pentylene, isopentylene, tert-pentylene, n-hexylene, tert-hexylene, isohexylene, neohexylene, and phenylene.

[0087] Preferably, the double-unsaturated hydrocarbon compound can be added in a naturally aggregated state at the feeding temperature. Preferably, the double-unsaturated hydrocarbon compound is added in gaseous form.

[0088] To ensure adequate absorption of the unsaturated hydrocarbon compounds and free radical initiators by the post-consumer recycled polyolefin composition, the components need to be mixed. Mixing can be carried out in any type of reactor, preferably any reactor suitable for solid-gas reactions. The mixing time is preferably 1 s to 30 min, more preferably 2 s to 5 min.

[0089] In a preferred embodiment, the reactor is a vertical flow-through reactor, wherein particles of the post-consumer recycled polyolefin composition are conveyed by gravity. Unsaturated hydrocarbon compounds are added to the reactor as a fluid, and mixing occurs in the unsaturated hydrocarbon compound fluid, preferably during the descent of the post-consumer recycled polyolefin composition.

[0090] Step (C) is preferably carried out at a temperature range of 20°C to 90°C, and more preferably at a temperature range of 40°C to 80°C.

[0091] When used in conjunction with step (C), the method of the present invention reduces the melt flow rate of the post-consumer recycled polyolefin composition. Without being theoretically limited, it is hypothesized that the polypropylene chains in the post-consumer recycled polyolefin composition, after being broken by a free radical initiator, recombine into a branched structure, thereby leading to an increase in melt flow rate (MFR).

[0092] Preferably, the third melt flow rate MFR2(C) of the modified polyolefin composition (i.e., the melt flow rate after applying steps (B) and (C) of the method) is, according to ISO 1133, measured at a load of 2.16 kg and a temperature of 230°C, from 0.1 g / 10 min to 50 g / 10 min, more preferably from 0.1 g / 10 min to 40 g / 10 min, and most preferably from 0.1 to 30 g / 10 min. The third melt flow rate exists only when step (C) is used. In this case, the second melt flow rate does not exist.

[0093] Preferably, the ratio of MFR2(C) to MFR2(1) is less than 1.00, more preferably less than 0.90. More preferably, the ratio of MFR2(C) to MFR2(1) is from 0.01 to 0.95, more preferably from 0.01 to 0.90.

[0094] The reduced melt flow rate makes the resulting modified polyolefin composition very easy to process and suitable for repeated use in a variety of polyolefin applications requiring enhanced mechanical stability.

[0095] Preferably, the modified polyolefin composition prepared by steps (B) and (C) has a uniform molecular weight, which is achieved by chain scission through a free radical initiator and controlled crosslinking of unsaturated hydrocarbon compounds.

[0096] By adding the unsaturated compound of step (C), the properties of the modified polyolefin compositions are altered through controlled introduction of long-chain branching. Excellent results were achieved in terms of processing properties and further application options for post-consumer recycled polyolefin compositions with different propylene polymer to ethylene polymer ratios. This is unexpected because the reaction with the free radical initiator leads to different mechanisms of action for the propylene and ethylene polymers. While the propylene polymer undergoes a viscosity-reducing reaction, the ethylene polymer typically forms a highly cross-linked structure upon reaction with the free radical initiator.

[0097] The method of the present invention uses step (C) to turn this problem into a possible advantage by combining the chain breaking of the propylene polymer with the branching and crosslinking reactions in the ethylene polymer, and involving some of the reactions between polymers that lead to improved compatibility.

[0098] When compared with post-consumer recycled polyolefin compositions, the molecular weight distribution of the polyolefin composition modified by step (C) may remain unchanged or may be changed. Preferably, the polydispersity determined by the GPC method is 5 to 15, more preferably 6 to 14, and most preferably 7 to 13. Figure 3 a describes the polydispersity of post-consumer recycled polyolefin compositions before and after treatment. Figure 3b shows the introduction of long-chain branching in the treated post-consumer recycled polyolefin composition.

[0099] Another method for characterizing the structure of branched polypropylene is the rheotensimetry measurement. Branched polypropylene exhibits higher melt strength as the shear force applied to the polymer increases, such as during melt extrusion. This property is known as strain hardening. In rheotensimetry, the strain hardening behavior of the polymer is analyzed using a rheotensimetry apparatus (Göttfert, Siemensstr. 2, 74711 Buchen, Germany), in which a melt strip is stretched at a specified acceleration. The relationship between the traction force F and the traction speed v is recorded. The test procedure is performed at 23°C. More details can be found in the experimental section.

[0100] By using step (C), the modified polyolefin composition is preferably characterized by improved strength properties, which can be reflected by at least one of the following parameters: a) The F value was determined according to the rheotensur apparatus method, ISO 16790:2005. 30 The melt strength is 3.5 cN to 30.0 cN, more preferably 4.0 cN to 25.0 cN, and most preferably 4.5 cN to 22.0 cN; b) According to the rheotensur apparatus method, ISO 16790:2005, the v was measured. 30 The melt ductility is from 150 mm / s to 300 mm / s, more preferably from 155 mm / s to 290 mm / s, and most preferably from 160 mm / s to 280 mm / s; c) F 30 The / MFR2(C) value is at least 0.5 cN·10 min / g, and / or the value is in the range of 0.5 cN·10 min / g to 80.0 cN·10 min / g; d) v 30 The / MFR2(C) value is at least 20 mm·600 / g, more preferably 50 mm·600 / g, and / or the value is from 20 mm·600 / g to 1200 mm·600 / g, more preferably from 50 mm·600 / g to 1200 mm·600 / g; e) As described below, at a strain rate of 1 s -1The Hencky strain is 2.5 and the strain hardening factor (SHF) measured at 180 °C is 2.0 to 20.0, more preferably 2.2 to 15.0, and most preferably 2.3 to 12.5; and / or f) The SHF / MFR2(C) value is at least 0.5 (g / 10°min) -1 More preferably at least 1.2 (g / 10°min) -1 And / or its value is 0.5 (g / 10°min) -1 Up to 40.0 (g / 10°min) -1 More preferably, it is 1.2 (g / 10°min). -1 Up to 30.0 (g / 10°min) -1 .

[0101] Step (D) - Extrusion Step (D) is performed after step (B), or if step (C) exists, it is performed after step (C).

[0102] In step (D) of the method of the present invention, a mixture (1) or (2) comprising a post-consumer recycled polyolefin composition, a free radical initiator, and optionally a diunsaturated hydrocarbon compound is extruded. The extrusion process is preferably carried out in the range of 180°C to 300°C, more preferably 200°C to 280°C, to obtain the extruded polyolefin composition. In this extrusion step, the post-consumer recycled polyolefin is typically melted.

[0103] Extrusion can be performed using any conventional method known in the art. Preferably, extrusion is carried out in a continuous melt mixing apparatus, such as a single-screw extruder, a co-rotating twin-screw extruder, or a blender. The barrel temperature is preferably in the range of 200°C to 280°C. The screw speed of the melt mixing apparatus is preferably adjusted to the range of 100 rpm to 750 rpm.

[0104] More preferably, the melt mixing apparatus includes a feeding zone, a kneading zone, and a die zone, and maintains a specific temperature profile along the screw of the melt mixing apparatus. The initial temperature in the feeding zone is T1, the highest temperature in the kneading zone is T2, and the final temperature in the die zone is T3. All temperatures are defined as barrel temperatures. The barrel temperature T1 (feeding zone) is preferably in the range of 180°C to 260°C. The barrel temperature T2 (in the kneading zone) is preferably in the range of 180°C to 300°C. The barrel temperature T3 (die zone) is preferably in the range of 180°C to 280°C.

[0105] In a preferred embodiment, part or all of the method of the present invention is carried out as a continuous process when using the above-described flow-through reactor, and the mixture (1) or (2) prepared in step (B) or (C) is directly fed into an extruder to prepare an extruded polyolefin composition.

[0106] Following step (D), the extruded polyolefin composition is preferably granulated in an underwater granulator or after one or more melt strips have been cured in a suitable granulation process. Suitable granulation processes include underwater granulation, water ring granulation, and strand granulation, which involves curing one or more melt strips in a water bath and then cutting them into granules.

[0107] Step (E) — Contact with solvent Step (E) is performed after step (D). Optionally, the extruded polyolefin composition may be granulated between steps (D) and (E).

[0108] In step (E), the extruded polyolefin composition is contacted with a solvent. Step (E) aims to reduce the content of volatile organic compounds (VOCs) and / or semi-volatile organic compounds (FOGs) in the extruded polyolefin composition by extraction.

[0109] The solvent can be any solvent capable of dissolving volatile organic compounds (VOCs) and / or semi-volatile organic compounds (FOGs) in the extruded polyolefin composition.

[0110] The solvent may be selected from n-alkanes having 4 to 10 carbon atoms, cycloalkanes having 4 to 10 carbon atoms, haloalkanes having 4 to 10 carbon atoms, aldehydes having 3 to 10 carbon atoms, ketones having 3 to 10 carbon atoms, and mixtures thereof.

[0111] Preferably, the solvent may be selected from n-alkanes having 4 to 10 carbon atoms, cycloalkanes having 4 to 10 carbon atoms, aldehydes having 3 to 10 carbon atoms, ketones having 3 to 10 carbon atoms, and mixtures thereof.

[0112] Preferably, the solvent may be selected from n-alkanes having 4 to 10 carbon atoms, cycloalkanes having 4 to 10 carbon atoms, aldehydes having 3 to 10 carbon atoms, ketones having 3 to 10 carbon atoms, and mixtures thereof.

[0113] Specific n-alkanes include n-butane, n-pentane, n-hexane, n-heptane, n-octane, n-nonane, and n-decane, and mixtures thereof, with n-hexane, n-heptane, and n-octane being preferred. Using n-heptane provides excellent solubility for volatile and / or semi-volatile organic compounds.

[0114] The specific cycloalkanes are cyclobutane, cyclopentane, cyclohexane, cycloheptane, cyclooctane, cyclononane, cyclodecane and mixtures thereof, with cyclohexane, cycloheptane and cyclooctane being preferred.

[0115] Specific halogenated n-alkanes are chlorinated n-alkanes, such as n-butane chloride, n-pentane chloride, n-hexane chloride, n-heptane chloride, n-octane chloride, n-nonane chloride, and n-decane chloride, as well as any mixtures thereof.

[0116] The specific aldehydes and ketones are acetone, methyl isobutyl ketone, or methyl ethyl ketone, with methyl ethyl ketone being preferred. Using methyl ethyl ketone provides excellent solubility for volatile and / or semi-volatile organic compounds.

[0117] In some embodiments, the solvent is a solvent with a boiling point below 120°C, preferably a solvent with a boiling point of 50°C to below 120°C.

[0118] In a specific embodiment, the solvent is selected from: n-alkanes having 4 to 10 carbon atoms, cycloalkanes having 4 to 10 carbon atoms, ketones having 3 to 10 carbon atoms, and any mixtures thereof.

[0119] In a further specific embodiment, the solvent is selected from n-alkanes having 4 to 10 carbon atoms, cycloalkanes having 4 to 10 carbon atoms, and any mixture thereof.

[0120] In a more specific embodiment, the solvent is selected from n-butane, n-pentane, n-hexane, n-heptane, n-octane, n-nonane, n-decane, cyclobutane, cyclopentane, cyclohexane, cycloheptane, cyclooctane, cyclononane, cyclodecane, and methyl ethyl ketone. More preferably, the solvent is n-hexane, n-heptane, n-octane, cyclohexane, cycloheptane, cyclooctane, and any mixture thereof. Most preferably, the solvent is n-hexane, n-heptane, n-octane, and any mixture thereof.

[0121] In step (E), the ratio (wt% / wt%) of the extruded polyolefin composition to the solvent is preferably 1:3 to 1:20, more preferably 3:1 to 10:1, and most preferably 3:1 to 5:1, such as 4:1.

[0122] Step (E) is preferably performed at a temperature range of 50°C to 120°C, more preferably 70°C to 110°C, and most preferably 80°C to 100°C. In some embodiments, step (E) is performed by heating the components in contact under reflux.

[0123] Step (E) is preferably performed for 30 to 180 minutes, more preferably 60 to 150 minutes. In other words, the residence time of the extruded polyolefin composition with the solvent is 30 to 180 minutes, more preferably 60 to 150 minutes.

[0124] Step (E) can be performed over a wide pressure range. Preferably, step (E) is performed over a pressure range of 0.1 MPa absolute pressure to 5.1 MPa absolute pressure, and more preferably at atmospheric pressure (i.e., approximately 0.1 MPa absolute pressure).

[0125] In a preferred embodiment, step (E) is performed for 30 to 180 minutes at a temperature range of 50°C to 120°C and an absolute pressure of 0.1 MPa to 5.1 MPa.

[0126] Preferably, step (E) is carried out under stirring. Therefore, any reactor capable of stirring can be used. In a preferred embodiment, step (E) is carried out in a continuous stirred tank reactor. Alternatively, a tubular reactor can be used.

[0127] In a preferred embodiment, the method of the present invention is carried out continuously when using the above-described flow-through reactor, and the extruded polyolefin composition is directly fed into the reactor of step (E).

[0128] Step (F) - Removal of solvent Step (F) is performed after step (E) to remove the solvent and obtain a modified polyolefin composition.

[0129] Solvent removal can be performed using methods known in the art that are suitable for this application.

[0130] In some embodiments, the solvent is removed by filtration. In some embodiments, the solvent is removed by stirring under reduced pressure, i.e., less than 0.1 MPa absolute pressure, for example, from 1,000 Pa absolute pressure to 10,000 Pa absolute pressure. Reduced-pressure stirring can be performed for 1 hour to 24 hours, preferably 10 hours to 15 hours.

[0131] In a preferred embodiment, filtration and / or vacuum stirring are used to remove the solvent.

[0132] Preferably, the solvent is removed to obtain the modified polyolefin composition in dried form. Optionally, a drying step is performed after step (F).

[0133] In step (F), significant amounts of volatile organic compounds (VOCs) and semi-volatile organic compounds (FOGs) can be removed from the extruded polyolefin composition by removing the solvent. The terms "volatile organic compounds (VOCs)" and "semi-volatile organic compounds (FOGs)" are widely accepted in the art. The boiling points of volatile compounds are considered to be between 50°C and 260°C.

[0134] Preferably, extraction steps (E) and (F) can reduce the amount of these compounds by 50% or more (compared to the extruded polyolefin composition prior to step (E)). Simultaneously, other contaminants can also be removed through the extraction steps. For example, polyethylene wax and polypropylene wax, as well as polystyrene, can also be removed.

[0135] Preferably, the method of the present invention reduces the content of low-boiling-point substances (LBS) by at least 60%, preferably at least 70%, and / or the content of high-boiling-point substances (HBS) by at least 50%, preferably at least 60%, as determined by the methods described below. More preferably, the contents of LBS and HBS should be reduced by the percentages described above.

[0136] Following step (F), a modified polyolefin composition is obtained, which preferably exhibits the determination results described below. i) Low-boiling-point substances (LBS) present in concentrations below 100 ppm, preferably below 80 ppm, more preferably below 60 ppm; and / or ii) High-boiling-point substances (HBS) in a concentration of less than 200 ppm, preferably less than 180 ppm, and more preferably less than 160 ppm.

[0137] In some embodiments, the method including steps (A) through (F) – wherein step (C) is optional – can be combined with a solvent-based recovery (SbR) process to further remove contaminants. In this embodiment, modified polyolefin compositions with even higher purity (fewer contaminants) can be obtained. In the SbR method, the polymer is first dissolved in a suitable solvent, and then the solubility of the dissolved polymer is reduced by adding a non-solvent (dissolution / precipitation), and / or the solvent is preferably completely separated from the cured polymer by thermal unit operations (evaporation, drying, etc.), thereby causing the polymer to solidify. For example, WO2022 / 219091 and WO 2022 / 219092 both disclose a solvent-based recovery method for recovering waste polymer materials.

[0138] Therefore, in a specific implementation of this method, the method includes the following steps: (A) A post-consumer recycled polyolefin composition is provided, which, based on the total weight determined by FTIR spectroscopy, comprises: (a) at least 50 wt% of one or more propylene (co)polymer components, and (b) Up to 50 wt% of one or more ethylene (co)polymer components; (B) Add a free radical initiator to the post-consumer recycled polyolefin composition, and optionally mix the free radical initiator and the post-consumer recycled polyolefin composition to form a first mixture (1); (C) Optional addition of a double unsaturated hydrocarbon compound having the general formula (1) (1) CH2=CH-(R)-CH=CH2, R may or may not be present. If present, R is an aliphatic or aromatic hydrocarbon group containing 1 to 6 carbon atoms. A second mixture (2) is formed by mixing a double unsaturated hydrocarbon compound, a free radical initiator and a post-consumer recycled polyolefin composition. (D) Extruding the first mixture (1) or the second mixture (2) to obtain an extruded polyolefin composition; (E) Contact the extruded polyolefin composition with a solvent to provide a polyolefin stream, said solvent being, for example, one or more C4-C10 n-alkanes, halogenated C4-C10 n-alkanes, C1-C10 aldehydes, C3-C10 ketones and any mixture thereof, preferably said solvent having a boiling point below 120°C; -Optionally remove at least a portion of the solvent from the polyolefin stream, for example by filtration and / or by agitation under reduced pressure; - Optionally, at least one polyolefin solvent is added, wherein the at least one polyolefin solvent may be the same as or different from the solvent in step (E), preferably wherein the at least one polyolefin solvent has a boiling point at 1 bar that is equal to or higher than 70°C, for example, 75°C to 250°C, particularly 80°C to 220°C, and more particularly 80°C to 180°C (e.g., one or more C4-C10 alkanes and / or C4-C10 cycloalkanes, such as cyclohexane, n-hexane, n-heptane, and n-octane); - At a dissolution temperature of 100°C to 300°C and a dissolution pressure of 1.0 MPa absolute pressure to 20.0 MPa absolute pressure, a polyolefin stream is heated with a solvent and optionally at least one polyolefin dissolving solvent to obtain a slurry stream of dissolved polyolefin and insoluble solids. - Remove insoluble solids from the slurry stream to obtain a polyolefin solution stream; and (F) The modified polyolefin composition is preferably obtained by removing the solvent and optionally the polyolefin dissolving solvent by gas-liquid separation (from the polyolefin solution).

[0139] The method can be carried out in a continuous manner, wherein the preferred (first) solvent (used as an extraction solvent) comprises one or more C4-C10 n-alkanes, and at least one polyolefin dissolving solvent preferably comprises one or more C4-C10 n-alkanes. More preferably, the (first) solvent (extraction solvent) and at least one polyolefin dissolving solvent are the same solvent, for example, both are n-hexane, n-heptane or n-octane.

[0140] This method can include more of the conventional steps in solvent-based polyolefin recovery processes.

[0141] In an alternative embodiment, the post-consumer recycled polyolefin composition provided in step (A) of the method described herein may be derived from a solvent-based polyolefin recycling method.

[0142] Typically, the method of the present invention can be characterized by the following further features.

[0143] Other additives During this process, other additives can be further added to the mixture. In particular, additives commonly used in polyolefin preparation methods, such as modifiers, stabilizers, antistatic agents, lubricants, nucleating agents, foam nucleating agents, deacidifiers, UV stabilizers, slip agents, and pigments, as well as fillers and reinforcing agents. The advantage of post-consumer recycled polyolefin compositions is that they typically contain additives from the preparation processes of virgin polymers and first-use articles, meaning that further additives may not be necessary. However, if stabilizers, especially primary and secondary antioxidants, have already been consumed during processing and use, it is preferable to add an appropriate amount of stabilizer.

[0144] Modified polyolefin compositions The present invention also relates to modified polyolefin compositions obtained by the method of the present invention in any of the above embodiments.

[0145] The above discussion of the method described several embodiments of the modified polyolefin composition and their characteristics. The modified polyolefin composition can be any of these embodiments.

[0146] Preferably, the modified polyolefin composition has a low content of volatile organic compounds (VOCs) and / or semi-volatile organic compounds (FOGs).

[0147] i) The content of low-boiling-point substances (LBS) is less than 100 ppm, preferably less than 80 ppm, more preferably less than 60 ppm; and / or ii) The content of high-boiling-point substances (HBS) is less than 200 ppm, preferably less than 180 ppm, more preferably less than 160 ppm, and more preferably both of the above indicators are met.

[0148] The low concentration of these compounds results in modified polyolefin compositions with less unpleasant odor and / or taste. Therefore, these compositions can be used in applications where odor and taste requirements are stringent. These compounds are sometimes associated with health problems. Therefore, eliminating these compounds is beneficial to the user's health. Furthermore, the avoidance of explosive atmospheres facilitates the disposal of these polyolefin compositions.

[0149] A preferred feature of the modified polyolefin composition is that the xylene insoluble (XHU) component, as determined according to EN 579, is present in a content of 0.0 wt% to 3.5 wt%, more preferably 0.1 wt% to 3.0 wt%, and most preferably 0.1 wt% to 2.5 wt% based on the total weight of the modified polyolefin composition.

[0150] Products The present invention also relates to the use of an article comprising the modified polyolefin composition of any of the above embodiments, and the modified polyolefin composition prepared by the method of the present invention.

[0151] The article is preferably a foamed article, a film, or an extruded coating. In a preferred embodiment, the article is a foamed article, a film, or an extruded coating, and based on the total weight of the article, the article contains more than 50 wt%, preferably more than 75 wt%, for example 90 wt%, of a modified polyolefin composition.

[0152] In a particularly preferred embodiment, the article is a foamed article that, based on the total weight of the foamed article, contains more than 50 wt%, preferably more than 75 wt%, such as 90 wt%, of a modified polyolefin composition, and the MFR2 of the modified polyolefin composition is 0.1 g / 10 min to 1.5 g / 10 min, as determined by ISO 1133 at a load of 2.16 kg and a temperature of 230°C.

[0153] In another particularly preferred embodiment, the article is a film or extrusion coating, preferably for a substrate such as paper, metal, fabric or non-woven textile, wherein the content of the modified polyolefin composition is more than 50 wt%, preferably more than 75 wt%, for example 90 wt%, based on the total weight of the film or extrusion coating, and the MFR2 of the modified polyolefin composition is 1.5 g / 10 min to 10.0 g / 10 min as determined by ISO 1133 at a load of 2.16 kg and a temperature of 230 °C.

[0154] Example Determination methods Unless otherwise stated, the following definitions of terms and measurement methods apply to the above overview of the invention and the following embodiments.

[0155] Melt Flow Rate (MFR) 2 ) Melt flow rate (MFR) is determined according to ISO 1133 and expressed in g / 10 min. MFR is an indicator of flowability and therefore a measure of polymer processing performance. A higher melt flow rate generally indicates a lower polymer viscosity. Here, MFR2 was measured at 230°C and a load of 2.16 kg.

[0156] F 30 Melt strength and v 30 Melt ductility The tests described here follow ISO 16790:2005. The strain hardening behavior was determined by the method described in MH Wagner's article "Rheotens-Mastercurves and Drawability of Polymer Melts" (MH Wagner, Polymer Engineering and Science, Vol. 36, pp. 925-935). The strain hardening behavior of the polymer was analyzed using a rheotensometer (Göttfert, Siemensstr. 2, 74711 Buchen, Germany), in which a melt strip is elongated by stretching at a specified acceleration. The rheotensometer experiment simulates industrial spinning and extrusion processes. The test principle involves pressing or extruding the melt through a circular die, and then drawing out the resulting melt strip. The stress of the extrudate is recorded as a function of melt properties and measured parameters (especially the ratio of output speed to traction speed, which is essentially a measure of elongation).

[0157] For the results presented below, the material was extruded using a laboratory extruder, the HAAKE Polylab system, and a gear pump (L / D = 6.0 / 2.0 mm) equipped with a cylindrical die. The gear pump was pre-adjusted to an extrusion rate of 5 mm / s, and the melt temperature was set to 200°C. The spun length between the die and the rheostat traction wheel was 80 mm. At the start of the experiment, the winding speed of the rheostat traction wheel was adjusted to the speed of the extruded polymer filament (tension zero). The experiment was then formally started, with the winding speed of the rheostat traction wheel slowly increased until the polymer filament broke.

[0158] The acceleration of the traction wheel is small enough to allow for tension measurement under quasi-steady-state conditions. The acceleration of the stretched melt strip is 120 mm / s². 2 The rheometry tensile tester is used in conjunction with the PC program EXTENS. EXTENS is a real-time data acquisition program that displays and stores measurement data for tension and traction speed. The endpoints of the rheometry tensile curve (tension versus roller speed curve) are used as F. 30 Melt strength and tensile strength values.

[0159] Strain hardening factor (SHF) strain hardening factor Defined as

[0160] in, It is uniaxial tensile viscosity; and It is the shear viscosity that varies with time within the linear deformation range. Three times the value.

[0161] The tensile linear viscoelastic envelope was determined using IRIS Rheo Hub 2008 software. The discrete relaxation time spectrum needs to be calculated from the storage modulus and loss modulus data (G', G''(ω)). The linear viscoelastic data (G', G''(ω)) were obtained by frequency scanning measurements at 180°C using an Anton Paar MCR 300 equipped with a 25 mm parallel plate. The basic calculation principle used to determine the discrete relaxation spectrum is found in Baumgärtel M and Winter HH, “Determination of the discrete relaxation and retardation time spectra from dynamic mechanical data”, Rheol. Acta 28:511519 (1989). The IRIS RheoHub 2008 software represents the relaxation time spectrum as the sum of N Maxwell model modes.

[0162] in and Material parameters, It is the equilibrium modulus.

[0163] When determining the discrete relaxation spectrum, the maximum number of modes N was determined using the "optimal" mode of IRIS RheoHub 2008 software. Equilibrium modulus. Set to zero. To obtain... The nonlinear fitting was performed using the Doi-Edwards model on the IRIS Rheo Hub 2008 software.

[0164] Uniaxial tensile viscosity is The results were obtained through uniaxial tensile rheological measurements performed on an Anton Paar MCR 501 machine equipped with a Sentmanat tensile fixture (SER-1). The temperature setting for the uniaxial tensile rheological measurements was 180°C, and the applied tensile (strain) rate was... ε / t ranges from 0.3 s -1 to 10 s -1 It covers the range of Hencky strain. ε = ln[(I–I0) / I0], Where I0 is the original length, I is the fixed length of the actual sample, and the Henki strain ranges from 0.3 to 3.0. Special attention is paid to the preparation of the tensile flow samples. The samples are molded at 230°C and then slowly cooled to room temperature (without forced water or air cooling). This procedure yields well-formed samples without residual stress. Before performing uniaxial tensile flow measurements, the samples are placed at the test temperature for several minutes to ensure their thermal stability (set temperature ±0.1°C).

[0165] The strain hardening factor (SHF) is determined at 180°C and a strain rate of 1 s⁻¹. -1 The results were measured under the condition of a Henki strain of 2.5.

[0166] XHU component content The content of xylene heat-insoluble matter (XHU) was determined according to EN 579. Approximately 2.0 g of polymer (mp) was weighed and placed into a pre-weighed metal mesh. The total weight was expressed as (m). p+m The polymer in the metal mesh was extracted in a Soxhlet extractor with boiling xylene for 5 hours. The eluent was then replaced with fresh xylene, and boiling continued for 1 hour. The metal mesh was subsequently dried and weighed again (m). XHU+m According to formula m) XHU+m -m m =m XHU The calculated mass of the heat-insoluble xylene (m) XHU ), which is related to polymer (m p The content of xylene insoluble components (m) is obtained by the weight ratio of xylene. XHU / m p .

[0167] Particle size The average particle size of the PCR polyolefin composition was determined using two methods, one for thickness and one for diameter. The median particle thickness, T50, was calculated by manually measuring the thickness of 10 particles using standard calipers. The median particle diameter, D50, was determined by optically measuring the particles using a PS25C high-speed CCD camera from OCS GmbH, Germany.

[0168] isotacticity and comonomer content of polypropylene Quantitative nuclear magnetic resonance (NMR) spectroscopy was used to quantify the isotactic regularity and comonomer content of the propylene (co)polymer components.

[0169] The spectra were observed at 400.15 MHz and 100.62 MHz using a Bruker Avance III 400 NMR spectrometer. 1 H and 13 Operation C: Recording quantitation in solution. 13 C{ 1 ¹H NMR spectroscopy. Utilizing… 13 The optimized 10mm variable temperature probe recorded all spectra at 125°C, and all pneumatic devices used nitrogen.

[0170] Dissolve approximately 200 mg of the sample in 1,2-tetrachloroethane. d 2 (TCE- d2) To ensure a homogeneous solution, after preparing the initial sample in the heat block, the NMR tube was further heated in a rotary oven for at least 1 hour. After being inserted into the magnet, the tube was rotated at 10 Hz. This setup was primarily to obtain the high resolution required for quantification of stereoregularity distribution (Busico, V., Cipullo, R., Prog. Polym. Sci. 26 (2001) 443; Busico, V.; Cipullo, R., Monaco, G., Vacatello, M., Segre, AL, Macromolecules 30 (1997) 6251). Standard single-pulse excitation was employed, using a decoupling scheme of NOE and dual-electrode WALTZ16 (Zhou, Z., Kuemmerle, R., Qiu, X., Redwine, D., Cong, R., Taha, A., Baugh, D. Winniford, B., J. Mag. Reson. 187 (2007) 225; Busico, V., Carbonniere, P., Cipullo, R., Pellecchia, R., Severn, J., Talarico, G., Macromol. Rapid Commun. 2007, 28, 11289). A total of 8192 (8k) transients were obtained for each spectrum.

[0171] Quantitative analysis was performed using a dedicated computer program. 13 C { 1 ¹H NMR spectral processing, integration, and determination of relevant quantitative properties from the integration.

[0172] All chemical shifts are the chemical shifts of the methyl group in the internal reference isotactic pentatonic group (mmmm) at 21.85 ppm.

[0173] Characteristic signals related to regional defects (Resconi, L., Cavallo, L., Fait, A., Piemontesi, F., Chem. Rev. 2000, 100, 1253; Wang, WJ., Zhu, S., Macromolecules 33 (2000), 1157; Cheng, HN, Macromolecules 17 (1984), 1950) or comonomers were observed.

[0174] The stereoregularity distribution was quantified by integrating the methyl region between 23.6 ppm and 19.7 ppm and correcting for any sites unrelated to the target stereo sequence (Busico, V., Cipullo, R., Prog. Polym. Sci. 26(2001) 443; Busico, V., Cipullo, R., Monaco, G., Vacatello, M., Segre, AL, Macromolecules 30 (1997) 6251).

[0175] Specifically, by subtracting representative regional defects and comonomer integrals from specific integral regions of the stereo sequence, the quantitative influence of regional defects and comonomers on the stereoregularity distribution is corrected.

[0176] Isotactic regularity is determined at the pentamematic level and expressed as the percentage of isotactic pentamematic (mmmm) sequences out of all pentamematic sequences: [mmmm] % = 100 * (mmmm / sum of all five-unit groups) Using the method of Wang et al. (Wang, WJ., Zhu, S., Macromolecules 33 (2000), 1157), by cross- 13 C { 1 The comonomer fraction is quantified by integrating multiple signals across the entire spectral region of the H spectrum. This method was chosen because of its stability and ability to account for regional defects when necessary. The integration region was slightly adjusted to improve its applicability across the entire range of comonomer contents encountered.

[0177] For systems where only isolated ethylene is observed in the PPEPP sequence, the method of Wang et al. is modified to reduce the influence of non-zero integrals from sites known to be absent. This method is achieved by overestimating the ethylene content and by reducing the number of sites used to determine the absolute ethylene content as follows: E = 0.5(S ββ + S βγ + S βδ + 0.5(S αβ + S αγ )) By using this set of sites, the corresponding integral equation becomes: E = 0.5(I H +I G + 0.5(I C + I D )) The same notation as that used in the literature of Wang et al. (Wang, WJ., Zhu, S., Macromolecules 33 (2000), 1157). The equation used to determine the absolute propylene content was not modified.

[0178] The molar percentage of comonomer incorporated is calculated from the molar fraction: E [mol %] = 100 * f E Calculate the weight percentage of comonomer incorporated from the mole fraction: E [wt %] = 100 * (f E * 28.06) / ((f E * 28.06) + ((1-f) E )* 42.08)) Average molecular weight, molecular weight distribution According to ASTM D 6474-99, gel permeation chromatography (GPC) was used to determine the molar mass averages (Mw and Mn) and the polydispersity Mw / Mn using the following formula:

[0179]

[0180]

[0181] Where Ai and Mi are the chromatographic peak slice area and the molecular weight (MW) of the polyolefin.

[0182] Mn is the exponential average molar mass, Mw is the weight average molar mass, and Mz is the Z-average molar mass.

[0183] A PolymerChar GPC instrument equipped with an infrared (IR) detector and three Olexis and one Olexis guard column from Polymer Laboratories was used at a constant flow rate of 160 °C and 1 mL / min, with 1,2,4-trichlorobenzene (TCB, stabilized with 250 mg / L 2,6-di-tert-butyl-4-methylphenol) as the solvent. 200 μL of sample solution was injected for each analysis. The column assembly was calibrated using a universal calibration (according to ISO 16014-2:2003) using at least 15 narrow MWD polystyrene (PS) standards ranging from 0.5 kg / mol to 11500 kg / mol. The Mark Houwink constants used for PS, PE, and PP were as described in ASTM D 6474-99. All samples were prepared by dissolving 5.0 mg to 9.0 mg of polymer in 8 ml of stable TCB (same as the mobile phase) at 160°C in the autosampler of the GPC instrument, and then gently shaking for 2.5 hours at 160°C.

[0184] Determination of radius of gyration (Rg) A gel permeation chromatography (GPC) system manufactured by PolymerChar (Valencia, Spain) was used, equipped with an infrared detector (IR5), an online four-capillary bridge viscometer, and a multi-angle light scattering (MALS) detector (Dawn Helios 2) from Wyatt Technology (Santa Barbara, USA) with 18 angles ranging from approximately 22.5° to 147.0°. Three Olexis columns and one Olexis guard column from Agilent were used as the stationary phase, with 1,2,4-trichlorobenzene (TCB, stabilized with 250 mg / L 2,6-di-tert-butyl-4-methylphenol) as the mobile phase, at a constant flow rate of 1 mL / min at 160°C. Polymer samples were dissolved in TCB at a concentration of 1 mg / mL for 150 min. 200 µL of polymer solution was injected for each analysis.

[0185] By analyzing a narrow-distribution polystyrene standard sample with a molar mass of 30,000 g / mol, the inter-detector volume was realized among different detectors, concentration (IR), LS, and viscometer detectors.

[0186] When determining MWD using GPC-VISC-MALS technology, different MALS angles were normalized using a narrow-distribution PS standard with a molar mass of 30,000 g / mol. The MALS detector was calibrated using a certified PE standard NIST1475a with a molecular weight of 54,000 g / mol at a laser wavelength (λ0) of 660 nm, with a dn / dc of 0.094 ml / mg. For calculating molecular weight, the laser wavelength (λ0) for PP in TCB solution was 660 nm, with a dn / dc of 0.094 ml / mg. Due to high baseline noise and frequent interference, the minimum three MALS angles were not used in all calculations. The second virial coefficient (A2=0) was ignored due to the low sample concentrations used. The absolute Mw and corresponding radius of gyration (Rg) for each chromatographic slice were obtained from the slope and intercept of the Debye plot. Zimm's formula is used to extrapolate the corresponding Rayleigh ratio (R(θ)) for different angles.

[0187] Crystex analysis, crystallization fraction (CF) and soluble fraction (SF) According to Annex B of ISO 6427, the crystalline fraction (CF) and soluble fraction (SF), as well as the ethylene content and intrinsic viscosity of each component, were analyzed using a CRYSTEX Polymer Char instrument (Valencia, Spain). Detailed information on the techniques and methods can be found in the literature (Ljiljana Jeremic, Andreas Albrecht, Martina Sandholzer & Markus Gahleitner (2020) Rapid characterization of high-impact ethylene–propylene copolymer composition by crystallization extraction separation: comparability to standard separation methods, International Journal of Polymer Analysis and Characterization, 25:8, 581-596).

[0188] The crystalline and amorphous components were separated by a temperature cycle of dissolution at 160°C, crystallization at 40°C, and redissolution at 160°C in 1,2,4-trichlorobenzene. Quantification of SF and CF and determination of ethylene content (C2) were achieved using an integrated infrared detector (IR4), and an online dual-capillary viscometer was used for determining intrinsic viscosity (IV).

[0189] The IR4 detector is a multi-wavelength detector that measures two different wavelengths (CH3 stretching vibration (center approximately 2960 cm)). -1 ) and CH tensile vibration (2700-3000 cm) -1 The infrared absorbance of the detector is used to determine the concentration and ethylene content in ethylene-propylene copolymers. The IR4 detector is calibrated with a series of eight ethylene-propylene (EP) copolymers, with known ethylene contents ranging from 2 wt% to 69 wt% (via...). 13 (C-NMR determination), the concentration of each copolymer ranged from 2 mg / ml to 13 mg / ml. To simultaneously meet the expected characteristics, concentration, and ethylene content of various polymer concentrations during Crystex analysis, the following calibration equation was applied: Conc = a + b*Abs(CH) + c*(Abs(CH))² + d*Abs(CH3) + e*(Abs(CH3)² + f*Abs(CH)*Abs(CH3) CH3 / 1000C = a + b*Abs(CH) + c* Abs(CH3) + d * (Abs(CH3) / Abs(CH)) + e *(Abs(CH3) / Abs(CH))² The constants a to e in Equation 1 and the constants a to f in Equation 2 are determined by using least squares regression analysis.

[0190] Use the following relationship to convert CH3 / 1000C to ethylene content expressed in wt%: wt% (ethylene in EP copolymer) = 100 - CH3 / 1000TC * 0.3 The intrinsic viscosity (IV) of PCR polyolefin compositions and their soluble and crystalline fractions was determined using an online dual-capillary viscometer and correlated with the corresponding IV determined according to ISO 1628-3 in decahydronaphthalene by a standard method. Calibration was performed using various ethylene-propylene (EP) and polypropylene (PP) (co) polymers with IV = 2–4 dL / g. The determined calibration curves were linear. IV (dL / g) = a * Vsp / c The samples to be analyzed were weighed at concentrations ranging from 10 mg / ml to 20 mg / ml. To avoid injecting gels and / or polymers, such as PET and PA, that are insoluble in TCB at 160°C, the weighed samples were placed in a stainless steel sieve with a MW of 0.077 / D of 0.05 mm.

[0191] After filling vials with 1,2,4-TCB containing 250 mg / L 2,6-tert-butyl-4-methylphenol (BHT) as an antioxidant, the sample was dissolved at 170°C until completely dissolved, typically for 60 minutes with continuous stirring at 400 rpm. To prevent sample degradation, the polymer solution was covered with a nitrogen atmosphere during dissolution.

[0192] A predetermined volume of sample solution is injected into a column packed with an inert support, where crystallization and separation of soluble components from crystalline fractions are performed. This process is repeated twice. During the first injection, the entire sample is measured at high temperature to determine the IV [dl / g] and C2 [wt%] of the polypropylene composition. During the second injection, the soluble components (at low temperature) and crystalline fractions (at high temperature) during the crystallization cycle are measured (wt% SF, wt% C2, IV). A predetermined volume of sample solution is injected into a column packed with an inert support, where crystallization and separation of soluble components from crystalline fractions are performed. This process is repeated twice. During the first injection, the entire sample is measured at high temperature to determine the IV [dl / g] and C2 [wt%] of the polypropylene composition. During the second injection, the soluble components (at low temperature) and crystalline components (at high temperature) in the crystallization cycle were measured (wt% SF, wt% CF, wt% C2, wt% C2(SF), wt% C2(CF), IV(SF), IV(CF)), where wt% CF was calculated as follows: wt% CF = 100 – wt% SF DSC analysis, crystallization temperature (Tc) and crystallinity Differential scanning calorimetry (DSC) was used to determine the crystallinity of ethylene polymers and the crystallization temperature Tc of polyolefin compositions. DSC parameters were measured on 5–7 mg samples using a TA Instrument Q200 DSC. DSC was performed on C2 samples in a heating / cooling / heating cycle at a scan rate of 10 °C / min over a temperature range of -30 °C to +225 °C, according to ISO 11357 / Part 3 / Methods. The crystallization temperature (Tc) was determined by the cooling step, while the melting temperature (Tm) and enthalpy of fusion (Hm) were determined by the second heating step. Crystallinity was calculated from the enthalpy of fusion by assuming an Hm value of 209 J / g for fully crystalline polypropylene. For fully crystalline polyethylene, it was 293 J / g (see Brandrup, J., Immergut, EH, Polymer Handbook, 3rd ed. Wiley, New York, 1989; Chapter 3).

[0193] PCR polyolefin compositions: Analysis of isotactic polypropylene (iPP) by Fourier transform infrared spectroscopy (FTIR) Content of polyvinyl chloride (PVC), polyethylene terephthalate (PET), polystyrene (PS), and polyamide (PA) All calibration samples and samples to be analyzed were prepared on fused plates in a similar manner.

[0194] Approximately 2 to 3 g of the compound to be analyzed was melted at 190 °C. Subsequently, a pressure of 60 to 80 bar was applied for 20 seconds in a hydraulic hot press. Next, to control the morphology of the compound, the sample was cooled to room temperature in a cold press under the same pressure over 40 seconds. The thickness of the slides was controlled by a metal calibration frame plate, measuring 2.5 cm × 2.5 cm and with a thickness of 100 μm to 200 μm (depending on the MFR of the sample); two slides were produced in parallel under the same time and conditions. The thickness of each slide was measured before all FTIR measurements; all slide thicknesses were between 100 μm and 200 μm.

[0195] To control the sheet surface and avoid any interference during the measurement process, all sheets were prepared by pressing between two sheets of double-sided silicone release paper.

[0196] For powder samples or heterogeneous mixtures, the pressing process is repeated three times to improve homogeneity by pressing and cutting the samples under the same conditions as described above.

[0197] Standard transmission FTIR spectrometers, such as the Bruker Vertex 70 FTIR spectrometer, use the following settings: • Spectral range of 4000-400 cm⁻¹ -1 , • Aperture is 6 mm. • Spectral resolution of 2 cm -1 , • Through 16 background scans and 16 spectral scans, The zero-fill factor of the interferogram is 32. Norton Beer's forced toe amputation.

[0198] The spectrum will be recorded and analyzed in Bruker Opus software.

[0199] Since FTIR is an auxiliary method, multiple calibration standards need to be prepared to cover the required analytical range, typically including: PA: 0.2 wt% to 2.5 wt% • PS: 0.1 wt% to 5 wt% • PET: 0.2 wt% to 2.5 wt% • PVC: 0.1 wt% to 4 wt% The following commercial materials are used in the preparation of these compounds: Borealis HC600TF as iPP, Borealis FB3450 as HDPE, and for target polymers such as RAMAPET N1S (Indorama Polymer) for PET, Ultramid® B36LN (BASF) for polyamide 6, Styrolution PS 486N (Ineos) for high-impact polystyrene (HIPS), and Inovyn PVC 263B (powder form) for polyvinyl chloride.

[0200] All compounds were prepared on a small scale in a Haake kneader at a temperature below 265°C for no more than 10 minutes to avoid degradation.

[0201] Add additional antioxidants such as Irgafos 168 (3000 ppm) to reduce degradation.

[0202] The calibration principle of FTIR is the same for all compounds: the intensity of a specific FTIR band divided by the sheet thickness and the distance passed through the FTIR band. 1 H or 13 The amount of components determined by NMR in solution state is related to the concentration of the components.

[0203] Each specific FTIR absorption band is chosen because its intensity increases with increasing component concentration, and because it isolates itself from the remaining peaks, regardless of the calibration criteria and the composition of the actual sample.

[0204] This method is described in the publication "Alterations of plastic spectra in MIR and the potential impacts on identification towards recycling" by Signoret et al., Resources, Conservation and Recycling journal, 2020, volume 161, article 104980.

[0205] The wavelength for each calibration band is: PA is 3300 cm -1 , PS is 1601 cm -1 , ·PET is 1410 cm -1 , ·PVC is 615 cm -1 , • iPP is 1167 cm -1 .

[0206] For each polymer component i, a linear calibration is constructed (based on the Beer-Lambert law). Typical linear correlations used for this type of calibration are as follows:

[0207] Where x i It is the fraction of polymer component i (in wt%). E i These are the absorption intensities (in absorbance units) of specific spectral bands associated with polymer component i. These specific bands are: PA at 3300 cm⁻¹. -1 PS is 1601 cm -1 PET is 1410 cm -1 PVC is 615 cm -1 The iPP is 1167 cm. -1 .

[0208] d is the thickness of the sheet. A i and B i These are the two correlation coefficients determined for each calibration curve. No specific isolated bands were found for the C2-rich components, thus indirectly estimating the C2-rich components.

[0209] The contents of EVA, chalk, and talc are estimated in a "semi-quantitative" manner. Therefore, the spectral position of EVA, chalk, and talc is used at 607 cm⁻¹. -1 1798 cm -1 and 3676 cm -1 The peak height at a certain point is used to semi-quantitatively determine the content of EVA, chalk, and talc. Therefore, this makes the content of C2-rich components "semi-quantitative".

[0210] For each calibration standard, the amount of each component is determined whenever possible through... 1 H or 13 C solution-state NMR was used as the primary method (except for PA). NMR measurements were performed on the exact same FTIR plate used to construct the FTIR calibration curves.

[0211] PCR polyolefin composition: content of talc and chalk Thermogravimetric analysis (TGA) experiments were performed using a PerkinElmer TGA 8000 according to ISO 3451-1 (1997). Approximately 10–20 mg of sample was placed in a platinum dish. The temperature was equilibrated at 50 °C for 10 minutes, and then increased to 950 °C at a heating rate of 20 °C / min under nitrogen. The weight loss between approximately 550 °C and 700 °C (WCO2) was attributed to CO2 released from CaCO3, and therefore the chalk content was assessed as follows: Chalk content = 100 / 44 × WCO2 The temperature was then reduced to 300°C at a cooling rate of 20°C / min. The gas was then switched to oxygen, and the temperature was raised again to 900°C. The weight loss in this step is attributed to carbon black (Wcb). The contents of carbon black and chalk are known; the ash content of chalk and carbon black is calculated as follows: Ash content = (ash residue) - 56 / 44 × WCO2 - Wcb The ash content is the weight percentage measured at 900°C in the first step under nitrogen atmosphere. It is estimated that the ash content is similar to the talc content of the recovered material studied.

[0212] PCR polyolefin composition: metal content The amount of metal was determined by X-ray fluorescence (XRF).

[0213] PCR polyolefin composition: paper and wood content The paper and wood content was determined using conventional laboratory methods, including grinding, flotation, microscopy, and thermogravimetric analysis (TGA).

[0214] PCR polyolefin composition: limonene measurement Limonene was quantified using solid-phase microextraction (HS-SPME-GC-MS) via the standard addition method.

[0215] After adding different concentrations of limonene and a glass-coated magnetic stir bar, 50 mg of the ground sample was weighed into 20 ml headspace vials. The vials were sealed with a magnetic cap lined with silicone / PTFE. Diluted limonene standards of known concentrations were added to the sample using a microcapillary (10 pL). Adding 0, 2, 20, and 100 ng equates to 0 mg / kg, 0.1 mg / kg, 1 mg / kg, and 5 mg / kg limonene, respectively. Additionally, standard amounts of 6.6 mg / kg, 11 mg / kg, and 16.5 mg / kg limonene were used in conjunction with some samples tested in this application. Quantitative analysis was performed using selected ion monitoring mode (SIM), with a mass-to-charge ratio of 93 selected as the characteristic ion for quantification. Enrichment of volatile components was achieved by headspace solid-phase microextraction for 20 min at 60 °C using a 2 cm stable flexible 50 / 30 pm DVB / Carboen / PDMS fiber. Desorption was performed directly at the heated injection port of the GCMS system at 270 °C. GCMS parameters: Column: 30 meters high, 5 MS 0.25*0.25 Injector: Connectorless, with 0.75 mm SPME liner, 270℃ Temperature program: -10℃ (1 min) Carrier gas: Helium 5.0, linear velocity 31 cm / s, constant flow rate MS: Single quadrupole, direct interface, interface temperature 280°C Data Acquisition: SIM Scanning Mode Scan parameters: 20-300 amu SIM parameters: m / Z 93, 100 ms dwell time Total free fatty acid content of PCR polyolefin compositions Fatty acid quantification was performed using headspace solid-phase microextraction (HS-SPME-GC-MS) via the standard addition method.

[0216] Weigh 50 mg of the ground sample into a 20 mL headspace vial. After adding different concentrations of limonene and a glass-coated magnetic stir bar, seal the vial with a silicone / PTFE-lined magnetic cap. Using a 10 µL microcapillary, add known concentrations of diluted free fatty acid mixture standards (acetic acid, propionic acid, butyric acid, valeric acid, hexanoic acid, and octanoic acid) to the sample, setting three spiking concentration gradients. Add 0, 50, 100, and 500 ng, equivalent to 0 mg / kg, 1 mg / kg, 2 mg / kg, and 10 mg / kg for each acid. For quantification, ion 60 obtained in SIM mode was used for all acids except propionic acid; ion 74 was used here.

[0217] GCMS parameters: Posts: 20-meter ZB Waxplus posts, 0.25*0.25 Injector: Split ratio 5:1, with glass-lined split liner, 250°C Temperature program: 40°C (1 minute), ramped up to 120°C at 6°C / min, ramped up to 245°C (5 minutes) at 15°C / min. Carrier gas: Helium 5.0, linear velocity 40 cm / s, constant flow rate MS: Single quadrupole, direct interface, interface temperature 220°C Data Acquisition: SIM Scanning Mode Scan parameters: 46-250 amu, 6.6 scans / s SIM parameters: m / z 60, 74, 6.6 scans / s LBS and HBS measurements This method describes a semi-quantitative determination of organic compounds released from polyolefins. It is similar to VDA 278 (October 2011), but includes specific adjustments.

[0218] Immediately after production, the samples (injection-molded plates, DIN-A5) are sealed in aluminized polyethylene bags and provided to the laboratory within 14 days. In the laboratory, they are open-stored at a temperature below 25°C for 7 days. Afterward, aliquots of 60 ± 5 mg are prepared from the stored samples. Trimming the aliquots should aim to obtain the maximum coherence area. The purpose is not to generate the maximum possible surface area by cutting the aliquots into smaller pieces. The diameter of the sample injection tube should be used first. The length and thickness should be selected accordingly, taking into account the specified aliquot weight. The aliquots are directly desorbed using heat and a helium gas flow. Volatile and semi-volatile organic compounds are extracted into the gas flow and cryogenically focused before being injected into a gas chromatography (GC) system for analysis. This method involves two extraction stages: when analyzing low-boiling-point substances (LBS), the aliquots are desorbed at 90°C for 30 minutes to determine volatile organic compounds up to n-C25 (n-pentane) in the boiling / elution range. The analysis of high-boiling-point substances (HBS) involves a further analytical step of 60 minutes at 120°C on the same aliquot of the sample to determine the semi-volatile compounds in the boiling / elution range from n-C14 (n-tetradecane) to n-C32 (n-triacontane).

[0219] Similar to the VOC and FOG values ​​in VDA 278, LBS is calculated as toluene equivalent (TE) and HBS as hexadecane equivalent (HE), using semi-quantitative methods and appropriate calibrations. Results are expressed in µg / g.

[0220] The integration parameters for LBS and HBS assessments are selected such that "area rejection" corresponds to an area of ​​1 μg / g (TE and HE, respectively). Therefore, smaller peaks do not increase the semi-quantitative results. The GC column oven program remains constant regardless of whether a calibration run, LBS assay, or HBS assay is performed. It starts at 50°C (holds for 1 min), then increases at a rate of 10°C / min, and finally reaches 320°C (holds for 10 min). For the GC column, an Agilent DB5: 50 m × 250 μm × 0.25 μm (or a similar product) is used. This method requires a thermal desorption system TDS 3 (Gerstel) and a cooling injection system CIS 4 (Gerstel), as well as a GC system with a flame ionization detector (FID) but without involving a mass spectrometer. The final CIS temperature is always set to 380°C, not 280°C.

[0221] Example Polyolefin compositions (“P”, hereinafter also referred to as “polyolefin”) were prepared by extrusion using four post-consumer recycled polyolefin compositions PCR1 to PCR4, which were compounded only with a free radical initiator or a free radical initiator and butadiene. As shown in Table 2, PCR1 was used to prepare P1 and P2; PCR2 was used to prepare P5 and P6; PCR3 was used to prepare P3; and PCR4 was used to prepare P4. The polyolefins P1, P2, P5, and P6 thus prepared were contacted with solvents to prepare the examples of the present invention, while the comparative examples did not include this extraction step.

[0222] Polyolefins P3 and P4 are used to measure several physical properties.

[0223] The properties of the PCR polyolefin compositions are shown in Table 1 below. The wt% in Table 1 is based on the total weight of the PCR compositions (unless otherwise stated in the corresponding method description).

[0224] Table 1: Properties of PCR Polyolefin Compositions

[0225] (ND = Undetermined) No PET or PVC was detected in the PCR composition by FTIR.

[0226] Preparation process: As shown in Table 1 above, Commercially available post-consumer recycled (PCR) polyolefin compositions from mtm Plastics GmbH, Germany, are used in granule or flake form and contain propylene and ethylene polymers.

[0227] For polyolefins P1 and P2, the particles were mixed with a peroxide (POX) (tert-butyl isopropyl carbonate peroxide, Trigonox BPIC C75, obtained from Nouryon) as a free radical initiator in a horizontal mixer with a paddle agitator at 65°C, maintaining an average residence time of approximately 20 minutes. The mixture was then fed into an extruder via a vertical connecting pipe, where butadiene was added (residence time <1 minute). The mixture was transferred under an inert atmosphere to a Theyson TSK60 co-rotating twin-screw extruder with a 60 mm barrel diameter and an L / D ratio of 48, equipped with a high-intensity mixing screw featuring three kneading zones and a two-step degassing device. A melt temperature profile was selected with an initial melt zone temperature T1 = 240°C, a final kneading zone temperature T2 = 240°C, and a final die zone temperature T3 = 230°C, all temperatures defined as barrel temperatures. The screw speed was set at 200 rpm or 220 rpm.

[0228] The resulting polymer melt was granulated in a Gala AW6 underwater granulator, which has a template with 24 holes of 2.4 mm in diameter.

[0229] Polyolefins P3 and P4 are prepared as described above, but have different melt temperature profiles. The initial temperature of the feed zone is T1 = 240°C, the highest temperature of the final kneading zone is T2 = 280°C, and the final temperature of the die zone is T3 = 230°C. The screw speed is 300 rpm or 480 rpm according to the MFR.

[0230] For polyolefins P5 and P6 (sheet form has been used), the PCR polyolefin composition was dry-mixed with peroxide and extruded directly in a Coperion ZSK18 co-rotating twin-screw extruder using a temperature profile similar to that of TSK60 described above.

[0231] The resulting melt is extruded through a template, and the two strips are solidified in a water bath before being granulated using a strip pelletizer.

[0232] Table 2 summarizes all process conditions up to (and including) extrusion. The wt% in Table 2 is based on the total weight of the modified polyolefin composition.

[0233] Table 2: Process conditions up to extrusion

[0234] The properties of the extruded polyolefin compositions were analyzed. The results are shown in Table 3.

[0235] Table 3: Parameters of Extruded Polyolefin Compositions

[0236] To remove low-boiling-point and high-boiling-point compounds, the extruded polyolefin compositions P1, P2, P5, and P6 were treated with solvents as described below: The first group of four polyolefins were mixed with n-heptane. 4 g of the polyolefin was added to 200 ml of heptane. The polymer-solvent mixture was heated at 98.4°C for 2 hours (under reflux). The insoluble components were separated from the solvent by filtration and dried in a vacuum oven at 90°C under vacuum (20-30 mbar) for 12 hours to reduce the solvent content. These polyolefins correspond to Examples IE1 to IE4 of this invention.

[0237] The second group of four polyolefins were combined with methyl ethyl ketone. 4 g of polyolefin was added to 200 ml of methyl ethyl ketone. The polymer solvent mixture was heated at 79.6°C for 2 hours (under reflux). The insoluble components were dried in a vacuum oven at 90°C under vacuum (20-30 mbar) for 12 hours to reduce the solvent content. These polyolefins correspond to Examples IE5 to IE8 of this invention.

[0238] The third group of four polyolefins were treated under vacuum (20-30 mbar) using a vacuum oven at 90°C with stirring for 12 hours. These polyolefins correspond to comparative examples CE5 to CE8.

[0239] The fourth group consists of four untreated polyolefins, corresponding to comparative examples CE1 to CE4.

[0240] The contents of low-boiling-point and high-boiling-point compounds were partially determined using the method described above.

[0241] The results are shown in Table 4 below. Figure 1 and Figure 2 As shown.

[0242] Table 4: Content of low-boiling-point substances (LBS) and high-boiling-point substances (HBS) in polyolefin compositions (based on the total weight of the polyolefin composition, in ppm).

[0243]

[0244] In embodiments of the invention, extraction with n-heptane and methyl ethyl ketone effectively reduced the content of low-boiling-point and high-boiling-point compounds (LBS and HBS), which indicate the content of volatile organic compounds (VOCs) and semi-volatile organic compounds (FOGs). Stirring alone at high temperatures did not provide a similar reduction. Particularly for high-boiling-point compounds, the removal efficiency was significantly reduced by stirring in the absence of solvent.

[0245] Physical properties of extruded polyolefin compositions The physical properties of the extruded polyolefin compositions P3 and P4 were tested. Details of the methods used are described in the Methods section above. The results are shown in Table 5 below.

[0246] Table 5: Physical properties of extruded polyolefin compositions

Claims

1. A method for modifying post-consumer recycled polyolefin compositions, comprising the following steps: (A) Provides a post-consumer recycled polyolefin composition, wherein, as determined by FTIR spectroscopy, the post-consumer recycled polyolefin composition comprises, based on its total weight, [amount missing]. (a) at least 50 wt% of one or more propylene (co)polymer components, and (b) Up to 50 wt% of one or more ethylene (co)polymer components; (B) Add a free radical initiator to the post-consumer recycled polyolefin composition, and optionally mix the free radical initiator and the post-consumer recycled polyolefin composition to form a first mixture (1); (C) Optionally, a double-unsaturated hydrocarbon compound having the general formula (1) is added. (1) CH2=CH-(R)-CH=CH2, R may or may not be present. If present, R is an aliphatic or aromatic hydrocarbon group containing 1 to 6 carbon atoms. The double unsaturated hydrocarbon compound, the free radical initiator, and the post-consumer recycled polyolefin composition are mixed to form a second mixture (2); (D) Extruding the first mixture (1) or the second mixture (2) to obtain an extruded polyolefin composition; (E) Contacting the extruded polyolefin composition with a solvent; and (F) Remove the solvent to obtain a modified polyolefin composition.

2. The method according to claim 1, wherein the solvent is selected from n-alkanes having 4 to 10 carbon atoms, haloalkanes having 4 to 10 carbon atoms, aldehydes having 1 to 10 carbon atoms, ketones having 3 to 10 carbon atoms, and mixtures thereof.

3. The method according to any one of the preceding claims, wherein the boiling point of the solvent is below 120°C.

4. The method according to any one of the preceding claims, wherein step (E) is performed at a temperature range of 50°C to 120°C and / or for 30 minutes to 180 minutes.

5. The method according to any one of the preceding claims, wherein the ratio (wt / wt) of the extruded polyolefin composition to the solvent in step (E) is in the range of 1:3 to 1:

20.

6. The method according to any one of the preceding claims, wherein the solvent removal in step (F) is carried out by filtration and / or stirring under reduced pressure.

7. The method according to any one of the preceding claims, wherein in step (B), the amount of the free radical initiator added is from 0.01 wt% to 1.50 wt% based on the total weight of the post-consumer recycled polyolefin composition; and / or, in step (C), the amount of the diunsaturated hydrocarbon compound added is from 0.05 wt% to 0.50 wt% based on the total weight of the post-consumer recycled polyolefin composition.

8. The method according to any one of the preceding claims, wherein the extrusion in step (D) is carried out in a temperature range of 180°C to 300°C.

9. The method according to any one of the preceding claims, wherein step (B) and / or step (C) are performed in a temperature range of 20°C to 90°C.

10. The method according to any one of the preceding claims, wherein the double unsaturated hydrocarbon compound is 1,3-butadiene and / or the free radical initiator is a peroxide compound, preferably selected from acyl peroxides, alkyl peroxides, hydroperoxides, peresters, peroxycarbonates and combinations thereof.

11. The method according to any one of the preceding claims, wherein the ethylene content (C2(CF)) of the crystalline fraction (CF) of the post-consumer recycled polyolefin composition, as determined by Crystex analysis as described in the specification, is from [C2 - 3.4] wt% to [C2 - 0.2] wt%, preferably from [C2 - 3.0] wt% to [C2 - 0.6] wt%, more preferably from [C2 - 2.4] wt% to [C2 - 1.2] wt%.

12. The method according to any one of the preceding claims, wherein the method reduces the content of low-boiling-point substances (LBS) by at least 60%, preferably at least 70%, and / or reduces the content of high-boiling-point substances (HBS) by at least 50%, preferably at least 60%, as determined in the specification.

13. A modified polyolefin composition obtained by the method described in any one of the preceding claims.

14. The modified polyolefin composition according to claim 13, wherein, As determined in the specification, the modified polyolefin composition comprises: i) Low-boiling-point substances (LBS) present in concentrations below 100 ppm, preferably below 80 ppm, more preferably below 60 ppm; and / or, ii) High-boiling-point substances (HBS) in a concentration of less than 200 ppm, preferably less than 180 ppm, and more preferably less than 160 ppm.

15. An article comprising the modified polyolefin composition according to claim 13 or 14, wherein the article is preferably a foamed article, a film, or an extruded coating.

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