Recycled polypropylene compositions

Abstract

The present disclosure relates to a recycled polypropylene composition comprising polypropylene in an amount of at least 80 weight % of the recycled polypropylene composition; and particulate contaminants having a density of at least 1.1 g / cm3. The volume fraction of particulate contaminants having a density of at least 1.1 g / cm3 that have a particle size of greater than 100 microns is less than 0.35 vol. % of the recycled polypropylene composition, as measured via X-ray computed tomography; and the recycled polypropylene composition has a melt flow rate (MFR2), determined according to ISO 1133 at 230 °C and 2.16 kg, in the range from 3 to 12 g / 10 min. The recycled polypropylene composition is recycled from waste polypropylene flexible packaging.

Description

[0001] RECYCLED POLYPROPYLENE COMPOSITIONS

[0002] Background

[0003] Packaging represents the largest fraction of plastic waste in the world. Current mechanical recycling schemes typically focus on the recovery of rigid packaging, such as bottles. However, the recycling rates for flexible packaging (films) are relatively low. Furthermore, existing recycling technologies for recycling post-consumer flexible plastics waste tend to produce recyclates that are of insufficiently high quality for the manufacture of flexible packaging.

[0004] According to Waste Management 153 (2022) 41-51, there are several reasons for low recycling rates of post-consumer flexible plastics. For example, films are often produced in multi-layered structures. In such structures, the main polymer can be contaminated with other synthetic polymers and materials, such as inks, paper and metal from e.g., metallized layers. Furthermore, films tend to be prone to surface contamination (e.g. with food and other biological contaminants) because their high surface-to-weight ratios. Although such contamination can be removed with e.g. using compressed air in the cleaning process, this can be more challenging in the case of flexible packaging because of the tendency of the packaging to fold during cleaning, inhibiting the efficacy of contaminant removal. In Waste Management 153 (2022) 41-51, it was reported that conventionally recovered plastic according to Duales System Deutschland GmbH (DSD) 323-2 was not suitable for manufacturing films because of the level of non-polyolefin contamination.

[0005] With more rigorous cleaning and sorting, it may be possible to improve the properties of films formed from recycled polypropylene. However, in Waste Management 153 (2022) 41-51, it was found that it was not possible to form films having properties comparable to those produced from virgin polymer. For instance, even where it was possible to match films cast from virgin polymer in terms of one property, e.g. the strain at break, it was not possible to achieve comparable properties in terms of other properties, such as elastic modulus and tensile strength. Similarly, for blown films, it was possible to match films formed from virgin polymer in terms of thermal shrinkage, but not in terms of e.g., elastic modulus, tensile strength or strain at break (see Figure 4 of Waste Management 153 (2022) 41-51). In summary, current practices show that it can be difficult to form high quality flexible packaging from recycled post-consumer flexible plastics. Furthermore, the contaminants present in such recyclates can cause difficulties during processing, and excessively high melt pressures may be required to extrude the recyclate compositions into films or pellets from which flexible packaging can be made. Additionally, it can be difficult to form films of uniform thickness, and / or desirable visual and / or mechanical properties.

[0006] Brief Description of Figures

[0007] Figure 1 shows images of films produced using the composition of Comparative Example CE1 and Inventive Example IE2B.

[0008] Figure 2A, 2B, 2C and 2D are 3D renderings of high density particulate contaminants having a particle size of greater than 100 microns in the compositions of Comparative Example CE1 and Inventive Examples IE2A, 2B and 2C, respectively.

[0009] Definitions

[0010] Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the invention pertains.

[0011] In describing and claiming the present invention, the following terminology will be used in accordance with the definitions set out below.

[0012] Unless clearly indicated otherwise, use of the terms “a,” “an,” and the like refers to one or more.

[0013] As used herein, post-consumer plastics waste refers to objects having completed at least a first use cycle (or life cycle), i.e. having already served their first purpose. Post-industrial plastics waste refers to manufacturing scrap, and does not normally reach a consumer.

[0014] Post-consumer plastics waste may originate from conventional collecting systems such as those implemented in the European Union. Post-consumer plastics waste may e.g. be characterized by a limonene content of from 0.10 to 500 ppm (as determined using solid phase microextraction (HS-SPME-GC-MS) by standard addition).

[0015] Virgin polypropylene denotes polypropylene as directly originating from the production process without intermediate use. Recycled polypropylene compositions, on the other hand, are formed from polypropylene that has typically undergone at least one use cycle. Accordingly, recycled polypropylene compositions can be characterised by characteristics not usually found in virgin polypropylene. For example, virgin polypropylene is also typically devoid of large particulate contaminants, such as particulate contaminants that are 100 pm or greater in size. Virgin polypropylene compositions also do not tend to include significant amounts of decomposed (e.g., oxidized) stabilizers, such as (tris (2,4-di-tert- butylphenyl)phosphate).

[0016] It should be understood that post-consumer plastics waste may vary broadly in composition, i.e. may include polyolefin homopolymers and polyolefin copolymers.

[0017] In the present disclosure, the recycled polypropylene composition comprises polypropylene that originates from waste flexible packaging or waste film. The waste flexible packaging may be post-consumer waste flexible packaging or industrial waste flexible packaging. The waste film may originate from post-consumer plastics waste or post-industrial plastics waste.

[0018] A blend denotes a mixture of two or more components, wherein at least one of the components is polymeric. In general, the blend can be prepared by mixing the two or more components. Suitable mixing procedures are known in the art.

[0019] If not indicated otherwise “%” refers to weight %.

[0020] When referred to compositions and the weight percent of the therein comprised ingredients it is to be understood that according to the present invention the overall amount of ingredients does not exceed 100% (±1% due to rounding).

[0021] In the present disclosure, particulate contaminants having a density of at least 1.1 g / cm3include organic polymer and inorganic particulate contaminants. Because the polypropylene composition of the present invention is recycled from waste flexible polypropylene packaging, it generally contains contaminants that originate from, for instance, inks, residual or spent additives, paper, polymers other than polypropylene and metal from e.g., metallized layers used in combination with the polypropylene in the waste flexible packaging . Examples of organic polymer particulate contaminants having densities of at least 1.1 g / cm3include polyamide and polyethylene terephthalate. Examples of inorganic particulate contaminants having densities of at least 1.1 g / cm3include compounds of calcium, silicon, titanium and aluminium. Example compounds include calcium carbonate and titanium dioxide.

[0022] The organic polymer particulate contaminants and inorganic particulate contaminants may be analysed and distinguished by X-ray computed tomography according to density. The organic polymer particulate contaminants may have densities in the range of 1.1 to less than 1.53 g / cm3. These may be classed as low density particulate contaminants. The inorganic particulate contaminants may have densities of at least 1.53 g / cm3, for example, greater than 1.53 g / cm3The latter may be classed as high density particulate contaminants. Accordingly, the particulate contaminants may comprise low density particulate contaminants and high density particulate contaminants. The low density particulate contaminants may have densities of at least 1.1 g / cm3to less than 1.53 g / cm3, and the high density particulate contaminants may have densities of at least 1.53 g / cm3.

[0023] Summary of the Invention

[0024] According to a first aspect, there is provided a recycled polypropylene composition comprising polypropylene in an amount of at least 80 weight % of the recycled polypropylene composition; and particulate contaminants having a density of at least 1.1 g / cm3; wherein the recycled polypropylene composition contains particulate contaminants having a density of at least 1.1 g / cm3that have a particle size of greater than 100 microns and the volume fraction of said particulate contaminants having a density of at least 1.1 g / cm3that have a particle size of greater than 100 microns is less than 0.35 vol. % of the recycled polypropylene composition, as measured via X-ray computed tomography; and wherein the recycled polypropylene composition has a melt flow rate (MFR2), determined according to ISO 1133 at 230 °C and 2.16 kg, in the range from 3 to 12 g / 10 min.

[0025] Preferably, the recycled polypropylene composition comprises polypropylene in an amount of at least 88 weight %, of the recycled polypropylene composition.

[0026] In the recycled polypropylene composition of the present invention, the volume fraction of particulate contaminants having a density of at least 1.1 g / cm3that have a particle size of greater than 100 microns is less than 0.35 vol. %. It has been found that, by limiting the volume fraction of such contaminants, it is possible to provide a recycled polypropylene composition that is more useful for the manufacture of film or flexible packaging. As discussed above, prior art methods describe improved cleaning and sorting processes to reduce the overall contaminant levels in recycled polypropylene compositions produced from post-consumer flexible polypropylene waste. However, while overall levels of contamination may be important, it has been found that the particle size and / or particle size distribution of such particulate contaminants can have an influence on the properties of films produced from such recycled polypropylene compositions. By reducing the volume fraction of particles that are greater than 100 microns in size, it is possible to obtain a recycled polypropylene composition that is more useful for the manufacture of film or flexible packaging.

[0027] Surprisingly, this allows flexible polypropylene waste (e.g. post-consumer or post-industrial waste) to be used to manufacture film or flexible packaging. Advantageously, the recycled polypropylene composition of the present disclosure may be used to manufacture film of substantially uniform thickness. The recycled polypropylene composition may also be used to manufacture film having desirable mechanical and / or visual properties. The recycled polypropylene composition may also be extruded at e.g. relatively low pressures, avoiding manufacturing difficulties, such as clogging during extrusion. In the present disclosure, particulate contaminants that have a density of at least 1.1 g / cm3are targeted because the volume fraction of these contaminants in the recycled polypropylene composition can be monitored using X-ray computed tomography. Such particulate contaminants are distinguishable from polypropylene because of their densities. Although there may be particulate contaminants formed, for example, from polymers such as polyethylene, that have densities below 1.1 g / cm3, particulate contaminants such as polyethylene tend not to cause significant manufacturing difficulties, such as clogging during extrusion because polyethylene contaminants have lower viscosities than polypropylene under the extrusion conditions. By identifying particulate contaminants having densities of at least 1.1 g / cm3as a target and controlling the particle size distribution of these particulate contaminants, a recycled polypropylene composition that is more useful for the manufacture of film or flexible packaging can be produced. Furthermore, such compositions can be melt extruded into pellets more conveniently, as manufacturing difficulties, such as clogging can be reduced.

[0028] Any suitable method may be used to reduce the volume fraction contaminant particles greater than 100 microns in size. In another aspect of the present invention, there is provided a method of producing a recycled polypropylene composition as described herein. The method comprises melt-extruding a waste polypropylene composition through a first filter and a second filter. A cascade of two or more filters may be used. For example, three, four or five filters may be used as a cascade. The second filter may have a mesh size that is smaller than the mesh size of the first filter. Where a cascade of two or more filters is used, the second or subsequent filter may have a mesh size that is smaller than the mesh size of the filter that immediately precedes it in the cascade.

[0029] The first filter may comprise a perforated metal plate or drum, and the second filter may comprise a metal fibre mesh. By passing a waste polypropylene composition through the first filter and the second filter, it may be possible to reduce the volume fraction of particles that are greater than 100 microns in size from the composition. In some cases, the particle size of such particles may be reduced through e.g., shear forces through the first filter and second filter. In some cases, such particles may be retained by the filter(s).

[0030] As discussed above, the volume fraction of particulate contaminants having a particle size of greater than 100 microns is less than 0.35 vol %. Preferably, the volume fraction of particulate contaminants having a particle size of greater than 100 microns may be less than 0.30 vol %, more preferably less than 0.25 vol %, yet more preferably less than 0.20 vol %, even more preferably less than 0.15 vol. %, still preferably less than 0.13 vol. %, or still yet more preferably less than 0.12 or less than 0.10 vol. % of the recycled polypropylene composition.

[0031] The volume fractions of particulate contaminants that have a particle size of greater than 50 microns may be less than 1.0 vol %, preferably less than 0.75 vol. %, more preferably less than 0.70 vol. %.

[0032] The particulate contaminants may comprise, consist essentially of or consist of low density particulate contaminants and high density particulate contaminants. The low density particulate contaminants may have densities of at least 1.1 g / cm3to less than 1.53 g / cm3, and the high density particulate contaminants may have densities of at least 1.53 g / cm3, for example, greater than 1.53 g / cm3The size and volume fractions of such particulate contaminants can be determined by X-ray computed tomography. By categorising the particulate contaminants according to their density in this manner, it may be possible to evaluate the inorganic particulate content and size distribution of the composition by X-ray computed tomography. In addition it may permit evaluation of low density particulate contaminants having densities of less than 1.53g / cm3that may not be identifiable and quantifiable via other analytical methods. These findings may be useful for, for example, evaluating the efficiency of filtering of different contaminants during the recycling process.

[0033] The high density particulate contaminants may be present in an amount of at least 0.005 vol. %, for example, at least 0.01 vol. % of the recycled polypropylene composition as measured by X-ray computed tomography, and / or the low density particulate contaminant may be present in an amount of at least 0.005 vol. %, for example, at least 0.01 vol. % of the recycled polypropylene composition as measured by X-ray computed tomography.

[0034] The high density particulate contaminant may be present in an amount of less than 2.5 vol. % as measured by X-ray computed tomography, and / or the low density particulate contaminant may be present in an amount of less than 2.5 vol. % of the recycled polypropylene composition as measured by X-ray computed tomography.

[0035] The high density particulate contaminant may be present in an amount of 0.005 vol. % to less than 2.5 vol. % as measured by X-ray computed tomography, and / or the low density particulate contaminant may be present in an amount of 0.005 vol. % to less than 2.5 vol. % of the recycled polypropylene composition as measured by X-ray computed tomography.

[0036] The volume fraction of low density particulate contaminants having a particle size of greater than 100 microns may be less than 0.13 vol. %, preferably less than 0.10 vol. %, more preferably less than 0.08 vol. % of the recycled polypropylene composition, and / or the volume fraction of the high density particulate contaminant having a particle size of greater than 100 microns is less than 0.23 vol. %, preferably less than 0.20 vol. %, more preferably less than 0.15 vol. % of the recycled polypropylene composition.

[0037] The volume fraction of the low density particulate contaminants having a particle size of greater than 50 microns may be less than 0.40 vol. %, preferably less than 0.35 vol. %, more preferably less than 0.30 vol. % and yet more preferably less than 0.25 vol. %, for example, less than 0.24 vol. % or less than 0.20 vol. % of the recycled polypropylene composition.

[0038] The high density particulate contaminant may comprise, consist essentially or consist of inorganic residue. The inorganic residue may comprise compounds of calcium, silicon, titanium and aluminium. Example compounds include calcium carbonate and titanium dioxide. This inorganic residue may originate, for example, from additives (e.g. filler) added to the original polypropylene composition prior to the manufacture of the original polypropylene flexible packaging. Alternatively or additionally, the inorganic residue may originate from, for example, inks applied to or adjacent the original flexible packaging.

[0039] The low density particulate component may comprise, consist essentially or consist of organic polymer particulate contaminant. The organic polymer particulate contaminant may be any organic polymer that has a density of at least 1.1 g / cm3to less than 1.53 g / cm3. This contaminant may comprise, consist essentially or consist of at least one of, polyamide and polyethylene terephthalate (PET). In some embodiments, this contaminant may comprise, consist essentially or consist of polyamide and polyethylene terephthalate (PET).

[0040] Preferably, the recycled polypropylene composition is obtainable by melt-extruding a waste polypropylene composition through a first filter and a second filter to form pellets of the recycled polypropylene composition. Advantageously, the recycled polypropylene composition is recycled from waste flexible polypropylene packaging.

[0041] According to yet another aspect of the present invention, there is provided a film or flexible packaging comprising a recycled polypropylene composition as described herein.

[0042] Detailed Description

[0043] Recycled polypropylene composition

[0044] As explained above, a first aspect of the present invention provides a recycled polypropylene composition comprising polypropylene in an amount of at least 80 weight % of the recycled polypropylene composition; and particulate contaminants having a density of at least 1.1 g / cm3; wherein the volume fraction of particulate contaminants having a density of at least 1.1 g / cm3that have a particle size of greater than 100 microns is less than 0.35 vol. % of the recycled polypropylene composition, as measured via X-ray computed tomography; and wherein the recycled polypropylene composition has a melt flow rate (MFR2), determined according to ISO 1133 at 230 °C and 2.16 kg, in the range from 3 to 12 g / 10 min.

[0045] The size and amount of particulate contaminants having a density of at least 1.1 g / cm3can be determined by X-ray computed tomography. These contaminants can include organic polymer and inorganic contaminants. The organic polymer contaminants and inorganic contaminants can be distinguished according to density. The organic polymer contaminants may have densities in the range of 1.1 to less than 1.53 g / cm3. These may be classed as low density particulate contaminants. The inorganic contaminants may have densities of at least 1.53 g / cm3. The latter may be classed as high density particulate contaminants. Accordingly, in some embodiments, the particulate contaminants may comprise low density particulate contaminants and high density particulate contaminants. The low density particulate contaminants may have densities of at least 1.1 g / cm3to less than 1.53 g / cm3, and the high density particulate contaminants may have densities of at least 1.53 g / cm3.

[0046] Preferably, the high density particulate contaminant is present in an amount of less than 2.5 vol. %, and / or the low density particulate contaminant is present in an amount of less than 2.5 vol. % of the recycled polypropylene composition, as determined by X-ray computed tomography. The high density particulate contaminant may be present in an amount of less than 2.0 vol. %vol. %, preferably less than 1.8 vol. %, more preferably less than 1.6 vol. %, yet more preferably less than 1.4 vol. %, still yet more preferably less than 1.2 vol. %, for example less than 1.0 vol. % of the recycled polypropylene composition, as determined by X-ray computed tomography. The low density particulate contaminant may be present in an amount of less than 2.0 vol. %, preferably less than 1.8 vol. %, more preferably less than 1.6 vol. %, yet more preferably less than 1.4 vol. %, still yet more preferably less than 1.2 vol. %, for example less than 1.0 vol. % of the recycled polypropylene composition, as determined by X-ray computed tomography.

[0047] The high density particulate contaminant may be present in an amount of at least 0.005 vol. %, for example, at least 0.01 vol. %, at least 0.02 vol. %vol. %, at least 0.05 vol. % of the recycled polypropylene composition, as determined by X-ray computed tomography. Additionally or alternatively, the low density particulate contaminant may be present in an amount of at least 0.005 vol. %, for example, at least 0.01 vol. %, at least 0.05 vol. %, or at least 0.10 vol. % of the recycled polypropylene composition, as determined by X-ray computed tomography.

[0048] In some embodiments, the high density particulate contaminant is present in an amount of 0.01 vol. %, 0.02 vol. % or 0.05 vol. % to less than 2.5 vol. %vol. %; 0.01 vol. %, 0.02 or 0.05 vol. % to less than 2.0 vol. %vol. %; 0.01 vol. %, 0.02 vol. % or 0.05 vol. % to less than 1.8 vol. %; 0.01 vol. %, 0.02 vol. % or 0.05 vol. % to less than 1.6 vol. %; 0.01 vol. %, 0.02 vol. % or 0.05 vol. % to less than 1.4 vol. %; 0.01 vol. %, 0.02 vol. % or 0.05 vol. % to less than 1.2 vol. %; or 0.01 vol. %, 0.02 vol. % or 0.05 vol. % to less than 1.0 vol. % of the recycled polypropylene composition. In some embodiments, the low density particulate contaminant is present in an amount of 0.005 vol. %, 0.01 vol. %, 0.05 vol. % or 0.10 vol. % to less than 2.5 vol. %vol. %; 0.005 vol. %, 0.01 vol. %, 0.05 vol. % or 0.10 vol. % to less than 2.0 vol. %vol. %; 0.005 vol. %, 0.01 vol. %, 0.05 vol. % or 0.10 vol. % to less than 1.8 vol. %; 0.005 vol. %, 0.01 vol. %, 0.05 vol. % or 0.10 vol. % to less than 1.6 vol. %; 0.005 vol. %, 0.01 vol. %, 0.05 vol. % or 0.10 vol. % to less than 1.4 vol. %; 0.005 vol. %, 0.01 vol. %, 0.05 vol. % or 0.10 vol. % to less than 1.2 vol. %; or 0.005 vol. %, 0.01 vol. %, 0.05 vol. % or 0.10 vol. % to less than 1.0 vol. % of the recycled polypropylene composition.

[0049] The total amount of particulate contaminants having a density of at least 1.1 g / cm3may be less than 5 vol. %, preferably less than 4.0 vol. %, more preferably less than 3.0 vol. %, still more preferably less than 2.5 vol. %, and yet more preferably less than 2.0 vol. %. For example, the total amount of such particulate contaminants may be at least 0.01 to less than 5 vol. %, preferably at least 0.01 to less than 4.0 vol. %, more preferably at least 0.01 to less than 3.0 vol. %, still more preferably at least 0.01 to less than 2.5 vol. %, and yet more preferably at least 0.01 to less than 2.0 vol. %

[0050] The total amount of high density and low density particulate contaminants may be less than 5 vol. %, preferably less than 4.0 vol. %, more preferably less than 3.0 vol. %, still more preferably less than 2.5 vol. %, and yet more preferably less than 2.0 vol. %. For example, the total amount of high density and low density particulate contaminants may be at least 0.01 to less than 5 vol. %, preferably at least 0.01 to less than 4.0 vol. %, more preferably at least 0.01 to less than 3.0 vol. %, still more preferably at least 0.01 to less than 2.5 vol. %, and yet more preferably at least 0.01 to less than 2.0 vol. %

[0051] Preferably, the recycled polypropylene composition comprises polypropylene in an amount of at least 82 weight %. In some embodiments, the recycled polypropylene composition comprises polypropylene in an amount of at least 84 weight %, still more preferably at least 85 weight %, yet more preferably at least 88 weight %, and even more preferably at least 90 weight % of the recycled polypropylene composition.

[0052] The polypropylene content of the recycled polypropylene may be determined by any suitable method. For example, the propylene content may be determined by spectroscopic methods. Preferably, the propylene content is determined by IR spectroscopy. The recycled polypropylene composition contains particulate contaminants having densities of at least 1.1 g / cm3that have a particle size of greater than 100 microns. The presence of such particles may be considered as a characteristic of the recycled nature of the polypropylene composition. Virgin polypropylene grades do not generally contain such large particles, as any additives tend to be more finely milled for more even distribution throughout the polymer matrix.

[0053] In the recycled polypropylene composition of the present invention, the volume fractions of particulate contaminants having densities of at least 1.1 g / cm3that have a particle size of greater than 100 microns is typically greater than 0 vol. %, for example, greater than 0.005 vol. % or 0.01 vol. %. However, as noted herein, in the present invention such particles are present in amounts less than 0.35 vol. %, for example, less than 0.30 vol. %, less than 0.25 vol. %, less than 0.20 vol. %, less than 0.15 vol. %, less than 0.13 vol. %, less than 0.12 vol. % or less than 0.10 vol. %. Thus, the volume fractions of particulate contaminants (e.g. the sum of the volume fractions of high density and low density particulate contaminants) that have a particle size of greater than 100 microns may be greater than 0, greater than 0.005 vol. % or greater than 0.01 vol. % to less than 0.35 vol. %; greater than 0, greater than

[0054] 0.005 vol. % or greater than 0.01 vol. % to less than 0.30 vol. %; greater than 0, greater than

[0055] 0.005 vol. % or greater than 0.01 vol. % to less than 0.25 vol. %; greater than 0, greater than

[0056] 0.005 vol. % or greater than 0.01 vol. % to less than 0.20 vol. %; greater than 0, greater than

[0057] 0.005 vol. % or greater than 0.01 vol. % to less than 0.15 vol. %; greater than 0, greater than

[0058] 0.005 vol. % or greater than 0.01 vol. % to less than 0.13 vol. %; greater than 0, greater than

[0059] 0.005 vol. % or greater than 0.01 vol. % to less than 0.12 vol. %; or greater than 0, greater than 0.005 vol. % or greater than 0.01 vol. % to less than 0.10 vol. %.

[0060] The volume fractions of particulate contaminants having a density of at least 1.1 g / cm3that have a particle size of greater than 50 microns may be less than 1.0 vol. %, preferably less than 0.75 vol. %. In some embodiments, this volume fraction may be less than 0.73 vol. %, preferably less than 0.70 vol. %, more preferably less than 0.65 vol. % of the recycled polypropylene composition. The recycled polypropylene composition typically contains particulate contaminants that have a particle size of greater than 50 microns. The presence of such particles may be considered as a characteristic of the recycled nature of the polypropylene composition. The volume fractions of particulate contaminants that have a particle size of greater than 50 microns may be greater than 0 vol. %, for example, greater than 0.005 vol. % or 0.01 vol. %. Thus, the volume fractions of particulate contaminants (e.g. the sum of the volume fractions of high density and low density particulate contaminants) that have a particle size of greater than 50 microns may be greater than 0, greater than 0.005 vol. % or greater than 0.01 vol. % to less than 1.0 vol. %; greater than 0, greater than 0.005 vol. % or greater than 0.01 vol. % to less than 0.75 vol. %; greater than 0, greater than 0.005 vol. % or greater than 0.01 vol. % to less than 0.73 vol. %; greater than 0, greater than 0.005 vol. % or greater than 0.01 vol. % to less than 0.70 vol. %; or greater than

[0061] 0, greater than 0.005 vol. % or greater than 0. 01 vol. % to less than 0.65 vol. %.

[0062] The volume fraction of low density particulate contaminant having a particle size of greater than 100 microns may be less than 0.13 vol. %, preferably less than 0.10 vol. %vol. %, more preferably less than 0.08 vol. % of the recycled polypropylene composition. Typically, the recycled polypropylene composition contains low density particulate contaminant having a particle size of greater than 100 microns. The presence of such particles may be considered as a characteristic of the recycled nature of the polypropylene composition. The volume fraction of low density particulate contaminant having a particle size of greater than 100 microns may be greater than 0 vol. %, for example, greater than 0.005 vol. % or 0.01 vol. %. Thus, the volume fraction of low density particulate contaminants that have a particle size of greater than 100 microns may be greater than 0, greater than 0.005 vol. % or greater than 0.01 vol. % to less than 0.13 vol. %; greater than 0, greater than 0.005 vol. % or greater than 0.01 vol. % to less than 0.10 vol. %; or greater than 0, greater than 0.005 vol. % or greater than 0.01 vol. % to less than 0.08 vol. %.

[0063] The volume fraction of the high density particulate contaminant having a particle size of greater than 100 microns is preferably less than 0.23 vol. %, more preferably less than 0.20 vol. %, yet more preferably less than 0.15 vol. % of the recycled polypropylene composition. Typically, the recycled polypropylene composition contains high density particulate contaminants having a particle size of greater than 100 microns. The presence of such particles may be considered as a characteristic of the recycled nature of the polypropylene composition. Thus, the volume fraction of such contaminants is greater than 0 vol. %, for example, greater than 0.005 vol. % or 0.01 vol. %. Thus, the volume fraction of particulate high density particulate contaminants that have a particle size of greater than 100 microns may be greater than 0, greater than 0.005 vol. % or greater than 0.01 vol. % to less than 0.23 vol. %; greater than 0, greater than 0.005 vol. % or greater than 0.01 vol. % to less than 0.20 vol. %; or greater than 0, greater than 0.005 vol. % or greater than 0.01 vol. % to less than 0.15 vol. %. The volume fraction of low density particulate contaminant having a particle size of greater than 100 microns may be less than 0.13 vol. %, preferably less than 0.10 vol. %vol. %, more preferably less than 0.08 vol. % of the recycled polypropylene composition and the volume fraction of the high density particulate contaminant having a particle size of greater than 100 microns may be less than 0.23 vol. %, preferably less than 0.20 vol. %, more preferably less than 0.15 vol. % of the recycled polypropylene composition. As indicated above, high density and low density particulate contaminants having particle sizes greater than 100 microns are typically present in the recycled polypropylene composition.

[0064] The volume fraction of the low density particulate contaminant having a particle size of greater than 50 microns may be less than 0.40 vol. %, preferably less than 0.35 vol. %, more preferably less than 0.30 vol. % and yet more preferably less than 0.25 vol. %, for example, less than 0.24 vol. % or less than 0.20 vol. % of the recycled polypropylene composition. In these embodiments, the lower limit for the volume fraction of the low density particulate contaminant may be greater than 0, greater than 0.005 vol. % or greater than 0.01 vol. %.

[0065] In a preferred embodiment, the recycled polypropylene composition comprises at least 88 weight % polypropylene and the volume fractions of particulate contaminants having a density of at least 1.1 g / cm3that have a particle size of greater than 100 microns may be less than 0.15 vol. %, preferably less than 0.12 vol. % or more preferably less than 0.10 vol. %. The volume fractions of particulate contaminants (e.g. the sum of the volume fractions of low density and high density particulate contaminants) having a particle size greater than 100 microns may be greater than 0, greater than 0.005 vol. % or greater than 0.01 vol. % to less than 0.15 vol. %; greater than 0, greater than 0.005 vol. % or greater than 0.01 vol. % to less than 0.12 vol. %; or greater than 0, greater than 0.005 vol. % or greater than 0.01 vol. % to less than 0.10 vol. %

[0066] In a preferred embodiment, the recycled polypropylene composition comprises at least 88 weight % polypropylene and the volume fractions of particulate contaminants having a density of at least 1.1 g / cm3that have a particle size of greater than 50 microns may be less than 0.26 vol. %, preferably less than 0.22 vol. %, more preferably less than 0.20 vol. % and even more preferably less than 0.18 vol. %. The volume fractions of particulate contaminants (e.g. the sum of the volume fractions of low density and high density particulate contaminants) having a particle size greater than 50 microns may be greater than 0, greater than 0.005 vol. % or greater than 0.01 vol. % to less than 0.26 vol. %; greater than 0, greater than 0.005 vol. % or greater than 0.01 vol. % to less than 0.22 vol. %; greater than 0, greater than 0.005 vol. % or greater than 0.01 vol. % to less than 0.20 vol. %; or greater than 0, greater than 0.005 vol. % or greater than 0.01 vol. % to less than 0.18 vol. %.

[0067] In certain embodiments, the recycled polypropylene composition comprises from 80 to less than 88 weight % polypropylene, and the volume fractions of particulate contaminants having a density of at least 1.1 g / cm3that have a particle size of greater than 100 microns may be less than 0.30 vol. %, preferably less than 0.15 vol. %. In these embodiments, the lower limit for the sum of the volume fractions of the low density and high density particulate contaminant may be greater than 0, greater than 0.005 vol. %, greater than 0.01 vol. %, or greater than 0.05 vol. %. For example, the recycled polypropylene composition comprises from 80 to less than 88 weight %, preferably 82 to 85 weight % polypropylene, and the volume fractions of particulate contaminants (e.g. the sum of the volume fractions of low density and high density particulate contaminants) that have a particle size of greater than 100 microns is greater than 0.01 to less than 0.30 vol, %, preferably greater than 0.05 to less than 0.15 vol. %.

[0068] As noted above, the presence of contaminant particles above a certain size threshold may be considered as a characteristic of the recycled nature of the polypropylene composition. Another indicator of the recyclate nature of the mixed-plastic polypropylene blend (PP) may be obtained from measuring the (P) content and / or the amount of oxidized phosphorus- based stabilizer, e.g., (tris (2,4-di-tert-butylphenyl)phosphate) in the composition.

[0069] The presence of phosphorus in polymer grades is almost 100% attributable to phosphorus- based stabilizers, such as antioxidants. The content of such additives in a virgin grade is consistent across almost all commercially available grades, corresponding to the amount required to sufficiently stabilize the polymer grade for the anticipated number of compounding steps (given that it is typically during these high temperature compounding steps that oxidation is most likely to occur) without incurring unnecessary costs by using too much stabilizer. By the time that a consumer article is recycled, the stabilizers will be largely used up (i.e. they will have been oxidized, preventing further use as an antioxidant). The presence of oxidized stabilizer or antioxidant, therefore, can be considered as a characteristic of the recycled nature of the composition. The recycled polypropylene composition may comprise oxidized antioxidant and unoxidized antioxidant, wherein the ratio of oxidized antioxidant to the total amount of oxidized and unoxidized antioxidant is at least 15%, preferably at least 20%, more preferably at least 25 %. The recycled polypropylene composition may comprise oxidized phosphorus-containing antioxidant and unoxidized phosphorus-containing antioxidant, wherein the weight ratio of oxidized phosphorus- containing antioxidant to the total amount of oxidized and unoxidized phosphorus-containing antioxidant is at least 15%, preferably at least 20%, more preferably at least 25 %.

[0070] Because stabilizers may be predominantly oxidized by the time that an article is recycled, further phosphorus-based stabilizers will need to be added to stabilize the recyclate grade, meaning that in recyclates the phosphorus present will either a) be at a typical level for a virgin grade, but be predominantly oxidized, or b) will be at a significantly higher level than would be typical for a virgin grade.

[0071] The total phosphorus content can be analyzed by X-ray fluorescence spectroscopy (XRF), whilst the ratio of non-oxidized stabilizer (tris (2,4-di-tert-butylphenyl)phosphite) and oxidized stabilizer (tris (2,4-di-tert-butylphenyl)phosphate) can be evaluated by HPLC analysis.

[0072] The recycled polypropylene composition may comprise at least 200 ppm, preferably at least 300 ppm, more preferably at least 400 ppm and yet more preferably at least 450 ppm of oxidized phosphorus-based antioxidant, for example, tris (2,4-di-tert-butylphenyl)phosphate as evaluated by HPLC analysis.

[0073] The recycled polypropylene composition may comprise unoxidized phosphorus-containing antioxidant, for instance, tris (2,4-di-tert-butylphenyl)phosphite and oxidized phosphorus- containing antioxidant, for instance, tris (2,4-di-tert-butylphenyl)phosphate, wherein the amount of oxidized phosphorus-containing antioxidant, for instance, tris (2,4-di-tert- butylphenyl)phosphate present may be at least 200 ppm, preferably at least 300 ppm, more preferably at least 400 ppm and yet more preferably at least 450 ppm as evaluated by HPLC analysis.

[0074] The content of oxidized phosphorus-containing antioxidant (e.g. tris (2,4-di-tert- butylphenyl)phosphate) expressed relative to the total content of oxidized and unoxidized phosphorus-containing antioxidant (e.g. tris (2,4-di-tert-butylphenyl)phosphite and tris (2,4- di-tert-butylphenyl)phosphate), as determined by HPLC analysis, is in the range from 20% to 100%, preferably 30 to 100%. Such significant proportions of oxidized phosphorus- containing antioxidant (e.g., tris (2,4-di-tert-butylphenyl)phosphate) can be indicative of the recycled nature of the polypropylene composition, distinguishing the recycled polypropylene compositions of the present disclosure from virgin compositions. The total phosphorus content, as determined by X-ray fluorescence spectroscopy (XRF), may be in the range from 15 to 60 ppm. This would be consistent with a recyclate grade that has not been further additivated. Alternatively, it is preferred that the total phosphorus content, as determined by X-ray fluorescence spectroscopy (XRF), is greater than 60 ppm. This would be consistent with a recyclate grade that has been further additivated with an additional source of phosphorus.

[0075] The recycled polypropylene composition originates from flexible plastics waste, for example, post-consumer or post-industrial flexible plastics waste. The plastics waste may be waste flexible polypropylene flexible packaging (e.g. labels, packets, wrappers, and / or metallized laminates). The flexible polypropylene packaging may be sourced from mixed-plastic recycling streams, for example, originating from household collection.

[0076] With flexible polypropylene packaging, the main polypropylene polymer can be contaminated with synthetic polymers other than polypropylene, as well as inks, residual or spent additives, paper and metal from e.g., metallized layers. Such synthetic polymers, inks, paper, residual or spent additives and metals are the source of the particulate contaminants having densities of at least 1.1 g / cm3in the recycled polypropylene composition. The low density particulate contaminant (i.e. having densities of at least 1.1 to less than 1.53 g / cm3) may originate from synthetic polymers (e.g. from adjacent or laminated layers) that contaminate the polypropylene in the flexible plastics waste, while the high density particulate contaminant (i.e. having densities of at least 1.53 g / cm3) may originate from the materials, such as inks, fillers, coatings, residual or spent additives, paper and metal in the flexible plastics waste. The synthetic polymers that contaminate the polypropylene in the flexible plastics waste may be present, for example, as a result of sorting mistakes during the recycling procedure, or may originate from the original article, for example, from adjacent or laminated layers of the original article.

[0077] Preferably, the low density particulate contaminant comprises at least one of polyamide and polyethylene terephthalate (PET). For example, the low density particulate contaminant consists essentially of or consists of at least one of polyamide and polyethylene terephthalate (PET).

[0078] The total amount of any polyamide and polyethylene terephthalate may be less than 2 weight %, preferably less than 1.5 weight %, for example, less than 1.0 weight % of the recycled polypropylene composition. In addition to any particulate contaminant having a density of at least 1.1 g / cm3, the recycled polypropylene composition of the present disclosure may also include organic polymer contaminants (e.g. polyethylene or polystyrene) having densities of less than 1.1 g / cm3.

[0079] Advantageously, such organic polymer contaminants may desirably have viscosities that are less than the viscosity of polypropylene under extrusion conditions. Accordingly, even if they form particulates at room temperature, these particulates may not give rise to significant clogging problems, for example, during extrusion.

[0080] In some embodiments, the amount of polyethylene contaminants in the recycled polypropylene composition may be 0.05 to 15.0 weight %, preferably 0.1 to 14.0 weight %, more preferably 0.5 to 13.0 weight % of the recycled polypropylene composition.

[0081] In some embodiments, the amount of polystyrene contaminants in the recycled polypropylene composition may be up to 2.0 weight %, preferably 0.01 to 1.5 weight %, more preferably 0.05 to 1.2 weight % of the recycled polypropylene composition.

[0082] Where it is desired to determine the amount of polyethylene, polyamide or polyethylene terephthalate in the recycled polypropylene composition, any suitable method may be used. Suitable methods include infrared spectroscopy and differential scanning calorimetry (DSC). Preferably, infrared spectroscopy is used.

[0083] As explained above, the high density particulate contaminant can comprise, consist essentially or consist of inorganic residue.

[0084] The nature and composition of the inorganic residue in the recycled polypropylene composition may be analysed using any suitable method. Examples include thermogravimetric analysis (TGA), Fourier-Transform Infrared Spectroscopy (FTIR) and X- ray fluorescence spectroscopy (XRF).

[0085] In some embodiments, the recycled polypropylene composition has a calcium (Ca) content, determined by X-ray fluorescence spectroscopy (XRF), of at least 100 ppm, more preferably of at least 500 ppm, yet more preferably of at least 800 ppm, even more preferably at least 900 ppm. In some embodiments, the recycled polypropylene composition has a titanium (Ti) content, determined by X-ray fluorescence spectroscopy (XRF), of at least 200 ppm, more preferably of at least 600 ppm, yet more preferably of at least 1000 ppm, even more preferably at least 1200 ppm.

[0086] In some embodiments, the recycled polypropylene composition has an aluminium (Al) content, determined by X-ray fluorescence spectroscopy (XRF), of at least 60 ppm, more preferably of at least 90 ppm.

[0087] In some embodiments, the recycled polypropylene composition has a silicon (Si) content, determined by X-ray fluorescence spectroscopy (XRF), of at least 50 ppm, more preferably of at least 100 ppm, most preferably of at least 120 ppm.

[0088] In some embodiments, the recycled polypropylene composition has a calcium (Ca) content, determined by X-ray fluorescence spectroscopy (XRF), of at least 100 ppm, more preferably of at least 500 ppm, yet more preferably of at least 800 ppm, even more preferably at least 900 ppm, and a titanium (Ti) content, determined by X-ray fluorescence spectroscopy (XRF), of at least 200 ppm, more preferably of at least 600 ppm, yet more preferably of at least 1000 ppm, even more preferably at least 1200 ppm. For example, the recycled polypropylene composition has a calcium (Ca) content, determined by X-ray fluorescence spectroscopy (XRF), of at least 900 ppm and a titanium content of at least 1200 ppm.

[0089] In some embodiments, the recycled polypropylene composition contains high density particulate contaminants, for example, inorganic contaminants in an amount of 0.05 to 8.0 weight %, as determined, for example, by TGA analysis.

[0090] In one embodiment, the recycled polypropylene composition originates from post-consumer polypropylene flexible packaging waste, for example, wrappers, lids, labels and / or packets. The packaging may be multi-layer. For example, the packaging may be in the form of a laminate, for instance, a metallised laminate. In one embodiment, the recycled polypropylene composition originates from post-consumer polypropylene labels and / or postconsumer metallised polypropylene laminates.

[0091] Where the recycled polypropylene composition originates from post-consumer polypropylene labels, the polypropylene content of this recycled polypropylene composition may be at least 85 weight %, preferably at least 88 weight %, more preferably at least 90 weight %. In these embodiments, the volume fraction of particulate contaminants having a density of at least 1.1 g / cm3(e.g. the total volume fraction of high density and low density particulate contaminants) that have a particle size of greater than 100 microns may be less than 0.15 vol. % of the recycled polypropylene composition. The volume fraction of low density particulate contaminant having a particle size of greater than 100 microns may be less than 0.13 vol. %, preferably less than 0.10 vol. %vol. %, more preferably less than 0.08 vol. % of the recycled polypropylene composition, and / or the volume fraction of the high density particulate contaminant having a particle size of greater than 100 microns may be less than 0.15 vol. %, preferably less than 0.10 vol. %, more preferably less than 0.08 vol. %, for example, less than 0.05 vol. % of the recycled polypropylene composition. In these embodiments, the volume fractions of particulate contaminants having a density of at least 1.1 g / cm3(e.g. the sum of the volume fractions of high density and low density particulate contaminants) that have a particle size of greater than 50 microns may also be less than 0.26 vol. %, preferably less than 0.22 vol. %, more preferably less than 0.20 vol. % and even more preferably less than 0.18 vol. %.

[0092] In one embodiment, the recycled polypropylene composition originates from post-consumer metallised film. The polypropylene content of this recycled polypropylene composition is at least 80 weight %, for example, at least 82 weight %. In these embodiments, the volume fractions of particulate contaminants (e.g. the sum of volume fractions of high density and low density particulate contaminants) having a density of at least 1.1 g / cm3that have a particle size of greater than 100 microns may be less than 0.35 vol. %, preferably less than 0.30 vol. % preferably less than 0.25 vol. %, more preferably less than 0.20 vol. % and even more preferably less than 0.15 vol. % of the recycled polypropylene composition.

[0093] The recycled polypropylene composition has a melt flow rate (MFR2), determined according to ISO 1133 at 230 °C and 2.16 kg, in the range from 3.0 to 12 g / 10 min, more preferably in the range from 3.5 to 10 g / 10 min, yet more preferably, 4.0 to 9 g / 10 min, most preferably in the range from 4.5 to 8 g / 10 min.

[0094] Method of producing a recycled polypropylene composition

[0095] In an aspect of the present invention, there is provided a method of producing a recycled polypropylene composition as described herein. The method comprises melt-extruding a waste polypropylene composition through a first filter and a second filter. Preferably, filtration through the second filter occurs at a reduced differential pressure compared to the first filter. By passing a waste polypropylene composition through the first filter and the second filter, it may be possible to at least partially remove particles that are greater than 100 microns in size from the composition, and / or reduce the size of such particles through e.g., shear forces through the first filter and second filter. The waste polypropylene composition may be melt-extruded to form pellets of the recycled polypropylene composition as described herein. Accordingly, the recycled polypropylene composition described herein may be in the form of pellets.

[0096] The first filter may comprise a perforated metal plate or drum, and the second filter may comprise a fibre mesh, for example, a metal fibre mesh. The second filter may be a screen changer or a belt filter. The first filter may have a mesh size of 70 to 150 pm, preferably 75 to 130 pm, more preferably 80 to 110 pm. The second filter may have a mesh size of 40 to 130 pm, preferably 45 to 110 pm, more preferably 50 to 100 pm. The second filter may have a mesh size smaller than that of the first filter.

[0097] In some embodiments, a cascade of filters may be used. For example, a cascade of more than two filters is used. In some examples, three, four or five filters are used in a cascade. Where a cascade of two or more filters is used, the second or subsequent filter may have a mesh size that is smaller than the mesh size of the filter that immediately precedes it in the cascade.

[0098] In some embodiments, perforations in the first filter may be formed by laser (laser filter).

[0099] The first filter may have perforations that are not uniform in cross-section. For example, the perforations may be frustoconical in cross section, such that each perforation has a minor and major diameter. In this embodiment, the second filter may have a mesh size that is smaller than at least the major diameter of the first filter, preferably smaller than both the major and minor diameter of the first filter.

[0100] The melt-extrusion is preferably undertaken using an extruder, more preferably a singlescrew or twin-screw extruder.

[0101] In particular, it is preferred to use a conventional compounding or blending apparatus, e.g. a Banbury mixer, a 2-roll rubber mill, Buss-co-kneader or a twin-screw extruder. More preferably, mixing is accomplished in a co-rotating twin-screw extruder. The extruded recycled polypropylene composition recovered from the extruder is preferably in the form of pellets, i.e. it is a pelletized recycled polypropylene composition. The melt-extrusion includes a melt filtration step, wherein fine particles are at least partially removed from the melt by filtration. As discussed herein, the melt extrusion involves the use of a first and second filter.

[0102] Any additives (Ad) added during extrusion are selected from additives known in the art, preferably selected from the group consisting of antioxidants, stabilizers, fillers, colorants, nucleating agents, antistatic agents, and mixtures thereof. Such additives are generally commercially available and are described, for example, in "Plastic Additives Handbook", pages 871 to 873, 5th edition, 2001 of Hans Zweifel.

[0103] Before or after extrusion, the recycled polypropylene composition or the waste polypropylene composition may be aerated to remove volatile organic compounds. Aeration ensures that the content of volatile organic compounds is minimized in the aerated extruded recycled polypropylene composition, avoiding any unpleasant odors that can be associated with similar recycled polyolefin blends. These volatile organic compounds can result from contamination of the polyolefin during the preceding use, for example through contact with foods, skin care products or other toiletries, or simply through decomposition of the polyolefin into volatile oligomeric chains during processing steps of the waste polypropylene composition. Aeration may be achieved, inter alia, through the use of air, inert gases or steam. Preferably, aeration is achieved by contacting the recycled polypropylene composition or the waste polypropylene composition with a gas being at least 60% by volume N2 gas. The temperature at which the aeration takes place is preferably in the range from 50 to 155 °C, more preferably in the range from 100 to 150 °C. It may also be beneficial to conduct the aeration at reduced pressure, for example less than 500 mbar, more preferably less than 200 mbar, most preferably less than 100 mbar.

[0104] Any precursor polypropylene recycling stream comprising flexible polypropylene packaging may be used as or to provide the waste polypropylene composition that is extruded to provide the recycled polypropylene composition of the present invention.

[0105] This precursor polypropylene recycling stream may originate from any suitable postconsumer or post-industrial plastics waste stream. The plastics waste stream may contain any waste polypropylene flexible packaging, including polypropylene-containing labels, polypropylene-containing packets, and / or polypropylene-containing wrappers. The plastics waste stream may include multi-layer flexible packaging. Examples include metallized polypropylene film. If appropriately sourced (e.g. appropriately sorted and cleaned), the precursor polypropylene recycling stream may be used as the waste polypropylene composition that is melt extruded to produce the recycled polypropylene composition of the present invention. In many instances, however, the precursor polypropylene recycling stream may be a mixed plastics recycling stream, which may need to be treated to provide the waste polypropylene composition that is extruded to produce the recycled polypropylene composition of the present invention.

[0106] Suitable treatment steps include sorting and washing steps. Such steps are well-known in the art. Sorting may be carried out on the basis of polymer type, for example, using spectroscopic methods including fluorescence, near infrared absorption or Raman fluorescence. Additionally or alternatively, sorting may be carried out according to density, for example, by floatation techniques and / or by wind sifting. Washing may be carried out using any suitable method, including alkaline washes in alkaline solutions.

[0107] A suitable mechanical polypropylene recycling process for treating a precursor polypropylene recycling stream to provide the waste polypropylene composition for extrusion may comprise: a) providing a precursor polypropylene recycling stream (A); and b) optionally sorting the precursor polypropylene recycling stream (A) by polymer type, thereby removing any pieces that contain polymers other than polypropylene, thereby generating a purified polypropylene recycling stream (B) that can be used as the waste polypropylene composition for extrusion.

[0108] In some embodiments, it is also preferred to reduce the size of the pieces during the mechanical polypropylene recycling process. Suitable size reduction techniques include milling and / or shredding. Size reduction can be performed at any suitable point during the mechanical recycling process. For example, in the embodiment above, size reduction can be performed either directly on the precursor polypropylene recycling stream (A) or on the purified polypropylene recycling stream (B). One suitable method involves milling the precursor polypropylene recycling stream (A) or the purified polypropylene recycling stream (B). An alternative method may involve shredding the precursor polypropylene recycling stream (A) or the purified polypropylene recycling stream (B). Alternatively or additionally to step a) and optional step b), the mechanical polypropylene recycling process can also comprise: c) washing the purified polypropylene recycling stream (B) or, in the case that step b) is absent, the precursor polypropylene recycling stream (A), in one or more washing steps, thereby obtaining a washed polypropylene stream (C) that can be used as the waste polypropylene composition for extrusion.

[0109] As an optional addition to step c), the mechanical polypropylene recycling process can also comprise: d) separating the washed polypropylene stream (C) into a heavy fraction and a light fraction polypropylene recycling stream (D) that can be used as the waste polypropylene composition for extrusion.

[0110] As described herein, the process of the present invention comprises melt extruding the waste polypropylene composition through a first filter and a second filter. As mentioned above, this melt extrusion may be a multistage filtration process carried out using a cascade of filters. Preferably the melt extrusion process comprises a vacuum degassing step. The melt extrusion preferably results in the formation of pellets of the recycled polypropylene composition of the present invention. In some embodiments, it is the light fraction polypropylene recycling stream (D) or, in the case that step d) is absent, the washed polypropylene stream (C), preferably wherein additives (Ad) are added in the melt state, to form an extruded, recycled polypropylene composition of the present invention.

[0111] The recycled polypropylene composition of the present invention is preferably in the form of pellets. These pellets can be cast or otherwise formed into flexible packaging as discussed below.

[0112] Film

[0113] According to yet another aspect of the present invention, there is provided a film e.g. a flexible packaging comprising a recycled polypropylene composition as described herein. The film e.g. flexible packaging may include labels, packets and / or wrappers. The film or flexible packaging may comprise a multilayer structure. The film or flexible packaging may be metallised. The film or flexible packaging may comprise at least 20 weight %, preferably at least 25 weight %, more preferably at least 30 weight %, even more preferably at least 35 weight % weight %, of the recycled polypropylene composition as described herein.

[0114] In some embodiments, the film or flexible packaging may be formed of at least 50 weight %, preferably at least 60 weight %, more preferably at least 70 weight %, even more preferably at least 80 weight %, yet more preferably at least 85 weight %, of the recycled polypropylene composition as described herein.

[0115] In some embodiments, the film or flexible packaging may be formed of at least 90 weight %, preferably at least 95 weight %, more preferably at least 98 or 99 weight %, of the recycled polypropylene composition as described herein. The film or flexible packaging may consist or consist essentially of the recycled polypropylene composition as described herein.

[0116] In some embodiments, the recycled polypropylene composition as described herein may be mixed or compounded with another polypropylene composition to form the film or flexible packaging. For example, the recycled polypropylene composition as described herein may be mixed or compounded with a virgin polypropylene composition to form the film or flexible packaging.

[0117] The film or flexible packaging may be formed of a mixture comprising 25 to 99 weight % of the recycled polypropylene composition as described herein, and 1 to 75 weight % of virgin polypropylene. In some embodiments, the film or flexible packaging may be formed of a mixture comprising 25 to 75 weight % of the recycled polypropylene composition as described herein, and 25 to 75 weight % of virgin polypropylene. In some embodiments, the film or flexible packaging may be formed of a mixture comprising 30 to 65 weight % of the recycled polypropylene composition as described herein, and 35 to 70 weight % of virgin polypropylene. In some embodiments, the film or flexible packaging may be formed of a mixture comprising 35 to 50 weight %, of the recycled polypropylene composition as described herein, and 50 to 65 weight %, of virgin polypropylene.

[0118] If other polymers than those present in the recycled polypropylene composition are used, then these may be modifiers or virgin polymer grades used to modify the properties of the recycled polypropylene composition. The film or flexible packaging may be formed of a single layer comprising the recycled polypropylene composition. The film or flexible packaging may be formed of a plurality of layers, each comprising the recycled polypropylene composition. The film or flexible packaging may be formed of a laminate, wherein at least one layer of the laminate comprises the recycled polypropylene composition. An inner layer, for example, of the core layer of the laminate may comprise the recycled polypropylene composition. The laminate may include an outer metallic layer or a layer formed of a different polymer.

[0119] To form the flexible packaging, the recycled polypropylene as described herein may be subjected to melt extrusion through a first filter and a second filter as described herein.

[0120] Examples

[0121] Analytical Methods

[0122] Melt Flow Rate

[0123] The melt flow rate (MFR) was determined according to ISO 1133 and was indicated in g / 10 min. The MFR is an indication of the flowability, and hence the processability, of the polymer. The higher the melt flow rate, the lower the viscosity of the polymer. The MFR2 of polypropylene was determined at a temperature of 230 °C and a load of 2.16 kg.

[0124] DSC

[0125] The DSC was measured with a TA Instrument Q2000 differential scanning calorimetry (DSC) on 5 to 7 mg samples. DSC was run according to ISO 113571 part 3 / method C2 in a heat I cool I heat cycle with a scan rate of 10 °C / min in the temperature range of -30 to +225 °C.

[0126] TGA

[0127] Thermogravimetric Analysis (TGA) experiments were performed with a Perkin Elmer TGA 8000. Approximately 15-25 mg of materials were placed in a platinum pan. The temperature was equilibrated at 50°C for 10 minutes, and afterwards raised to 950°C under nitrogen at 20°C / min. The weight loss between ca. 550°C and 700°C (WC02) was assigned to CO2 evolving from CaCOs, and therefore the chalk content was evaluated as:

[0128] Chalk content = 100 / 44 x WC02

[0129] Afterwards the temperature was lowered to 300°C at 20°C / min, gas switched to oxygen, and the temperature was raised again to 900°C. The weight loss in this step was assigned to carbon black (Web). Knowing the content of carbon black and chalk, the content of inorganic residues excluding chalk and carbon black can be calculated from the ash residue as:

[0130] Inorganic residues content = (Ash residue) - 56 / 44 x WC02 - Web

[0131] Where Ash residue is the weight% measured at 850°C in the first step conducted under nitrogen.

[0132] FTIR

[0133] Sample preparation:

[0134] All calibration samples and samples to be analyzed were prepared in similar way, on molten pressed plates.

[0135] Around 2 to 3 g of compounds to be analyzed were melted at 190°C. Subsequently, for 20 seconds, 60 to 80 bar pressure was applied in a hydraulic heating press. Next, the samples were cooled to room temperature in 40 seconds in a cold press under the same pressure, in order to control the morphology of the compound. The thickness of the plates was controlled by metallic calibrated frame plates 2.5 cm by 2.5 cm, 100 to 200 pm thick (depending MFR from the sample); two plates were produced in parallel at the same time and in the same conditions. The thickness of each plate was measured before any FTIR measurements were performed; all plates were between 100 to 200 pm thick.

[0136] To control the plate surface and to avoid any interference during the measurement, all plates were pressed between two double-sided silicone release papers.

[0137] In case of powder samples or heterogeneous compounds, the pressing process was repeated three times to increase homogeneity by pressed and cutting the sample in the same conditions as described before.

[0138] Spectrometer:

[0139] Standard transmission FTIR spectroscope such as Bruker Vertex 70 FTIR spectrometer was used with the following set-up: o a spectral range of 4000-400 cm-1 , o an aperture of 6 mm, 1 o a spectral resolution of 2 cm-1 , o with 16 background scans, 16 spectrum scans, o an interferogram zero filling factor of 32 o Norton Beer strong apodisation.

[0140] Spectra were recorded and analysed in Bruker Opus software.

[0141] Calibration samples:

[0142] As FTIR is a secondary method, several calibration standards were compounded to cover the targeted analysis range, typically from: o 0,2 wt% to 2,5 wt% for PA o 0,1 wt% to 5 wt% for PS o 0,2 wt% to 2,5 wt% for PET o 0,1 wt% to 4 wt% for PVC

[0143] The following commercial materials were used for the compounds: Borealis HC600TF as iPP, Borealis FB3450 as HDPE and for the targeted polymers such RAMAPET N1S (Indorama Polymer) for PET, Ultramid® B36LN (BASF) for Polyamide 6, Styrolution PS 486N (Ineos) for High Impact Polystyrene (HIPS), and for PVC Inovyn PVC 263B (under powder form).

[0144] All compounds were made at small scale in a Haake kneader at a temperature below 265°C and less than 10 minutes to avoid degradation.

[0145] Additional antioxidant such as Irgafos 168 (3000 ppm) was added to minimize the degradation.

[0146] Calibration:

[0147] The FTIR calibration principle was the same for all the components: the intensity of a specific FTIR band divided by the plate thickness is correlated to the amount of component determined by 1 H or 13C solution state NMR on the same plate.

[0148] Each specific FTIR absorption band was chosen due to its intensity increase with the amount of the component concentration and due to its isolation from the rest of the peaks, whatever the composition of the calibration standard and real samples.

[0149] This methodology is described in the publication from Signoret and al. “Alterations of plastic spectra in MIR and the potential impacts on identification towards recycling”, Resources, conservation and Recycling journal, 2020, volume 161 , article 104980.

[0150] The wavelength for each calibration band was: o 3300 cm-1 for PA, o 1601 cm-1 for PS, o 1410 cm-1 for PET, o 615 cm-1 for PVC, o 1167 cm-1 for iPP.

[0151] For each polymer component i, a linear calibration (based on linearity of Beer-Lambert law) was constructed. A typical linear correlation used for such calibrations is given below: where xi is the fraction amount of the polymer component i (in wt%)

[0152] Ei is the absorbance intensity of the specific band related to the polymer component i (in a.u. absorbance unit, values see above). d is the thickness of the sample plate

[0153] Ai and Bi are two coefficients of correlation determined for each calibration curve

[0154] No specific isolated band can be found for C2 rich fraction and as a consequence the C2 rich fraction is estimated indirectly, C2 rich 100

[0155] The Chalk and Talc contents are estimated “semi-quantitatively”. Hence, this renders the C2 rich content “semi-quantitative”.

[0156] For each calibration standard, wherever available, the amount of each component was determined by either 1 H or 13C solution state NMR, as primary method (except for PA). The NMR measurements were performed on the exact same FTIR plates used for the construction of the FTIR calibration curves.

[0157] HPLC analysis

[0158] The content of antioxidants (compounds Irgafos® 168, i.e., Tris (2,4-di-t-butylphenyl) phosphite, as well as oxidised variants thereof) was determined via high performance liquid chromatography (HPLC) after extraction with ethyl acetate. First, about 10 g of the sample were cryo-milled with the aid of liquid nitrogen. After that, a portion of approximately 0.5 g of the milled sample was extracted using ethyl acetate as a solvent. Extraction was performed at 95 °C for 90 min under constant stirring. After letting the mixture cool down to room temperature again it was filtered and put to the HPLC test for the quantification of antioxidants. The HPLC system was equipped with a C18 column for the separation and a diode array detector (DAD) for detection.

[0159] X-ray fluorescence (XRF)

[0160] The instrument used for the XRF measurements was a wavelength dispersive Zetium (2,4kW) from Malvern Panalytical. The instrument was calibrated with a custom set of calibration standards (referred to in the following as “Custom”) also from Malvern Panalytical according to the following table

[0161] The analysis was conducted under vacuum on a plaque with a diameter of 40 mm and a thickness of 2 mm.

[0162] The method was used to determine the quantitative content of Al, Si, P, Ca, Ti, in a given polyolefin matrix within defined ranges of these standards.

[0163] The content of each precise element was evaluated with the following standards (LCD = limit of detection):

[0164] Elements which are not covered by standards, or the content is outside of the calibrated standard range, were analyzed with a semi-quantitative mode (software Omnian from Malvern Panalytical). For elements not covered by the calibration standards, no value was reported if the corresponding peak is not visible and therefore cannot be analysed with the software Omnian. The CH content needed to run the semiquantitative evaluation with Omnian was estimated by the software itself.

[0165] X-ray Computed Tomography (X-ray CT)

[0166] X-ray Computed Tomography (CT) was performed using a Thermo Fisher Scientific Heliscan MK2 (Thermo Fisher Scientific) device. Pellets were scanned as delivered and placed in a cylindrical sample holder. The Voxelsize was set to 4 pm. The X-ray tube was operated with LaB6 filament, voltage was set to 60 kV, focal spot size was set to medium and a pre-filter made of steel with 0.1 mm thickness was used. The specimens were scanned with Space Filling trajectory. For the reconstruction, the values for shift and scale, that are used for converting 32 bit to final 16 bit data, was fixed for all scans to be able to compare multiple data.

[0167] Together with the specimens, discs with 5 mm in diameter and 500 pm in thickness, made of different polymers, were scanned at once. At least a disc made of one PP grade and one PET grade have to be scanned.

[0168] The software Avizo for industrial inspection (Thermo Fisher Scientific) was used for data analysis. From the PP and PET discs, the grey values were determined acting as guide for thresholding. Specimen data was segmented into Polymer and air for the determination of total volume with a threshold which is 72 % lower than that of PP.

[0169] Specimen data was segmented with a grey value threshold, which is 11 % higher than that of PET leading to the fraction of high density particulate contaminants . Taking the density of PP with 0.905 g / cm3and that of PET with 1.38 g / cm3into account, this threshold corresponds to a density of 1 .53 g / cm3.

[0170] A second analysis was performed with a lower threshold leading to the fraction of Low density particulate contaminants. For this threshold the peak grey value of the pellets was determined. A threshold which was 26 % higher than that of the polymer peak was applied. All inclusions with a grey value higher than that of the first analysis, the high density particulate contaminants , were subtracted from this segmentation.

[0171] Each particle was segmented into an individual object using a Connected Component filter. The minimum object size was set to 5 Voxels. For each object, the features average grey value, position, volume, length, width and thickness were determined. Comparative Example CE1 , and Examples IE2A to IE2C

[0172] Post-consumer metallised flexible polypropylene packaging was used as the feedstock for these examples. The material was sourced via domestic collection. The main collection criterion was “any brand of crisp packet”. After collection, the material was hand sorted to remove waste bags and cardboard boxes.

[0173] The feedstock was treated as follows:

[0174] Step 1: The precursor recycling stream was sorted by polyolefin type to generate a target product polypropylene flexible packaging material of mixed colour. The sorted packaging was metallized with a layer of vapour deposited aluminium and was heavily printed.

[0175] Step 2: The precursor was subjected to a low temperature alkaline wash, followed by a high temperature alkaline wash. Any material having a different density from the polypropylene packaging was separated by a si nk / float separation step.

[0176] Step 3: The product was then separated into heavy (rigid pieces) and light (flexible pieces) fractions using a wind sifter.

[0177] Step 4: The light fraction of Step 2 was melt extruded to form pellets of recycled polypropylene composition. The extrusion parameters are shown in Table 1 below. A laser filter was used as a first filter and a screen changer was used as a second filter for the inventive examples, IE2A to IE2C. The laser filter was formed with through-holes having a frustoconical cross-section, each through-hole having a minor diameter of 90 pm, and a major diameter of 110 pm. Single filtration using the first filter only was used for Comparative Example, CE1.

[0178] Table 1

[0179] Properties of the resulting recycled polypropylene compositions are summarised in Table 2A and 2B.

[0180] Table 2A

[0181] PP = polypropylene; P = phosphorus; Stb = tris (2,4-di-tert-butylphenyl)phosphite (P-containing stabiliser); Stb ox = tris (2,4-di-tert- butylphenyl)phosphate (oxidised P-containing stabiliser) n.d. = not determined

[0182] Table 2B

[0183] Melt pressure build up test

[0184] 50 m thick multilayer films were cast, with the compositions of CE1, IE2A to IE2C were used to form the core layer, which represented 70 wt% of the film thickness. Each multilayer film contained 35 weight % of the compositions of CE1 , IE2A to IE2C, respectively.

[0185] The melt pressure build-up was tested using a Collin-manufactured cast film lab line. The line featured a 30 mm extruder with a length of 30 / LD. The die width was 300 mm. The die was equipped with a flexible die-lip ranging from 0.5-1.2 mm and resulted in a final film width of approximately 230 mm. The chill roll unit included three polished chill rolls tempered between 15-60 °C. The film was wound onto 3-inch cores, with an overall thickness set at 50 pm.

[0186] The throughput was fixed at 8 kg / h and controlled by an automatic weight control system. Each pressure build-up test was started with fresh filters, which were collected for subsequent analysis after the test. A filter-pack with mesh sizes of 50 / 80 / 120 / 80 / 50 per inch was utilized.

[0187] The test was commenced by introducing the test material into the line, and the melt pressure level was recorded every 10 minutes in the first hour. After 1 hour, the melt pressure level was noted every 15 minutes. The measurement was stopped if the melt pressure limit exceeded 350 bar. The pressure build up values reported for the samples under consideration were taken after 90 minutes.

[0188] Table 3 shows the pressure build up values measured for CE1, IE2A to IE2C. Table 3

[0189] PBU = pressure build up

[0190] Film Quality

[0191] 50 m thick single-layer films were cast from the compositions of CE1, IE2A to IE2C (thus the films contained 100% recycled polypropylene).

[0192] The films made with the composition of CE1 was observed to contain a large number of voids. The visual and mechanical properties of films formed using the compositions of IE2A, IE2B and IE2C were superior to those formed using the composition of CE1 despite the composition of CE1 containing comparable total amounts of high density and low density particulate contaminants (see e.g., CE1 vs IE2C). Figure 1 shows a comparison of films formed using the compositions of CE1 and IE2B. It can be seen that the film formed using the composition of IE2B has fewer voids and is more even in appearance.

[0193] Figures 2A, 2B, 2C and 2D are 3D renderings of high density particulate contaminants having a particle size of greater than 100 microns present in the compositions of CE1 , IE2A, IE2B and IE2C, respectively. It can be seen that the composition of CE1 (single melt filtration only) contains the largest volume fraction of such particulate contaminants.

[0194] Examples IE3A to IE3D

[0195] The following sources of post-consumer polypropylene waste were used as precursors:

[0196] IE3A, IE3B - colored (IE3A) and transparent (IE3B) fraction from post-consumer plastic trash fulfilling the German specification DSD323-2 was used as precursor.

[0197] IE3C - transparent fraction from German post-consumer plastic trash enriched in postconsumer flexible polypropylene articles.

[0198] IE3D - post-consumer polypropylene waste stream mainly consisting of labels available as a byproduct of a bottle recycling process. The precursors were treated as follows:

[0199] Step 1: The precursors were washed in a low temperature alkaline washing step, followed by a high temperature alkaline washing step. Material having densities different to polypropylene was removed via a sink / float separation.

[0200] Step 2: The product from Step 1 was then separated into heavy (rigid pieces) and light (flexible pieces) fractions using a wind sifter.

[0201] Step 3: The light fraction of Step 2 was melt extruded to form pellets of recycled polypropylene composition. The extrusion parameters are shown in Table 4 below. For IE3A to IE3D, a laser filter was used as a first filter and a screen changer was used as a second filter. The laser filter was formed with through-holes having a frustoconical crosssection, each through hole having a minor diameter of 90 pm, and a major diameter of 110 pm.

[0202] Table 4

[0203] Properties of the resulting recycled polypropylene compositions are summarised in Tables 5, 6 and 7. Table 5

[0204] PE = po yethylene; PA = polyamide; PS = polystyrene; PET = polyethylene terephthalate

[0205] Table 6

[0206] Stb = tris (2,4-di-tert-butylphenyl)phosphite (P-containing stabiliser); Stb ox = tris (2,4-di-tert- butylphenyl)phosphate (oxidised P-containing stabiliser)

[0207] Table 7

[0208] Melt pressure build up test

[0209] 50 pm thick single layer films were cast using a blend of virgin polypropylene and 35 weight % of recycled polypropylene compositions of each of IE3A to IE3D, respectively.

[0210] The melt pressure build-up was tested using a Collin-manufactured cast film lab line. The line featured a 30 mm extruder with a length of 30 / LD. The die width was 300 mm. The die was equipped with a flexible die-lip ranging from 0.5-1.2 mm and resulted in a final film width of approximately 230 mm. The chill roll unit included three polished chill rolls tempered between 15-60 °C. The film was wound onto 3-inch cores, with an overall thickness set at 50 pm.

[0211] The throughput was fixed at 8 kg / h and controlled by an automatic weight control system. Each pressure build-up test was started with fresh filters, which were collected for subsequent analysis after the test. A filter-pack with mesh sizes of 50 / 80 / 120 / 80 / 50 per inch was utilized. The test was commenced by introducing the test material into the line, and the melt pressure level was recorded every 10 minutes in the first hour. After 1 hour, the melt pressure level was noted every 15 minutes. The measurement was stopped if the melt pressure limit exceeded 350 bar. The pressure build up values reported for the samples under consideration were taken after 90 minutes.

[0212] Table 8 shows the pressure build up values measured for IE3A to IE3D.

[0213] Table 8

[0214] PBU = pressure build up

[0215] Thickness Variation Assessment

[0216] 100 pm films were prepared by using a ME25 / 5800 V3 extruder with each of the compositions of Examples IE3A to IE3D. The line was equipped with a 25 mm extruder in a length of 251 LD. The cast film line was equipped with a standard chill roll unit, a line scan camera for failure detection and a tension controlled film winder.

[0217] The thickness variations measured in machine direction with capacitive method are reported in Table 9 below.

[0218] Table 9

[0219] Although all Inventive Examples IE3A to IE3D can be used to produce films having acceptably uniform thickness, Inventive Examples IE3B to IE3D can be used to provide better thickness uniformity than Inventive Example IE3A. Without wishing to be bound by any theory, it is believed that, when the recycled polypropylene composition comprises at least 88 weight % polypropylene, it is advantageous for the sum of the volume fractions of high density and low density particulate contaminants that have a particle size of greater than 50 microns to be less than 0.26 vol. %, preferably less than 0.22 vol. %, more preferably less than 0.20 vol. % and even more preferably less than 0.18 vol. %.

[0220] Aspects of the invention will now be described in the following numbered clauses:

[0221] 1. A recycled polypropylene composition comprising polypropylene in an amount of at least 80 weight % of the recycled polypropylene composition; and particulate contaminants having a density of at least 1.1 g / cm3; wherein the volume fraction of particulate contaminants having a density of at least 1.1 g / cm3that have a particle size of greater than 100 microns is less than 0.35 vol. % of the recycled polypropylene composition, as measured via X-ray computed tomography; and wherein the recycled polypropylene composition has a melt flow rate (MFR2), determined according to ISO 1133 at 230 °C and 2.16 kg, in the range from 3 to 12 g / 10 min.

[0222] 2. A recycled polypropylene composition as recited in clause 1 , having a polypropylene content of at least 88 weight %.

[0223] 3. A recycled polypropylene composition as recites in clause 1 or 2, wherein the volume fraction of the particulate contaminants having a density of at least 1.1 g / cm3that have a particle size of greater than 100 microns is less than 0.30 vol. %, preferably less than 0.25 vol. %, more preferably less than 0.20 vol. %, even more preferably less than 0.15 vol. %, still preferably less than 0.13 vol. %, or still yet more preferably less than 0.12 or less than 0.10 vol. % of the recycled polypropylene composition, as measured via X-ray computed tomography.

[0224] 4. A recycled polypropylene composition as recited in any one of the preceding clauses, wherein the volume fraction of particulate contaminants having a density of at least 1.1 g / cm3that have a particle size of greater than 50 microns is less than 1.0 vol. %, preferably less than 0.75 vol. % of the recycled polypropylene composition, as measured via X-ray computed tomography. A recycled polypropylene composition as recited in any one of the preceding clauses, wherein the particulate contaminants comprise low density particulate contaminants having a density of at least 1.1 g / cm3to less than 1.53 g / cm3; and high density particulate contaminants having a density of at least 1.53 g / cm3. A recycled polypropylene composition as recited in clause 5, wherein the high density particulate contaminants are present in an amount of 0.005 vol. % to less than 2.5 vol. %vol. %; and / or wherein the low density particulate contaminants are present in an amount of 0.005 vol. % to less than 2.5 vol. %, as measured via X-ray computed tomography. A recycled polypropylene composition as recited in clause 5 or 6, wherein the volume fraction of the low density particulate contaminants having a particle size of greater than 100 microns is less than 0.13 vol. %, preferably less than 0.10 vol. %vol. %, more preferably less than 0.08 vol. % of the recycled polypropylene composition; and / or the volume fraction of the high density particulate contaminants having a particle size of greater than 100 microns is less than 0.23 vol. %, preferably less than 0.20 vol. %, more preferably less than 0.15 vol. % of the recycled polypropylene composition, as measured via X-ray computed tomography. A recycled polypropylene composition as recited in any one of clauses 5 to 7, wherein the volume fraction of the low density particulate contaminants having a particle size of greater than 50 microns is less than 0.40 vol. %, preferably less than 0.35 vol. %, more preferably less than 0.30 vol. % and yet more preferably less than 0.25 vol. %, for example, less than 0.24 vol. % or less than 0.20 vol. % of the recycled polypropylene composition, as measured via X-ray computed tomography. A recycled polypropylene composition as recited in any one of clauses 5 to 8, wherein the high density particulate contaminants comprises inorganic residue selected from at least one of calcium carbonate and titanium dioxide. A recycled polypropylene composition as recited in any one of clauses 5 to 9, wherein the low density particulate contaminants comprise at least one of polyamide, and polyethylene terephthalate (PET). 11. A recycled polypropylene composition as recited in any one of the preceding clauses, which is obtainable by melt-extruding a waste polypropylene composition through a first filter and a second filter to form pellets of the recycled polypropylene composition.

[0225] 12. A recycled polypropylene composition as recited in any one of the preceding clauses, which is recycled from waste flexible polypropylene packaging.

[0226] 13. A recycled polypropylene composition as recited in any one of the preceding claims, wherein the recycled polypropylene composition contains particulate contaminants having a density of at least 1.1 g / cm3that have a particle size of greater than 100 microns.

[0227] 14. A method of producing a recycled polypropylene composition according to any one of the preceding clauses, said method comprising melt-extruding a waste polypropylene composition through a first filter and a second filter.

[0228] 15. A method as recited in clause 14, wherein the first filter comprises a perforated metal plate or drum, and the second filter comprises a metal fibre mesh.

[0229] 16. A film comprising a recycled polypropylene composition as recited in any one of clauses 1 to 13.

Claims

Claims1. A recycled polypropylene composition comprising polypropylene in an amount of at least 80 weight % of the recycled polypropylene composition; and particulate contaminants having a density of at least 1.1 g / cm3; wherein the recycled polypropylene composition contains particulate contaminants having a density of at least 1.1 g / cm3that have a particle size of greater than 100 microns and the volume fraction of said particulate contaminants having a density of at least 1.1 g / cm3that have a particle size of greater than 100 microns is less than 0.35 vol. % of the recycled polypropylene composition, as measured via X-ray computed tomography; and wherein the recycled polypropylene composition has a melt flow rate (MFR2), determined according to ISO 1133 at 230 °C and 2.16 kg, in the range from 3 to 12 g / 10 min.

2. A recycled polypropylene composition as claimed in claim 1, having a polypropylene content of at least 88 weight %.

3. A recycled polypropylene composition as claimed in claim 1 or 2, wherein the volume fraction of the particulate contaminants having a density of at least 1.1 g / cm3that have a particle size of greater than 100 microns is less than 0.30 vol. %, preferably less than 0.25 vol. %, more preferably less than 0.20 vol. %, even more preferably less than 0.15 vol. %, still preferably less than 0.13 vol. %, or still yet more preferably less than 0.12 or less than 0.10 vol. % of the recycled polypropylene composition, as measured via X-ray computed tomography.

4. A recycled polypropylene composition as claimed in any one of the preceding claims, wherein the volume fraction of particulate contaminants having a density of at least 1.1 g / cm3that have a particle size of greater than 50 microns is less than 1.0 vol. %, preferably less than 0.75 vol. % of the recycled polypropylene composition, as measured via X-ray computed tomography.

5. A recycled polypropylene composition as claimed in any one of the preceding claims, wherein the particulate contaminants comprise low density particulate contaminants having a density of at least 1.1 g / cm3to less than 1.53 g / cm3; and high density particulate contaminants having a density of at least 1.53 g / cm3.

6. A recycled polypropylene composition as claimed in claim 5, wherein the high density particulate contaminants are present in an amount of 0.005 vol. % to less than 2.5 vol. %vol. %; and / or wherein the low density particulate contaminants are present in an amount of 0.005 vol. % to less than 2.5 vol. %, as measured via X-ray computed tomography.

7. A recycled polypropylene composition as claimed in claim 5 or 6, wherein the volume fraction of the low density particulate contaminants having a particle size of greater than 100 microns is less than 0.13 vol. %, preferably less than 0.10 vol. %vol. %, more preferably less than 0.08 vol. % of the recycled polypropylene composition; and / or the volume fraction of the high density particulate contaminants having a particle size of greater than 100 microns is less than 0.23 vol. %, preferably less than 0.20 vol. %, more preferably less than 0.15 vol. % of the recycled polypropylene composition, as measured via X-ray computed tomography.

8. A recycled polypropylene composition as claimed in any one of claims 5 to 7, wherein the volume fraction of the low density particulate contaminants having a particle size of greater than 50 microns is less than 0.40 vol. %, preferably less than 0.35 vol. %, more preferably less than 0.30 vol. % and yet more preferably less than 0.25 vol. %, for example, less than 0.24 vol. % or less than 0.20 vol. % of the recycled polypropylene composition, as measured via X-ray computed tomography.

9. A recycled polypropylene composition as claimed in any one of claims 5 to 8, wherein the high density particulate contaminants comprises inorganic residue selected from at least one of calcium carbonate and titanium dioxide.

10. A recycled polypropylene composition as claimed in any one of claims 5 to 9, wherein the low density particulate contaminants comprise at least one of polyamide, and polyethylene terephthalate (PET).

11. A recycled polypropylene composition as claimed in any one of the preceding claims, which is obtainable by melt-extruding a waste polypropylene composition through a first filter and a second filter to form pellets of the recycled polypropylene composition.

12. A recycled polypropylene composition as claimed in any one of the preceding claims, which is recycled from waste flexible polypropylene packaging.

13. A method of producing a recycled polypropylene composition according to any one of the preceding claims, said method comprising melt-extruding a waste polypropylene composition through a first filter and a second filter.

14. A method as claimed in claim 13, wherein the first filter comprises a perforated metal plate or drum, and the second filter comprises a metal fibre mesh.

15. A film comprising a recycled polypropylene composition as claimed in any one of claims 1 to 12.

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