Patent Description:
Polyolefin compositions for this use, in particular suitcase, are described in <CIT> as being made of:.

The above mentioned compositions are endowed with good stiffness, impact resistance and stress-whitening resistance.

Generally speaking, polyolefin compositions, although being appreciated in terms of performances, give raise to concerns in terms of sustainability with particular reference to the fact that their production is based on the use of non-renewable sources.

As a result, a common attempt to mitigate the problem is that of using, in multicomponent polyolefin compositions, variable amounts of recycled polyolefins such as polypropylene or polyethylene.

The recycled polyolefin derive from streams of post-consumer waste (PCW) material that undergoes various step of separation from other polymers, such as PVC, PET or PS.

One of the key problems in polyolefin recycling, especially when dealing with material streams from post-consumer waste (PCW) is the difficulty to quantitatively separate polypropylene (PP) from polyethylene (PE) and vice-versa. Thus, although named recycled PE (rPE) or recycled PP (rPP), the commercially available products from PCW sources have been found to be mixtures of PP and PE, the minor component reaching up to <<NUM> wt %.

This fact, associated to the presence in the recycled material of additives and minor components that may not be totally suitable for the application in which they are supposed to be used, leads to the consequence that such recycled PP/PE-blends may suffer from deteriorated mechanical, optical and aesthetic properties and poor compatibility between the main polymer phases during remolding. The result is a perceived lower reliability of articles coming from the use of r-PP or r-PE due to the lower performances of the compositions from which they derive.

As a consequence, the use of recycled material in applications requiring a high-performance level, is strongly discouraged and limited to low-cost and non-demanding applications.

It has now been unexpectedly found that certain specific formulations based on recycled polypropylene can be used in the preparation of injection molded articles having an excellent combination of mechanical and aesthetic properties.

It is therefore an object of the present disclosure a polypropylene composition comprising (per cent by weight):.

the whole composition having a value of melt flow rate (ISO <NUM><NUM>/<NUM>) ranging from <NUM>/<NUM>' to <NUM>/<NUM>', preferably from <NUM> to <NUM>/<NUM>', more preferably from <NUM> to <NUM>/<NUM>'; the percentages of (a), (b), (c) and (d) being referred to the total weight of the polypropylene composition.

The term "copolymer" as used herein refers to both polymers with two different recurring units and polymers with more than two different recurring units, such as terpolymers, in the chain. By "ambient temperature" and "room temperature" is meant a temperature of <NUM>.

By the term "crystalline polypropylene" is meant in the present application a propylene polymer having an amount of isotactic pentads (mmmm), measured by <NUM>C-MNR on the fraction insoluble in xylene at <NUM>° C, higher than <NUM> molar %; by "elastomeric" polymer is meant a polymer having solubility in xylene at ambient temperature higher than <NUM> wt%.

The features of the components forming the polypropylene composition are not inextricably linked to each other. This means that a certain level of preference of one the features should not necessarily involve the same level of preference of the remaining features of the same or different components. On the contrary, it is intended in the present disclosure that any component (a) to (d) and any preferred range of features of components (a) to (d) can be combined with any preferred range of one or more of the features of components (a) to (d) and with any possible additional component, and its features, described in the present disclosure.

The r-PP component (a) comprises plastic waste of post-industrial or post-consumer origin. Preferably, it origins from post-consumer waste (PCW) PP packaging waste, such as for example detergent and shampoo bottles, dairy pots and meat trays, etc. The PP raw material waste can be pre-sorted by waste management companies. One suitable PP source can for example be the waste material collected under the DSD324 (<NUM>-<NUM>) and DSD324-<NUM> standard (<NUM>-<NUM>). Optical sorting can also be used to remove unwanted polymers, but polystyrene or polyethylene (PE) contamination in the feed still occurs to a certain extent that prevent from using it as the only polymer component of the composition.

PP is available in three different families of products, PP homopolymers (PPh), PP random copolymer (PPr) and PP impact copolymer (or heterophasic PP copolymer, PPc).

The waste material can for example be characterized as originating from following sources (a) extrusion sheet and film material, mostly PP homopolymers (PPh) and PP random copolymers (PPr), virtually without rubber (such as for example biaxially-oriented polypropylene (BOPP)); and (b) injection molded material, which are a mix of PP homopolymer (PPh), PP random copolymers (PPr) and impact copolymer (PPc), containing about <NUM> wt% rubber.

The recycled PP component (a) can contain approximately half of packaging material (BOPP) and half of rubber-containing injection molded material. This injection molded material can contain rubbers, such as for example C2-C3 rubber, thermoplastic elastomers (TPE), ethylene propylene diene monomers (EPDM) or ethylene propylene rubber (EPR).

The resulting mix of the recycled PP itself used in the polymer composition as component (a) can for example have a rubber content of between <NUM>-<NUM> wt% (rubber from rubber-containing injection molded material; wherein wt% is relative to the total amount of the mix of the recycled PP). The recycled PP (a) of the polymer composition is preferably made-up of between <NUM>-<NUM> wt% BOPP and between <NUM>-<NUM> wt% rubber-containing injection molded material; wherein wt% is relative to the total amount of recycled PP.

The recycled PP is present between preferably <NUM> to <NUM>%, more preferably <NUM>-<NUM>% within the polypropylene composition; wherein wt% is relative to the total weight of the polypropylene composition.

While the melt flow rate (ISO <NUM><NUM>/<NUM>) of the recycled PP is not critical, it can generally range from <NUM> to <NUM>/<NUM>', preferably from <NUM> to <NUM>/<NUM>' and more preferably from <NUM> to <NUM>/<NUM>'.

The polymer component (b) comprises recycled PE (rPE) which in turn comprises PE waste collected from various sources such as, for example, PE bottles, PE vessels having a volume of <NUM> liters or more and being cleaned in accordance with environmental specifications or PE extrusion pipes. The recycled PE preferably comprises recycled High-Density Polyethylene (HDPE) to at least <NUM> wt%, more preferably at least <NUM> wt%, most preferably at least <NUM> wt%.

The recycled PE can contains a variety of contaminants that are removed by means of a plurality of steps, including cleaning steps, washing steps and sorting steps. The PE recyclate may preferably comprise <NUM>-<NUM> wt%, more preferably between <NUM>-<NUM> wt%, most preferably between <NUM>-<NUM> wt% polypropylene and up to <NUM> wt% polystyrene contaminants, wherein wt% is relative to the total amount of recycled PE.

The recycled PE preferably has a density in the range of approximately <NUM>-<NUM>/cm<NUM>.

The MFR of the recycled PE (<NUM>, <NUM>) may preferably be in the range of <NUM>-<NUM>/<NUM>' more preferably in the range <NUM>-<NUM>/<NUM>' which is suitable for blow molding materials. In a particular embodiment, the recycled PE may preferably have a MFR <NUM>, <NUM> (g/<NUM>) of between <NUM>-<NUM>, more preferably between <NUM>-<NUM>.

The recycled PE is preferably present between <NUM>-<NUM> wt%, preferably between <NUM>-<NUM> wt%, within the polymer composition, wherein wt% is relative to the total weight of the polypropylene composition.

Component (c) comprises a polyolefin elastomer (POE) which is an ethylene-alpha-olefin as defined in claim <NUM>.

The POE can preferably be a C<NUM>-C<NUM> copolymer or a C<NUM>-C<NUM> copolymer with between <NUM>-<NUM> wt% ethylene, more preferably between <NUM>-<NUM> wt%, most preferably between <NUM>-<NUM> wt%; wherein wt% ethylene is relative to the POE.

The POE used in the present disclosure preferably comprises an ethylene (C2) octene (C8) elastomer obtained by the use of a single site transition metal compound based catalyst.

The POE preferably has a density of between <NUM>-<NUM>/cm<NUM>, more preferably between <NUM>-<NUM>/cm<NUM>, most preferably between <NUM>-<NUM>/cm<NUM>.

The POE preferably has an MFR of between <NUM>-<NUM>, more preferably between <NUM>-<NUM>, most preferably between <NUM>-<NUM> (<NUM>, <NUM>).

The POEs are commercially available. Example of POEs are Infuse <NUM>, Infuse <NUM> and Engage XLT8677 commercialized by Dow Chemical Company.

The POE is present at between <NUM> to <NUM>%, preferably <NUM> to <NUM>%, more preferably from <NUM> to <NUM>% with respect to the total weight of the polypropylene composition.

Component (d) of the composition contains at least two components: a crystalline polypropylene component and a copolymer component. The crystalline polypropylene component (i) is present in an amount ranging from <NUM> to <NUM>%, preferably <NUM> to <NUM>%, most preferably <NUM> to <NUM>% of the total weight of the masterbatch composition. Conversely, the copolymer component (ii) is present in an amount of from <NUM> to <NUM>%, preferably <NUM> to <NUM>%, most preferably <NUM> to <NUM>% of the total weight of the masterbatch composition, with the sum of the percentage amounts of the individual components equal to <NUM> percent.

The fractions A1 and A2, which form the crystalline polypropylene component (i) can each be a propylene homopolymer, a random copolymer of propylene containing up to <NUM>%, preferably <NUM> to <NUM>% of ethylene, or a random copolymer of propylene containing up to <NUM>%, preferably <NUM> to <NUM>%, of at least one C<NUM>-C<NUM> α-olefin which conforms to the formula CH<NUM>=CHR, wherein R is a linear or branched alkyl C<NUM>-C<NUM> radical or an aryl radical such as phenyl. Illustrative C<NUM>-C<NUM> α-olefin include <NUM>-butene, <NUM>-pentene, <NUM>-hexene, <NUM>-methyl-l-pentene and <NUM>-octene, with <NUM>-butene being particularly preferred.

Fractions A1 and A2 differ from one another in their average molecular weight, as described by their melt flow rate. Fraction A1 has a relatively high molecular weight (low melt flow rate MFRI of from <NUM> to <NUM>/<NUM>. ) while fraction A2 has a relatively low molecular weight (high melt flow rate). This relationship is defined by the ratio MFRII/MFRI, which can range from <NUM> to <NUM>, preferably <NUM> to <NUM>, more preferably <NUM> to <NUM>, still more preferably <NUM> to <NUM>.

Generally, the content of polymer which is insoluble in xylene at room temperature for fractions A1 and A2 is not less than <NUM>%, more preferably not less than <NUM>%, and most preferably not less than <NUM>% by weight. For propylene homopolymers, the content of polymer which is insoluble in xylene at room temperature is not less than <NUM>%, more preferably not less than <NUM>%, and most preferably not less than <NUM>% by weight, based on the weight of the single fraction.

Component (ii) is a copolymer component of ethylene and propylene containing from <NUM> to <NUM>% of ethylene, and optionally a minor amount of a diene. The ethylene content of the copolymer component is preferably <NUM> to <NUM>%, most preferably <NUM> to <NUM>%.

Suitable dienes include, butadiene, <NUM>,<NUM>-hexadiene, <NUM>,<NUM>-hexadiene and ethylidene-norbonene-<NUM>. When present, the diene is typically in an amount of <NUM> to <NUM>% by weight with respect to the weight of the copolymer component (ii).

The copolymer component (ii) is soluble in xylene at room temperature, and has an intrinsic viscosity [n] in tetraline at <NUM> of from <NUM> to <NUM>, preferably <NUM> to <NUM>, most preferably <NUM> to <NUM> dl/g.

The melt flow rate of the whole component (d) can range from <NUM> to <NUM>/<NUM>. , more preferably from <NUM> to <NUM>/<NUM>. and more preferably from <NUM> to <NUM>/<NUM>'.

Component (d) can be prepared by either mechanically blending components (i) and (ii) or obtaining it via sequential polymerization step as described for example in <CIT> the relevant part of which is incorporated by reference.

Optionally, an inorganic filler is present as a further component (e). Suitable filler can be chosen from the group consisting of talc, fiber glass, CaCOs, clays carbon black and mica. Among them talc is preferred. Talc can for example be unmodified and does preferably not have a surface coating or surface treatment. Talc may increase the stiffness and strength of the polymer composition and produced articles. Preferably, it has very small particle size with average size lower than <NUM>.

The filler can derive in total or in part from the filler present in recycled components of the composition and/or be added as a fresh filler in the preparation of the polypropylene composition.

In general, component (e) is preferably present in amounts ranging from <NUM> to <NUM> wt%, based on the total weight of polypropylene composition.

As an optional component (f), a SEBS rubber can be used.

SEBS rubbers are (partly) hydrogenated styrene-butadiene-styrene block copolymers. They belong to the family of styrenic block copolymers (SBC). These polymers are triblock copolymers, having styrene at both extremities of the polymer chain with an internal polybutadiene, polyisoprene or hydrogenated polybutadiene or polyisoprene block.

SEBS copolymers are commercially available, for example under the tradenames of Kraton and Tuftec, such as for example Kraton SEBS G1657MS.

If used, the SEBS is present between <NUM>-4wt%, preferably between <NUM>-3wt%, based on the total weight of polypropylene composition.

The polypropylene composition can further comprise between <NUM>-10wt%, preferably <NUM>-<NUM> wt%, of additives.

Additives may comprise polyethylenes (for example virgin HDPE or recycled HDPE), maleic anhydride grafted PEs (PEMA), maleic anhydride grafted PPs (PPMA), stabilizers, peroxides, calcium oxides (CaO) or colorants and stripping agents.

Examples of PE are High-Density PE (HDPE), Low-Density PE (LDPE) and Linear Low-Density PE (LLDPE).

A PP compatible acid having a polar group can be added, such as for example a PPMA.

A PEMA, PE or PPMA can for example be added to the polymer composition between <NUM>-<NUM> wt%, preferably between <NUM>-<NUM> wt%, more preferably between <NUM>-<NUM> wt%.

A stabilizer can be added, such as for example masterbatches like Tosaf ME <NUM>, which is a blend of about <NUM> wt% LDPE with a phenolic stabilizer (Irganox B225) and an Irgafos. Typically, such a masterbatch is added in an amount between <NUM> and <NUM> wt%, preferably between <NUM> and <NUM> wt%.

A peroxide, in the form of an organic compound or masterbatch can be added. The peroxide improves the flow of the material and can be used to achieve a desired melt flow.

The peroxide can for example be selected from the group of Zebraflow T028, Zebraflow T0214 or Zebraflow T0318, which are masterbatches of a peroxide with a polyolefin. The specific amount of peroxide is determined by the skilled in the art having in mind the melt flow rate of the single components, their respective amounts and the final desired melt flow rate. As an example, the peroxide can amount to <NUM>-<NUM> wt% of the entire additive package.

A CaO can be added to inhibit release of HCl. The CaO can be also added as a masterbatch with for example LDPE. CaO can for example be added in a range between <NUM>-<NUM> wt%.

A black colorant can for example be added to the polymer composition between <NUM>-<NUM> wt%, preferably between <NUM>-<NUM> wt% in the form of a masterbatch blend.

Stripping agents are compounds used to remove volatiles during processing of the composition. BYK <NUM> is one of the commercially available products.

The amount of the whole package of additives ranges from <NUM> to <NUM>%wt preferably from <NUM> to <NUM>%wt based on the total amount of the polypropylene composition.

In a preferred embodiment of the present disclosure, the polypropylene composition consists of the following components (per cent by weight):.

the whole composition having a value of melt flow rate (ISO <NUM><NUM>/<NUM>) ranging from <NUM>/<NUM>' to <NUM>/<NUM>', preferably from <NUM> to <NUM>/<NUM>', more preferably from <NUM> to <NUM>/<NUM>'; the percentages of (a), (b), (c), (d) and additives being referred to the to the total weight of polypropylene composition.

The polymer composition according to the present disclosure preferably has a Flexural modulus ranging between <NUM>-<NUM> MPa, preferably between <NUM>-<NUM> MPa.

The polymer composition preferably has a Charpy impact strength at <NUM> of <NUM>-<NUM> kJ/m<NUM>, more preferably between <NUM>-<NUM> kJ/m<NUM>. The Charpy impact strength at -<NUM> ranges from <NUM> to <NUM> kJ/m<NUM>, more preferably between from <NUM> to <NUM> kJ/m<NUM>.

The composition of the present disclosure may exhibit a tensile strength at yield equal to or higher than <NUM> MPa, an elongation at yield equal to or higher than <NUM>%, and a tensile strength at break equal to or higher than <NUM> MPa.

The composition of the present disclosure can be obtained by mechanical blending of the components (a)-(d) and optionally further components and additives according to conventional techniques.

The process of making the polymer composition may use a co-rotating twin screw tandem extruder to which the components (a-d) and optionally further components and additives are added.

Additives can be added in a reclaim extruder (first extruder) and a compounding extruder (second extruder) of a tandem extruder.

The polypropylene polymer composition can be presented in granule or flake form to be used for manufacturing articles.

The polypropylene polymer composition of the present disclosure recycled PP is suitable for manufacturing products for long-term use, such as for example boxes, trays, suitcases or consumer goods.

The articles made from the polymer composition are preferably formed by injection molding or blow-molding.

The following examples are given in order to illustrate, but not limit the present disclosure.

<NUM> of polymer and <NUM> of xylene are introduced in a glass flask equipped with a refrigerator and a magnetic stirrer. The temperature is raised in <NUM> minutes up to the boiling point of the solvent. The resulting clear solution is then kept under reflux and stirred for <NUM> minutes. The closed flask is then kept for <NUM> minutes in a bath of ice and water, then in a thermostatic water bath at <NUM> for <NUM> minutes. The resulting solid is filtered on quick filtering paper. <NUM> of the filtered liquid is poured in a previously weighed aluminum container, which is heated on a heating plate under nitrogen flow to remove the solvent by evaporation. The container is then kept on an oven at <NUM> under vacuum until a constant weight is obtained. The weight percentage of polymer soluble in xylene at room temperature is then calculated.

The content of the xylene-soluble fraction is expressed as a percentage of the original <NUM> grams and then, by the difference (complementary to <NUM>%), the xylene insoluble percentage (%);.

XS of components B) and C) have been calculated by using the formula:
<MAT>
wherein Wa, Wb and Wc are the relative amount of components A, B and C, respectively, and (A+B+C=<NUM>).

Measured according to ISO <NUM> at <NUM> with a load of <NUM>, unless otherwise specified.

The sample is dissolved in tetrahydronaphthalene at <NUM> and then poured into a capillary viscometer. The viscometer tube (Ubbelohde type) is surrounded by a cylindrical glass jacket; this setup allows for temperature control with a circulating thermostatic liquid. The downward passage of the meniscus is timed by a photoelectric device.

The passage of the meniscus in front of the upper lamp starts the counter which has a quartz crystal oscillator. The meniscus stops the counter as it passes the lower lamp and the efflux time is registered: this is converted into a value of intrinsic viscosity through Huggins' equation (Huggins, M. , <NUM>, <NUM>, <NUM>) provided that the flow time of the pure solvent is known at the same experimental conditions (same viscometer and same temperature). One single polymer solution is used to determine [ η ].

Determined at a temperature of <NUM> by using a parallel plates rheometer model RMS-<NUM> marketed by RHEOMETRICS (USA), operating at an oscillation frequency which increases from <NUM> rad/sec to <NUM> rad/sec. From the crossover modulus one can derive the P. by way of the equation: <MAT> in which Gc is the crossover modulus which is defined as the value (expressed in Pa) at which G'=G" wherein G' is the storage modulus and G" is the loss modulus.

<NUM>C NMR spectra were acquired on a Bruker AV-<NUM> spectrometer equipped with cryoprobe, operating at <NUM> in the Fourier transform mode at <NUM>.

The peak of the Sββ carbon (nomenclature according to "Monomer Sequence Distribution in Ethylene-Propylene Rubber Measured by 13C NMR. Use of Reaction Probability Mode " C. Harrington and C. Wilkes, Macromolecules, <NUM>, <NUM>, <NUM>) was used as internal reference at <NUM> ppm. The samples were dissolved in <NUM>,<NUM>,<NUM>,<NUM>-tetrachloroethane-d2 at <NUM> with a <NUM> % wt/v concentration. Each spectrum was acquired with a <NUM>° pulse, <NUM> seconds of delay between pulses and CPD to remove <NUM>-13C coupling. <NUM> transients were stored in <NUM> data points using a spectral window of <NUM>.

The assignments of the spectra, the evaluation of triad distribution and the composition were made according to Kakugo ("Carbon-<NUM> NMR determination of monomer sequence distribution in ethylene-propylene copolymers prepared with δ-titanium trichloride-diethylaluminum chloride" M. Mizunuma and T. Miyatake, Macromolecules, <NUM>, <NUM>, <NUM>) using the following equations: <MAT> <MAT> <MAT>.

The molar percentage of ethylene content was evaluated using the following equation:.

E% mol = <NUM> * [PEP+PEE+EEE]The weight percentage of ethylene content was evaluated using the following equation: <MAT>
where P% mol is the molar percentage of propylene content, while MWE and MWP are the molecular weights of ethylene and propylene, respectively.

The product of reactivity ratio r<NUM>r<NUM> was calculated according to Carman (C. Harrington and C. Wilkes, Macromolecules, <NUM>; <NUM>, <NUM>) as: <MAT>.

The tacticity of Propylene sequences was calculated as mm content from the ratio of the PPP mmTββ (<NUM>-<NUM> ppm) and the whole Tββ (<NUM>-<NUM> ppm).

Ethylene C2 content of component b2 has been measured by measuring the C2 content on component B) and then calculated by using the formula C2tot= Xb <NUM> C2b <NUM> + Xb2C2b2 wherein Xb1 and Xb2 are the amounts of components b1 and b2 in the composition.

Samples have been obtained according to ISO <NUM>-<NUM>:<NUM>.

The melting point has been measured by using a DSC instrument according to ISO <NUM>-<NUM>, at scanning rate of <NUM>/min both in cooling and heating, on a sample of weight between <NUM> and <NUM>. , under inert N<NUM> flow. Instrument calibration made with Indium.

Extrusion products and injection-molded articles are produced and assessed following ISO19069-<NUM>:<NUM>, ISO294-E2017 and ISO294-<NUM>:<NUM>.

The POE component (c) used was Infuse <NUM>.

Component (d) is the composition prepared according to example <NUM> of US <CIT>.

The additive package contained a conventional stabilizer mix (Irgafos <NUM>/Irganox <NUM>), ZebraFlow T028 as a peroxide and BYK4200 as stripping agent.

In comparative example <NUM> the same composition of example <NUM> was used with the difference that component (d) was not used.

Claim 1:
A polypropylene composition comprising (per cent by weight):
(a) <NUM> to <NUM>%, of a recycled polypropylene (r-PP);
(b) <NUM>-<NUM> wt% of a recycled polyethylene;
(c) from <NUM> to <NUM>% of a polyolefin elastomer (POE) being an ethylene-alpha-olefin copolymer selected from C<NUM>-C<NUM> copolymers, C<NUM>-C<NUM> copolymers and C<NUM>-C<NUM> copolymers with an amount of ethylene ranging from <NUM> to <NUM>%wt;
(d) from <NUM> to <NUM>%, of a composition comprising:
i) <NUM>%-<NUM>% of a crystalline polypropylene component containing from <NUM>% to <NUM>% of a fraction Al having a melt flow rate MFRI, measured according to ISO <NUM> at <NUM> with a load of <NUM>, of from <NUM> to <NUM>/<NUM>., and from <NUM>% to <NUM>% of a fraction A2 having a melt flow rate MFRII , measured according to ISO <NUM> at <NUM> with a load of <NUM>, such that a ratio MFRII/MFRI is from <NUM> to <NUM>; and wherein fractions Al and A2 are independently selected from the group consisting of a propylene homopolymer, a random copolymer of propylene containing up to <NUM>% of ethylene, and a random copolymer of propylene containing up to <NUM>% of at least one C<NUM>-C<NUM> α-olefin; and
ii) <NUM>%-<NUM>% of a copolymer component of ethylene and propylene, the copolymer containing from <NUM> to <NUM>% of ethylene, and optionally minor amounts of a diene, said copolymer being soluble in xylene at room temperature, and having an intrinsic viscosity [η] of from <NUM> to <NUM> dl/g;
the whole composition having a value of melt flow rate (ISO <NUM><NUM>/<NUM>) ranging from <NUM>/<NUM>' to <NUM>/<NUM>', preferably from <NUM> to <NUM>/<NUM>', more preferably from <NUM> to <NUM>/<NUM>'; the percentages of (a), (b), (c) and (d) being referred to the to the total weight of polypropylene composition.