Recycled polypropylene composition

Abstract

A recycled polypropylene composition comprising: a) at least 30 wt% of a recycled polypropylene mixture; b) from 0.1 wt% to 2.0 wt% of cylcoalkene (polyalkenamer) rubber; wherein the amounts of a) and b) are calculated on the whole polypropylene composition.

Description

TITLERECYCLED POLYPROPYLENE COMPOSITIONFIELD OF THE INVENTION

[0001] The present disclosure relates to a recycled polypropylene composition comprising cylcoalkene (polyalkenamer) rubber, preferably polyoctenamer rubber, having improved mechanical properties.BACKGROUND OF THE INVENTION

[0002] Polyolefins, in particular polypropylene, are increasingly consumed in large amounts for many applications, including packaging for food and other goods, fibers, automotive components, and a great variety of manufactured articles. However, the said massive use of polyolefins is creating a concern as regards the environmental impact of the waste materials generated after the first use. In fact, large amounts of waste plastic materials are presently coming from differential recovery of municipal plastic wastes, mainly constituted of flexible packaging (cast film, blown film and BOPP film), rigid packaging, blow moulded bottles and injection moulded containers. Usually, through a step of separation from other polymers, such as PVC, PET or PS, two main polyolefinic fractions are obtained, namely polyethylenes (in particular HDPE LDPE, LLDPE) and polypropylenes (homopolymers, random copolymers, heterophasic copolymers).

[0004] However, the multicomponent nature of the recycled material often results in low mechanical performances even if they are used in polyolefin formulations in which part of the recycled polymer is replaced by virgin polymer.

[0003] The problem of mechanical performances in fact, is solved by adding virgin polymers to the recycled polypropylene for example W02007 / 071494 discloses the use of a heterophasic polyolefin composition having flexural modulus equal to or lower than 600 MPa as a compatibilizer agent for a recycled polyolefin composition.

[0004] It has now unexpectedly been found that by using a particular additive in formulations of recycled material it is possible to improve mechanical properties of the recycled polypropylene based material, in particular it is possible to improve the elongation at break without worsening the other features.SUMMARY OF THE INVENTION

[0005] Thus an object of the present disclosure is a recycled polypropylene composition comprising: a) at least 30.0 wt%; preferably at least 50.0 wt%; more preferably at least 90.0 wt%; even more preferably at least 99.0 wt% of a a recycled polypropylene (r-PP) having the following features: a propylene content, measured with13C-NMR, higher than 60 wt%, preferably higher than 65 wt%; even more preferably higher than 70 wt%;Melt Flow Rate (ISO 1133 230°C / 2.16 kg) ranging from 2 to 35 g / lOmin; preferably ranging from 5 to 29 g / lOmin; more preferably ranging from 8 to 22 g / lOmin;Flexural modulus, measured according to ISO 527-2, ranging from 620N / mm2to 1620 N / mm2; preferably ranging from 850 N / mm2to 1450 N / mm2; more preferably ranging from 950 N / mm2to 1350 N / mm2;Charpy impact test at 23°C, determined according to ISO 179-leA, and ISO 1873-2, ranging from 2.2 KJ / m2to 12.0 KJ / m2; preferably ranging from 3.4 KJ / m2to 9.2 KJ / m2; more preferably ranging from 4.0 KJ / m2to 7.3 KJ / m2Elongation at break, measured according To ISO 527, ranging from 10 % to 100 %;preferably ranging from 15 % to 80 %; more preferably ranging from 25 % to 68 % the FTTR spectrum of film recorded as described in the example section shows at least two peaks at different wavenumbers (cm-1) selected from:3303 ±1 cm’1; 1726 ±1 cm’1; 1642 ±1 cm’1; 1600 ±1 cm’1; 1550 ±1 cm’1; 906 ±1 cm’1; 839 ±1 cm’1, 818 ±1 cm’1;748 ±1 cm’1; 695 ±1 cm’1; b) from 0.1 wt% to 2.0 wt%; preferably from 0.2 wt% to 1.5 wt%; more preferably from 0.4 wt% to 1.0 wt% of cylcoalkene (polyalkenamer) rubber; wherein the amounts of a) and b) are calculated on the whole polypropylene composition.BRIEF DESCRIPTION OF THE DRAWINGSFig 1 shows the FTIR spectrum of component a) used in the examples.DETAILED DESCRIPTION OF THE IN VENTIONThe cycloalkene rubber, component b), is preferably compound having at least 20 weight % macrocycles (cyclic content). The cyclic and linear portions of the cycloalkene rubber have the following general chemical structures:n= 30-10000Suitable cyclic olefins that can be used to make the cycloalkene rubber include unsaturated hydrocarbons with 4 to 12 ring carbon atoms in one or more rings e.g., 1-3 rings, which exhibit in at least one ring an unsubstituted double bond which is not in conjugation to a second double bond which may be present and which may have any degree of substitution; the substituents are preferably alkyl groups of 1 to 4 carbon atoms or a part of a cyclic structure of 4 to 8 carbon atoms. Examples are cyclobutene, cyclopentene, cycloheptene, cis- and trans-cyclooctene, cyclononene, cyclodecene, cycloundecene, cis- and trans-cyclododecene, cis, cis-cyclooctadiene, 1 -methyl- 1,5- cyclooctediene, 3 -methyl- 1,5 -cyclooctadiene, and 3,7-dimethyl-l,5-cyclooctadiene.Examples of suitable polyalkenamer rubbers are polypentenamer rubber, polyheptenamer rubber, polyoctenamer rubber, polydecenamer rubber and polydodecenamer rubber. Polyoctenamer rubbers are commercially available from Evonik Degussa GmbH of Marl, Germany and sold under the VESTENAMER tradename. Preferably polyoctenamer rubber , component b), is used in the present disclosure. The polyalkenamer rubber, component b), used in the present disclosure preferably has one or more of the following properties:- a molecular weight higher than 80,000 or greater (measured according to GPC);- a glass transition temperature (Tg) lower than -55° C. (measured according to ISO 6721); a cis-to-trans ratio of double bonds comprised between 40:60 to 10:90 preferably comprised between 30:70 to 15:85 (measured according to IR);- a Mooney viscosity ML (1+4) 100° C. of less than 12; preferably less than 11 (measured according to ASTM-D 1646);- a viscosity number J / 23° C. comprised between 160 and 100 ml / g preferably comprised between 130 and 110 ml / g (measured according to ISO 1628-1);- a density comprised between 0.83 and 0.98 g / cm3preferably comprised between 0.85 and 0.95 g / cm3 ,more preferably comprised between 0.88 and 0.93 g / cm3(measured according to ISO 1183);- melting point, measured at 20°C / min according to ISO 11357-1, 2009 and 11357-3, 2011 higher than 40° C, preferably higher than 50°C;One example of a commercially-available material that can be used in accordance with this disclosure is VESTENAMER 8012 (trans-bond content of 80% and a melting point of 54° C.). recycled propylene based polymers.The term “recycled” is referred to material containing polymers whose pellets have been processed more than one time. On the contrary the term “virgin” means that the polymers pellets do not have been processed.

[0006] Component a) can be a Post-Industrial Resin (PIR) or Post-Consumer Resin (PCR).

[0007] Post-Industrial Resin (PIR) is the waste generated from the manufacturing process that is reclaimed or used again in the same material.

[0008] Post-Consumer Resin (PCR) defined as a resin used by the consumer for its intended purpose, that has reached its end of use, and then tossed into a recycling bin is excluded.

[0009] Preferably recycled propylene based polymers contains from 0.1 ppm to 25 ppm of limonene.

[0010] The recycled polypropylene composition of the present disclosure can further contains other polypropylene or polyethylene based polymers component c), preferably virgin polypropylene based polymers, such as propylene homopolymer, propylene ethylene copolymer having an ethylene derived units content ranging from 0.5 wt% to 10.0 wt%, heterophasic propylene ethylene copolymer having a xylene soluble fraction at 25°C rangingfrom 8.0 wt% to 50.0 wt% or propylene ethylene 1 -butene terpolymer or propylene ethylene 1- hexene terpolymer.

[0011] The amount of component c), when present is less than 70.0 wt% preferably less than 50.0 wt% more preferably less than 10.0 wt% and even more preferably less than 1.0 wt%.

[0012] The recycled polypropylene composition of the present disclosure shows improved mechanical properties in particular the recycled polypropylene composition of the present disclosure shows an improved elongation at break. The elongation at break measured as described in the examples section ranges from 100% to 500%; preferably from 150 % to 400 %.

[0013] A further object of the present disclosure is a process for improving the mechanical properties of the recycled polypropylene composition above disclosed comprising the steps of: i) providing at least 30 wt%; preferably at least 50 wt%; more preferably at least 90 wt%; even more preferably at least 99 wt% of the recycled polypropylene mixture component (a); from 0.1 wt% to 2.0 wt%; preferably from 0.2 wt% to 1.5 wt%; more preferably from 0.4 wt% to 1.0 wt% of a cylcoalkene (polyalkenamer) rubber (component b), wherein component a) and b) are defined as above and optionally from 0.001 to 0.20 wt%, more preferably from 0.05 to 0.50 wt% of a peroxide, component d), having a decomposition temperature lower than 250°C preferably ranging from 150° to 250°C; wherein the amount of a), b) and c) are referred to the whole composition. ii) melting and extruding the mixture obtained in step i).

[0014] Preferably the peroxide, component d) ranges from 0.05 to 0.20 wt% ; more preferably the peroxide component c) ranges from 0.05 to 0.10 wt%.

[0015] Examples of peroxides that can be used in the process of the present disclosure are di- tert-butyl peroxide, dicumyl peroxide, the 2,5-dimethyl-2,5-di (tert-butylperoxy)hexyne, and 2,5- dimethy 1-2, 5 -di(tert-butylperoxy) hexane (traded by Akzo or Arkema under the name Trigonox 101 or Luperox 101 respectively).EXAMPLECharacterization methodsMelting temperature and crystallization temperature: Determined by differential scanning calorimetry (DSC)

[0016] . The melting points of the polymers (Tm) were measured by differential scanning calorimetry (DSC) on a Perkin Elmer DSC-1 calorimeter, previously calibrated against indium melting points, and according to ISO 11357-1, 2009 and 11357-3, 2011, at 20°C / min. The weight of the samples in every DSC crucible was kept at 6.0 ± 0.5 mg.Melt Flow Rate: Determined according to the method ISO 1133-1 (230° C, 2.16 kg).Xylene-soluble fraction (XS) at 25°C

[0017] Xylene Solubles at 25°C have been determined according to ISO 16152: 2005; with solution volume of 250 ml, precipitation at 25°C for 20 minutes, 10 of which with the solution in agitation (magnetic stirrer), and drying at 70°C.Intrinsic Viscosity (LV.)

[0018] The sample is dissolved by tetrahydronaphthalene at 135 °C and then it is poured into the capillary viscometer.

[0019] The viscometer tube (Ubbelohde type) is surrounded by a cylindrical glass jacket; this setup allows temperature control with a circulating thermostated liquid.

[0020] 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 throughEthylene content

[0021] 13C NMR spectra were acquired on a Bruker AV-600 spectrometer equipped with cry oprobe, operating at 160.91 MHz in the Fourier transform mode at 120 °C.

[0022] The peak of the SPP carbon (nomenclature according to “Monomer Sequence Distribution in Ethylene-Propylene Rubber Measured by13C NMR. 3. Use of Reaction Probability Mode ” C. J. Carman, R. A. Harrington and C. E. Wilkes, Macromolecules, 1977, 10, 536) was used as an internal reference at 29.9 ppm. The samples were dissolved in 1 , 1 ,2,2-tetrachloroethane- d2 at 120 °C with a 8 % wt / v concentration. Each spectrum was acquired with a 90° pulse, and 15 seconds of delay between pulses and CPD to removeJH-13C coupling. 512 transients were stored in 32K data points using a spectral window of 9000 Hz.

[0023] The assignments of the spectra, the evaluation of triad distribution and the composition were made according to Kakugo (“Carbon- 13 NMR determination of monomer sequence distribution in ethylene-propylene copolymers prepared with 5-titanium trichloride- diethyl-aluminum chloride” M. Kakugo, Y. Naito, K. Mizunuma and T. Miyatake, Macromolecules, 1982, 15, 1150) using the following equations:PPP = 1OO TP0 / S PPE = 1OO TP8 / S EPE = 100 T88 / SPEP = 100 SPP / S PEE= 100 SP5 / S EEE = 100 (0.25 Sy8+0.5 S88) / SS = TPP + TP8 + T88 + SPP + Sp8 + 0.25 Sy8 + 0.5 S88

[0024] The molar percentage of ethylene content was evaluated using the following equation:

[0025] E% mol = 100 * [PEP+PEE+EEE]The weight percentage of ethylene content was evaluated using the following equation:100 * E% mol * MWEE% wt. = E% mol * MWE + P% mol * MWP

[0026] where P% mol is the molar percentage of propylene content, while MWE and MWP are the molecular weights of ethylene and propylene, respectively.

[0027] The product of reactivity ratio rlr2 was calculated according to Carman (C.J. Carman, R.A. Harrington and C.E. Wilkes, Macromolecules, 1977; 10, 536) as:

[0028] The tacticity of Propylene sequences was calculated as mm content from the ratio of the PPP mmTpp (28.90-29.65 ppm) and the whole Tpp (29.80-28.37 ppm).

[0029] Charpy impact test measured according to according to ISO 179-leA, e ISO 1873-

[0030] Elongation at yield: measured according to ISO 527.

[0031] Elongation at break: measured according To ISO 527

[0032] Stress at break: measured according to ISO 527.

[0033] Impact test: ISO 180-1 A

[0034] Samples for the mechanical analysis

[0035] Samples have been obtained according to ISO 1873-2:2007 excepting for the flexural modulus for which ISO 3167 has been used.

[0036] Flexural Modulus

[0037] Determined according to ISO 178.

[0038] Melting point a and crystallization point

[0039] The melting point has been measured by using a DSC instrument according toISO 11357-3, at scanning rate of 20C / min both in cooling and heating, on a sample of weight between 5 and 7 mg., under inert N2 flow. Instrument calibration made with Indium.Component a)Component a) is a recycled polypropylene sold by QCP with the tradename QCP300P Component a) contains residue-drained, rigid, system-compatible items made of polypropylene, volume < 5 litres, e.g. bottles, bottles, cups and trays, incl. secondary components such as lids, labels etc.Component al) is at least 94 wt%, metallic and mineral impurities with a unit weight of >100 g and cartridges for sealants are not permittedImpuritiesExamples of other residues are:GlassPaper, Board, CardboardComposite paper / cardboard materials (e.g. liquid packaging boards) Aluminized plasticsOther materials (e.g. rubber, stones, wood, textiles, nappies) Compostable waste (e.g. food, garden waste)The Melt flow rate (230 °C / 2.16 kg) of Component a) is 16 g / 10 min and the melting point is 150°C.The limonene content is higher than 0.1 ppm and lower than 25 ppm.Limonene detectionLimonene quantification can be carried out using solid phase microextraction (HS-SPME-GC- MS) by standard addition. 50 mg ground samples are weighed into 20 mL headspace vials and after the addition of limonene in different concentrations and a glass-coated magnetic stir bar, the vial is closed with a magnetic cap lined with silicone / PTFE. Micro capillaries (10 pL) are used to add diluted limonene standards of known concentrations to the sample. Addition of 0, 2, 20 and 100 ng equals 0 mg / kg, 0.1 mg / kg, 1 mg / kg and 5 mg / kg limonene, in addition standard amounts of 6.6 mg / kg, 11 mg / kg and 16.5 mg / kg limonene is used in combination with some of the samples tested in this application. For quantification, ion-93 acquired in SIM mode is used.Enrichment of the volatile fraction is carried out by headspace solid phase microextraction with a 2 cm stable flex 50 / 30 pm DVB / Carboxen / PDMS fibre at 60°C for 20 minutes. Desorption is carried out directly in the heated injection port of a GCMS system at 270°C.GCMS Parameters: Column: 30 m HP 5 MS 0.25*0.25 Injector: Splitless with 0.75 mm SPME Liner, 270°C Temperature program: -10°C (1 min) Carrier gas: Helium 5.0, 31 cm / s linear velocity, constant flow MS: Single quadrupole, direct interface, 280°C interface temperature o Acquisition: SIM scan mode o Scan parameter: 20-300 amu o SIM Parameter: m / Z 93, 100 ms dwell timeComponent b)Component b) is Vestenamer 8012 sold by Evonik Degussa GmbH. It is a polyoctenamer rubber having: trans-bond content of 80%; melting point 54°C; a molecular weight (measured according to GPC) 90000; glass transition temperature (Tg) (measured according to ISO 6721) -65; a cis-to-trans ratio of double bonds (IR) 20:80 %Mooney viscosity ML (1+4) 100° C (measured according to DIN 53 523) <10 a viscosity number J / 23° C (ISO 1628-1 ) 120 ml / g; density (measured according to DIN 53 479 A) 0.91 g / cm3Component c)Compoentn c) is Trigonox 101 sold by AkzoComponents a) b) and optionally c) have been mixed and extruded in a twin screw extruderBerstorff ZE 25 (length / diameter ratio of screws: 34) and extruded under nitrogen atmosphere in the following conditions:Rotation speed: 250 rpm;Extruder output: 15 kg / hour;Melt temperature: 245 °C.The characterization of the resulting polymer is reported in table 1Table 1From table 1 clearly results that the compositions of the present invention show an improved elongation at break while the other mechanical feature are substantially unchanged or slightly improved.

Claims

CLAIMS1. A recycled polypropylene composition comprising: a) at least 30 wt% of a recycled polypropylene (r-PP) ) having the following features: a propylene content, measured with13C-NMR, higher than 60 wt%;Melt Flow Rate (ISO 1133 230°C / 2.16 kg) ranging from 2 to 35 g / lOmin;Flexural modulus, measured according to ISO 527-2, ranging from 620N / mm2to 1620 N / mm2;Charpy impact test at 23°C, determined according to ISO 179-leA, and ISO 1873-2, ranging from 2.2 KJ / m2to 12.0 KJ / m2;Elongation at break, measured according To ISO 527, ranging from 10 % to 100 %; the FUR spectrum of film recorded as described in the example section shows at least two peaks at different wavenumbers (cm-1) selected from:3303 ±1 cm’1; 1726 ±1 cm’1; 1642 ±1 cm’1; 1600 ±1 cm’1; 1550 ±1 cm’1; 906 ±1 cm’1; 839 ±1 cm'1, 818 ±1 cm'1;748 ±1 cm'1; 695 ±1 cm'1; b) from 0.1 wt% to 2.0 wt% of cylcoalkene (polyalkenamer) rubber; wherein the amounts of a) and b) are calculated on the whole polypropylene composition.

2. The recycled polypropylene composition to claim 1 wherein component b) is a cycloalkene rubber, having at least 20 weight % macrocycles (cyclic content).

3. The recycled polypropylene composition according to any of claims 1-2 wherein component b) is a polyoctenamer rubber.

4. The recycled polypropylene composition according to any of claims 1-3 wherein component b) has:- a glass transition temperature (Tg) lower than -55° C (measured according to ISO 6721);-a Mooney viscosity ML (1+4) 100° C. of less than 12 (measured according to ASTM-D 1646);- a density comprised between 0.83 and 0.98 g / cm3(measured according to ISO 1183);- melting point, measured at 20°C / min according to ISO 11357-1, 2009 and 11357-3, 2011 higher than 40° C.

5. The recycled polypropylene composition according to any of claims 1-5 wherein component b) has the melting point, measured at 20°C / min according to ISO 11357-1, 2009 and 11357-3, 2011 higher than 40° C.

6. The recycled polypropylene composition according to any of claims 1-6 comprising at least 50 wt% of component a) and from 0.2 wt% to 1.5 wt% of component b).

7. The recycled polypropylene composition according to any of claims 1-6 wherein component a) has a melt flow rate (ISO 1133 230°C / 2.16 kg) ranging between 5 to 29 g / lOmin g / 10 min.

8. The recycled polypropylene composition according to any of claims 1-7 wherein component a) has afFlexural modulus, measured according to ISO 527-2, ranging from 850 N / mm2to 1450 N / mm2.

9. The recycled polypropylene composition according to any of claims 1-8 containing: a) at least 30 wt% of a recycled polypropylene (r-PP) as described in claim 1; b) from 0.1 wt% to 2.0 wt% of cylcoalkene (polyalkenamer) rubber; and c) less than 70.0 wt% of virgin polypropylene based polymers, wherein the amounts of a), b) and c) are calculated on the whole polypropylene composition.

10. The recycled polypropylene composition according to any of claims 1-9 wherein: Component a) is at least 50 wt%; component b) ranges from 0.2 wt% to 1.5 wt%; and component c) is less than 50.0 wt%;11. The recycled polypropylene composition according to any of claims 1-10 wherein component c) is selected from one or more polymer of the group consisting of propylene homopolymer, propylene ethylene copolymer having an ethylene derived units content ranging from 0.5 wt% to 10.0 wt%, heterophasic propylene ethylene copolymer having a xylene soluble fraction at 25°C ranging from 8.0 wt% to 50.0 wt% or propylene ethylene 1-butene terpolymer or propylene ethylene 1 -hexene terpolymer.

12. The recycled polypropylene composition according to any of claims 1-11 wherein in component a) the Charpy impact test at 23°C, determined according to ISO 179-leA, and ISO 1873-2, ranges from 3.4 KJ / m2to 9.2 KJ / m213 A process for improving the mechanical properties of the recycled polypropylene composition comprising the steps of : i) providing at least 30 wt%; of the recycled polypropylene mixture component a) defined in claims 1-12; from 0.1 wt% to 2.0 wt%; of a cylcoalkene (polyalkenamer) rubber (component b) as defined in claims 1-12 and optionally from 0.05 to 0.5 wt% of a peroxide, component c) ), having a decomposition temperature lower than 250°C: ii) melting and extruding the mixture obtained in step i)14 The process according to claim 13 wherein the peroxides component c) is selected from the group consisting of di- tert-butyl peroxide, dicumyl peroxide, the 2,5-dimethyl-2,5-di (tert- butylperoxy)hexyne, and 2,5- dimethy 1-2, 5 -di(tert-butylperoxy) hexane.15 The process according to any of claims 13-14 wherein the peroxide component c) ranges from ranges from 0.05 to 0.20 wt%.

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