Recycled polypropylene composition

Abstract

A recycled polypropylene composition comprising: a) at least 30 wt% of a recycled polypropylene mixture; b) 0.1 wt% to 2.0 wt% of a cyclic olefin (ring-opening poly cyclic olefin) rubber; wherein the amount of a) and the amount of b) are calculated based on the entire polypropylene composition.

Description

Technical Field

[0001] This disclosure relates to a recycled polypropylene composition having improved mechanical properties, the recycled polypropylene composition comprising cyclic olefin (open-ring polycyclic olefin) rubber, preferably open-ring polycyclic octene rubber. Background Technology

[0002] Polyolefins, particularly polypropylene, are increasingly being consumed in large quantities in many applications, including food and other commodity packaging, fibers, automotive parts, and a wide variety of manufactured goods. However, this widespread use of polyolefins has raised concerns about the environmental impact of the waste materials generated after initial use. Indeed, a significant amount of waste plastic material currently comes from the differentiated recycling of municipal plastic waste, primarily consisting of flexible packaging (cast films, blown films, and BOPP films), rigid packaging, blow-molded bottles, and injection-molded containers. Typically, two main polyolefin fractions are obtained through a separation step from other polymers such as PVC, PET, or PS: polyethylene (especially HDPE, LDPE, LLDPE) and polypropylene (homopolymers, random copolymers, heteropolymers). However, even when used in polyolefin formulations where recycled polymers partially replace virgin polymers, the multi-component nature of recycled materials often results in low mechanical properties.

[0003] In fact, mechanical property issues can be addressed by adding virgin polymers to recycled polypropylene. For example, WO2007 / 071494 discloses the use of a heterogeneous polyolefin composition as a compatibilizer in a recycled polyolefin composition having a flexural modulus equal to or less than 600 MPa.

[0004] Surprisingly, it has now been discovered that the mechanical properties of recycled polypropylene-based materials can be improved by using specific additives in the formulation of recycled materials. In particular, the elongation at break can be increased without deteriorating other properties. Summary of the Invention

[0005] Therefore, the object of this disclosure is a recycled polypropylene composition comprising:

[0006] a) at least 30.0% by weight, preferably at least 50.0% by weight, more preferably at least 90.0% by weight, and even more preferably at least 99.0% by weight of recycled polypropylene (r-PP), which has the following characteristics:

[0007] use 13The propylene content measured by C-NMR is greater than 60% by weight, preferably greater than 65% by weight, and even more preferably greater than 70% by weight;

[0008] Melt flow rate in the range of 2 to 35 g / 10 min, preferably in the range of 5 to 29 g / 10 min, and more preferably in the range of 8 to 22 g / 10 min (ISO 1133, 230°C / 2.16 kg).

[0009] The measurement range according to ISO 527-2 is 620 N / mm. 2 Up to 1620 N / mm 2 The preferred range is 850 N / mm. 2 Up to 1450 N / mm 2 A more preferred range is 950 N / mm 2 Up to 1350 N / mm 2 Flexural modulus;

[0010] The range, as determined by ISO 179-1eA and ISO 1873-2, is 2.2 kJ / m³. 2 Up to 12.0 KJ / m 2 The preferred range is 3.4 KJ / m 2 Up to 9.2 KJ / m 2 A more preferred range is 4.0 KJ / m 2 Up to 7.3 KJ / m 2 Charpy impact test at 23°C;

[0011] The elongation at break, measured according to ISO 527, ranges from 10% to 100%, preferably from 15% to 80%, and more preferably from 25% to 68%.

[0012] The FTIR spectra of the membranes recorded as described in the Examples section show at least two peaks at different wavenumbers (cm⁻¹) selected from the following:

[0013] 3303±1cm -1 1726±1cm -1 1642±1cm -1 1600±1cm -1 1550±1cm -1 906±1cm -1 839±1cm -1 818±1cm -1； 748±1cm -1 695±1cm -1 ;

[0014] b) 0.1% to 2.0% by weight, preferably 0.2% to 1.5% by weight, more preferably 0.4% to 1.0% by weight of cyclic olefin (ring-opening polycyclic olefin) rubber;

[0015] The amounts of a) and b) are calculated based on the entire polypropylene composition. Attached Figure Description

[0016] Figure 1 The FTIR spectrum of component a) used in the examples is shown. Detailed Implementation

[0017] Cycloolefin rubber component b) is preferably a compound having at least 20% by weight of a macrocyclic compound (ring content). The cyclic and linear portions of the cycloolefin rubber have the following general chemical structures:

[0018]

[0019] Suitable cyclic olefins for use in the manufacture of cyclic olefin rubbers include unsaturated hydrocarbons having 4 to 12 ring carbon atoms in one or more rings (e.g., 1 to 3 rings), wherein the unsaturated hydrocarbon exhibits an unsubstituted double bond in at least one ring that is not conjugated with a second double bond that may be present and may have any degree of substitution; the substituent is preferably an alkyl group of 1 to 4 carbon atoms, or preferably part of a cyclic structure of 4 to 8 carbon atoms. Examples are cyclobutene, cyclopentene, cycloheptene, cis-cyclooctene and trans-cyclooctene, cyclononene, cyclodecene, cycloundecene, cis-cyclododecene and trans-cyclododecene, cis, cis-cyclooctadiene, 1-methyl-1,5-cyclooctadiene, 3-methyl-1,5-cyclooctadiene, and 3,7-dimethyl-1,5-cyclooctadiene.

[0020] Examples of suitable ring-opening polycyclic olefin rubbers are ring-opening polycyclic pentene rubber, ring-opening polycyclic hepten rubber, ring-opening polycyclic octene rubber, ring-opening polycyclic decene rubber, and ring-opening polycyclic dodecene rubber. Ring-opening polycyclic octene rubber is commercially available from Evonik Degussa GmbH in Mar, Germany, and sold under the trademark VESTENAMER. Ring-opening polycyclic octene rubber component b) is preferably used in this disclosure. Ring-opening polycyclic olefin rubber component b) used in this disclosure preferably has one or more of the following properties:

[0021] - Molecular weight greater than 80,000 (measured according to GPC);

[0022] - Glass transition temperature (Tg) below -55°C (measured according to ISO 6721);

[0023] - The double bond cis-trans ratio is included between 40:60 and 10:90, preferably between 30:70 and 15:85 (based on IR measurements).

[0024] - Mooney viscosity ML(1+4) at 100°C less than 12, preferably less than 11 (measured according to ASTM-D 1646).

[0025] - A viscosity number (measured according to ISO 1628-1) between 160 and 100 ml / g, preferably between 130 and 110 ml / g.

[0026] - Included in 0.83 and 0.98 g / cm 3 The concentration is preferably between 0.85 and 0.95 g / cm³. 3 More preferably, it is included between 0.88 and 0.93 g / cm³. 3 Density between (measured according to ISO 1183);

[0027] - Melting point above 40°C, preferably above 50°C, measured at 20°C / min according to ISO 11357-1, 2009 and ISO 11357-3, 2011;

[0028] An example of a commercially available material that can be used according to this disclosure is VESTENAMER 8012 (80% trans bond content and melting point of 54°C).

[0029] Recycled propylene-based polymers.

[0030] The term "recycled" refers to materials containing polymer pellets that have been processed more than once. Conversely, the term "virgin" means that the polymer pellets have not been processed.

[0031] Component a) can be post-industrial resin (PIR) or post-consumer resin (PCR).

[0032] Post-industrial resins (PIRs) are waste products generated during the manufacturing process that are recycled or reused in the same material.

[0033] Post-consumer resin (PCR) is defined as resin that has been used by consumers for its intended purpose (it has achieved its end use) and then discarded into a recycling bin.

[0034] Preferably, the recycled propylene polymer contains 0.1 ppm to 25 ppm of limonene.

[0035] The recycled polypropylene compositions disclosed herein may further contain other polypropylene or polyvinyl polymer components (c), preferably virgin polypropylene polymers such as propylene homopolymers; propylene-ethylene copolymers having an ethylene-derived unit content ranging from 0.5 wt% to 10.0 wt%; heterogeneous propylene-ethylene copolymers having a xylene-soluble fraction at 25°C ranging from 8.0 wt% to 50.0 wt%; or propylene-ethylene-1-butene terpolymers; or propylene-ethylene-1-hexene terpolymers.

[0036] When present, the amount of component c) is less than 70.0% by weight, preferably less than 50.0% by weight, more preferably less than 10.0% by weight, and even more preferably less than 1.0% by weight.

[0037] The recycled polypropylene compositions of this disclosure exhibit improved mechanical properties, and in particular, the recycled polypropylene compositions of this disclosure exhibit improved elongation at break. The elongation at break, as described in the Examples section, ranges from 100% to 500%, preferably from 150% to 400%.

[0038] Another object of this disclosure is a process for improving the mechanical properties of the recycled polypropylene compositions disclosed above, the process comprising the following steps:

[0039] i) Provides: at least 30% by weight, preferably at least 50% by weight, more preferably at least 90% by weight, and even more preferably at least 99% by weight of a recycled polypropylene mixture component a); 0.1% by weight to 2.0% by weight, preferably 0.2% by weight to 1.5% by weight, more preferably 0.4% by weight to 1.0% by weight of a cyclic olefin (ring-opening polycyclic olefin) rubber component b), wherein components a) and b) are as defined above; and optionally 0.001% by weight to 0.20% by weight, more preferably 0.05% by weight to 0.50% by weight of a peroxide component d) having a decomposition temperature below 250°C, preferably in the range of 150°C to 250°C, wherein the amounts of a), b) and c) refer to the whole composition.

[0040] ii) Melt and extrude the mixture obtained in step i).

[0041] Preferably, the peroxide component d) ranges from 0.05 to 0.20 by weight; more preferably, the peroxide component c) ranges from 0.05 to 0.10 by weight.

[0042] Examples of peroxides that can be used in the processes disclosed herein are di-tert-butyl peroxide, dicumyl peroxide, 2,5-dimethyl-2,5-di(tert-butylperoxy)hexyne, and 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane (sold by Akzo or Arkema under the names Trigonox 101 or Luperox 101, respectively).

[0043] Example

[0044] Characterization methods

[0045] Melting and crystallization temperatures were determined by differential scanning calorimetry (DSC). The melting point (Tm) of the polymer was measured by differential scanning calorimetry (DSC) at 20 °C / min on a Perkin Elmer DSC-1 calorimeter previously calibrated for indium melting point, according to ISO 11357-1, 2009 and ISO 11357-3, 2011. The weight of the sample in each DSC crucible was maintained at 6.0 ± 0.5 mg.

[0046] Melt flow rate: determined according to method ISO 1133-1 (230°C, 2.16 kg).

[0047] Xylene soluble fraction (XS) at 25°C

[0048] The xylene soluble content at 25°C was determined according to ISO 16152:2005; the solution volume was 250 ml, and the solution was precipitated at 25°C for 20 minutes, including 10 minutes of stirring (magnetic stirrer), and then dried at 70°C.

[0049] Intrinsic viscosity (IV)

[0050] The sample was dissolved in tetrahydronaphthalene at 135°C and then poured into a capillary viscometer.

[0051] The viscometer tube (Ubbelohde type) is surrounded by a cylindrical glass jacket; this setup allows for temperature control using a circulating thermostatic liquid.

[0052] The downward passage of the meniscus is timed by a photoelectric device. When the meniscus passes in front of the upper lamp, it activates a counter with a quartz crystal oscillator. Upon passing the lower lamp, the meniscus stops the counter and records the outflow time, which is then converted to an intrinsic viscosity value using the following method.

[0053] ethylene content

[0054] Acquired on a Bruker AV-600 spectrometer equipped with a cryoprobe. 13The spectrometer was used for C NMR spectroscopy and operated at 160.91 MHz in Fourier transform mode at 120 °C.

[0055] The peak of Sββ carbon at 29.9 ppm (according to "Monomer Sequence Distribution in Ethylene-Propylene Rubber Measured by 13C NMR. 3. Use of Reaction Probability Mode"). 13 C10 NMR. 3. Use of Reaction Probability Mode (CJ Carman, RA Harrington, and CE Wilkes, *Macromolecules*, 1977, 10, 536) was used as an internal reference. The sample was dissolved at 120 °C in 1,1,2,2-tetrachloroethane-d2 at a concentration of 8 wt / v%. A 90° pulse was applied, with a 15-second delay between the pulse and the CPD to remove [reaction probability]. 1 H- 13 C-coupling was used to obtain each spectrum. 512 transients were stored in 32K data points using a spectral window of 9000Hz.

[0056] According to Kakugo ("Carbon-13 NMR determination of monomer sequence distribution in ethylene-propylene copolymers prepared with δ-titaniumtrichloride-diethylaluminum chloride", M. Kakugo, Y. Naito, K. Mizunuma and T. Miyatake, *Macromolecules*, 1982, Vol. 15, p. 1150), the following equation was used to assign spectra, evaluate ternary distributions, and determine composition:

[0057] PPP = 100 Tββ / S PPE = 100 Tβδ / S EPE = 100 Tδδ / S

[0058] PEP = 100 Sββ / S PEE= 100 Sβδ / S EEE = 100 (0.25 Sγδ+0.5 Sδδ) / S

[0059] S = Tββ + Tβδ + Tδδ + Sββ + Sβδ + 0.25 Sγδ + 0.5 Sδδ

[0060] The molar percentage of ethylene content is evaluated using the following equation:

[0061] The weight percentage of ethylene content, E% mol = 100 * [PEP+PEE+EEE], is evaluated using the following equation:

[0062] 100 * E% mol * MWE

[0063] E% wt. = E% mol * MWE + P% mol * MWP

[0064] Where P% mol is the molar percentage of propylene content, and MWE and MWP are the molecular weights of ethylene and propylene, respectively.

[0065] The product of the reactivity ratios, r1r2, is calculated according to Carman (CJ Carman, RA Harrington, and CE Wilkes, *Macromolecules*, 1977; 10, 536):

[0066]

[0067] The stereoregularity of the propylene sequence is determined by PPP mmT ββ (28.90 to 29.65 ppm) and total T ββ The ratio of (29.80 to 28.37 ppm) is calculated as mm content.

[0068] Charpy impact test: measured according to ISO 179-1eA, e ISO 1873-2.

[0069] Yield elongation: Measured according to ISO 527.

[0070] Elongation at break: Measured according to ISO 527

[0071] Fracture stress: Measured according to ISO 527.

[0072] Impact test: ISO 180-1A

[0073] Samples for mechanical analysis

[0074] Except for flexural modulus, samples were obtained according to ISO 1873-2:2007, and ISO 3167 was used for flexural modulus.

[0075] Flexural modulus

[0076] Measured according to ISO 178.

[0077] Melting point and crystallization point

[0078] Melting point was measured under an inert N2 flow on samples weighing between 5 mg and 7 mg using a DSC instrument according to ISO 11357-3, with a scan rate of 20°C / min in both cooling and heating conditions. The instrument was calibrated with indium.

[0079] Component a)

[0080] Component a) is recycled polypropylene sold by QCP under the trademark name QCP300P.

[0081] Component a) contains a rigid, system-compatible article made of polypropylene with a volume of <5 liters, such as bottles, jars, cups, and trays (including minor components such as caps, labels, etc.).

[0082] Component a1) consists of at least 94% by weight of metallic and mineral impurities, with a unit weight >100g, and the use of sealant cartridges is not permitted.

[0083] impurities

[0084]

[0085] Examples of other residues are:

[0086] Glass

[0087] Paper, cardboard, hardboard

[0088] Aluminized plastic composite paper / cardboard materials (e.g., liquid packaging cardboard)

[0089] Other materials (e.g., rubber, stone, wood, textiles, diapers) can be composted from waste (e.g., food, garden waste).

[0090] The melt flow rate (230℃ / 2.16kg) of component a) is 16g / 10min, and the melting point is 150℃.

[0091] The limonene content is higher than 0.1 ppm and lower than 25 ppm.

[0092] Limonene detection

[0093] Limonene quantification was performed using solid-phase microextraction (HS-SPME-GC-MS) via the standard addition method. 50 mg of the ground sample was weighed into a 20 mL headspace vial, and after adding different concentrations of limonene and a glass-coated magnetic stir bar, the vial was sealed with a silicone / PTFE-lined magnetic cap. Diluted limonene standards of known concentrations were added to the sample using a microcapillary (10 pL). Adding 0 ng, 2 ng, 20 ng, and 100 ng equates to adding 0 mg / kg, 0.1 mg / kg, 1 mg / kg, and 5 mg / kg of limonene, respectively. Additionally, standard amounts of 6.6 mg / kg, 11 mg / kg, and 16.5 mg / kg of limonene were used in combination with some samples tested in this application. For quantification, Ion-93 obtained in SIM mode was used. Volatile fractions were enriched by headspace solid-phase microextraction at 60 °C for 20 min using a 2 cm stable flexible 50 / 30 pm DVB / Carboxen / PDMS fiber. Desorption was performed directly at 270°C in the heated injection port of the GCMS system.

[0094] GCMS parameters:

[0095] Column: 30 m HP 5 MS 0.25 * 0.25

[0096] o Injector: shunt-free, with a 0.75mm SPME liner, 270℃

[0097] Temperature program: -10℃ (1 min)

[0098] Carrier gas: Helium 5.0, linear velocity 31 cm / s, constant flow rate

[0099] oMS: Single quadrupole, direct interface, 280℃ interface temperature

[0100] o Obtain: SIM scanning mode

[0101] o Scan parameters: 20 to 300 amu

[0102] oSIM parameters: m / Z 93, 100ms dwell time

[0103] Component b)

[0104] Component b) is Vestenamer 8012, sold by Evonik Degussa AG. It is a ring-opening polycyclic octene rubber with the following properties:

[0105] -80% trans bond content;

[0106] Melting point: -54℃;

[0107] Molecular weight of -90,000 (measured according to GPC).

[0108] --65 glass transition temperature (Tg) (measured according to ISO 6721);

[0109] -20:80% double bond cis-trans ratio (IR)

[0110] Mooney viscosity ML(1+4) <10 at 100°C (measured according to DIN 53 523)

[0111] Viscosity number J / 23℃ of -120 ml / g (ISO 1628-1);

[0112] -0.91g / cm 3 Density (measured according to DIN 53 479 A)

[0113] Component c)

[0114] Component c) is Trigonox 101 sold by Akzo Corporation.

[0115] Components a), b), and optionally c) are mixed and extruded in a twin-screw extruder, Berstorff ZE 25 (screw length / diameter ratio: 34), and extruded under a nitrogen atmosphere.

[0116] Speed: 250 rpm;

[0117] Extruder output: 15 kg / hour;

[0118] Melting temperature: 245℃.

[0119] The characterization of the obtained polymers is reported in Table 1.

[0120] Table 1

[0121]

[0122] As can be clearly seen from Table 1, the compositions of the present invention exhibit improved elongation at break, while other mechanical properties remain essentially unchanged or are slightly improved.

Claims

1. A recycled polypropylene composition, said recycled polypropylene composition comprising: a) At least 30% by weight of recycled polypropylene (r-PP), said recycled polypropylene (r-PP) having the following characteristics: use 13 Propylene content exceeding 60% by weight, as measured by C-NMR; Melt flow rate in the range of 2 to 35 g / 10 min (ISO 1133, 230 °C / 2.16 kg). The measurement range according to ISO 527-2 is 620 N / mm. 2 Up to 1620 N / mm 2 Flexural modulus; The range, as determined by ISO 179-1eA and ISO 1873-2, is 2.2 kJ / m³. 2 Up to 12.0 KJ / m 2 Charpy impact test at 23°C; The range of elongation at break, measured according to ISO 527, is 10% to 100%. The FTIR spectra of the membranes recorded as described in the Examples section show at least two peaks at different wavenumbers (cm⁻¹) selected from the following: 3303±1cm -1 ;1726±1cm -1 ;1642±1cm -1 ;1600±1cm -1 ;1550±1cm -1 ;906±1cm -1 ;839±1cm -1 ;818±1cm -1； 748±1cm -1 ;695±1cm -1 ; b) 0.1% to 2.0% by weight of cyclic olefin (ring-opening polycyclic olefin) rubber; The amounts of a) and b) are calculated based on the entire polypropylene composition.

2. The recycled polypropylene composition according to claim 1, wherein component b) is a cyclic olefin rubber having at least 20% by weight of macrocyclic compounds (cyclic content).

3. The recycled polypropylene composition according to any one of claims 1 to 2, wherein component b) is a ring-opening polycyclic octene rubber.

4. The recycled polypropylene composition according to any one of claims 1 to 3, wherein component b) has: - Glass transition temperature (Tg) below -55°C (measured according to ISO 6721); - Mooney viscosity ML(1+4) less than 12 at 100°C (measured according to ASTM-D 1646). - Included in 0.83 and 0.98 g / cm³ 3 Density between (measured according to ISO 1183); - Melting point above 40°C, measured at 20°C / min according to ISO 11357-1, 2009 and ISO 11357-3, 2011.

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

6. The recycled polypropylene composition according to any one of claims 1 to 6, wherein the recycled polypropylene composition comprises at least 50% by weight of component a) and 0.2% to 1.5% by weight of component b).

7. The recycled polypropylene composition according to any one of claims 1 to 6, wherein component a) has a melt flow rate in the range of 5 to 29 g / 10 min (ISO 1133, 230 °C / 2.16 kg).

8. The recycled polypropylene composition according to any one of claims 1 to 7, wherein component a) has a range of 850 N / mm as measured according to ISO 527-2. 2 Up to 1450 N / mm 2 Flexural modulus.

9. The recycled polypropylene composition according to any one of claims 1 to 8, wherein the recycled polypropylene composition comprises: a) At least 30% by weight of recycled polypropylene (r-PP) as described in claim 1. b) 0.1% to 2.0% by weight of cyclic olefin (ring-opening polycyclic olefin) rubber; and c) Less than 70.0% by weight of virgin polypropylene-based polymers, The amounts of a), b) and c) are calculated based on the entire polypropylene composition.

10. The recycled polypropylene composition according to any one of claims 1 to 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 one of claims 1 to 10, wherein component c) is selected from one or more polymers of the group consisting of: propylene homopolymer; propylene-ethylene copolymer having an ethylene-derived unit content ranging from 0.5 wt% to 10.0 wt%; heterogeneous 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 one of claims 1 to 11, wherein in component a), the Charpy impact test, measured at 23°C according to ISO 179-1eA and ISO 1873-2, ranges from 3.4 kJ / m. 2 Up to 9.2 KJ / m 2 .

13. A process for improving the mechanical properties of a recycled polypropylene composition, the process comprising the following steps: i) Provides at least 30% by weight of a recycled polypropylene blend component a) as defined in claims 1 to 12; 0.1% to 2.0% by weight of a cyclic olefin (ring-opening polycyclic olefin) rubber component b) as defined in claims 1 to 12; and optionally 0.05% to 0.5% by weight of a peroxide component c) having a decomposition temperature below 250°C. ii) Melt and extrude the mixture obtained in step i).

14. The process according to claim 13, wherein the peroxide component c) is selected from the group consisting of: di-tert-butyl peroxide, dicumyl peroxide, 2,5-dimethyl-2,5-di(tert-butylperoxy)hexyne and 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane.

15. The process according to any one of claims 13 to 14, wherein the peroxide component c) ranges from 0.05 to 0.20 by weight.

Images