Propylene-based composition fit to be recycled

Abstract

A polypropylene based composition comprising: A) from 40 wt% to 85 wt% of a first heterophasic propylene ethylene copolymer (HECO1) B) from 15 wt% to 60 wt%; of a second heterophasic propylene ethylene copolymer (HECO2) having: i) fraction soluble in xylene at 25°C ranging from 20.0 wt% to 38.0 wt%; ii) the melt flow rate (230°C / 5 kg.. ISO 1133) ranging from 0.2 g / 10min to 4.0 g / 10min; iii) intrinsic viscosity, measured in tetralin, of the fraction soluble in xylene at 25°C ranging from 5.7 dl / g to 9.2 dl / g.

Description

TITLEPropylene-based composition fit to be recycledFIELD OF THE INVENTION

[0001] The present disclosure relates to a polypropylene based composition comprising a first heterophasic propylene ethylene copolymer (HECO1) and a second heterophasic propylene ethylene copolymer (HECO2) fit to be recycled.BACKGROUND OF THE INVENTION

[0002] Propylene polymer ethylene copolymer are already known in the art.It is well known in the art that in order to recycle a propylene based composition the latter has to be melted one or more time. The melting usually worse some mechanical properties so that said recycled composition cannot be used for some applications the requires higher mechanical features or lower melt flow rate. For example EP 4331 800 relates to a process for preparing an article containing at least 30 wt% of a recycled polypropylene composition, based on the total weight of the article comprising a) providing a recycled polypropylene composition comprising an additive package and a propylene based polymer being a Post-Industrial Resin (PIR) or Post-Consumer Resin (PCR); b) melting the recycled polypropylene composition a) and c) recover the final article; wherein the additive package comprises at least one antioxidant and vitamin E. With this process it is possible to use an additive packages limiting the increasing of Melt Flow Rate after several melting cycles.EP 3 036 284 Bl relates to polyolefin compositions comprising two heterophasic propylene polymers which have improved properties such as excellent balance of stiffness, toughness and flowability. Examples IE1-IE5 (table 3) disclose compositions comprising 60-85 wt% of HECO1 and 20-40 wt% of HECO2a (IE1 and IE2) and 15-40 wt% of HECO2b (IE3-IE5).EP 2 902 438 Bl relates to polyolefin compositions comprising two heterophasic propylene polymers which have improved properties such as excellent balance of stiffness, toughness and flowability. Examples IE2 and IE3 of D2 (table 3) disclose compositions comprising 93-95 wt% of HECO1 and 5-7 wt% of HECO2.EP 3 330 315 Bl relates to a polypropylene composition (C) comprising two heterophasic propylene copolymers suitable for the production of foamed articles, Examples IE1-IE4 disclose compositions comprising 42.5-56.5 wt% of HECO1 and 25.5-26.5 wt% of HECO2 (table 2).EP4296306 relates to the use of a clarifying agent is l,2,3-trideoxy-4,6:5,7-bis-0[(4-propylphenyl)methylene] -nonitol (NX8000) to maintain optical properties during the various melting without the need to add further additive and maintain the yellow index at acceptable values.However the applicant found that a particular blend between two heterophasic copolymers can maintain the mechanical properties and the MFR thought several melting passages, so that it can be recycled more than one time for the same application without losing properties.SUMMARY OF THE INVENTION

[0003] Thus an object of the present disclosure is a polypropylene based composition comprising:A) from 40 wt% to 95 wt%; preferably from 50 wt% to 80 wt% more preferably from 60 wt% to 75 wt% of a first heterophasic propylene ethylene copolymer (HECO1) having: al) from 55.0 wt% to 77.0 wt%; preferably from 60.0 wt% to 76.0 wt% more preferably from 65.0 wt% to 74.0 wt% of a propylene homopolymer having a fraction soluble in xylene at 25°C, determined according to ISO 16 152, lower than 3.0 wt% preferably lower than 2.5 wt%;a2) from 7.0 wt% to 45.0 wt%; preferably from 8.0 wt% to 30.0 wt%; more preferably from 9.0 wt% to 20.0 wt% of a copolymer of propylene and ethylene having an amount of recurring units deriving from ethylene ranging from 30.0 wt% to 70.0 wt%, preferably from 35.0 wt% to 60.0 wt%, more preferably from 38.0 wt% to 52.0 wt%;wherein intrinsic viscosity, measured in tetralin, of the fraction soluble in xylene at 25°C of al+a2 ranges from 2.5 dl / g to 5.5 dl / g;; preferably from 2.8 dl / g to 4.5 dl / g; more preferably from 3.2 dl / g to 4.3 dl / g;a3) from 0 wt% to 23 wt%; preferably from 10.0 wt% to 21.0 wt%, more preferably from 15.0 wt% to 20.0 wt% of polyethylene;wherein the sum of wt% of al), a2) and a3) being 100 wt%;B) from 5 wt% to 60 wt%; preferably from 20 wt% to 50 wt% more preferably from 25 wt% to 40. wt% of a second heterophasic propylene ethylene copolymer (HECO2) having: i) fraction soluble in xylene at 25°C ranging from 20.0 wt% to 38.0 wt%; preferably from 22.0 wt% to 36.0 wt%; more preferably from 25.0 wt% to 33.0 wt%;ii) the melt flow rate (230°C / 5 kg.. ISO 1133) ranging from 0.2 g / lOmin to 4.0 g / lOmin; preferably from 0.4 g / lOmin to 3.5 g / lOmin; more preferably from 0.6 g / lOmin to 2.0 g / lOmin;iii) intrinsic viscosity, measured in tetralin, of the fraction soluble in xylene at 25°C ranging from 5.7 dl / g to 9.2 dl / g; preferably from 6.3 dl / g to 8.75 dl / g; more preferably from 6.5 dl / g to 8.2 dl / g;said propylene, ethylene copolymer composition comprising:bl) from 27 wt% to 40 wt%; preferably from 29 wt% to 38 wt%; more preferably from 30 wt% to 36 wt% of a propylene homopolymer having a melt flow rate MFR1 (230°C / 2.16 kg. ISO 1133) ranging from 62.0 g / lOmin to 100.0 g / lOmin; preferably from 68 g / lOmin to 92 g / lOmin; more preferably from 72 g / lOmin to 86 g / 10min;b2) from 27 wt% to 40 wt%; preferably from 29 wt% to 38 wt%; more preferably from 30 wt% to 36 wt% of a propylene homopolymer;wherein the melt flow rate MFR2 (230°C / 2.16 kg. ISO 1133) of bl) + b2) ranges from 3.0 g / lOmin to 15.0 g / lOmin; preferably from 4.0 g / lOmin to 12 g / lOmin; more preferably from 5.2 g / 10min to 10.3 g / 10min;b3) from 20 wt% to 46 wt% preferably from 24 wt% to 42 wt%; more preferably from 28 wt% to 40 wt% of a propylene ethylene copolymer having a content of ethylene derived units ranging from 18.0 wt% to 48.0 wt%; preferably from 22 wt% to 44 wt%; more preferably from 27 wt% to 39 wt%.DETAILED DESCRIPTION OF THE INVENTION

[0004] The term copolymer means a polymer containing only two monomers; preferably propylene and ethylene.

[0005] The polypropylene based composition of the present disclosure can be melted more than one time without losing mechanical properties, this means that the polypropylene based composition of the present disclosure can be recycled more than one time without the need to add compatibilizer and particular additives.

[0006] With the polyolefin composition of the present disclosure it is possible to obtain molded objects such as injection molded articles but also extruded articles such as pipes.

[0007] In component A) component a3) is preferably an homopolymer of ethylene.

[0008] In a further embodiment of the disclosure, the composition of the present disclosure further comprises an inorganic filler agent in an amount ranging from 0.5 to 60 parts by weight with respect to 100 parts by weight of the said composition. Typical examples of such filler agents are calcium carbonate, barium sulphate, titanium bioxide and talc. Talc and calcium carbonate are preferred. A number of filler agents can also have a nucleating effect, such as talc that is also a nucleating agent. The amount of a nucleating agent is typically from 0.2 to 5 wt% with respect to the polymer amount.

[0009] The composition of the disclosure is also suitable for providing pipes with walls of any configuration other than those with smooth inner and outer surface. Examples are pipes with a sandwich-like pipe wall, pipes with a hollow wall construction with longitudinally extending cavities, pipes with a hollow wall construction with spiral cavities, pipes with a smooth inner surface and a compact or hollow, spirally shaped, or an annularly ribbed outer surface, independently of the configuration of the respective pipe ends.

[0010] Articles, pressure pipes and related fittings according to the present disclosure are produced in a manner known per se, e.g. by (co-)extrusion or moulding, for instance.

[0011] Extrusion of articles can be made with different type of extruders for polyolefin, e.g.single or twin screw extruders.

[0012] A further embodiment of the present disclosure is a process wherein the said composition is molded into said articles.

[0013] The composition of the present disclosure can be prepared by blending component A? and B). Component A) and B) can be prepared in a single polymerization process by sequential polymerization steps.

[0014] The polymerization of A) and B) can be carried out in the presence of Ziegler-Natta catalysts. An essential component of said catalysts is a solid catalyst component comprising a titanium compound having at least one titanium-halogen bond, and an electron-donor compound, both supported on a magnesium halide in active form. Another essential component (co-catalyst) is an organoaluminium compound, such as an aluminium alkyl compound.

[0015] An external donor is optionally added.

[0016] The catalysts generally used in the process of the disclosure are capable of producing polypropylene with a value of xylene insolubility at ambient temperature greater than 90%, preferably greater than 95%.

[0017] Catalysts having the above mentioned characteristics are well known in the patent literature; particularly advantageous are the catalysts described in US patent 4,399,054 and European patent 45977. Other examples can be found in US patent 4,472,524.

[0018] The solid catalyst components used in said catalysts comprise, as electron-donors (internal donors), compounds selected from the group consisting of ethers, ketones, lactones, compounds containing N, P and / or S atoms, and esters of mono- and dicarboxylic acids.

[0019] Particularly suitable electron-donor compounds are esters of phtalic acid and 1,3- diethers of formula:

[0020] wherein RI and RII are the same or different and are Cl -Cl 8 alkyl, C3-C18 cycloalkyl or C7-C18 aryl radicals; RIII and RIV are the same or different and are C1-C4 alkyl radicals; or are the 1,3 -di ethers in which the carbon atom in position 2 belongs to a cyclic or polycyclic structure made up of 5, 6, or 7 carbon atoms, or of 5-n or 6-n' carbon atoms, and respectively n nitrogen atoms and n' heteroatoms selected from the group consisting of N, O, S and Si, where n is 1 or 2 and n' is 1, 2, or 3, said structure containing two or three unsaturations (cyclopolyenic structure), and optionally being condensed with other cyclic structures, or substituted with one or more substituents selected from the group consisting of linear or branched alkyl radicals; cycloalkyl, aryl, aralkyl, alkaryl radicals and halogens, or being condensed with other cyclic structures and substituted with one or more of the above mentioned substituents that can also be bonded to the condensed cyclic structures; one or more of the above mentioned alkyl, cycloalkyl, aryl, aralkyl, or alkaryl radicals and the condensed cyclic structures optionally containing one or more heteroatom(s) as substitutes for carbon or hydrogen atoms, or both.

[0021] Ethers of this type are described in published European patent applications 361493 and 728769.

[0022] Representative examples of said diethers are 2-methyl-2-isopropyl-l,3- dimethoxypropane, 2,2-diisobutyl-l,3-dimethoxypropane, 2-isopropyl-2-cyclopentyl-l,3- dimethoxypropane, 2-isopropyl-2-isoamyl-l,3-dimethoxypropane, 9,9-bis (methoxymethyl) fluorene.

[0023] Other suitable electron-donor compounds are phthalic acid esters, such as diisobutyl, dioctyl, diphenyl and benzylbutyl phthalate.

[0024] The preparation of the above mentioned catalyst component is carried out according to various methods.

[0025] For example, a MgC12»nROH adduct (in particular in the form of spheroidal particles) wherein n is generally from 1 to 3 and ROH is ethanol, butanol or isobutanol, is reacted with an excess of TiC14 containing the electron-donor compound. The reaction temperature is generally from 80 to 120° C. The solid is then isolated and reacted once more with TiC14, in the presence or absence of the electron-donor compound, after which it is separated and washed with aliquots of a hydrocarbon until all chlorine ions have disappeared.

[0026] In the solid catalyst component the titanium compound, expressed as Ti, is generally present in an amount from 0.5 to 10% by weight. The quantity of electron-donor compound which remains fixed on the solid catalyst component generally is 5 to 20% by moles with respect to the magnesium dihalide.

[0027] The titanium compounds, which can be used for the preparation of the solid catalyst component, are the halides and the halogen alcoholates of titanium. Titanium tetrachloride is the preferred compound.

[0028] The reactions described above result in the formation of a magnesium halide in active form. Other reactions are known in the literature, which cause the formation of magnesium halide in active form starting from magnesium compounds other than halides, such as magnesium carboxylates.

[0029] The Al-alkyl compounds used as co-catalysts comprise the Al-trialkyls, such as Al- triethyl, Al-triisobutyl, Al-tri-n-butyl, and linear or cyclic Al-alkyl compounds containing two or more Al atoms bonded to each other by way of O or N atoms, or SO4 or SO3 groups.

[0030] The Al-alkyl compound is generally used in such a quantity that the Al / Ti ratio be from 1 to 1000.

[0031] The electron-donor compounds that can be used as external donors include aromatic acid esters such as alkyl benzoates, and in particular silicon compounds containing at least one Si-OR bond, where R is a hydrocarbon radical.

[0032] Examples of silicon compounds are (tert-butyl)2Si(OCH3)2, (cyclohexyl)(methyl)Si (OCH3)2, (cyclopentyl)2Si(OCH3)2 and (phenyl)2Si(OCH3)2 and (1,1,2- trimethylpropyl)Si(OCH3)3.

[0033] 1,3 -diethers having the formulae described above can also be used advantageously. If the internal donor is one of these diethers, the external donors can be omitted.

[0034] In particular, even if many other combinations of the previously said catalyst components may allow to obtain compositions according to the present disclosure, the components A) and B) are preferably prepared by using catalysts containing a phthalate as internal donor and (cyclopentyl)2Si(OCH3)2 as external donor, or the said 1,3-diethers as internal donors.

[0035] A further The Ziegler-Natta catalysts that can be used to produce a propylene polymer of the present disclosure is a solid catalyst component comprising a magnesium halide, a titanium compound having at least a Ti-halogen bond as above described and at least two electron donor compounds selected from succinates and the other being selected from 1,3 diethers.

[0036] However component A) and component B) can be commercial grades.

[0037] The polypropylene based composition of the present disclosure is preferably endowed with one or more of the following features:

[0038] - Melt Flow Rate, determined according to the method ISO 1133 (230° C, 5 kg or 2.16 kg), ranging from 0.2 g / 10 min to 30.0 g / 10 min; preferably from 0.5 g / 10 min to 8.0 g / 10 min;

[0039] Tensile Modulus, determined according to ISO 527-2, ranging from 700 MPa to 1600 Mpa; preferably ranging from 900 MPa to 1400 Mpa;

[0040] - Charpy Impact test measured at 23°C, measured according to ISO 179-1:2010, ranging from 30 KJ / m2to 110 KJ / m2, preferably ranging from 60 KJ / m2to 95 KJ / m2;

[0041] - Charpy Impact test measured at 03°C, measured according to ISO 179-1:2010, ranging from 7 KJ / m2to 30 KJ / m2, preferably ranging from 10 KJ / m2to 20 KJ / m2;

[0042] - Elongation at break: measured according to ISO 527-2, and according to ISO 1873-2 ranging from 200% and 800 %; preferably from 280% and 700%.

[0043] The polypropylene based composition according to the present disclosure can be used for obtaining films and injection molded articles.

[0044] The following examples are given to illustrate the present disclosure without limiting purpose.EXAMPLESCharacterization methodsXylene-soluble (XS) Fraction at 25 °C

[0045] Xylene Solubles at 25°C have been determined according to ISO 16 152.DSC method for melting point

[0046] Melting point has been measured according to ISO 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

[0047] Melt Flow Rate: Determined according to the method ISO 1133 (230° C, 5 kg or 2.16 kg) .Ethylene content in the copolymers

[0048] 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.

[0049] 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 l,l,2,2-tetrachloroethane-<72 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.

[0050] 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 8- titanium trichloride- diethyl-aluminum chloride” M. Kakugo, Y. Naito, K. Mizunuma and T. Miyatake, Macromolecules, 1982, 15, 1150) using the following equations:PPP = 100 Tpp / S PPE = 1OO TP8 / S EPE= 100 T88 / SPEP = 100 SPP / S PEE= 100 SP5 / S EEE = 100 (0.25 SyS+0.5 S88) / S S = TPP + TP8 + T88 + SPP + SpS + 0.25 SyS + 0.5 S88

[0051] The molar percentage of ethylene content was evaluated using the following equation: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

[0052] where P% mol is the molar percentage of propylene content, while MWE and MWP are the molecular weights of ethylene and propylene, respectively. Preparation of injection molded specimens: test specimens 80 x 10 x 4 mm were obtained according to the method ISO 1873-2:2007.Flexural modulus: Determined according to the method ISO 178:2019 on injection molded test specimens.Tensile Modulus: Determined according to ISO 527-2, on injection molded test specimens. Charpy Impact test : measured according to ISO 179-1:2010 on injection molded specimens.Elongation at break: measured according to ISO 527-2, and according to ISO 1873-2 Polydispersity Index (PI): Determined at a temperature of 200°C by using a parallel plates rheometer model RMS-800 marketed by RHEOMETRICS (USA), operating at an oscillation frequency which increases from 0.1 rad / sec to 100 rad / sec. From the crossover modulus one can derive the P.I. by way of the equation:P.I.= 105 / Gc

[0053] 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.

[0054] Component A)

[0055] Component A) has been obtained with a process similar to that one of example 1 of WO 2006 / 125720. The features of component A has been reported on table 1.Table 1Component B)Component B) has been obtained with a process similar to that one of example 4 of WO 2004 / 087805. The features of component B has been reported on table 2.Table 2<<* C2= ethylene derived units

[0056] Component A) (70 wt%) has been blended with 30 wt% component B. The resulting composition has been extruded at 230°C several times The properties of the blend at eachpassage have been measured as reported in table 3. Table 4 reports the results of the same passage of component A) alone.Table 3

[0057] From table 4 clearly result that the impact properties of the blend 1 is higher withr respect to comparative blend 2 and component A alone, while flexural modulus and tensile modulus are the flexural modulus are substantially unchanged.Table 4From table 3 clearly results that the properties of the blend are maintained even if several melting steps have been carried out. On the contrary in table 4 the deterioration of the properties of component A alone are clearly shown.

Claims

CLAIMSWhat is claimed is:

1. A polypropylene based composition comprising:A) from 40 wt% to 95 wt% of a first heterophasic propylene ethylene copolymer (HECO1) having:al) from 55.0 wt% to 77.0 wt% of a propylene homopolymer having a fraction soluble in xylene at 25°C, determined according to ISO 16 152, lower than 3.0 wt%;a2) from 7.0 wt% to 45.0 wt%; of a copolymer of propylene and ethylene having an amount of recurring units deriving from ethylene ranging from 30.0 wt% to 70.0 wt%; wherein intrinsic viscosity, measured in tetralin, of the fraction soluble in xylene at 25°C of al+a2 ranges from 2.5 dl / g to 5.5 dl / g;a3) from 0 wt% to 23 wt%; of polyethylene;wherein the sum of wt% of al), a2) and a3) being 100 wt%;B) from 5 wt% to 60 wt%; of a second heterophasic propylene ethylene copolymer (HECO2) having:i) fraction soluble in xylene at 25°C ranging from 20.0 wt% to 38.0 wt%;ii) the melt flow rate (230°C / 5 kg.. ISO 1133) ranging from 0.2 g / lOmin to 4.0 g / lOmin; iii) intrinsic viscosity, measured in tetralin, of the fraction soluble in xylene at 25°C ranging from 5.7 dl / g to 9.2 dl / g;said propylene, ethylene copolymer composition comprising:bl) from 27 wt% to 40 wt%; of a propylene homopolymer having a melt flow rate MFR1 (230°C / 2.16 kg. ISO 1133) ranging from 62.0 g / lOmin to 100.0 g / lOmin;b2) from 27 wt% to 40 wt%; of a propylene homopolymer;wherein the melt flow rate MFR2 (230°C / 2.16 kg. ISO 1133) of bl) + b2) ranges from 3.0 g / lOminto 15.0 g / 10min;b3) from 20 wt% to 46 wt% of a propylene ethylene copolymer having a content of ethylene derived units ranging from 18.0 wt% to 48.0 wt%;the sum of amounts of bl+b2+b3 being 100 wt%;amounts of A+B being 100 wt%.

2. The polypropylene based composition according to claim 1 wherein component A) ranges from 50 wt% to 80 wt% and component B) ranges from 20 wt% to 50 wt%.

3. The polypropylene based composition according to claims 1 or 2 wherein in component B) bl) ranges 29 wt% to 38 wt%; b2) ranges from 29 wt% to 38 wt%; and component b3) ranges 24 wt% to 42 wt%;3. The polypropylene based composition according to anyone of claims 1-3 wherein in component A) al) ranges from 60.0 wt% to 76.0 wt%; component a2) ranges from 8.0 wt% to 30.0 wt% and component a3 ranges from 10.0 wt% to 21.0 wt%,.

4. The polypropylene based composition according to anyone of claims 1-4 wherein in component A) component a3) is ethylene homopolymer.

5. The polypropylene based composition according to anyone of claims 1-5 wherein in the component B) the intrinsic viscosity, measured in tetralin, of the fraction soluble in xylene at 25 °C ranges from 6.0 dl / g to 8.75 dl / g;6. The polypropylene based composition according to anyone of claims 1-5 wherein in the component B) the fraction soluble in xylene at 25°C ranges from 22.0 wt% to 36.0 wt%.

7. The polypropylene based composition according to anyone of claims 1-6 wherein in the component B) component bl) has the melt flow rate MFR1 (230°C / 2.16 kg. ISO 1133) ranging from 72 g / lOmin to 87 g / lOmin.

8. The polypropylene based composition according to anyone of claims 1-7 wherein in the component B) the melt flow rate MFR2 (230°C / 2.16 kg. ISO 1133) of components bl)+b2) ranges from 4.0 g / lOmin to 12 g / lOmin.

9. The polypropylene based composition according to anyone of claims 1-8 wherein in the component B) component b3) has a content of ethylene derived units ranging from 22 wt% to 44 wt%.

10. The polypropylene based composition according to anyone of claims 1-9 wherein in component A) the intrinsic viscosity, measured in tetralin, of the fraction soluble in xylene at 25°C of al)+a2) ranges from 2.8 dl / g to 4.5 dl / g.

11. The polypropylene based composition according to anyone of claims 1-10 wherein in component A) component a2) has an amount of recurring units deriving from ethylene ranging from 35.0 wt% to 60.0 wt%.

12. The polypropylene based composition according to anyone of claims 1-11 wherein component B) has the fraction soluble in xylene at 25 °C ranging from 25.0 wt% to 33.0 wt%.

14. The polyolefin composition according to anyone of claims 1-13 wherein component B) has the intrinsic viscosity, measured in tetralin, of the fraction soluble in xylene at 25°C ranging from 6.2 dl / g to 8.2 dl / g;15. A film comprising the polyolefin composition of claims 1-14

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