Thermoplastic composition

Abstract

The present invention relates to a thermoplastic composition comprising polypropylene, polyethylene and a compatibiliser, wherein said compatibiliser is a random copolymer of ethylene and at least one branched α-olefin.

Description

[0001] 24POLY0105-WO-ORD 1

[0002] THERMOPLASTIC COMPOSITION

[0003] The present invention relates to a thermoplastic composition comprising polypropylene, polyethylene and a compatibiliser.

[0004] Compositions of polypropylene and polyethylene are desirable as they potentially allow tuning of the material properties by selecting the type and amounts of the individual components. However, it is well known that polyethylene and polypropylene are immiscible. It is further a disadvantage that polypropylene and polyethylene substantially do not interact so that a blend of polyethylene and polypropylene generally results in a two-phase system having a polypropylene phase and a polyethylene phase with poor physical properties.

[0005] Accordingly attempts have been made to increase the interaction between the phases in such blends by adding a compatibiliser. Compatibilisers are materials that have affinity with both phases and enhance the bonding strength. As a result, a material with improved properties can be obtained.

[0006] Blends of polypropylene and polyethylene comprising a compatibiliser are known in the art. For example, US 6,114,443 discloses a composition comprising a blend of polyethylene and an isotactic poly-alpha-olefin homopolymer (such as polypropylene), together with a diblock copolymer compatibiliser of polyethylene block and an atactic poly-alpha-olefin block. The diblock compatibiliser of this US patent may be prepared using sequential polymerisation of the monomers for each block in the presence of a metallocene catalyst. Furthermore, Science 2017, (355), 814-816 discloses the use of polyethylene-polypropylene multiblock copolymers as compatibilisers for polyethylene / polypropylene blends. As the abovementioned diblock copolymer, these multiblock copolymers may be prepared using sequential polymerisation of the monomers for each block in the presence of a single-site catalyst. The disadvantage of these di- or multiblock copolymers is their complex synthesis, which makes them difficult to be produced in an economically viable industrial scale process.

[0007] WO2016 / 188817 discloses a composition comprising polypropylene, polyethylene and a compatibiliser, wherein said compatibiliser is a non-aromatic polyester having an 24POLY0105-WO-ORD 2 average M / E ratio of at least 10, wherein M is the number of backbone carbon atoms in the polyester not including the carbonyl carbons and E is the number of ester groups in the polyester. In that disclosure the non-aromatic polyester is used as a compatibiliser leading to a polyethylene and polypropylene blend wherein there is a more gradual transition between the polypropylene and polyethylene phases in the blend.

[0008] Branched a-olefins are a-olefins (CH2=CHR) having a branched hydrocarbyl substituent (R). branched a-olefins, such as for example 4-methylpent-1-ene can for example be manufactured by the (co)-dimerization or trimerization of ethylene and / or a-olefins.

[0009] Accordingly, the manufacture of these kind of branched a-olefins may be integrated in existing (poly)olefin manufacturing complexes.

[0010] An advantage is first of all that such a-olefins do not contain oxygen or other heteroatoms and secondly they can be co-polymerised with ethylene using, optionally modified, existing manufacturing units. Depending on the comonomer content and the effect thereof on the molecular structure of the copolymer, the resulting copolymer may have parts of polymer chains that are able to crystallise with one-another or with polyethylene chains and further have parts that are not able to crystallise but will be of such a structure that these are compatible with the amorphous phase of a polypropylene.

[0011] Based on these advantages and technical considerations the present inventors found that certain copolymers of ethylene and branched a-olefins are capable of acting as a compatibiliser in a thermoplastic composition comprising otherwise substantially incompatible polyethylene and polypropylene.

[0012] Accordingly, the present invention is directed at a thermoplastic composition comprising polypropylene, polyethylene and a compatibiliser, wherein said compatibiliser is a random copolymer of ethylene and at least one branched a-olefin, wherein the amount of a-olefin in the random copolymer is between 0.1 and 10 mol%, preferably 0.2 and 5 mol%.

[0013] In particular the present invention is directed at a thermoplastic composition comprising polypropylene, polyethylene and a compatibiliser, wherein said compatibiliser is a random copolymer of ethylene and at least one branched a-olefin, wherein the amount 24POLY0105-WO-ORD 3 of a-olefin in the random copolymer is from 0.1 - 10 mol%, preferably 0.2 - 5 mol% and wherein the branched a-olefin is selected from the group consisting of 3-methylbut-1- ene, 3-methylpent-1-ene, vinylcyclobutene, 4-methylpent-1-ene, 4-methylhex-1-ene, vinylcyclohexane and mixtures of two or more of the foregoing.

[0014] The present inventors have found that a random copolymer of ethylene and at least one branched a-olefin shows a compatibilising effect when used in relatively low amounts in thermoplastic compositions comprising polypropylene and polyethylene. The present inventors in particular observed that these copolymers may, at least in part, co-crystallise with the polyethylene crystals in the polyethylene phase, and / or may crystallise epitaxially onto polyethylene crystals in the polyethylene phase. At the same time the parts of the copolymer that are not able to form crystals, due to the presence of the branched and bulky comonomer, appear to be compatible with the amorphous phase of the polypropylene. In line with these observations the present inventors conceived that the properties of the polyethylene - polypropylene blend are improved by addition of a relatively small amount of the compatibiliser as herein defined. This finding is quite surprising given that polyethylene and polypropylene generally do not, or at least not significantly interact.

[0015] Random copolymer of ethylene and branched comonomer

[0016] The compatibiliser should be a random copolymer of ethylene and the branched a-olefin. Random copolymers are known to the skilled person per se and typically the copolymer will have a random distribution of the comonomer over the polymer chain. In a specific embodiment, however, the random copolymer may be gradient copolymer, which is considered as a specific type of random copolymer. Gradient copolymers are known to the skilled person per se, as are their methods of manufacture. While the comonomer distribution is still considered as random, the distribution in gradient copolymers is such that the comonomer content one side of the chain increases compared to the comonomer content on the other side of the chain. Gradient copolymers however are distinctly different from block-copolymers. That is, the random copolymer of ethylene and at least one branched a-olefin is not a block copolymer.

[0017] The amount of comonomer, i.e. the branched a-olefin, in the compatibiliser copolymer is at most 10 mol% and more particularly from 0.1 - 10 mol%, preferably from 0.2 - 5 mol%. 24POLY0105-WO-ORD 4

[0018] The lower the amount of branched a-olefin, the better the copolymer can crystallise with polyethylene. Accordingly, compatibilisers with a relatively high content of branched a- olefin may have a higher affinity for polypropylene. Furthermore, the molecular weight of the random copolymer might also affect the affinity for each of the polyethylene and polypropylene phases of the blend. Either way, the amount of comonomer, and to a certain extent the molecular weight, can be used to fine tune the compatibilisation effect.

[0019] The comonomer preferably has the structure I, II, II, or IV.

[0020] (I)

[0021] (II)

[0022] (HI)

[0023] (IV) wherein

[0024] R, R’, R” are linear, branched or cyclic alkyl groups of 1 - 10 carbons and R and R’ or R’ and R” may form a cyclic alkyl ring structure of 3 - 10 carbons.

[0025] Preferably the branched a-olefin, i.e. the comonomer, is selected from the group consisting of 3-methylbut-1-ene, 3-methylpent-1-ene, vinylcyclobutene, 4-methylpent-1- ene, 4-methylhex-1-ene, vinylcyclohexane and mixtures of two or more of the foregoing. The branched a-olefin is most preferably 4-methylpent-1-ene or vinylcyclohexane. The branched a-olefin preferably does not comprise or consist of 4-ethylhex-1-ene. 24POLY0105-WO-ORD 5

[0026] The molecular weight of the compatibiliser copolymer may vary and is generally selected such that a material is obtained that can be blended with the polyethylene and polypropylene relatively easily. For example, the number average molecular weight ( / Wn) is preferably from 5000 to 250,000 g / mol, more preferably from 50,000 to 500,000 g / mol, even more preferably from 100,000 to 250,000 g / mol, said number average molecular weight being determined as the polyethylene-equivalent molecular weight by high temperature size exclusion chromatography performed at 150°C in 1 ,2-dichlorobenzene using polystyrene as standard.

[0027] The copolymer may be manufactured by known gas-phase or solution processes using heterogeneous Ziegler-Natta or supported or homogeneous single-site olefin polymerization catalysts.

[0028] The polyethylene in the thermoplastic composition according to the present invention may be a very low density polyethylene (VLDPE), linear low density polyethylene (LLDPE), low density polyethylene (LDPE), medium density polyethylene (MDPE), high density polyethylene (HDPE), preferably HDPE. The polyethylene may also be a mixture of at least two or at least two types of the foregoing polyethylenes. For example the polyethylene may be a mixture of LLDPE and LDPE or it may be a mixture of two different types of LDPE.

[0029] The terms VLDPE, LDPE, LLDPE, MDPE and HDPE are known in the art. Very low density polyethylene (VLDPE) generally means polyethylene with a density of less than 915 kg / m3. Linear low density polyethylene and low density polyethylene means polyethylene with a density of from 915 to 935 kg / m3. High density polyethylene means polyethylene with a density of more than 935 kg / m3.

[0030] Preferably the melt flow rate of the polyethylene is from 0.1 - 100 g / 10 min as measured in accordance with ISO 1133 (2.16 kg, 190°C).

[0031] The polypropylene in the thermoplastic composition may be:

[0032] - one or more of a propylene homopolymer, 24POLY0105-WO-ORD 6

[0033] - one or more of a propylene - ethylene or a propylene - a-olefin random copolymer, preferably a propylene - ethylene or a propylene - C4- C8a-olefin random copolymer,

[0034] - one or more of a propylene - a-olefin block copolymer,

[0035] - one or more of a heterophasic polypropylene copolymer comprising a matrix phase and a disperse phase, the matrix phase consisting of a propylene homopolymer and / or a propylene copolymer with up to 3 wt.% of ethylene and / or at least one C4- C8a-olefin, the wt.% being based on the matrix phase, and the disperse phase consisting of an ethylene - C3- C8a-olefin copolymer, a mixture of any of the foregoing polypropylenes.

[0036] While it is essential that the polypropylene is at least partially amorphous the polypropylene may have a very low or no crystallinity. Isotactic polypropylene is preferred.

[0037] If the polypropylene is a heterophasic copolymer it is preferred that the matrix phase consists of a propylene homopolymer or a propylene - ethylene copolymer with up to 3 wt.% of ethylene and further that the disperse phase consists of an ethylene propylene copolymer with from 20 - 80 wt.% of propylene and 80 - 20 wt.% of ethylene, the wt.% based on the disperse phase. For the avoidance of doubt the term consisting in the context of the heterophasic copolymers means that no other polymers apart from the polymers making up the matrix and disperse phase are present. The matrix and / or disperse phase may contain minor amounts of other components such as in particular anti-oxidants, light stabilisers, UV stabilisers and the like. Such components are present in an amount of at most 3 wt.%, at most 2 wt.% more preferably at most 1 wt.% based on the weight of the heterophasic copolymer.

[0038] The polypropylene is preferably a propylene homopolymer or a propylene - ethylene or a propylene - C4- C8a-olefin random copolymer. The random copolymer contains at most 5 wt.%, on the basis of the copolymer, of said ethylene or a-olefin. The random copolymer is preferably a propylene - ethylene random copolymer. 24POLY0105-WO-ORD 7

[0039] Preferably the melt flow rate of the polypropylene is from 0.1 - 100 g / 10 min as measured in accordance with ISO 1133 (2.16 kg, 230 °C). More preferably the melt flow rate is from 5.0 to 60 g / 10 min.

[0040] The amounts of polypropylene and polyethylene in the thermoplastic composition may vary within wide limits. The amount of polypropylene may vary from 5 - 95 wt.% on the basis of the total amount of polyethylene and polypropylene. Preferably the amount of polypropylene is from 20 - 90 wt.%, 40 - 90 wt.%, 50 - 90 wt.% on the basis of the total amount of polyethylene and polypropylene. More preferably the amount of polypropylene is from 50 - 95 wt.%, more preferably 75 - 95 wt.%, more preferably 80 - 95 wt.% on the basis of the total amount of polyethylene and polypropylene.

[0041] Accordingly, the amount of polyethylene may vary from 95 - 5 wt.% on the basis of the total amount of polyethylene and polypropylene. Preferably the amount of polyethylene is from 80 - 10 wt.%, 60 - 10 wt.%, 50 - 10 wt.% on the basis of the total amount of polyethylene and polypropylene. In an embodiment the amount of polypropylene is from 60 - 90 wt.% and the amount of polyethylene from 40 - 10 wt.% on the basis of the total amount of polyethylene and polypropylene. It is preferred that the amount of polyethylene is from 5 - 50 wt.%, more preferably 5 - 25 wt.%, more preferably 5 - 20 wt.% on the basis of the total amount of polyethylene and polypropylene.

[0042] The thermoplastic composition preferably comprises a combined amount of polyethylene and polypropylene of at least 70 wt.%, preferably at least 80 wt.%, more preferably at least 90 wt.% based on the weight of the thermoplastic composition.

[0043] The amount of compatibiliser is preferably from 0.5 - 10 wt.%, preferably from 1 - 5 wt.% based on the weight of the thermoplastic composition. The amount of compatibiliser may be from 1 - 3 wt.%.

[0044] In accordance with the invention the polypropylene preferably comprises an amorphous portion and the polyethylene comprises a crystalline portion. 24POLY0105-WO-ORD 8

[0045] The polypropylene and or polyethylene may comprise or consist of mechanically recycled polypropylene and / or polyethylene respectively.

[0046] The thermoplastic composition of the present invention preferably comprises, based on the weight of the thermoplastic composition, (A) polypropylene, (B) polyethylene, (C) from 0.5 - 10 wt.% of the compatibiliser and (D) from 0 - 5 wt.% of optional further components, wherein the total amount of components (A), (B), (C) and (D) is 100 wt.%. The preferred features with regards to these components in the thermoplastic composition are as set out herein.

[0047] The thermoplastic composition in accordance with the invention preferably comprises an amount of components (D) from 0 - 3 wt.%, preferably from 0 - 2 wt.%.

[0048] The optional components (D) typically comprise one or more commonly used additives for polymer compositions such as anti-oxidants, inorganic fillers, UV stabilisers, mould release agents, flame retardants, colorants and the like.

[0049] Typically the component (D) does not comprise a polymer component other than optionally poly-tetrafluoro-ethylene as an anti-drip agent and / or or polymeric flame retardants.

[0050] The melt flow rates of the compatibiliser, polypropylene and polyethylene are selected such that homogeneous blends can be prepared using common melt blending techniques, such as extrusion or internal mixing. In this respect a homogeneous blend means a blend wherein the polyethylene and polypropylene concentrations are distributed throughout the material essentially evenly, while noting that the polyethylene may form a disperse phase in the polypropylene matrix or vice versa. The compatibiliser needs to have a melt flow such that during the melt processing of the thermoplastic composition the compatibiliser can migrate, at least in part, to the interface of the polyethylene and polypropylene phase.

[0051] A preferred method of manufacture of the thermoplastic composition comprises the steps of 24POLY0105-WO-ORD 9

[0052] Preparing a masterbatch by melt mixing the polymer that will form the disperse phase in the thermoplastic composition and the compatibiliser,

[0053] Melt mixing the masterbatch so obtained with the polymer that will form the matrix phase in the thermoplastic composition.

[0054] In this method it is preferred that a major part, preferably substantially all, of the compatibiliser is contained in the masterbatch and that a minor part, preferably substantially none, of compatibiliser is added during the melt mixing so as to form the thermoplastic composition. That is, during the step of preparing the masterbatch from 80 - 100% of the total amount of compatibiliser (in the final thermoplastic composition) is added to the masterbatch and 0 - 20% of the total amount of compatibiliser is added during the step of preparing the thermoplastic composition from the masterbatch and the polymer that will form the matrix phase in the thermoplastic composition.

[0055] This method has the advantage that the compatibiliser is more effective resulting in optimised properties of the thermoplastic composition.

[0056] The melt flow rate of the compatibiliser is preferably similar to the melt flow rate of the polymer forming the disperse phase. For example the ratio of melt flow rate of the polymer forming the disperse phase and the compatibiliser may be from 0.05 - 50, more preferably from 0.1 - 10 even more preferably from 0.5 - 5, when measured under similar conditions. Likewise the ratio of melt flow rate of the polypropylene an the melt flow rate of the polyethylene may be from 0.05 - 50, more preferably from 0.1 - 10 even more preferably from 0.5 - 5, when measured under similar conditions.

[0057] The amount of compatibiliser is from 0.1 - 10 wt.%, preferably from 0.5 - 10 wt.% such as from 2 - 10 wt.% or 3 - 8 wt.% on the basis of the sum of the amount of polypropylene, polyethylene and compatibiliser or alternatively on the basis of the thermoplastic composition when comprising at most 5 wt.% of optional further components (D).

[0058] The present invention further relates to a compound comprising the thermoplastic composition as disclosed herein and at least one inorganic filler and / or at least one impact modifier and / or at least one flame retardant. The amount of inorganic filler in the compound is preferably from 1 - 40 wt.% based on the weight of the compound and 24POLY0105-WO-ORD 10 preferably selected from the group consisting of talc, mica, clay, glass fibers, glass flakes, glass beads. The amount of impact modifier is preferably from 1 - 40 wt.%, based on the weight of the compound, and preferably the impact modifier is selected from one or more of an ethylene -a-olefin elastomer, such as ethylene - propylene, ethylene - butene, ethylene - hexene, ethylene - octene elastomer or ethylene-propylene-diene elastomer. Flame retardants may be present in the compound in an amount of 10 - 30 wt.%, based on the weight of the compound.

[0059] Articles

[0060] The present invention further relates to articles comprising or consisting of the thermoplastic composition or the compound as disclosed herein. Generally the thermoplastic composition is converted into an article using a moulding technique such as injection moulding, extrusion moulding, blow moulding and compression moulding. Accordingly the present invention also relates to an article obtained by moulding the thermoplastic composition or compound according to the present invention. It is also possible to manufacture profiles, tubes or pipes by means of profile, tube or pipe extrusion.

[0061] Articles may be automotive interior articles, automotive exterior articles, household appliances, pipes, films, sheets, containers, water containers, infuse bags.

[0062] Use

[0063] In another aspect the present invention relates to the use of the copolymer of ethylene and branched a-olefin as disclosed herein as a compatibiliser in a thermoplastic composition comprising or consisting of polyethylene and polypropylene. The preferred embodiments as set out herein for the thermoplastic composition likewise apply to this use.

[0064] In yet a further aspect the present invention relates to the use of the random copolymer of ethylene and at least one branched a-olefin as a compatibiliser, and as disclosed herein in all its aspects, in a thermoplastic composition comprising polypropylene and polyethylene for improving the strain at break as determined in accordance with ISO 527- 24POLY0105-WO-ORD 11

[0065] 3 in comparison with an otherwise identical thermoplastic composition not containing said compatibiliser.

[0066] EXAM PLES

[0067] The present invention will be described in greater detail with specific examples. The following examples are offered for illustrative purposes only and are not intended to limit the invention in any manner. The evaluation parameters were determined in accordance with the methodology provided below.

[0068] The synthesis of compatibilisers according to the invention was carried out in batch mode in a 2 L stainless-steel Buchi reactor. Prior to the polymerization, the reactor was dried in vacuo at 100 °C and flushed with nitrogen three times.

[0069] As a selected example (Table 1 , sample 4M1 P), heptane (1.0 L) was introduced to the reactor followed by TEA (3.0 mL, 1 .0 M solution in toluene, 3.0 mmol) and 4-methyl-pent- 1-ene (51 .0 mL, neat, 400.0 mmol). The reactor was subsequently charged with ethylene (35 g) and the reactor was heated to 115 °C. After the temperature and pressure stabilized, the reaction was started by injection a mixture of the catalyst precursor {CH2[CH(Me)O-C6H4-2-(2-NCi2H8)-4-Me-C6H2O]2}HfMe2 (0.3 mg; 0.3 pmol; in 15 mL toluene) and MAO (0.33 mL; 150 pmol; 3 wt% in toluene) into the stirred (600 rpm) reactor. The polymerization reaction was followed by monitoring the pressure drop (batch mode). The reaction was terminated when the ethylene conversion was over 40 % by discharging the reactor using a bottom valve and quenching the reactor mixture in acidified isopropanol (2.5 vol% of hydrochloric acid 37 %). Subsequently, the polymer was filtrated, treated with Irganox 1010 (5 mL, 5 mM in acetone, 25 pmol) and dried under reduced pressure at 70 °C for 24 h.

[0070] Peak melting temperature (Tm): the peak melting temperature was determined using Differential Scanning Calorimetry (DSC) in accordance with ASTM D3418-15. Using a nitrogen purge gas at a flow rate of 50 ± 5 mL / min, two heating and cooling cycles between -40 °C to 230 °C and a heating and cooling rate of 10 °C / min were used. The peak melting temperature was determined using the second heating cycle. For the measurement, 3-6 mg samples were used. 24POLY0105-WO-ORD 12

[0071] Crystallization temperature (Tc): the crystallization temperature was determined using Differential Scanning Calorimetry (DSC) in accordance with ASTM D3418-15. Using a nitrogen purge gas at a flow rate of 50 ± 5 mL / min, two heating and cooling cycles between -40 °C to 230 °C and a heating and cooling rate of 10 °C / min were used. The crystallization temperature was determined using the second cooling cycle. For the measurement, 3-6 mg samples were used.

[0072] Level of crystallinity (Xc): determined by differential scanning calorimetry (DSC) in accordance with ASTM D3418-15. The Crystallinity (Xc) content was determined by comparing the enthalpies of melting transition (2t / - / m) of the sample with melting transition of the fully crystalline HDPE ( 1 / - / m(HDPE) = 293 J / g) and fully crystalline PP (2t / - / m(pp) = 207 J / g).

[0073] Weight average molecular weight ( / Ww) and Number average molecular weight (Mn): is determined in accordance with ASTM D6474-12. SEC measurements were performed at 150 °C on a Polymer Char GPC-IR® built around an Agilent GC oven model 7890, equipped with an autosampler and the Integrated Detector IR4. 1 ,2-Dichlorobenzene (o- DCB) was used as an eluent at a flow rate of 1 mL / min. The data were processed using Calculations Software GPC One®. The molecular weights ( / Wn, Mw) were calculated with respect to polystyrene (PS) standards.

[0074] Polydispersity Index (£)): £) is calculated by dividing the weight average molecular weight (Mw) by the number average molecular weight ( / Wn) and wherein each of / Wwand Mnare measured in accordance with ASTM D6474-12.

[0075] Yield Stress (aY), Stress at Break (ab) and Elongation at break (eb): Tensile tests were performed using a Zwick type Z020 tensile tester equipped with a 1.0 kN load cell according to ISO 527-3 standard (specimen type B5). A grip-to-grip separation of 15 mm was used. The samples were pre-stressed to 3 N, then loaded with a constant crosshead speed 15 mm / min. Young Modulus was estimated with a constant crosshead speed of 1 mm / min. The reported values are an average of at least 5 to 10 measurements of each composition. 24POLY0105-WO-ORD 13

[0076] The film samples were prepared via compression-molding on a LabEcon 600 high- temperature press (Fontijne Presses, the Netherlands). The following compressionmolding cycle was applied: heating to 190 °C, stabilizing for 5 min with no force applied, 5 min with 100 kN normal force and followed by cooling to 40 °C with 10 °C / min and 100 kN normal force.

[0077] The results from the test analysis are provided Table 1 .

[0078] Table 1

[0079] C2-4M1 P = poly(ethylene-co-4-methyl-1-pentene)

Claims

24POLY0105-WO-ORD 14C L A I M S1. Thermoplastic composition comprising polypropylene, polyethylene and a compatibiliser, wherein said compatibiliser is a random copolymer of ethylene and at least one branched a-olefin, wherein the amount of branched a-olefin in the random copolymer is from 0.1 - 10 mol%, preferably 0.2 - 5 mol%.

2. The composition of claim 1 wherein the branched a-olefin in the random copolymer has the structure I, II, II, or IV.(I)(II)(HI)(IV)wherein R, R’, R” are linear, branched or cyclic alkyl groups having 1 - 10 carbon atoms and / or R and R’ or R’ and R” form a cyclic alkyl ring structure having 3 - 10 carbon atoms.

3. The thermoplastic composition of claim 1 or 2 wherein the branched a-olefin is selected from the group consisting of 3-methylbut-1-ene, 3-methylpent-1-ene,24POLY0105-WO-ORD 15 vinylcyclobutene, 4-methylpent-1-ene, 4-methylhex-1-ene, vinylcyclohexane and mixtures of two or more of the foregoing.

4. The thermoplastic composition of any one or more of claims 1 - 3 wherein the branched a-olefin does not comprise or does not consist of 4-ethylhex-1-ene.

5. The thermoplastic composition of any one or more of claims 1 - 4 wherein the amount of polypropylene is from 5 - 95 wt.% on the basis of the total amount of polyethylene and polypropylene.

6. The thermoplastic composition of any one or more of claims 1 - 5 wherein the amount of polypropylene is from 50 - 95 wt.%, more preferably 75 - 95 wt.%, more preferably 80 - 95 wt.% on the basis of the total amount of polyethylene and polypropylene.

7. The thermoplastic composition of any one or more of claims 1 - 6 wherein the amount of compatibiliser is from 0.5 - 10 wt.%, preferably from 1 - 5 wt.% on the basis of the sum of the amount of polypropylene, polyethylene and compatibiliser.

8. The thermoplastic composition of any one or more of claims 1 - 7 wherein said polypropylene comprises an amorphous portion and said polyethylene comprises a crystalline portion.

9. Thermoplastic compound comprising the thermoplastic composition of any one or more of claims 1 - 8 and at least one inorganic filler and / or at least one impact modifier and / or at least one flame retardant.

10. The compound of claim 9 wherein the amount of inorganic filler is from 1 - 40 wt.% based on the weight of the compound and preferably selected from the group consisting of talc, mica, clay, glass fibres, glass flakes, glass beads.11 . The compound of claim 9 or 10 wherein the amount of impact modifier is from 1 - 40 wt.%, based on the weight of the compound, and preferably the impact modifier is selected from one or more of an ethylene elastomer, ethylene-propylene elastomer or ethylene-propylene-diene elastomer.24POLY0105-WO-ORD 1612. An article, preferably a moulded article, comprising or consisting of the thermoplastic composition of any one or more of claims 1 - 8 or the compound of one or more of claims 9 - 10.

13. The article of claim 12, said article being selected from the group consisting of hard packaging material such as bottles, containers and cups, automotive interior articles, automotive exterior articles, household appliances and pipes.

14. Use of a random copolymer of ethylene and at least one branched a-olefin as a compatibiliser in a thermoplastic composition comprising polypropylene and polyethylene.

15. Use of a random copolymer of ethylene and at least one branched a-olefin as a compatibiliser in a thermoplastic composition comprising polypropylene and polyethylene for improving the strain at break as determined in accordance with ISO 527-3 in comparison with an otherwise identical thermoplastic composition not containing said compatibiliser.

Images