Polymer composition with improved haze

Abstract

The present invention relates to a polymer composition comprising a random propylene copolymer, wherein the random propylene copolymer has • - an MFR in the range of 1 to 80 g / lOmin as measured according to ISO1133 at 230°C, 2.16kg; • - a comonomer content in the range of 1.5-4.5 wt% basing on the total amount of the random propylene copolymer, wherein the comonomer is moiety derived from a group consisting of ethylene, 1-butene, 1-hexene and combination thereof; • - a Crystex soluble part of at most 7 basing on the total amount of the random propylene copolymer, said polymer composition has improved blooming performance.

Description

[0001] Polymer composition with improved haze

[0002] The present invention relates to a polymer composition comprising a random propylene copolymer and a clarifier. The present invention further relates to the process for the preparation of the polymer composition and an article comprising said composition.

[0003] A polymer composition comprising a random propylene copolymer and a clarifier is widely used in the industry for applications requiring low haze and / or good transparency. It is known that the haze value of random propylene copolymer increases over time after forming, this phenomena is called blooming. Although the haze can be reduced by e.g. increasing the comonomer content in the random propylene copolymer of the polymer composition, such modification may not be desirable for the deterioration of other properties, e.g. stiffness of the polymer composition by increasing the comonomer content.

[0004] Hence there is still a need to have a polymer composition with lower initial haze value and a lower increase of haze over time.

[0005] The inventers of the present invention surprisingly found that the said need is satisfied by a polymer composition comprising a random propylene copolymer, wherein the random propylene copolymer has an MFR in the range of 1 to 80 g / 1 Omin as measured according to ISO1133 at 230°C, 2.16kg; a comonomer content in the range of 1 .5-4.5 wt% basing on the total amount of the random propylene copolymer, wherein the comonomer is moitie derived from a group consisting of ethylene, 1 -butene, 1 -hexene and combination thereof; a Cystex soluble part of at most 7 basing on the total amount of the random propylene copolymer, Random propylene copolymer

[0006] The random propylene copolymer according to the invention has an MFR in the range of 1 to 80 g / 1 Omin as measured according to ISO1133 at 230°C, 2.16kg; a comonomer content in the range of 1 .5-4.5 wt% basing on the total amount of the random propylene copolymer, wherein the comonomer is moiety derived from a group consisting of ethylene, 1 -butene, 1 -hexene and combination thereof; a Cystex soluble part of at most 7 basing on the total amount of the random propylene copolymer.

[0007] Preferably the Crystex soluble part of the random propylene copolymer is in the range from 3.7 to 6.9 wt%, preferably in the range from 4.6 to 6.9 wt%, even more preferably in the range from 5.1 to 6.8 wt% basing on the total amount of the random propylene copolymer.

[0008] Preferably the MFR of the random propylene copolymer is in the range from 1 to 60 g / 1 Omin, preferably from 1 to 50 g / 1 Omin as measured according to ISO1133 at 230°C, 2.16kg.

[0009] Preferably the conomoner content of the random propylene copolymer is in the range from 2.0 to 4.2 wt%, preferably from 2.5 to 4.2 wt%, even more preferably from 3.0 to 4.1 wt% most preferably from 3.3 to 4.1 wt% basing on the total amount of the random propylene copolymer.

[0010] Preferably the comonomer is moiety derived from ethylene.

[0011] Process for the preparation of the random propylene copolymer

[0012] The person skilled in the art is aware of how to prepare a random propylene copolymer. The preparation of a random propylene copolymer is for example described in Moore, E. P. (1996) Polypropylene Handbook. Polymerization, Characterization, Properties, Processing, Applications, Hanser Publishers: New York.

[0013] Catalyst

[0014] The random propylene copolymer is produced in a process comprises the step of polymerizing propylene and ethylene comonomers in the presence of a catalyst in a gas phase. The catalyst used for the preparation for the polypropylene composition according to the invention is preferably the catalyst described in detail in WO2021 / 063930, incorporated herein by reference. The catalyst preferably comprises a procatalyst, a cocatalyst and optionally an external electron donor.

[0015] The procatalyst is obtainable by a process comprising contacting a magnesium- containing support with a halogen-containing titanium compound, and an internal electron donor according to Formula I:

[0016] Formula I wherein R1is a secondary alkyl group and R2is a non-secondary alkyl group having at least 5 carbon atoms, preferably R2is a non-secondary alkyl group having at least 5 carbon atoms and being branched at the 3-position or further positions.

[0017] The process for providing said procatalyst follow the one describe in W02021 / 063930A1 (which in incorporated by reference) and comprises the steps of: i) contacting a compound R4zMgX42-z with an alkoxy- or aryloxy-containing silane compound to give a first intermediate reaction product, being a solid Mg(0Ra)xX12-x, wherein: Rais a linear, branched or cyclic hydrocarbyl group independently selected from alkyl, alkenyl, aryl, aralkyl, alkoxycarbonyl or alkylaryl groups, and one or more combinations thereof; wherein said hydrocarbyl group may be substituted or unsubstituted, may contain one or more heteroatoms and preferably has from 1 to 20 carbon atoms; wherein R4is a linear, branched or cyclic hydrocarbyl group independently selected from alkyl, alkenyl, aryl, aralkyl, alkoxycarbonyl or alkylaryl groups, and one or more combinations thereof; wherein said hydrocarbyl group may be substituted or unsubstituted, may contain one or more heteroatoms and preferably has from 1 to 20 carbon atoms, preferably R4is butyl; wherein X4and X1are each independently selected from the group of consisting of fluoride (F-), chloride (Cl—), bromide (Br-) or iodide (I-), preferably chloride; z is in a range of larger than 0 and smaller than 2, being 0 < z < 2, x is an integer between 0 and 2; ii) optionally contacting the solid Mg(ORa)xX12-x obtained in step i) with at least one activating compound selected from the group formed by activating electron donors and metal alkoxide compounds of formula M1(0Rb)v-w(0R3)w or M2(ORb)v-w(R3)w, to obtain a second intermediate product; wherein: M1is a metal selected from the group consisting of Ti, Zr, Hf, Al or Si; v is the valency of M1; M2is a metal being Si; v is the valency of M2; Rband R3are each a linear, branched or cyclic hydrocarbyl group independently selected from alkyl, alkenyl, aryl, aralkyl, alkoxycarbonyl or alkylaryl groups, and one or more combinations thereof; wherein said hydrocarbyl group may be substituted or unsubstituted, may contain one or more heteroatoms, and preferably has from 1 to 20 carbon atoms; wherein w is smaller than v, preferably v being 3 or 4; iii) contacting the first or second intermediate reaction product, obtained respectively in step i) or ii), with a halogen-containing Ti-compound and said compound represented Formula I, as the internal electron donor.

[0018] In an embodiment, during step ii) as activating compounds an alcohol is used as activating electron donor and titanium tetraalkoxide is used as metal alkoxide compound.

[0019] In an embodiment, an activator is present in the process for providing said procatalyst. In an embodiment, said activator is ethyl benzoate. In an embodiment, said activator is a benzamide according to formula X:

[0020] Formula X wherein R70and R71are each independently selected from hydrogen or an alkyl, and R72, R73, R74, R75, R76are each independently selected from hydrogen, a heteroatom or a hydrocarbyl group, preferably selected from alkyl, alkenyl, aryl, aralkyl, alkoxycarbonyl or alkylaryl groups, and one or more combinations thereof, more preferably wherein R70and R71are both methyl and wherein R72, R73, R74, and R75are all hydrogen, being N,N’- dimethylbenzamide (Ba-2Me).

[0021] Preferably, the internal electron donor used is according to Formula I:

[0022] Formula I wherein R1is a secondary alkyl group having at least three carbon atoms and R2is a nonsecondary alkyl group having at least 5 carbon atoms, preferably R1et R2is having at most seven carbon atoms, preferably at most six carbon atoms , preferably iso-propyl, iso-butyl, iso-pentyl, cyclopentyl, n-pentyl, and iso-hexyl, preferably R2is being branched at the 3-position or further positions.

[0023] In another embodiment, the internal electron donor is 3,3-bis(methoxymethyl)-2,6- dimethyl heptane, according to Formula I wherein R1 is iso-propyl being secondary alkyl and R2 is iso-pentyl being non-secondary and having a branch on the third carbon atom (abbreviated as iPiPen, wherein iP stands for iso-propyl and iPen stands for iso-pentyl, also known as 3-methyl-butyl). This compound iPiPen has a chemical formula of C13H28O2; an exact mass of 216.21 and a molecular weight of 216.37. In a more preferred embodiment of the invention, iPiPen is used as internal donor and / or wherein the activating compound is preferably N,N-dimethylbenzamide. iPiPen

[0024] In another embodiment, the internal electron donor is (1 -methoxy-2-(methoxymethyl)-5- methylhexan-2-yl)cyclopentane, according to Formula I wherein R1is secondary alkyl cyclopentyl and R2is secondary cyclopentyl (abbreviated as CPiPen, wherein CP stands for cyclopentyl and iPen stands for iso-pentyl, also known as 3-methyl-butyl). This compound CPiPen has a chemical formula of C15H30O2; an exact mass of 242.22 and a molecular weight of 242.40. In a more specific embodiment, CPiPen is used as internal donor and / V, / V-dimethylbenzamide is preferably used as activator.

[0025] CPiPen

[0026] In another embodiment, the internal electron donor is 3,3-bis(methoxymethyl)-2,7- dimethyloctane, according to Formula I wherein R1is the secondary alkyl iso-propyl and R2is non-secondary iso-hexyl with a branch on the four carbon atom (abbreviated as iPiHex, wherein iP stands for iso-propyl and iHex stands for iso-hexyl, also known as 4- methyl-pentyl). This compound iPiHex has a chemical formula of C14H30O2 ; an exact mass of 230.22 and a molecular weight of 230.39. In a more specific embodiment, iPiHex is used as internal donor and / V, / V-dimethylbenzamide is preferably used as activator. iPiHex

[0027] In another embodiment, the internal electron donor is 3,3-bis(methoxymethyl)-2- methyloctane, according to Formula I wherein R1is secondary alkyl iso-propyl and R2is non-secondary non-branched n-pentyl (abbreviated as iPnPen, wherein iP stands for isopropyl and nPen stands for n-pentyl). This compound iPnPen has a chemical formula of C13H28O2 ; an exact mass of 216.21 and a molecular weight of 216.37. In a more specific embodiment, iPnPen is used as internal donor and / V, / V-dimethylbenzamide is preferably used as activator. iPnPen

[0028] In another embodiment, the internal electron donor is 3,3-bis(methoxymethyl)-2,6- dimethyloctane, according to Formula I wherein R1is secondary alkyl iso-propyl and R2is non-secondary branched hexyl having a branch at the third carbon atom (abbreviated as iP3Hex, wherein iP stands for iso-propyl and wherein 3Hex stands for hexyl having a branch at the third carbon atom, also known as 3-methyl-pentyl). This compound iPiHex has a chemical formula of C14H32O2 ; an exact mass of 230.22 and a molecular weight of 230.39. In a more preferred embodiment, iP3Hex is used as internal donor and / or / V, / V-dimethylbenzamide is preferably used as activator. iP3Hex

[0029] In another embodiment, the procatalyst used according to the present invention provides a polymer yield of at least 50 kg polymer per gram of procatalyst used. In an embodiment, the substituent R1is isopropyl or cyclopentyl. In an embodiment, the substituent R2is isopentyl or isohexyl. The below table shows the embodiments above with their abbreviations and the R1and R2groups as well if these groups are secondary or not and branched or not.

[0030] According to the present invention, it is further preferred that R1is a secondary alkyl group and R2is a non-secondary alkyl group being branched at the 3-position or further positions.

[0031] Preferably, the co-catalyst is selected from the group consisting of trimethylaluminum, triethylaluminum, triisobutylaluminum, trihexylaluminum, di-isobutylaluminum hydride, trioctylaluminium, dihexylaluminum hydride and mixtures thereof.

[0032] Preferably, the external electron donor is chosen from the group of compounds having a structure according to:

[0033] - Formula III : (R90)2N— Si(OR91)3,

[0034] - Formula IV: (R92)Si(OR93)3,

[0035] Formula V: Si(ORa)4-nRbn, and

[0036] - mixtures thereof, wherein each of R90, R91, R92and R93groups are each independently a linear, branched or cyclic, substituted or unsubstituted alkyl having between 1 and 10 carbon atoms, preferably wherein R90, R91, R92and R93groups are each independently a linear unsubstituted alkyl having between 1 and 8 carbon atoms, wherein n can be from 0 up to 2, and each of Raand Rb, independently, represents an alkyl or aryl group, optionally containing one or more hetero atoms for instance 0, N, S or P, with, for instance, 1 -20 carbon atoms The external donor is for example ethyl, methyl or n-propyl, for example diethylaminotriethoxysilane (DEATES), n-propyl triethoxysilane, (nPTES), n-propyl trimethoxysilane (nPTMS); and organosilicon compounds having general formula Si(ORa)4-nRbn, wherein n can be from 0 up to 2, and each of Raand Rb, independently, represents an alkyl or aryl group, optionally containing one or more hetero atoms for instance 0, N, S or P, with, for instance, 1 -20 carbon atoms; such as diisobutyl dimethoxysilane (DiBDMS), t-butyl isopropyl dimethyxysilane (tBuPDMS), cyclohexyl methyldimethoxysilane (CHMDMS), dicyclopentyl dimethoxysilane (DCPDMS) or di(iso- propyl) dimethoxysilane (DiPDMS). More preferably, the external electron donor is chosen from the group of di(iso-propyl) dimethoxysilane (DiPDMS) or diisobutyl dimethoxysilane (DiBDMS).

[0037] Preferably, the external donor comprises or consists of a compound selected from the list comprising organo-silicon compounds, silanes, alkoxy silanes, alkyl silane, alkyl alkoxy silane and aliphatic / aromatic ester, for example dicyclopentyldimethoxysilane, di-tert- butyldimethoxysilane, methylcyclohexyldimethoxysilane, ethylcyclohexyldimethoxysilane, diphenyldimethoxysilane, diisopropyldimethoxysilane, di-n-propyldimethoxysilane, diisobutyldimethoxysilane, di-n-butyldimethoxysilane, cyclopentyltrimethoxysilane, isopropyltrimethoxysilane, npropyltrimethoxysilane, n- propyltriethoxysilane, ethyltriethoxysilane, tetramethoxysilane, tetraethoxysilane, cyclopentylpyrrolidinodimethoxysilane, bis(pyrrolidino )-dimethoxysilane, and mixtures thereof, preferentially di(iso-propyl) dimethoxysilane (DiPDMS)

[0038] The compounds mentioned above as examples of the external electron donor are sometimes referred as Selectivity Control Agent (SCA). The external electron donor may consist of SCA. Alternatively, in addition to SCA, the external electron donor may further comprise compounds known as an activity limiting agent (ALA). Preferably, the Activity Limiting Agent (ALA) is selected from the group consisting of: ethyl acetate, ethyl benzoate, p-ethoxy ethyl benzoate, methyl trimethylacetate, isopropyl myristate, di-n- butyl sebacate, (poly)(alkylene glycol) mono- or diacetates, (poly)(alkylene glycol) mono- or di-myristates, (poly)(alkylene glycol) mono- or di- laurates, (poly)(alkylene glycol) mono- or di-dioleates, glyceryl tri(acetate), mixed glycerides of linoleic, oleic, palmitic and stearic acids, and mixtures thereof. More preferably, the Activity Limiting Agent (ALA) is isopropyl myristate.

[0039] The ratio of Selectivity Control Agent (SCA) to Activity Limiting Agent (ALA) is in principle not critical, best results are obtained for a SCA / ALA ratio in the range from 0.010 to 100, more preferably in the range from 0.10 to 20.

[0040] Preferably, the molar ratio of Al in the co-catalyst to Si in the external electron is in the range from 1 to 25, preferably from 1 to 15, more preferably from 1 to 10, even more preferably from 2 to8, most preferably from 2 to 5.

[0041] It was found that the preferred catalyst system according to the invention result in a low value of Crystex soluble content.

[0042] Clarifier

[0043] Preferably the polymer composition according to the invention comprises a clarifier, clarifiers (also known as clarifying agents) are known to the person skilled in the art and are commercially available from for example Milliken. The clarifier according to the invention is based on sorbitol.

[0044] Preferably the amount clarifier is in the range from 100 to 5000 ppm, preferably in the range from 500 to 3000 ppm, even more preferably in the range from 700 to 2800 ppm basing on the total amount of the polymer composition.

[0045] Preferably the clarifier is selected from a group consisting of dibenzilidene sorbitol optionally substituted with one or more alkyl groups, 1 ,3:2,4-bis(p-methylbenzilidene) sorbitol, 1 ,3:2,4-bis(3,4-dimethylbenzilidene) sorbitol, 1 ,3:2,4-bis(p-ethylbenzylidene)- sorbitol and 1 ,2,3- tridesoxy-4,6:5,7-bis-O-[(4-propylphenyl)methylene]nonitol sorbitol.

[0046] Said clarifier is commercially available, for example 1 ,3:2,4-bis(p-methylbenzilidene) sorbitol (MDBS) is available as Millad 3940; Milliken, 1 ,3:2,4-bis(3,4- dimethylbenzilidene) sorbitol ) is available as Millad 3988; Milliken, 1 ,2,3- tridesoxy- 4,6:5,7-bis-O-[(4-propylphenyl)methylene]nonitol sorbitol ) is available as Millad NX8000; Milliken or Sunwise Chemical Co.), 1 ,3:2,4-bis(p-ethylbenzylidene)-sorbitol ) is available as NC-4; Mitsui.

[0047] Polymer composition

[0048] The amount of the random propylene copolymer is preferably in the range from 97.5 to 99.5 wt%, more preferably in the range from 98.5 to 99.5 wt% basing on the total amount of the polymer composition.

[0049] Preferably the total amount of the random propylene copolymer and the clarifier is in the range from 98.0 to 100 wt%, preferably 99.0 to 100.0 wt%, more preferably 99.5 to 100.0 wt% basing on the total amount of the polymer composition.

[0050] The polymer composition according to the invention may be prepared by melt mixing the random propylene copolymer, the optional clarifier and potentially further additives in an extruder.

[0051] The present invention further relates to an article comprising the polymer composition according to the invention wherein the article is a packaging item or cap and closure or fiber or film.

[0052] Preferably the amount of the polymer composition is at least 97 wt%, more preferably at least 99 wt% basing on the total amount of the article.

[0053] The present invention further relates to a process for the preparation of said article, e.g. by injection molding.

[0054] Examples Each of the examples consists of a resin part and an additive package, wherein the additive package was added to the resin part in a compounding step. The total amount of the resin part and additive package is 100 wt% of an example.

[0055] For the preparation of the resin part of all inventive examples (lEs), the procatalyst was prepared according to the method disclosed in W02021 / 063930A1 , example 1. The cocatalyst for the preparation of lEs is TEA and external electron donor is DiPDMS. The Al / Si ratio is 5, Al / Si is the molar ratio of the co-catalyst (TEA) to the external donor (DiPDMS).

[0056] For the preparation of the resin part of the comparative examples (CEs), the preferred catalyst according to the present invention was not used.

[0057] Resin part of all examples where produced in a gas-phase polymerization process which was performed in one horizontally stirred gas-phase reactor (plus the secondary reactor blanketed) with downstream powder processing units (= degassing & catalyst deactivation) for powder collection.

[0058] The temperature of the powder bed was controlled between 66 to 76 °C which measured via a series of internal thermocouples. The data from these thermocouples is used to control the quench flow to the individual quench nozzles.

[0059] Hydrogen was fed to the reactor to control the melt flow rate. Ethylene was fed to obtain the resin part of lEs.

[0060] In avoidance of any confusion, the powder produced from the polymerization process is the same as resin part after polymerization.

[0061] The resin parts of IE1 , IE2 and IE3 were the same after the polymerization having an MFR of 12 g / 10min, the resin parts of IE1 and IE2 were then peroxide shifted to MFR 23 g / 10min and 39 g / 10min respectively in the compounding step. The resin part of IE4 has an MFR of 40 g / 10min and its was not shifted in the compounding step. The additive packages of IE1 , CE1 , IE3, CE3, IE4 and CE4 are the same consisting of 2260 ppm Millad NX8000, 1000 ppm anti-oxidant, 750 ppm acid scavenger basing on the total amount of each example.

[0062] The additive packages of IE2 and CE2 are the same consisting of 1800 ppm Millad 3988, 1000 ppm anti-oxidant, 1000 ppm acid scavenger basing on the total amount of each example.

[0063] Blooming and Haze

[0064] The determination of the Haze was carried out in accordance with the standard ASTM D1003A. The test specimens are small plaque 65*65*1 mm with hinge, injected in machine Arburg 60T / DEMAG 60T.

[0065] Haze was measured 3 times: On the day of injection molding of the test specimen, 21 days after the injection molding of the test specimen and 42 days after the injection molding. During the interval of the measurement, the test specimen were stored in an oven with a temperature set to 50 °C.

[0066] MFR

[0067] MFR of the examples were carried out according to ISO1133 at 230°C, 2.16kg.

[0068] Ethylene content

[0069] Ethylene content was measured using 13C-NMR spectroscopy. To this end, approximately 150 mg of material was dissolved in 1 ,1 ,2,2-tetrachloroethane-d2 (TCE- d2). To ensure a homogeneous solution, the sample preparation has been conducted in a heated rotary oven. The NMR measurements were carried out in the solution-state using a Bruker 500 Advance III HD spectrometer operating at 500.16 and 125.78 MHz for 1 H and 13C, respectively, and equipped with a 10 mm DUAL cryogenically-cooled probe head operating at 125 °C. The 13C-NMR experiments were performed using standard single pulse excitation utilizing the NOE and bi-level WALTZ16 decoupling scheme (Zhou Z. et al. J. Mag. Reson 187 (2007) 225. A total of 512 transients were acquired per spectrum. The spectra were calibrated by setting the central signal of TCE’s triplet at 74.2 ppm. Quantitative 13C NMR spectra were processed, integrated and relevant quantitative properties determined from the integrals using proprietary computer programs.

[0070] Crystex soluble

[0071] Crystex soluble refers to the amount of amorphous soluble fraction in the samples (CXS equiv. whole sample). The measurement was performed according to CRYSTEX method by a CRYSTEX QC instrument of CRYSTEX QC Polymer Char (Valencia, Spain). A schematic representation of the CRYSTEX QC instrument is presented in Del Hierro, P.; Ortin, A.; Monrabal, B.; ‘Soluble Fraction Analysis in polypropylene, The Column’, February 2014. Pages 18-23.

[0072] A sample was weighed in concentrations of 10 mg / mL. After automated filling of the vial with 1 ,2,4-TCB containing 250 mg / L 2,6-tert-butyl-4-methylphenol (BHT) as antioxidant, the sample was dissolved at 170°C until complete dissolution is achieved, for 120 min, with constant stirring of 800rpm.

[0073] The crystalline insoluble fraction and the amorphous soluble fraction are separated through temperature cycles of dissolution at 165°C, crystallization at 40°C and redissolution in 1 ,2,4-trichlorobenzene (1 ,2,4-TCB) at 165°C.

[0074] The CXS content is determined by calibrating the instrument with various PP polymers with known CXS content determined according to standard gravimetric method according to ISO16152.

[0075] Due to the low amount of the additive package, the MFR, ethylene content and Crystex soluble measured on each sample are essentially the same as that of the resin part of the same sample. Flexural modulus

[0076] Flexural modulus was determined in accordance to ASTM D790 with specimens molded in the flow direction. Result

[0077] The measurement result of all the examples is presented in the table as below:

[0078] Table 1 measurement result of a I examples

Claims

Claims1. A polymer composition comprising a random propylene copolymer, wherein the random propylene copolymer has an MFR in the range of 1 to 80 g / 1 Omin as measured according to ISO1133 at 230°C, 2.16kg; a comonomer content in the range of 1 .5-4.5 wt% basing on the total amount of the random propylene copolymer, wherein the comonomer is moitie derived from a group consisting of ethylene, 1 -butene, 1 -hexene and combination thereof; a Cystex soluble part of at most 7 basing on the total amount of the random propylene copolymer,2. The polymer composition according to claim 1 wherein the polymer composition comprises a clarifier, wherein the clarifier is based on sorbitol, wherein the amount clarifier is in the range from 100 to 5000 ppm, preferably in the range from 500 to 3000 ppm, even more preferably in the range from 700 to 2800 ppm basing on the total amount of the polymer composition.

3. The polymer composition according to claim 1 or 2 wherein the Crystex soluble part of the random propylene copolymer is in the range from 3.7 to 6.9 wt%, preferably in the range from 4.6 to 6.9 wt%, even more preferably in the range from 5.1 to 6.8 wt% basing on the total amount of the random propylene copolymer.

4. The polymer composition according to any one of the previous claims wherein the MFR of the random propylene copolymer is in the range from 1 to 60 g / 1 Omin, preferably from 1 to 50 g / 1 Omin as measured according to ISO1133 at 230°C, 2.16kg.

5. The polymer composition according to any one of the previous claims wherein the conomoner content is in the range from 2.0 to 4.2 wt%, preferably from 2.5 to 4.2 wt% basing on the total amount of the random propylene copolymer6. The polymer composition according to any one of the previous claims wherein the comonomer is moiety derived from ethylene.

7. The polymer composition according to any one of claims 2 to 6 wherein the clarifier is selected from a group consisting of dibenzilidene sorbitol optionally substituted with one or more alkyl groups, 1 ,3:2,4-bis(p-methylbenzilidene) sorbitol, 1 ,3:2,4-bis(3,4- dimethylbenzilidene) sorbitol, 1 ,3:2,4-bis(p-ethylbenzylidene)-sorbitol and 1 ,2,3- tridesoxy-4,6:5,7-bis-O-[(4-propylphenyl)methylene]nonitol sorbitol.

8. The polymer composition according to any one of claims 2 to 7 wherein the total amount of the random propylene copolymer and the clarifier is in the range from 98.0 to 100 wt%, preferably 99.0 to 100.0 wt%, more preferably 99.5 to 100.0 wt% basing on the total amount of the polymer composition9. The polymer composition according to any one of the previous claims wherein the random propylene copolymer is produced in a process comprises the step of polymerizing propylene and ethylene comonomers in the presence of a catalyst in a gas phase, wherein said catalyst comprises a procatalyst, a co-catalyst and optionally an external electron donor, wherein the procatalyst is obtainable by a process comprising the steps of: contacting a magnesium-containing support with a halogen-containing titanium compound, and an internal electron donor according to Formula I:wherein R1is a secondary alkyl group and R2is a non-secondary alkyl group having at least 5 carbon atoms, preferably R2is a non-secondary alkyl group having at least 5 carbon atoms and being branched at the 3-position or further positions; said procatalyst is prepared according to the following steps: i) contacting a compound R4zMgX42-z with an alkoxy- or aryloxy-containing silane compound to give a first intermediate reaction product, being a solid Mg(0Ra)xX12-x, wherein: Rais a linear, branched or cyclic hydrocarbyl group independently selected fromalkyl, alkenyl, aryl, aralkyl, alkoxycarbonyl or alkylaryl groups, and one or more combinations thereof; wherein said hydrocarbyl group may be substituted or unsubstituted, may contain one or more heteroatoms and preferably has from 1 to 20 carbon atoms; wherein R4is a linear, branched or cyclic hydrocarbyl group independently selected from alkyl, alkenyl, aryl, aralkyl, alkoxycarbonyl or alkylaryl groups, and one or more combinations thereof; wherein said hydrocarbyl group may be substituted or unsubstituted, may contain one or more heteroatoms and preferably has from 1 to 20 carbon atoms, preferably R4is butyl; wherein X4and X1are each independently selected from the group of consisting of fluoride (F-), chloride (Cl—), bromide (Br-) or iodide (I-), preferably chloride; z is in a range of larger than 0 and smaller than 2, being 0 < z < 2, x is an integer between 0 and 2; ii) optionally contacting the solid Mg(ORa)xX12-x obtained in step i) with at least one activating compound selected from the group formed by activating electron donors and metal alkoxide compounds of formula M1(0Rb)v-w(0R3)w or M2(ORb)v-w(R3)w, to obtain a second intermediate product; wherein: M1is a metal selected from the group consisting of Ti, Zr, Hf, Al or Si; v is the valency of M1; M2is a metal being Si; v is the valency of M2; Rband R3are each a linear, branched or cyclic hydrocarbyl group independently selected from alkyl, alkenyl, aryl, aralkyl, alkoxycarbonyl or alkylaryl groups, and one or more combinations thereof; wherein said hydrocarbyl group may be substituted or unsubstituted, may contain one or more heteroatoms, and preferably has from 1 to 20 carbon atoms; wherein w is smaller than v, preferably v being 3 or 4; iii) contacting the first or second intermediate reaction product, obtained respectively in step i) or ii), with a halogen-containing Ti-compound and said compound represented Formula I, as the internal electron donor.

10. The polymer composition according to claim 9, wherein the co-catalyst is selected from the group consisting of trimethylaluminum, triethylaluminum, triisobutylaluminum, trihexylaluminum, di-isobutylaluminum hydride, trioctylaluminium, dihexylaluminum hydride and mixtures thereof.11 . The polymer composition according to any one of claims 9 or 10, the catalyst comprises an external donor, wherein the external electron donor is a silane containing external donor, preferably wherein the external electron donor is selected from the group of compounds having a structure according to:- Formula III : (R90)2N— Si(OR91)3,- Formula IV: (R92)Si(OR93)3, Formula V: Si(ORa)4-nRbn, and- mixtures thereof, wherein each of R90, R91, R92and R93groups are each independently a linear, branched or cyclic, substituted or unsubstituted alkyl having between 1 and 10 carbon atoms, preferably wherein R90, R91, R92and R93groups are each independently a linear unsubstituted alkyl having between 1 and 8 carbon atoms, wherein n can be from 0 up to 2, and each of Ra and Rb, independently, represents an alkyl or aryl group, optionally containing one or more hetero atoms for instance 0, N, S or P, with, for instance, 1 -20 carbon atoms12. The polymer composition according to any one of claims 9 to 11 , wherein the molar ratio of co-catalyst to external electron donor is in the range from 1 to 25, or from 1 to15, or from 1 to 10, or from 2 to8, or 2 to 5,13. The polymer composition according to any one of claims 9 to 12, wherein during step ii) as activating compounds an alcohol is used as activating electron donor and titanium tetraalkoxide is used as metal alkoxide compound.

14. The polymer composition according to any one of claims 9 to 13, wherein an activator is present in the process for the preparation of the procatalyst, the activator preferably being a benzamide according to formula X:wherein R70and R71are each independently selected from hydrogen or an alkyl, and R72, R73, R74, R75, R76are each independently selected from hydrogen, a heteroatom or a hydrocarbyl group, preferably selected from alkyl, alkenyl, aryl, aralkyl, alkoxycarbonyl or alkylaryl groups, and one or more combinations thereof, more preferably wherein R70and R71are both methyl and wherein R72, R73, R74, and R75are all hydrogen, being N,N’-dimethylbenzamide (Ba-2Me).

15. An article comprising the polymer according to any one of the previous claims wherein the article is a packaging item or cap and closure or fiber or film.

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