RANDOM PROPYLENE POLYMER COMPOSITION AND USE IN EXTRUSION BLOW MOULDING

Abstract

The present invention is directed to a propylene polymer composition comprising at least one propylene copolymer (C-PP), and an α-nucleating agent (NU), wherein the propylene copolymer (C-PP) comprises two propylene copolymer fractions (PP1) and (PP2), wherein propylene copolymer fraction (PP1) is contained in the propylene copolymer (C-PP) in an amount of 30 to 70 wt. % and the propylene copolymer fraction (PP2) is contained in the propylene copolymer (C-PP) in an amount of 70 to 30 wt. %, the comonomer content of propylene copolymer fraction (PP1) is in the range of 0.5 to 2.5 wt.-% and the comonomer content of the propylene copolymer fraction (PP1) is lower compared to the comonomer content of the propylene copolymer fraction (PP2), and the propylene polymer composition has (a) a melt flow rate MFR.sub.2 (230° C.) measured according to according to ISO 1133 of 1 to 5 g/10 min., and (b) a comonomer content of 4.0 to 8.0 wt. %, the comonomer(s) being ethylene and/or at least one C.sub.4 to C.sub.12 α-olefin. The above propylene polymer composition has improved impact and optical properties. The invention further provides a method of producing the above propylene polymer composition and an extrusion blow molded article comprising the above propylene polymer composition.

Claims

1. A propylene polymer composition comprising at least one propylene copolymer (C-PP), and an α-nucleating agent (N), wherein the propylene copolymer (C-PP) comprises two propylene copolymer fractions (PP1) and (PP2), wherein propylene copolymer fraction (PP1) is contained in the propylene copolymer (C-PP) in an amount of 30 to 70 wt. % and the propylene copolymer fraction (PP2) is contained in the propylene copolymer (C-PP) in an amount of 70 to 30 wt. %, the comonomer content of propylene copolymer fraction (PP1) is in the range of 0.5 to 2.6 wt.-% and the comonomer content of the propylene copolymer fraction (PP1) is lower compared to the comonomer content of the propylene copolymer fraction (PP2), and the propylene polymer composition has (a) a melt flow rate MFR.sub.2 (230° C.) measured according to according to ISO 1133 of 1 to 5 g/10 min., (b) a comonomer content of 4.0 to 8.0 wt. %, the comonomer(s) being ethylene and/or at least one C4 to C12 α-olefin, and (c) a soluble fraction (SF), determined by CRYSTEC fractionation with CRYSTEX QC, Polymer Char (Valencia, Spain) as described herein, of from 8 to 20 wt. %.

2. The propylene polymer composition according to claim 1 having (a) a melting temperature Tm in the range of from 148 to 162° C.; and/or (b) a crystallization temperature Tc of not less than 115° C.

3. The propylene polymer composition according to claim 1 wherein the polypropylene composition has (c) a Charpy notched impact strength according to ISO 179 1 eA at +23° C. in the range of from 20 to 100 kJ/m.sup.2.

4. The propylene polymer composition according to claim 1 wherein the comonomer content of propylene copolymer fraction (PP2) is in the range of 6 to 20 wt.-%.

5. The propylene polymer composition according to claim 1 wherein propylene copolymer fraction (PP1) and propylene copolymer fraction (PP2) differ in their melt flow rate MFR.sub.2 (230° C.) measured according to according to ISO 1133.

6. The propylene polymer composition according to claim 1 wherein the melt flow rate MFR.sub.2 (230° C.) of the first propylene copolymer fraction (PP1) to the melt flow rate MFR.sub.2 (230° C.) of the propylene copolymer (C-PP) differ by no more than 6.0 g/10 min., measured according to ISO 1133, respectively.

7. The propylene polymer composition according to claim 1 comprising an a-nucleating agent (N) selected from the group consisting of (i) salts of monocarboxylic acids and polycarboxylic acids, (ii) dibenzylidenesorbitol and C1-C8-alkyl-substituted dibenzylidenesorbitol derivatives, or substituted nonitol-derivatives, (iii) salts of diesters of phosphoric acid, (iv) polymeric α-nucleating agent, and (v) mixtures thereof.

8. The propylene polymer composition according to claim 7, wherein the α-nucleating agent is selected from vinylcycloalkane polymers and vinylalkane polymers.

9. A method of producing the propylene polymer composition according to claim 1, wherein propylene copolymer (C-PP) is obtained in a multi-stage polymerisation process in the presence of (a) a Ziegler-Natta catalyst (ZN-C) comprises a titanium compound (TC), a magnesium compound (MC) and an internal donor (ID), wherein said internal donor (ID) is a non-phthalic acid ester, (b) optionally a co-catalyst (Co), and (c) optionally an external donor (ED).

10. The method according to claim 9, wherein the internal donor (ID) is selected from the group consisting of optionally substituted malonates, maleates, succinates, glutarates, cyclohexene-1,2-dicarboxylates, benzoates and derivatives and/or mixtures thereof.

11. An extrusion blow molded article comprising the propylene polymer composition according to claim 1.

12. The extrusion blow molded article according to claim 11 having a Charpy notched impact strength according to ISO 179 1 eA at +23° C. in the range of from 20 to 100 kJ/m2.

13. The extrusion blow molded article according to claim 11 being a bottle or a container.

14. (canceled)

15. A method of preparing an extrusion blow molded article comprising extrusion blow molding of a propylene polymer composition according to claim 1.

Description

2. EXAMPLES

[0241] The catalyst used in the polymerization process for the propylene copolymer of the inventive examples (1E1) and (1E2) was produced as follows:

[0242] Catalyst

[0243] 3.4 litre of 2-ethylhexanol and 810 ml of propylene glycol butyl monoether (in a molar ratio 4/1) were added to a 20 l reactor. Then 7.8 litre of a 20% solution in toluene of BEM (butyl ethyl magnesium) provided by Crompton GmbH, were slowly added to the well stirred alcohol mixture. During the addition the temperature was kept at 10° C. After addition the temperature of the reaction mixture was raised to 60° C. and mixing was continued at this temperature for 30 minutes. Finally after cooling to room temperature the obtained Mg-alkoxide was transferred to a storage vessel.

[0244] 21.2 g of Mg alkoxide prepared above was mixed with 4.0 ml bis(2-ethylhexyl) citraconate for 5 min. After mixing the obtained Mg complex was used immediately in the preparation of the catalyst component.

[0245] 19.5 ml of titanium tetrachloride was placed in a 300 ml reactor equipped with a mechanical stirrer at 25° C. Mixing speed was adjusted to 170 rpm. 26.0 g of Mgcomplex prepared above was added within 30 minutes keeping the temperature at 25° C. 3.0 ml of Viscoplex® 1-254 and 1.0 ml of a toluene solution with 2 mg Necadd 447™ was added. Then 24.0 ml of heptane was added to form an emulsion.

[0246] Mixing was continued for 30 minutes at 25° C., after which the reactor temperature was raised to 90° C. within 30 minutes. The reaction mixture was stirred for a further 30 minutes at 90° C.

[0247] Afterwards stirring was stopped and the reaction mixture was allowed to settle for 15 minutes at 90° C. The solid material was washed 5 times:

[0248] Washings were made at 80° C. under stirring for 30 min with 170 rpm. After stirring was stopped the reaction mixture was allowed to settle for 20-30 minutes and followed by siphoning.

[0249] Wash 1: Washing was made with a mixture of 100 ml of toluene and 1 ml donor Wash 2: Washing was made with a mixture of 30 ml of TiCl4 and 1 ml of donor.

[0250] Wash 3: Washing was made with 100 ml of toluene.

[0251] Wash 4: Washing was made with 60 ml of heptane.

[0252] Wash 5: Washing was made with 60 ml of heptane under 10 minutes stirring.

[0253] Afterwards stirring was stopped and the reaction mixture was allowed to settle for 10 minutes while decreasing the temperature to 70° C. with subsequent siphoning, followed by N2 sparging for 20 minutes to yield an air sensitive powder.

[0254] Ti content was 3.76 wt-%.

[0255] External Donor:

[0256] In the Examples, the external donor D (Dicyclopentyl dimethoxy silane CAS 126990-35-0) was used.

[0257] The co-catalyst component used was triethyl aluminium (TEAL).

[0258] The catalyst and the polymer of CE1 was prepared as described for 1E1 of WO 2014/206950 A1. Two propylene copolymers P1 and P2 were produced using the above described catalyst and co-catalyst and using the polymerisation conditions according to Table 1 below.

[0259] The polymerization conditions are listed in the Table below.

TABLE-US-00002 TABLE 1 Polymerization conditions Unit P1 P2 Prepolymerizer Teal g/t C3 150 150 Donor g/t C3 60 60 Temperature ° C. 25 25 Loop Temperature ° C. 70 70 Feed C2/C3 mol/kmol 2.36 4.65 Feed H2/C3 mol/kmol 1.53 1.51 MFR g/10 min 5.8 5 C2 wt % 1.3 2.6 Split wt % 40.8 40.2 First gas phase reactor Temperature ° C. 80 80 C2/C3 mol/kmol 39.8 39.8 H2/C3 mol/kmol 2.51 2.59 MFR g/10 min 1.53 1.48 C2 wt % 4.9 5

[0260] Examples IE1, 1E2, were prepared by compounding the copolymers P1 (IE1) and P2(1E2) with 0.1 wt.-% of Irganox B225 (1:1-blend of Irganox 1010 and Irgafos 168) of BASF AG, Germany), and 0.05 wt.-% calcium stearate by using a ZSK 57 twin screw extruder, with a melt temperature of 220° C., under nitrogen atmosphere and final polymer properties were measured as shown in Table 2 below.

TABLE-US-00003 TABLE 2 Properties of the Examples Unit IE1 IE2 CE1 Base P1 P2 RB307MO MFR2 g/10 min 1.9 1.9 1.5 NU PVCH PVCH DMDBS SF wt % 13.2 13.0 7.4 C2 wt % 4.9 5.0 4.7 C2(SF) wt % 17.8 17.6 16.6 C2(CF) wt % 3.6 3.7 4.2 Ratio C2(SF)/C2(CF) 5.0 4.7 3.9 IV dl/g 2.6 2.6 2.9 IV(SF) dl/g 1.8 1.8 1.5 IV(CF) dl/g 2.7 2.7 2.9 Melting ° C. 154 150 144 temperature Crystallisation ° C. 122 119 113 Temperature Flex MPa 817 792 892 NIS/23° C. kJ/m.sup.2 39.6 40.7 15 Haze/1 mm % 21.4 20.1 20 Bottle/0.6 mm Drop height m 5.5 5.5 4 top load N 401 378 411 Haze % 29 28 20 Clarity % 79.0 79.6 74

[0261] The above results show that the propylene polymer compositions of the present invention combine excellent mechanical properties such as high impact strength and high flexural modulus with improved optical properties such as low haze and high clarity. A particular ratio between C2(SF)/C2(CF) may preferably contribute to the desired combination of properties.

[0262] The specific polymer setting provides better impact behavior in the sense of higher impact strength and higher drop height while maintaining optical properties (e.g. haze) at a low level.