Polyolefin composition with improved thoughness

Abstract

A polyolefin composition comprising a heterophasic propylene copolymer and a polar modified -polyolefin.

Claims

1. A polyolefin composition (PO) comprising a heterophasic propylene copolymer (HECO) and a polar modified -polyolefin (PMP), wherein said heterophasic propylene copolymer (HECO) comprises: (a) a (semi)crystalline polypropylene (PP) that is a (semi)crystalline propylene homopolymer (H-PP); and (b) an elastomeric propylene copolymer (EPC) dispersed in said (semi)crystalline polypropylene (PP); wherein said polyolefin composition (PO) has: (i) a xylene cold soluble (XCS) fraction in the range of 28 to 45 wt. %; wherein further the xylene cold soluble (XCS) fraction of said polyolefin composition has: (ii) an intrinsic viscosity (IV) in the range of 1.80 to 3.30 dl/g.

2. The polyolefin composition (PO) according to claim 1, wherein: (a) the intrinsic viscosity (IV) of the xylene cold insoluble (XCI) fraction of the heterophasic propylene copolymer (HECO) is in the range of 1.00 to 1.30 dl/g; and/or (b) the melt flow rate MFR.sub.2 (230 C.) measured according to ISO 1133 of the (semi)crystalline polypropylene (PP) of the heterophasic propylene copolymer (HECO) is in the range of 45 to 150 g/10 min; and/or (c) the comonomer content of the xylene cold soluble (XCS) fraction of the heterophasic propylene copolymer (HECO) is in the range of 21 to 55 mol %; and/or (d) the intrinsic viscosity (IV) of the xylene cold soluble (XCS) fraction of the heterophasic propylene copolymer (HECO) is in the range of 1.50 to 3.00 dl/g.

3. A polyolefin composition (PO) comprising a heterophasic propylene copolymer (HECO) and a polar modified -polyolefin (PMP), wherein said heterophasic propylene copolymer (HECO) comprises: (a) a (semi)crystalline polypropylene (PP) having a melt flow rate MFR.sub.2 (230 C.) measured according to ISO 1133 in the range of 45 to 150 g/10 min, wherein the (semi)crystalline polypropylene (PP) is a (semi)crystalline propylene homopolymer (H-PP); and (b) an elastomeric propylene copolymer (EPC) dispersed in said (semi)crystalline polypropylene (PP); wherein said heterophasic propylene copolymer (HECO) has: (i) a xylene cold soluble (XCS) fraction in the range of 25 to 40 wt. %; wherein further the xylene cold soluble (XCS) fraction of said heterophasic propylene copolymer (HECO) has: (ii) a comonomer content in the range of 21 to 55 mol %; and (iii) optionally an intrinsic viscosity (IV) in the range of 1.50 to 3.00 dl/g, and optionally still further, (iv) the intrinsic viscosity (IV) of the xylene cold insoluble (XCI) fraction of the heterophasic propylene copolymer (HECO) is in the range of 1.00 to 1.30 dl/g.

4. A polyolefin composition (PO) comprising a heterophasic propylene copolymer (HECO) and a polar modified -polyolefin (PMP), wherein said heterophasic propylene copolymer (HECO) comprises: (a) a (semi)crystalline polypropylene (PP) optionally having a melt flow rate MFR.sub.2 (230 C.) measured according to ISO 1133 in the range of 45 to 150 g/10 min, wherein the (semi)crystalline polypropylene (PP) is a (semi)crystalline propylene homopolymer (H-PP); and (b) an elastomeric propylene copolymer (EPC) dispersed in said (semi)crystalline polypropylene (PP); wherein said heterophasic propylene copolymer (HECO) has: (i) a xylene cold soluble (XCS) fraction in the range of 25 to 40 wt. %; wherein further the xylene cold soluble (XCS) fraction of said heterophasic propylene copolymer (HECO) has: (ii) a comonomer content in the range of 21 to 55 mol %; and (iii) optionally an intrinsic viscosity (IV) in the range of 1.50 to 3.00 dl/g, and still further; (iv) the intrinsic viscosity (IV) of the xylene cold insoluble (XCI) fraction of the heterophasic propylene copolymer (HECO) is in the range of 1.00 to 1.30 dl/g.

5. The polyolefin composition (PO) according to claim 3, wherein: (a) said polyolefin composition (PO) has a xylene cold soluble (XCS) fraction in the range of 28 to 45 wt. %; and/or (b) the xylene cold soluble (XCS) fraction of said polyolefin composition (PO) has an intrinsic viscosity (IV) in the range of 1.80 to 3.30 dl/g.

6. The polyolefin composition (PO) according to claim 1, wherein the heterophasic propylene copolymer (HECO) has: (a) a melt flow rate MFR.sub.2 (230 C.) measured according to ISO 1133 in the range of 15 to 55 g/10 min; and/or (b) a comonomer content in the range of 10.0 to 28.0 mol %.

7. The polyolefin composition (PO) according to claim 1, wherein: (a) the xylene cold soluble (XCS) fraction of said polyolefin composition (PO) has a comonomer content in the range of 21 to 55 mol %; and/or (b) said polyolefin composition (PO) has a comonomer content in the range of 25 to 60 mol %.

8. The polyolefin composition (PO) according claim 1, having a melt flow rate MFR.sub.2 (230 C.) measured according to ISO 1133 in the range of 5 to 30 g/10 min.

9. The polyolefin composition (PO) according to claim 1, wherein the weight ratio between the (semi)crystalline polypropylene (PP) and the elastomeric propylene copolymer (EPC) of the heterophasic propylene copolymer (HECO) [(PP)/(EPC)] is in the range of 50/50 to 85/15.

10. The polyolefin composition (PO) according to claim 1, wherein: (a) the (semi)crystalline polypropylene (PP) of the heterophasic propylene copolymer (HECO) is a (semi)crystalline propylene homopolymer (H-PP) having a xylene cold soluble (XCS) fraction of less than 4.5 wt. %; and/or (b) the elastomeric propylene copolymer (EPC) of the heterophasic propylene copolymer (HECO) is an ethylene propylene rubber (EPR).

11. The polyolefin composition (PO) according to claim 1, wherein: (a) the weight ratio between the heterophasic propylene copolymer (HECO) and the polar modified -polyolefin (PMP) is in the range of 4/1 to 85/1; and/or (b) said polyolefin composition (PO) comprises: (i) 60 to 99 wt. %, based on the total weight of the polyolefin composition (PO), of the heterophasic propylene copolymer (HECO); and (ii) at least 1 wt. %, based on the total weight of the polyolefin composition (PO), of the polar modified -polyolefin (PMP).

12. The polyolefin composition (PO) according to claim 1, wherein the polar modified -polyolefin (PMP) has a melt flow rate MFR.sub.2 (230 C.) measured according to ISO 1133 in the range of 0.5 to 10 g/10 min.

13. The polyolefin composition (PO) according to claim 1, wherein the polar modified -polyolefin (PMP) is a polar modified -polyolefin (PMP) grafted with maleic anhydride.

14. The polyolefin composition (PO) according to claim 1, wherein the -polyolefin (pre-PMP) to be modified is an elastomeric ethylene copolymer (EEC).

15. The polyolefin composition (PO) according to claim 1, wherein the polyolefin composition (PO) has: (a) a tensile modulus of at least 700 MPa, and/or (b) an impact strength at 23 C. of at least 40 kJ/m.sup.2, and/or (c) a shrinkage in flow (sector, radius 300 mm, opening angle 20) of below 1.50%.

16. An automotive article comprising a polyolefin composition (PO) according to claim 1, wherein the automotive article is an exterior automotive article.

17. A process for the preparation of the polyolefin composition (PO) according to claim 1, by extruding the heterophasic propylene copolymer (HECO) and the polar modified -polyolefin (PMP) in an extruder.

18. The process according to claim 17, wherein the heterophasic propylene copolymer (HECO) is obtained by producing the (semi)crystalline polypropylene (PP) in a first reaction zone comprising at least one reactor, transferring said (semi)crystalline polypropylene (PP) in a subsequent reaction zone comprising at least one reactor, where in the presence of the (semi)crystalline polypropylene (PP) the elastomeric propylene copolymer (EPC) is produced.

19. The polyolefin composition (PO) according to claim 4, wherein: (a) said polyolefin composition (PO) has a xylene cold soluble (XCS) fraction in the range of 28 to 45 wt. % and/or (b) the xylene cold soluble (XCS) fraction of said polyolefin composition (PO) has an intrinsic viscosity in the range of 1.80 to 3.30 dl/g.

20. An automotive article comprising a polyolefin composition (PO) according to claim 3, wherein the automotive article is an exterior automotive article.

21. An automotive article comprising a polyolefin composition (PO) according to claim 4, wherein the automotive article is an exterior automotive article.

22. A process for the preparation of the polyolefin composition (PO) according to claim 3, by extruding the heterophasic propylene copolymer (HECO) and the polar modified -polyolefin (PMP) in an extruder.

23. A process for the preparation of the polyolefin composition (PO) according to claim 4, by extruding the heterophasic propylene copolymer (HECO) and the polar modified -polyolefin (PMP) in an extruder.

Description

EXAMPLES

(1) 1. Definitions/Measuring Methods

(2) The following definitions of terms and determination methods apply for the above general description of the invention as well as to the below examples unless otherwise defined.

(3) Quantification of microstructure by NMR spectroscopy

(4) Quantitative nuclear-magnetic resonance (NMR) spectroscopy was used to quantify the comonomer content of the polymers. Quantitative .sup.13C {.sup.1H} NMR spectra were recorded in the solution-state using a Bruker Advance III 400 NMR spectrometer operating at 400.15 and 100.62 MHz for .sup.1H and .sup.13C respectively. All spectra were recorded using a .sup.13C optimised 10 mm extended temperature probehead at 125 C. using nitrogen gas for all pneumatics. Approximately 200 mg of material was dissolved in 3 ml of 1,2-tetrachloroethane-d.sub.2 (TCE-d.sub.2) along with chromium-(III)-acetylacetonate (Cr(acac).sub.3) resulting in a 65 mM solution of relaxation agent in solvent (Singh, G., Kothari, A., Gupta, V., Polymer Testing 28 5 (2009), 475). To ensure a homogenous solution, after initial sample preparation in a heat block, the NMR tube was further heated in a rotatary oven for at least 1 hour. Upon insertion into the magnet the tube was spun at 10 Hz. This setup was chosen primarily for the high resolution and quantitatively needed for accurate ethylene content quantification. Standard single-pulse excitation was employed without NOE, using an optimised tip angle, 1 s recycle delay and a bi-level WALTZ16 decoupling scheme (Zhou, Z., Kuemmerle, R., Qiu, X., Redwine, D., Cong, R., Taha, A., Baugh, D. Winniford, B., J. Mag. Reson. 187 (2007) 225; Busico, V., Carbonniere, P., Cipullo, R., Pellecchia, R., Severn, J., Talarico, G., Macromol. Rapid Commun. 2007, 28, 1128). A total of 6144 (6 k) transients were acquired per spectra.

(5) Quantitative .sup.13C {.sup.1H} NMR spectra were processed, integrated and relevant quantitative properties determined from the integrals using proprietary computer programs. All chemical shifts were indirectly referenced to the central methylene group of the ethylene block (EEE) at 30.00 ppm using the chemical shift of the solvent. This approach allowed comparable referencing even when this structural unit was not present. Characteristic signals corresponding to the incorporation of ethylene were observed Cheng, H. N., Macromolecules 17 (1984), 1950).

(6) With characteristic signals corresponding to 2,1 erythro regio defects observed (as described in L. Resconi, L. Cavallo, A. Fait, F. Piemontesi, Chem. Rev. 2000, 100 (4), 1253, in Cheng, H. N., Macromolecules 1984, 17, 1950, and in W-J. Wang and S. Zhu, Macromolecules 2000, 33 1157) the correction for the influence of the regio defects on determined properties was required. Characteristic signals corresponding to other types of regio defects were not observed.

(7) The comonomer fraction was quantified using the method of Wang et. al. (Wang, W-J., Zhu, S., Macromolecules 33 (2000), 1157) through integration of multiple signals across the whole spectral region in the .sup.13C{.sup.1H} spectra. This method was chosen for its robust nature and ability to account for the presence of regio-defects when needed. Integral regions were slightly adjusted to increase applicability across the whole range of encountered comonomer contents.

(8) For systems where only isolated ethylene in PPEPP sequences was observed the method of Wang et. al. was modified to reduce the influence of non-zero integrals of sites that are known to not be present. This approach reduced the overestimation of ethylene content for such systems and was achieved by reduction of the number of sites used to determine the absolute ethylene content to:
E=0.5(S+S+S+0.5(S+S))

(9) Through the use of this set of sites the corresponding integral equation becomes:
E=0.5(I.sub.H+I.sub.G+0.5(I.sub.C+I.sub.D))
using the same notation used in the article of Wang et. al. (Wang, W-J., Zhu, S., Macromolecules 33 (2000), 1157). Equations used for absolute propylene content were not modified.

(10) The mole percent comonomer incorporation was calculated from the mole fraction:
E[mol %]=100*fE

(11) The weight percent comonomer incorporation was calculated from the mole fraction:
E[wt %]=100*(fE*28.06)/((fE*28.06)+((1fE)*42.08))

(12) The comonomer sequence distribution at the triad level was determined using the analysis method of Kakugo et al. (Kakugo, M., Naito, Y., Mizunuma, K., Miyatake, T.

(13) Macromolecules 15 (1982) 1150). This method was chosen for its robust nature and integration regions slightly adjusted to increase applicability to a wider range of comonomer contents.

(14) The Maleic Anhydride Content was Determined by FTIR

(15) For the FTIR measurement compression moulded films of 300 m thickness (pressed at 190 C.) were used. FTIR was done in transmission mode.

(16) The carbonyl group absorption peaks for both, maleic anhydride (MAH) and maleic acid show up at 1790 cm.sup.1 and 1712 cm.sup.1, respectively. In unmodified polypropylene this area of the spectra is relatively devoid of other peaks. Therefore the ranges for determination of the maleic anhydride content were set from 1815 cm.sup.1 to 1750 cm.sup.1. To quantify the amount of maleic anhydride present, a calibration curve was built with different concentrations of known MAH content. The curve was made up of 4 points: 0, 0.7, 1.05 and 1.4 wt % of MAH in isotactic propylene homopolymer. 0 wt % corresponds to the unmodified pure isotactic propylene homopolymer.

(17) For the calculation of the MAH content, the spectra of the propylene homopolymer without MAH is subtracted from the substrate with the unknown MAH concentration. After baseline correction the peak area under 1790 cm.sup.1 (integration range as describe above) is integrated and divided by the sample thickness and multiplied with the slope from the calibration curve. Finally a correction factor which describes the deviation from the zero point needs to be considered.

(18) MFR.sub.2 (230 C.) is measured according to ISO 1133 (230 C., 2.16 kg load).

(19) MFR.sub.2 (190 C.) is measured according to ISO 1133 (190 C., 2.16 kg load).

(20) Density is measured according to ISO 1183-1method A (2004). Sample preparation is done by compression moulding in accordance with ISO 1872-2:2007.

(21) Xylene cold soluble fraction (XCS wt.-%): Content of xylene cold solubles (XCS) is determined at 25 C. according ISO 16152; first edition; 2005 Jul. 1. The part which remains insoluble is the xylene cold insoluble (XCI) fraction.

(22) Intrinsic viscosity is measured according to DIN ISO 1628/1, October 1999 (in Decalin at 135 C.).

(23) The tensile modulus was measured according to ISO 527-2 (cross head speed=1 mm/min; 23 C.) using injection molded specimens as described in EN ISO 1873-2 (dog bone shape, 4 mm thickness). The measurement is done after 96 h conditioning time of the specimen.

(24) Charpy notched impact strength is determined according to ISO 180/1A at 23 C. and at 20 C. by using injection moulded test specimens as described in EN ISO 1873-2 (80104 mm).

(25) Median particle size (D.sub.50) (Sedimentation) is calculated from the particle size distribution [mass percent] as determined by gravitational liquid sedimentation according to ISO 13317-3 (Sedigraph)

(26) Cutoff particle size (D.sub.95) (Sedimentation) is calculated from the particle size distribution [mass percent] as determined by gravitational liquid sedimentation according to ISO 13317-3 (Sedigraph)

(27) Coefficient of linear thermal expansion: The coefficient of linear thermal expansion (CLTE) was determined in accordance with ISO 11359-2:1999 on 10 mm long pieces cut from the same injection molded specimens as used for the tensile modulus determination. The measurement was performed in a temperature range from 30 to +80 C. at a heating rate of 1 C./min and a temperature range from 23 to +80 C. at a heating rate of 1 C./min, respectively.

(28) Shrinkage in flow and shrinkage cross flow were deterimed on film gate injection moulded discs: One is a sector (radius 300 mm and opening angle of 20) and the other one a stripe (34065 mm). The two specimens are injection moulded at the same time in different thicknesses and back pressures (2 mm and 300, 400, 500 bars; 2.8 mm and 300, 400, 500 bars; 3.5 mm and 300, 400, 500 bars). The melt temperature is 240 C. and the temperature of the tool 25 C. Average flow front velocity is 3.00.2 mm/s for the 2 mm tool, 3.50.2 mm/s for the 2.8 mm tool and 00.2 mm/s for the 3.5 mm tool.

(29) After the injection moulding process the shrinkage of the specimens is measured at 23 C. and 50% humidity. The measurement intervals are 1, 4, 24, 48 and 96 hours after the injection moulding. To determine the shrinkage 83 and 71 measurement points (generated by eroded dots on the tool surface) of the sector and the stripe, respectively, are recorded with a robot. Both, in flow and cross flow shrinkage of the 2.8 mm thick plates exposed to a back pressure of 400 bars at 96 hours after the injection moulding process are reported as final results.

(30) Examples

(31) Preparation of HECOs 1 and 2

(32) Catalyst for HECO1 and HECO2

(33) First, 0.1 mol of MgCL.sub.23 EtOH was suspended under inert conditions in 250 ml of decane in a reactor at atmospheric pressure. The solution was cooled to the temperature of 15 C. and 300 ml of cold TiCl.sub.4 was added while maintaining the temperature at said level. Then, the temperature of the slurry was increased slowly to 20 C. At this temperature, 0.02 mol of dioctylphthalate (DOP) was added to the slurry. After the addition of the phthalate, the temperature was raised to 135 C. during 90 minutes and the slurry was allowed to stand for 60 minutes. Then, another 300 ml of TiCl.sub.4 was added and the temperature was kept at 135 C. for 120 minutes. After this, the catalyst was filtered from the liquid and washed six times with 300 ml heptane at 80 C. Then, the solid catalyst component was filtered and dried. Catalyst and its preparation concept is described in general e.g. in patent publications EP 0 491 566, EP 0 591 224 and EP 0 586 390.

(34) The catalyst was further modified (VCH modification of the catalyst).

(35) 35 ml of mineral oil (Paraffinum Liquidum PL68) was added to a 125 ml stainless steel reactor followed by 0.82 g of triethyl aluminium (TEAL) and 0.33 g of dicyclopentyl dimethoxy silane (donor D) under inert conditions at room temperature. After 10 minutes 5.0 g of the catalyst prepared above (Ti content 1.4 wt.-%) was added and after additionally 20 minutes 5.0 g of vinylcyclohexane (VCH) was added. The temperature was increased to 60 C. during 30 minutes and was kept there for 20 hours. Finally, the temperature was decreased to 20 C. and the concentration of unreacted VCH in the oil/catalyst mixture was analysed and was found to be 200 ppm weight.

(36) TABLE-US-00001 TABLE 1a Polymerization of HECO1 and HECO2 (Part 1) HECO1 HECO2 Prepoly Residence time [h] 0.25 0.26 Temperature [ C.] 27 28 Co/ED ratio [mol/mol] 5.94 5.9 Co/TC ratio [mol/mol] 184 221 Loop (R1) Residence time [h] 0.26 0.4 Temperature [ C.] 61 62 H.sub.2/C.sub.3 ratio [mol/kmol] 13.9 10.6 MFR [g/10 min] 63 54 XCS [wt %] 3.3 3.2 C2 content [mol %] 0 0 1.sup.st GPR (R2) Residence time [h] 0.09 0.1 Temperature [ C.] 79 80 Pressure [kPa] 15 15 H.sub.2/C.sub.3 ratio [mol/kmol] 161 152 MFR [g/10 min] 63 55 XCS [wt %] 3.4 2.6 C2 content [mol %] 0 0

(37) TABLE-US-00002 TABLE 1b Polymerization of HECO1 and HECO2 (Part 2) HECO1 HECO2 2.sup.nd GPR (R3) Residence time [h] 0.12 0.382 Temperature [ C.] 60 60 Pressure [kPa] 13 14 C.sub.2/C.sub.3 ratio [mol/kmol] 548 552 H.sub.2/C.sub.2 ratio [mol/kmol] 472 500 MFR [g/10 min] 33 32 XCS [wt %] 22 20.4 C2 content [mol %] 12.9 12.9 3.sup.rd GPR (R4) Residence time [h] 0.12 0.84 Temperature [ C.] 80 80 Pressure [kPa] 1500 15 C.sub.2/C.sub.3 ratio [mol/kmol] 549 549 H.sub.2/C.sub.2 ratio [mol/kmol] 391 513 Split (R1 + 2/R3 + 4) [] 66.1/33.9 71.7/28.3 MFR.sub.2 [g/10 min] 23 29 XCS [wt %] 32.8 26.1 IV of XCI [dl/g] 1.22 1.24 IV of XCS [dl/g] 2.12 1.98 C2 of XCS [mol %] 49 48 C2 content [mol %] 20.9 15.9

(38) The HECOs 1 and 2 were mixed in a twin-screw extruder with 0.1 wt % of Pentaerythrityl-tetrakis(3-(3,5-di-tert. butyl-4-hydroxyphenyl)-propionate, (CAS-no. 6683-19-8, trade name Irganox 1010) supplied by BASF AG, 0.1 wt % Tris (2,4-di-t-butylphenyl) phosphite (CAS-no. 31570-04-4, trade 10 name Irgafos 168) supplied by BASF AG, and 0.05 wt % Calcium stearate (CAS-no. 1592-23-0) supplied by Croda Polymer Additives.

(39) The inventive and comparative compositions were melt blended on a co-rotating twin screw extruder.

(40) TABLE-US-00003 TABLE 2 Properties of the examples Units IE1 IE2 IE3 CE1 CE2 CE3 HECO1 [wt.-%] 96 90 100 HECO2 [wt.-%] 88 100 90 PMP [wt.-%] 4 10 12 Plastomer [wt.-%] 10 MFR [g/10 min] 14 10 17 23 27 28 XCS [wt.-%] 35.0 38.0 34.9 32.6 26.1 34 IV(XCS) [dl/g] 2.13 2.30 1.91 2.12 1.98 1.80 C2(XCS) [mol %] 48.3 49.8 48.5 48.2 45.7 52 SHif [%] 1.15 0.91 1.03 0.98 1.11 0.71 SHaf [%] 1.33 1.12 1.26 1.16 1.33 0.92 TM [MPa] 877 800 921 1007 1215 1010 CHI(23) [kJ/m.sup.2] 56 61 47 28 8.6 35 CHI(20)0 [kJ/m.sup.2] 11 20 6 6.8 5 5 CLTE23 [m/mK] 112 112 115 121 119 106 CLTE 30 [m/mK] 99 98 100 106 104 94 SHif Shrinkage in flow SHaf Shrinkage across flow TM Tensile Modulus CHI(23) Charpy impact strength at 23 C. CHI(20) Charpy impact strength at 20 C. CLTE23 CLTE +23/80 C./MD CLTE 30 CLTE 30/80 C./MD PMP is the commercial maleic anhydride grafted ethylene propylene copolymer Exxelor VA 1803 of ExxonMobil having a density of 860 kg/m.sup.3 and a MFR.sub.2 (230 C.) of 3.3 g/10 min. The anhydride content is 1.9 wt.-%. The propylene content of the ethylene propylene copolymer is 37.6 mol-% Plastomer is the commercial ethylene-1-octene copolymer Engage 8407 of Dow having a density of 870 kg/mol, a 1-octene content of 14.2 mol-% and a MFR.sub.2 (190 C.) of 30 g/10 min.