Use of a polymer composition for the production of articles with improved paintability and surface appearance

Abstract

The present invention is directed to the use of a polypropylene composition comprising at least one heterophasic polypropylene and a filler for the production of at least partially painted articles which show both a good paintability and a good surface appearance; and the painted articles produced therefrom. Further the invention is directed to a polypropylene composition showing improved surface appearance and paintability.

Claims

1. A method comprising producing at least partially painted articles from a polypropylene composition comprising (A) a heterophasic polypropylene having a xylene cold soluble fraction (XCS) of 10.0 to 45 wt % and an intrinsic viscosity (IV) of the xylene cold soluble (XCS) fraction of 2.1 to 4.5 dl/g, (B) a heterophasic polypropylene having an intrinsic viscosity (IV) of (XCS) >5.0 dl/g, (C) a filler, and (D) a C.sub.2-α-Olefin having a MFR (190° C./2.16 kg) <0.5 g/10 min, with the polypropylene composition having an intrinsic viscosity (IV) of (XCS) of >3.0 dl/g and a ratio of intrinsic viscosity (IV) of (XCS)/xylene cold soluble fraction (XCS) of >0.113 dl/g.

2. The method according to claim 1 wherein in the polypropylene composition component (A) is present in an amount of 40 to 80 wt % and component (B) is present in an amount of 10 to 50 wt %, based on a total weight of the polypropylene composition.

3. The method according to claim 1 wherein component (B) is present in the polypropylene composition in an amount of 10 to 40 wt % based on the total weight of the polypropylene composition.

4. The method according to claim 1 wherein the polypropylene composition has an MFR (230° C./2.16 kg) in the range of 5.0 to 80 g/10 min.

5. The method according to claim 1 wherein component (A) has an MFR (230° C. 2.16 kg) of 4.0 to 120 g/10 min.

6. The method according to claim 1 wherein the intrinsic viscosity (IV) of (XCS) of component (A) is in the range of 2.2 to 4.5 dl/g.

7. The method according to claim 1 wherein the MFR (230° C./2.16 kg) of component (B) is >5.0 g/10 min.

8. The method according to claim 1 wherein the intrinsic viscosity (IV) of (XCS) of component (B) is in a range of 6.0 to 12.0 dl/g.

9. The method according to claim 1 wherein component (C) is present in the polypropylene composition in an amount of 5 to 25 wt % based on the total weight of the polypropylene composition.

10. The method according to claim 1 wherein the C.sub.2-a-Olefin of component (D) is having 4 C-atoms.

11. The method according to claim 1 wherein the intrinsic viscosity (IV) of (XCS) of component (D) is >2.0 dl/g.

12. The method according to claim 1 wherein component (D) is present in an amount of 10 to 20 wt % based on the total weight of the polypropylene composition.

13. The method according to claim 1 wherein the polypropylene composition is comprising 40 to 70 wt % of component (A), 10 to 40 wt % of component (B) 5 to 25 wt % of component (C) and 10 to 20 wt % of component (D), based on the total weight of the final polypropylene composition.

14. The method according to claim 1 wherein the at least partially painted articles show a sum of the average delaminated area DA.sub.2 (measured according to DIN 55662 Method C) and the average delaminated area DA.sub.3 (measured according to DIN 55662 Method C) of <55.0 mm.sub.2.

15. The method according to claim 14 wherein the at least partially painted articles show a Tigerskin value (measured according to PPS 25 Intern. Conf. Polym. Proc. Soc 2009 or Proceedings of the SPIE, Volume 6831, pp 68130T-68130T-8 (2008)) of <46.0.

16. The method according to claim 1 wherein the at least partially painted articles show an average delaminated area DA.sub.2 (measured according to DIN 55662 Method C) of <1 mm.sup.2 and a Tigerskin value (measured according to PPS 25 Intern. Conf. Polym. Proc. Soc 2009 or Proceedings of the SPIE, Volume 6831, pp 68130T- 68130T-8 (2008)) of <6.8.

17. At least partially painted article comprising a polypropylene composition comprising (A) a heterophasic polypropylene having a xylene cold soluble fraction (XCS) of 10.0 to 45 wt % and an intrinsic viscosity (IV) of the xylene cold soluble (XCS) fraction of 2.1 to 4.5 dl/g, (B) a heterophasic polypropylene having an intrinsic viscosity (IV) of (XCS) >5.0 dl/g, (C) a filler, and (D) a C2-α-Olefin having a MFR (190° C./2.16 kg) <0.5 g/10 min, with the polypropylene composition having an intrinsic viscosity (IV) of (XCS) of >3.0 dl/g and a ratio of intrinsic viscosity (IV) of (XCS)/xylene cold soluble fraction (XCS) of >0.113 dl/g.

18. The at least partially painted article according to claim 17 with the at least partially painted article being an automotive article.

19. Polypropylene composition comprising (A) a heterophasic polypropylene having a xylene cold soluble fraction (XCS) of 10.0 to 45 wt % and an intrinsic viscosity (IV) of (XCS) of 2.1 to 4.5 dl/g, (B) a heterophasic polypropylene having an intrinsic viscosity (IV) of (XCS) >5.0 dl/g, (C) a filler, and (D) a C.sub.2-a-Olefin having an MFR (190° C./2.16 kg) <0.5 g/10 min with the polypropylene composition having an intrinsic viscosity (IV) of (XCS) of >3.0 dl/g and a ratio of intrinsic viscosity (IV) of (XCS)/xylene cold soluble fraction (XCS) of >0.113 dl/g.

20. At least partially painted article comprising a polypropylene composition comprising (A) a heterophasic polypropylene having a xylene cold soluble fraction (XCS) of 10.0 to 45 wt % and an intrinsic viscosity (IV) of the xylene cold soluble (XCS) fraction of 2.1 to 4.5 dl/g, (B) a heterophasic polypropylene having an intrinsic viscosity (IV) of (XCS) >5.0 dl/g, and (C) a filler wherein the polypropylene composition has an intrinsic viscosity (IV) of (XCS) of >3.0 dl/g and a ratio of intrinsic viscosity (IV) of (XCS)/xylene cold soluble fraction (XCS) of >0.113 dl/g, and wherein the at least partially painted articles show a sum of the average delaminated area DA.sub.2 (measured according to DIN 55662 Method C) and the average delaminated area DA.sub.3 (measured according to DIN 55662 Method C) of <55.0 mm.sup.2.

Description

EXAMPLES

(1) 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.

1. MEASURING METHODS

(2) Xylene cold soluble (XCS) fraction is determined at 23° C. according to ISO 6427.

(3) Intrinsic viscosity (IV) of (XCS) is measured according to DIN ISO 1628/1, October 1999 (in Decalin at 135° C.).

(4) MFR (190° C./2.16 kg) is measured according to ISO 1133 (190° C., 2.16 kg load).

(5) MFR (230° C./2.16 kg) is measured according to ISO 1133 (230° C., 2.16 kg load).

(6) Tensile Modulus and elongation at break were measured according to ISO 527-2 (cross head speed=50 mm/min; 23° C.) using injection-molded specimens as described in (ISO 527-2:2012) (dog bone shape, 170×10×4 mm).

(7) Charpy Impact Test: The Charpy notched impact strength (Charpy NIS) is measured according to ISO 1791eA/DIN 53453 at 23° C., and −20° C., using injection moulded bar test specimens of 80×10×4 mm.sup.3 mm.sup.3 prepared in accordance with ISO 294-1:1996.

(8) Median particle size d50 (Sedimentation) is calculated from the particle size distribution 20 [mass percent] as determined by gravitational liquid sedimentation according to ISO 13317-3 (Sedigraph).

(9) Cutoff particle size d95 (Sedimentation) is calculated from the particle size distribution 30 [mass percent] as determined by gravitational liquid sedimentation according to ISO 13317-3 (Sedigraph).

(10) Surface area: BET with N2 gas according to DIN 66131/2, apparatus Micromeritics Tristar 3000: sample preparation at a temperature of 50° C., 6 hours in vacuum.

(11) Surface Appearance/Tiger Skin Value

(12) The tendency to show flow marks measured in the present invention in mean square error (MSE) was examined with a method as described below. This method is described in detail in WO 2010/149529, which is incorporated herein in its entirety.

(13) An optical measurement system, as described by Sybille Frank et al. in PPS 25 Intern. Conf. Polym. Proc. Soc 2009 or Proceedings of the SPIE, Volume 6831, pp 68130T-68130T-8 (2008) was used for characterizing the surface quality.

(14) This method consists of two aspects:

(15) 1. Image Recording:

(16) The basic principle of the measurement system is to illuminate the plates with a defined light source (LED) in a closed environment and to record an image with a CCD-camera system.

(17) 2. Image Analysis:

(18) The specimen is floodlit from one side and the upwards reflected portion of the light is deflected via two mirrors to a CCD-sensor. The thus created grey value image is analyzed in lines. From the recorded deviations of grey values the mean square error average (MSE) is calculated allowing a quantification of surface quality/homogeneity, i.e. the higher the MSE value the more pronounced is the surface defect.

(19) Generally, for one and the same material, the tendency to flow marks and thus to higher MSE values increases when the injection speed is increased and hence the filling time is decreased.

(20) The MSE values, called Tigerskin values were collected on injection-moulded plaques 440×148×2.8 mm produced with grain G1. The plaques were injection-moulded with different filling times of 1.5, 3 and 6 sec respectively.

(21) Further Conditions:

(22) Melt temperature: 240° C.

(23) Mould temperature 30° C.

(24) Dynamic pressure: 10 bar hydraulic

(25) Paint Adhesion/Paintability is characterized as the resistance of the pre-fabricated scratch template to pressure-water jetting according to DIN 55662 (Method C).

(26) Injection moulded sample plates (150 mm×80 mm×2 mm) were cleaned with a mixture of isopropanol and water (1:1). Subsequently the surface was activated via flaming where a burner with a speed of 600 mm/s spreads a mixture of propane and air in a ratio of 1:23 with a flow rate of 150 l/h on the polymer substrate. Afterwards, the polymer substrate was coated with 2 layers of black paint, i.e. a base coat (Black BMW 668) and a clear coat (BMW 68895). The step of flaming was performed two times.

(27) A steam of hot water with temperature T was directed for time t at distance d under angle α to the surface of the test panel. Pressure of the water jet results from the water flow rate and is determined by the type of nozzle installed at the end of the water pipe.

(28) The following parameters were used:

(29) T (water)=60° C.; t=60 s; d=130 mm, α=90°, water flow rate 11.3 l/min, nozzle type=MPEG 2506.

(30) The adhesion was assessed by quantifying the failed or delaminated painted area per test line i.e. DA.sub.2 (delaminated area for 2-layers painted systems) DA.sub.3 (delaminated area for 3-layers painted systems). For each example 5 panels (150 mm×80 mm×2 mm) have been tested. The panels were produced by injection moulding with 240° C. melt temperature and 50° C. mold temperature. The flow front velocity during injection was 100 mm/s. On each panel certain lines were used to assess the paintability failure in [mm.sup.2]. For this purpose, an image of the test point before and after steam jet exposure was taken. Then the delaminated area was calculated with an image processing software. The average delaminated area for 5 test lines on 5 test specimens (i.e. in total the average of 25 test points) was reported as average delaminated area.

2. EXAMPLES

(31) 2.1. Catalyst Preparation for Heterophasic Polypropylenes A1, A2, A4 and B Used in Inventive Examples IE1 to IE9 and in Comparative Examples CE2, CE3

(32) First, 0.1 mol of MgCl.sub.2×3 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 were 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. over a period of 90 minutes and subsequently the slurry was allowed to stand for 60 minutes. Then, another 300 ml of TiCl.sub.4 were 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. The catalyst and its preparation concept is described in general e.g. in patent publications EP 491566, EP 591224 and EP 586390.

(33) The catalyst was further modified (VCH modification of the catalyst) as described in EP 2960256A1. 52 ml of mineral oil (Paraffinum Liquidum PL68) was added to a 125 ml stainless steel reactor followed by 1.17 g of triethyl aluminium (TEAL) and 0.73 g of dicyclopentyl dimethoxy silane (D-donor) under inert conditions at room temperature. After 10 minutes, 5.0 g of the catalyst prepared above (Ti content 1.8 wt.-%) was added, and after additional 20 minutes 5.0 g of vinylcyclohexane (VCH) was added. The respective processes are described in EP 1028984, EP 1183307 and EP 591224.

(34) 2.2. Catalyst Preparation for Heterophasic Polypropylene A3 Used in Comparative Example CE1

(35) 80 mg of ZN104-catalyst of LyondellBasell is activated for 5 minutes with a mixture of Triethylaluminium (TEAL; solution in hexane 1 mol/l) and Dicyclopentyldimethoxysilane as donor (0.3 mol/l in hexane)—in a molar ratio of 18.7 (Co/ED) after a contact time of 5 min and 10 ml hexane in a catalyst feeder. The molar ratio of TEAL and Ti of catalyst is 220 (Co/TC)). After activation the catalyst is spilled with 250 g propylene into the stirred reactor with a temperature of 23° C. Stirring speed is hold at 250 rpm. After 6 min prepolymersation at 23° C. the polymerization starts as indicated in table 1.

(36) 2.3. Preparation of Heterophasic Polypropylenes A1 to A4 Used in Examples IE1 to IE3, IE5 to IE9, CE1 to CE3 and of Heterophasic Polypropylene B Used in Examples IE1, IE4 to IE8, CE3

(37) A Borstar PP pilot plant comprised of a stirred-tank prepolymerization reactor, a liquid-bulk loop reactor and three gas phase reactors (GPR1 to GPR3) was used for the main polymerization.

(38) The polymerization conditions of the heterophasic polypropylenes A1 to A4 and B used in inventive Examples IE1 to IE9 and in comparative Examples CE1 to CE3 are shown in Tables 1 and 2.

(39) TABLE-US-00001 TABLE 1 Polymerization conditions of the heterophasic polypropylenes A1 to A4 of IE1 to IE3, IE5 to IE9, CE1 to CE3 A4 A1 A2 IE1, IE7, IE1, IE2, IE3, IE5, A3 IE8, IE9, IE9 IE6, CE1 CE2, CE3 Donor DCPDMS DCPDMS DCPDMS Cocatalyst TEAL TEAL TEAL TEAL Co/ED ratio [mol/mol] 7.3 10.0 18 10 Co/TC ratio [mol/mol] 220 205 220 220 Prepolymerization Residence time [h] 0.08 0.09 0.1 0.08 Temperature [° C.] 30 30 30 30 Matrix (PM1) Loop Reactor (LR) Split [wt %] 39 29 32.5 52 Temperature [° C.] 72 72 70 75 Pressure [kPa] 5633 5532 5355 5530 H2/C3 [mol/kmol] 14.8 21 14 22 MFR [g/10 min] 55 120 35 160 Matrix (PM1) 1st Gas Phase Reactor (GPR1) Split [wt %] 26 36 34.5 34 Temperature [° C.] 80 85 78 80 Pressure [kPa] 2231 2500 2214 2200 H2/C3 [mol/kmol] 150 204 78 175 MFR [g/10 min] 55 120 35 160 Elastomer (EPR1) 2nd Gas Phase Reactor (GPR2) Split [wt %] 20 22 21 14 Temperature [° C.] 70 75 71 80 Pressure [kPa] 2201 2000 2202 2190 H2/C2 ratio [mol/kmol] 116 84.75 219 250 C2/C3 ratio [mol/kmol] 584 701 715 550 C2 [mol %] 12.2 10.8 12 11.5 MFR [g/10 min] 20 40 12 95 XCS wt % 20 18 19 15 Elastomer (EPR1) 3rd Gas Phase Reactor (GPR3) Temperature [° C.] 85 85 83 n.a. Pressure [kPa] 1421 1400 1383 n.a. C2/C3 ratio [mol/kmol] 585.2 699 747 n.a. H2/C2 ratio [mol/kmol] 92.7 129 203 n.a. MFR [g/10 min] 11 24 13 n.a. split [wt %] 15 13 12 0 XCS [wt %] 32.5 29 31 n.a. wt % based on the weight of the heterophasic polypropylene (A) DCPDMS Dicyclopentyldimethoxysilane TEAL Triethylaluminium MFR Melt flow rate at 230° C. H2/C3 Molar ratio of hydrogen to propylene C2/C3 Molar ratio of ethylene to propylene H2/C2 Molar ratio of hydrogen to ethylene

(40) TABLE-US-00002 TABLE 2 Polymerization conditions of the heterophasic polypropylene B of IE1, IE4 to IE8, CE3 B IE1, IE4, IE5, IE6, IE7, IE8, CE3 Donor DCPDMS Cocatalyst TEAL Co/ED ratio [mol/mol] 10 Co/TC ratio [mol/mol] 200 Prepolymerization Residence time [h] 0.26 Temperature [° C.] 30 Matrix (PM1) Loop Reactor (LR) Split [wt %] 35 Temperature [° C.] 76 Pressure [kPa] 5633 H2/C3 [mol/kmol] 25 MFR [g/10 min] 160 Matrix (PM1) 1st Gas Phase Reactor (GPR1) Split [wt.-%] 40 Temperature [° C.] 80 Pressure [kPa] 2400 H2/C3 [mol/kmol] 45 MFR2 [g/10 min] 55 Elastomer (EPR1) 2nd Gas Phase Reactor (GPR2) Split [wt %] 15 Temperature [° C.] 67 Pressure [kPa] 2100 H2/C2 ratio [mol/kmol] 23 C2/C3 ratio [mol/kmol] 242 C2 [mol %] 10 MFR [g/ 10 min] 20 XCS [wt %] 18 Elastomer (EPR1) 3rd Gas Phase Reactor (GPR3) Temperature [° C.] 67 Pressure [kPa] 1500 C2/C3 ratio [mol/kmol] 250 H2/C2 ratio [mol/kmol] 22 MFR [g/10 min] 5.5 split [wt %] 10 XCS [wt %] 25 wt % based on the weight of the heterophasic polypropylene B

(41) TABLE-US-00003 TABLE 3 Properties of the heterophasic polypropylenes A1 to A4 and B of IE1 to IE9 and CE1 to CE3 B A1 A4 IE1, IE4, IE1, A2 IE1, IE7, IE5, IE6, IE2, IE3, IE5, A3 IE8, IE9, IE7, IE8, IE9 IE6 CE1 CE2, CE3 CE3 MFR [g/10 min] 11 24 13 95 5.5 XCS [wt %] 32.5 29 31 15 25 IV (XCS) [dl/g] 3.3 3.2 2.2 2.3 7.0

(42) TABLE-US-00004 TABLE 4 Properties of C.sub.2 α-Olefin component D of IE8 and of propylene homopolymer component X of IE9 D X IE8 IE9 MFR [g/10 min] 0.46 8 XCS [wt %] 19 2.8 IV (XCS) [dl/g] 2.1 1.8
2.4. Preparation of Polypropylene Composition Comprising Heterophasic Polypropylenes A1 to A4 and/or B Used in Inventive Examples IE1 to IE9 and in Comparative Examples CE1 to CE3

(43) The compositions were prepared via melt blending on a co-rotating twin screw extruder with 0.1 wt.-% of Songnox 1010FF (Pentaerythrityl-tetrakis(3-(3′,5′-di-tert. butyl-4-hydroxyphenyl)), 0.1 wt.-% Kinox-68 G (Tris (2,4-di-t-butylphenyl) phosphite) from HPL Additives, 0.2 wt % glycerin monostearate. The polymer melt mixture was discharged and pelletized.

(44) The constituents of the polypropylene compositions used in inventive Examples IE1 to IE9 and in comparative Examples CE1 to CE3 are shown in Tables 5 and 6.

(45) The properties of the polypropylene compositions used in inventive Examples IE1 to IE9 and in comparative Examples CE1 to CE3 are shown in Tables 7 and 8.

(46) TABLE-US-00005 TABLE 5 Constituents of polypropylene compositions of inventive Examples IE1 to IE9 IE1 IE2 IE3 IE4 IE5 IE6 IE7 IE8 IE9 A1 [wt %] 47 87 47 A2 [wt %] 87 67 57 A3 A4 20 47 47 20 B [wt %] 20 87 20 20 40 15 D [wt %] 15 X [wt %] 20 C [wt %] 10 10 10 10 10 20 10 20 10 Additivation [wt %] 3 3 3 3 3 3 3 3 3

(47) TABLE-US-00006 TABLE 6 Constituents of polypropylene compositions of comparative Examples CE1 to CE3 CE1 CE2 CE3 A3 [wt %] 87 A4 [wt %] 87 47 B [wt %] 15 Engage HM7467 [wt %] 15 C [wt %] 10 10 20 Additivation [wt %] 3 3 3

(48) wt % is based on the weight of the final polypropylene composition.

(49) Component D of IE8 is the commercial ethylene-butene copolymer Engage HM 7487 by Dow having a density of 0.860 g/cm3, a melt flow rate MFR (190° C., 2.16 kg) of 0.26 g/10 min, a MFR (230° C., 2.16 kg) of 0.46 g/10 min and a 1-butene content of 19.1 mol %.

(50) Engage HM 7467 of CE3 is the commercial ethylene-butene copolymer Engage HM 7467 by Dow having a density of 0.862 g/cm3, a melt flow rate MFR (190° C., 2.16 kg) of 1.18 g/10 min, a MFR (230° C., 2.16 kg) of 2.4 g/10 min and a 1-butene content of 18.1 mol %.

(51) Component X of IE9 is the commercial product HD120 MO by Borealis, a propylene homopolymer grade with MFR (230° C.) of 8.0 g/10 min.

(52) Component C is the commercial talc Steamic T1 CA of Luzenac having a mean particle size d.sub.50 of 2.1 μm (Sedigraph of compacted talc).

(53) TABLE-US-00007 TABLE 7 Properties of the Polypropylene compositions of inventive Examples IE1 to IE9 IE1 IE2 IE3 IE4 IE5 IE6 IE7 IE8 IE9 XCS [wt %] 23.3 28.3 25.2 21.8 24.4 21.5 17.0 25.8 18.3 IV(XCS) [dl/g] 4.2 3.5 3.1 6.0 3.7 3.8 4.5 3.5 3.3 MFR [g/10 min] 15.98 11.4 21.0 6.7 16.0 14.32 26.4 19.0 17.0 Tensile [MPa] 1676 1440 1433 1601 1503 2063 1882 1861 1835 Modulus Elongation 43.0 56.0 38.0 403 56.47 40.55 35.43 49.32 40.2 at break Charpy [kJ/m.sup.2] 12.13 20.5 13.1 50.4 14.45 10.99 7.91 19.70 8.0 ISO1791eA; +23° C. IV(XCS)/ 0.180 0.124 0.123 0.275 0.152 0.177 0.265 0.136 0.180 XCS DA.sub.2 average [mm.sup.2] 0 0 0 0 0 0 0 1 0 DA.sub.3 average [mm.sup.2] 0.8 0 0 0 0 0 0 29 0 Tigerskin value 1.5 sec 6.10 21.8 5.9 4.3 5.6 5.5 5.3 6.8 45.1   3 sec 3.9 45.9 3.1 3.6 3.3 5.5 3.3 5.0 14.0   6 sec 2.8 4.7 4.9 4.1 2.6 3.3 2.7 3.7 3.7

(54) TABLE-US-00008 TABLE 8 Properties of the polypropylene composition of comparative Examples CE1 to CE3 CE1 CE2 CE3 XCS [wt %] 26.9 13 25.8 IV(XCS) [dl/g] 2.0 2.3 2.9 MFR [g/10 min] 12.2 80.2 23.6 Tensile Modulus [MPa] 1303 2063 1785 Elongation at 420 5.5 58.4 break Charpy [kJ/m.sup.2] 25.1 3.2 30 ISO1791eA; +23 ° C. IV(XCS)/XCS 0.074 0.177 0.112 DA.sub.2 average [mm.sup.2] 29 0 58 DA.sub.3 average [mm.sup.2] 29 139 83 Tigerskin value 1.5 sec 85.7 6.9 6.8   3 sec 51.1 3.4 6.5   6 sec 20.4 3.2 5.2

(55) The polypropylene compositions of Inventive Examples IE2, IE3 and IE9 of Table 7 comprise at least one component A, whereupon the composition of IE9 in addition to two different A components A1 and A4 also comprises a propylene homopolymer X with an intrinsic viscosity (IV) of (XCS) of <2 dl/g. Table 7 shows that those compositions even without containing component (B) achieve very good paintability values as long as the intrinsic viscosity (IV) and the IV (XCS)/XCS ratio are within the ranges specified in present claim 1. Paintability requirements for both the two layer and the three layer system are certainly fulfilled. Moreover there can additionally be achieved excellent surface appearance values as e.g. shown in example IE3. Accordingly such compositions can be used both for fully and for partially painted articles. In comparison to that as is derivable from Table 8, the compositions of Comparative Examples CE1 and CE2 which also contain only components A3 and A4 but don't contain component B do not show the required paintability values. Those compositions do not comprise the IV (XCS) and IV (XCS)/XCS features of present claim 1. Articles made of those compositions are thus not suitable for being painted optionally with the two—or with the three layer system.

(56) From a comparison of IE9 with IE1 of Table 7 it can be seen that in addition to the excellent paintability values achievable even with a homopolymer component having a low intrinsic viscosity IV (XCS), the surface appearance of the final polypropylene composition clearly improves if instead of the homopolymer component X the heterophasic polypropylene component B is used. The thus obtained articles containing both component A and component B are suitable both for fully and for partially painted articles.

(57) Similarly compositions IE5, IE6 and IE7 shown in Table 7 comprise both component A and component B and having IV and IV/XCS values according to present claim 1. They also show both very good paintability and surface appearance properties. Moreover IE7 shows that an excessively high IV (XCS)/XCS ratio does not result in any further advantage in the paintability and surface appearance properties compared to a composition such as in IE6 with some lower IV (XCS)/XCS ratio which of course is still within the limits given in present claim 1.

(58) The composition shown in IE8 of Table 7 comprises component D with a low MFR value of <0.5 g/10 min as specified in claim 12 of the present invention. This results in very good mechanical properties, as for example both impact strength (Charpy) and Tensile Modulus of the final polypropylene composition are as required. Surprisingly such compositions in addition to a good surface appearance show acceptable paintability values. This seems mainly due to the fact that component D of IE8 is a branched Elastomer. In comparison to that, the results of the composition of CE3 which is composed of the same constituents as the one of IE8 except that instead of the branched elastomer an unbranched elastomer is used are clearly worse. Actually the unbranched elastomer of CE3 shows an MFR >0.5 g/10 min and results in good mechanical properties of the final composition but both paintability and surface appearance values are not satisfying.