Polypropylene composite

Abstract

Fiber reinforced composition comprising (a) a polypropylene random copolymer comprising ethylene and/or C.sub.4 to C.sub.8 a-olefin (PP-RACO), (b) glass fibers (GF), and (c) a polar modified polypropylene as adhesion promoter (AP), wherein (i) the polypropylene random copolymer comprising ethylene and/or C4 to C8 a-olefin (PP-RACO) heaving a melt flow rate MFR.sub.2 (230 C.) measured according to ISO 1133 of at least 2.5 g/10 min, (ii) the glass fibers (GF) are cut glass fibers and (iii) the polymer contained in the reinforced composition forms a continuous phase being the matrix of the fiber reinforced composition.

Claims

1. A fiber reinforced composition comprising (a) 50.0 to 84.5 wt. % of a metallocene catalyzed polypropylene random copolymer comprising ethylene and/or C.sub.4 to C.sub.8 -olefin (PP-RACO), (b) 15.0 to 45.0 wt. % glass fibers (GF) and (c) 0.5 to 5.0 wt. % a modified polypropylene as adhesion promoter (AP), based on the total weight of the fiber reinforced composition, wherein (i) the polypropylene random copolymer comprising 1.0 to 10.0 wt. % of ethylene and/or C.sub.4 to C.sub.8 -olefin (PP-RACO) having a melt flow rate MFR.sub.2 (230 C.) measured according to ISO 1133 of at least 2.5 g/10 min up to 15.0 g/10 min, having a xylene cold soluble content (XCS) measured according ISO 16152 (25 C.) in the range of 10 to 25 wt. %, and having a polydispersity (Mw/Mn) as determined by size exclusion chromatography in the range of 1.5 to 6.5, (ii) the glass fibers (GF) are cut glass fibers and (iii) the complete polymer contained in the reinforced composition forms a monophasic continuous phase being the matrix of the fiber reinforced composition.

2. The fiber reinforced composition according to claim 1, wherein the adhesion promoter (AP) is a polypropylene homo- or copolymer with grafted polar groups.

3. The fiber reinforced composition according to claim 1, wherein the overall tensile modulus measured at 23 C. according to ISO 527-2, measured at a cross head speed of 1 mm/min, is at least 2,500 MPa.

4. The fiber reinforced composition according to claim 1, wherein the tensile strain at break measured at 23 C. according to ISO 527-2, measured at a cross head speed of 50 mm/min, is at least 4.0%.

5. The fiber reinforced composition according to claim 1, wherein the amount of volatile organic compounds (VOC) measured according to VDA 278:2002 is equal to or below 50 ppm.

6. The fiber reinforced composition according to claim 1, wherein the amount of fogging compounds (FOG) measured according to VDA 278:2002 is equal to or below 130 ppm.

7. The fiber reinforced composition according to claim 1, wherein the polypropylene random copolymer (PP-RACO) is prepared by polymerizing propylene and ethylene and/or C.sub.4-8 -olefin in the presence of a catalyst, the catalyst comprising an asymmetrical complex of formula (I) ##STR00007## wherein M is zirconium or hafnium; each X is a sigma ligand; L is a divalent bridge selected from R.sub.2C, R.sub.2CCR.sub.2, R.sub.2Si, R.sub.2SiSiR.sub.2, and R.sub.2Ge, wherein each R is independently a hydrogen atom, C.sub.1-20-hydrocarbyl, tri(C.sub.1-20-alkyl)silyl, C.sub.6-20-aryl, C.sub.7-20-arylalkyl or C.sub.7-20-alkylaryl; R.sup.2 and R.sup.2 are each independently a C.sub.1-20 hydrocarbyl radical optionally containing one or more heteroatoms from groups 14-16; R.sup.5 is a C.sub.1-20 hydrocarbyl group optionally containing one or more heteroatoms from groups 14-16 and optionally substituted by one or more halo atoms; R.sup.6 and R.sup.6 are each independently hydrogen or a C.sub.1-20 hydrocarbyl group optionally containing one or more heteroatoms from groups 14-16; R.sup.7 and R.sup.7 are each independently hydrogen or C.sub.1-20 hydrocarbyl group optionally containing one or more heteroatoms from groups 14-16; Ar is an aryl or heteroaryl group having up to 20 carbon atoms optionally substituted by one or more groups R.sup.1; Ar is an aryl or heteroaryl group having up to 20 carbon atoms optionally substituted by one or more groups R.sup.1; each R.sup.1 is a C.sub.1-20 hydrocarbyl group or two R.sup.1 groups on adjacent carbon atoms taken together can form a fused 5 or 6 membered non aromatic ring with the Ar group, said ring being itself optionally substituted with one or more groups R.sup.4; and each R.sup.4 is a C.sub.1-20 hydrocarbyl group.

8. The fiber reinforced composition according to claim 7, wherein the polypropylene random copolymer (PP-RACO) is prepared by polymerizing propylene and ethylene and/or C.sub.4-8 -olefin in the presence of a catalyst, the catalyst comprising an asymmetrical complex of formula (V) or (V) ##STR00008## wherein each X is a sigma ligand; R is independently a C.sub.1-6 alkyl or C.sub.3-10 cycloalkyl; R.sup.1 is C.sub.3-8 alkyl; R.sup.6 is hydrogen or a C.sub.3-8 alkyl group; R.sup.6 is a C.sub.3-8 alkyl group or C.sub.6-10 aryl group; R.sup.3 is a C.sub.1-6 alkyl group, or C.sub.6-10 aryl group optionally substituted by one or more halo groups; and n is 0, 1 or 2.

9. A process for preparing the fiber reinforced composition according to claim 1 comprising the steps of adding (a) polypropylene random copolymer (PP-RACO), (b) the glass fibers (GF), and (c) the polar modified polypropylene as adhesion promoter (AP) to an extruder and extruding the same obtaining the fiber reinforced composition.

10. An automotive article comprising the fiber reinforced composition according to claim 1.

11. A foamed article comprising the fiber reinforced composition according to claim 1.

Description

EXPERIMENTAL PART

(1) 1. Methods

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

(3) Quantification of Copolymer Microstructure by NMR Spectroscopy

(4) Quantitative nuclear-magnetic resonance (NMR) spectroscopy was used to quantify the comonomer content of the polymers.

(5) 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 as described in G. Singh, A. Kothari, V. Gupta, Polymer Testing 2009, 28(5), 475.

(6) To ensure a homogenous solution, after initial sample preparation in a heat block, the NMR tube was further heated in a rotatory 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 as described in Z. Zhou, R. Kuemmerle, X. Qiu, D. Redwine, R. Cong, A. Taha, D. Baugh, B. Winniford, J. Mag. Reson. 187 (2007) 225 and V. Busico, P. Carbonniere, R. Cipullo, C. Pellecchia, J. Severn, G. Talarico, Macromol. Rapid Commun. 2007, 28, 1128. A total of 6144 (6 k) transients were acquired per spectra. Quantitative .sup.13C{.sup.1H} NMR spectra were processed, integrated and relevant quantitative properties determined from the integrals. 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.

(7) 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.

(8) Characteristic signals corresponding to the incorporation of ethylene were observed (as described in Cheng, H. N., Macromolecules 1984, 17, 1950) and the comonomer fraction calculated as the fraction of ethylene in the polymer with respect to all monomer in the polymer.

(9) The comonomer fraction was quantified using the method of W-J. Wang and S. Zhu, Macromolecules 2000, 33 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.

(10) The mole percent comonomer incorporation was calculated from the mole fraction.

(11) The weight percent comonomer incorporation was calculated from the mole fraction.

(12) The Xylene Solubles (XCS, Wt.-%):

(13) Content of xylene cold solubles (XCS) is determined at 25 C. according ISO 16152; first edition; 2005.

(14) DSC Analysis, Melting Temperature (T.sub.m) measured with a TA Instrument Q200-differential scanning calorimetry (DSC) on 5 to 7 mg samples. DSC is run according to ISO 11357/part 3/method C.sub.2 (1999) in a heat/cool/heat cycle with a scan rate of 10 C./min in the temperature range of 30 to +225 C. The melting temperature is determined from the second heating step.

(15) Size Exclusion Chromatography (SEC):

(16) Number average molecular weight (Mn), weight average molecular weight (Mw) and polydispersity (Mw/Mn) are determined by size exclusion chromatography (SEC) using Waters Alliance GPCV 2000 instrument with online viscometer. The oven temperature is 140 C. Trichlorobenzene is used as a solvent (ISO 16014: 2003).

(17) Tensile Tests:

(18) The tensile modulus, the tensile strain at break and the tensile stress at break were measured at 23 C. according to ISO 527-2 (cross head speed 1 mm/min for tensile modulus, 50 mm/min for others) using injection moulded specimens moulded at 230 C. according to ISO 527-2(1B), produced according to EN ISO 1873-2 (dog 10 bone shape, 4 mm thickness).

(19) Charpy Impact Test:

(20) The Charpy impact strength (IS) was measured according to ISO 179-1eU: 2000 at +23 C. and the Charpy notched impact strength (NIS) was measured according to ISO 179-1eA:2000 at +23 C., using injection-molded bar test specimens of 80104 mm.sup.3 prepared in accordance with ISO 1873-2:2007.

(21) Heat Distortion Temperature (HDT) was determined according to ISO 75-2 Method A (1.80 MPa surface stress) using injection molded test specimens of 80104 mm.sup.3 produced as described in EN ISO 1873-2 (80104 mm).

(22) Total Emissions of Volatiles

(23) The total emission of the polymers was determined by using multiple head space extraction according to VDA 277:1995 using a gas chromatograph and a headspace method. The equipment was a Hewlett Packard gas chromatograph with a WCOT-capillary column (wax type) of 30 m length and 0.25 mm2.5 m inner diameter (0.25 m film thickness). A flame ionisation detector was used with hydrogen as a fuel gas.

(24) The GC settings were as follows: 3 minutes isothermal at 50 C., heat up to 200 C. at 12 K/min, 4 minutes isothermal at 200 C., injection-temperature: 200 C., detection-temperature: 250 C., carrier helium, flow-mode split 1:20 and average carrier-speed 22-27 cm/s.

(25) The emission potential was measured on the basis of the sum of all values provided by the emitted substances after gas chromatography analysis and flame ionization detection with acetone as the calibration standard. Sample introduction (pellets, about 1 gram) was by headspace analysis (10 ml head space vial) after conditioning at 120 C. for 5 hours prior to the measurement.

(26) The unit is gC/g (g carbon per g of sample), respectively ppm.

(27) VOC/FOG Emission

(28) The VOC/FOG emission was measured according to VDA 278:2002 on the granulated compounds. The volatile organic compounds are measured in toluene equivalents per gram sample (gTE/g). The fogging is measured in hexadecane equivalents per gram sample (gHD/g).

(29) The measurements were carried out with a TDSA supplied by Gerstel using helium 5.0 as carrier gas and a column HP Ultra 2 of 50 m length and 0.32 mm diameter and 0.52 m coating of 5% Phenyl-Methyl-Siloxane.

(30) The VOC-Analysis was done according to device setting 1 listed in the standard using following main parameters: flow mode splitless, final temperature 90 C.; final time 30 min, rate 60K/min. The cooling trap was purged with a flow-mode split 1:30 in a temperature range from 150 C. to +280 C. with a heating rate of 12 K/sec and a final time of 5 min. The following GC settings were used for analysis: 2 min isothermal at 40 C. heating at 3 K/min up to 92 C., then at 5 K/min up to 160 C., and then at 10 K/min up to 280 C., 10 minutes isothermal; flow 1.3 ml/min.

(31) The VOC amounts account for C.sub.10 to C.sub.16 species.

(32) The FOG analysis was done according to device setting 1 listed in the standard using following main parameters: flow-mode splitless, rate 60K/min; final temperature 120 C.; final time 60 min. The cooling trap was purged with a flow-mode split 1:30 in a temperature range from 150 C. to +280 C. with a heating rate of 12 K/sec. The following GC-settings were used for analysis: isothermal at 50 C. for 2 min, heating at 25 K/min up to 160 C., then at 10 K/min up to 280 C., 30 minutes isothermal; flow 1.3 ml/min.

(33) The FOG amounts account for C.sub.1-6 to C.sub.30 species.

EXAMPLES

(34) Catalyst Preparation:

(35) The catalyst used in the Inventive Examples IE1 to IE4 has been prepared following the procedure described in WO 2013/007650 A1 for catalyst E2, by adjusting the metallocene and MAO amounts in order to achieve the Al/Zr ratios indicated in table 1. The catalyst has been off-line prepolymerized with propylene, following the procedure described in WO 2013/007650 A1 for catalyst E2P.

(36) The complex used was rac-anti-Me.sub.2Si(2-Me-4-(p-tBuPh)-Ind)(2-Me-4-Ph-5-OMe-6-tBu-Ind)ZrCl.sub.2.

(37) Degree of off-line pre-polymerization 3.3 g/g

(38) Al/Zr molar ratio in catalyst 431 mol/mol

(39) Metallocene complex content of off-line prepolymerized catalyst 0.696 wt. %

(40) The same catalyst was used for preparing the polymer of Comparative Examples CE1 and CE2.

(41) For Comparative Examples CE3 and CE4 commercially available base polymers based on ZN catalysts have been used.

(42) For Comparative Example CE5 the catalyst used in the polymerization process of the base polymer for CE5 has been produced as follows: 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.

(43) 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 EP491566, EP591224 and EP586390. As cocatalyst triethyl-aluminium (TEAL) and as donor dicyclo pentyl dimethoxy silane (D-donor) was used. The aluminium to donor ratio was 5 mol/mol. Before the polymerization, the catalyst was prepolymerized with vinyl cyclohexane in an amount to achieve a concentration of 200 ppm poly(vinyl cyclohexane) (PVCH) in the final polymer. The respective process is described in EP 1 028 984 and EP 1 183 307.

(44) Preparation of Base Polymer (PP-RACO)

(45) The base polymers for IE1 to IE 4 and the base polymer of CE1 and CE2 have been prepared in a Borstar PP pilot plant with a prepolymerization reactor, a loop reactor and 2 gas phase reactors (GPR1 and GPR2) connected in series.

(46) TABLE-US-00001 TABLE 1 Preparation of base polymers for IE1 to IE 4 and for CE1 and CE2 The base polymers (BP1) for IE1 and IE 2 are the same, the base polymers for IE3 and IE4 (BP2) are the same and the base polymers for CE1 and CE2 (BP3) are the same IE1/IE2 IE3/IE4 CE1/CE2 unit (BP1) (BP2) (BP3) Prepolymerization Amount of cat g/kg C.sub.3 0.079 0.085 0.110 Temperature C. 20 20 20 Residence time h 0.45 0.43 0.47 Loop Temperature C. 80 80 80 Split % 49 43 46 H.sub.2/C.sub.3 ratio mol/kmol 0.26 0.18 0.31 C.sub.2 content % 0 0 0 MFR.sub.2 g/10 min 6.3 3.3 8.2 XS % 0.9 0.8 1.8 GPR1 Temperature C. 80 80 80 Split % 51 49 54 Pressure kPa 1800 2109 3000 H.sub.2/C.sub.3 ratio mol/kmol 6.21 8.19 1.96 C.sub.2 content % 2.8 1.7 0 MFR.sub.2 g/10 min 9.0 10.0 8.0 XS % 13.2 3.2 1.3 GPR2 Temperature C. n.a. 75 n.a Split % n.a. 8 n.a. Pressure kPa n.a. 2600 n.a. H.sub.2/C.sub.3 ratio Mol/kmol n.a. 5.03 n.a. C.sub.2/C.sub.3 ratio Mol/kmol n.a. 10000 n.a. Final product MFR.sub.2 g/10 min 8.2 7.4 9.0 XS % 11.6 12.9 1.3 C.sub.2 content % 2.6 8.7 0 Mw (SEC) kg/mol 220 230 202 Mw/Mn (SEC) 4.2 5.1 3.2 n.a. . . . not applicaple, since not used

(47) Base polymer (BP4) for CE3 is a mixture of 79.2 wt. % of HF700SA, being a PP homopolymer commercially available from Borealis AG, Austria, having an MFR (230 C./2.16 kg) of 21 g/10 min, a density of 905 kg/m.sup.3 and a melting point (DSC) of 165 C. and 20.8 wt. % of BE50, being a PP homopolymer commercially available from Borealis AG, Austria, having an MFR (230 C./2.16 kg) of 0.3 g/10 min, a density of 905 kg/m.sup.3 and a melting point (DSC) of 165 C.

(48) Base polymer (BP5) for CE4 is a mixture of of 79.1 wt. % of HF700SA, being a PP homopolymer commercially available from Borealis AG, Austria, having an MFR (230 C./2.16 kg) of 21 g/10 min, a density of 905 kg/m.sup.3 and a melting point (DSC) of 165 C. and 20.9 wt. % of BE50, being a PP homopolymer commercially available from Borealis AG, Austria, having an MFR (230 C./2.16 kg) of 0.3 g/10 min, a density of 905 kg/m.sup.3 and a melting point (DSC) of 165 C.

(49) Polymerization Conditions for Base Polymer (BP6) for CE5

(50) TABLE-US-00002 Base polymer unit CE5 Prepolymerization Temperature C. 25 pressure bar 52 Residence time h 0.35 C.sub.2 content wt. % 0 Loop Temperature C. 65 pressure bar 55 Residence time h 0.38 MFR.sub.2 g/10 min 19 C.sub.2 content wt. % 1.35 XCS wt. % 2.4 GPR Temperature C. 80 pressure bar 23 Residence time h 1.1 MFR.sub.2 g/10 min 14 C.sub.2 content wt.-% 1.8 XCS wt.-% 2.3 Split Loop/GPR % 56/44

(51) Base polymer (BP7) for CE6 is the commercial polypropylene random copolymer (PP-RACO) RF366MO of Borealis AG with an MFR.sub.2 of 20 g/10 min, a melting temperature of 151 C., an ethylene content of 3.3 wt.-%, a XCS content of 6.0 wt. %, a density of 905 kg/m.sup.3, and a tensile modulus of 1,200 MPa;

(52) Preparation of Blends

(53) The following inventive examples IE1 to IE4 and comparative examples CE1 to CE6 were prepared by compounding on a co-rotating twin-screw extruder with a screw configuration typical for glass fiber mixing using a temperature range between 200 and 240 C.

(54) Compound Recipe of the Compositions

(55) TABLE-US-00003 Component IE1 IE2 IE3 IE4 CE1 CE2 CE3 CE4 CE5 CE6 BP1 [wt. %] 78.45 68.45 BP2 [wt. %] 78.45 68.45 BP3 [wt. %] 78.45 68.45 BP4 [wt. %] 78.45 BP5 [wt. %] 68.45 BP6 [wt. %] 62.5 BP7 [wt. %] 62.5 AP-1 [wt. %] 1 1 1 1 1 1 1 1 AP-2 [wt. %] 1.5 1.5 DSTDP 0.25 0.25 0.25 0.25 0.25 0.25 0.25 0.25 AO3 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 P168 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 MB-1 2.0 2.0 GF 20 30 20 30 20 30 20 30 32 32 AP-1 is the commercial maleic anhydride functionalized polypropylene Exxelor PO1020 of Exxon Mobil with a density 0.9 g/cm.sup.3, an MFR.sub.2 of 430 g/10 min and an MAH content of 1.0 mol.-%; AP-2 is the commercial maleic anhydride functionalized polypropylene Scona TPPP 2112FA of Kometra GmbH, Germany with a density of 0.9 g/cm.sup.3, having an MFR.sub.2 of 5 g/10 min and an MAH content of 1.2 mol.-%. DSTDP is the heat stabilizer Di-stearyl-thio-di-propionate (CAS No. 693-36-7) commercially available as Irganox PS-802 FL from BASF AG, Germany AO3 is the primary antioxidant Bis-(3,3-bis-(4--hydroxy-3-tert. butylphenyl)butanic acid)-glycolester (CAS No. 32509-66-3) commercially available as Hostanox O3 from Clariant SE, Switzerland P168 is the secondary antioxidant Tris (2,4-di-t-butylphenyl) phosphite (CAS No. 31570-04-4) commercially available as Irgafos 168 from BASF AG, Germany MB-1 is the commercial carbon black masterbatch Plasblak PE4103 of Cabot Corporation, Germany GF are the commercial glass fibers Thermo Flow Chopped Strand 636 for PP of Johns Manville, which are E-glass fibers coated with a silane based sizing, a length of 4 mm, and an average diameter of 13 m

(56) The compositions have the following properties

(57) TABLE-US-00004 Parameter unit IE1 IE2 IE3 IE4 CE1 CE2 CE3 CE4 CE5 CE6 MFR.sub.2 g/10 min 4 3 3 2 4 3 3 2 4.2 6.2 CV ppm 3 2 1 1 7 6 30 23 33 35 VOC ppm 28 25 33 25 44 43 104 93 122 134 FOG ppm 74 74 95 93 138 147 254 239 266 287 TM MPa 3807 5486 3958 5756 4767 6814 5087 6982 7060 6158 Bstress MPa 66 82 66 83 82 102 85 104 108 95 Bstrain % 5.59 5.26 5.05 4.93 3.9 3.7 3.58 3.36 3.4 4.2 IS kJ/m.sup.2 11.48 14.8 12.6 15.2 9.7 12.2 9.2 11.6 n.d n.d NIS kJ/m.sup.2 7.2 9.3 8.5 10.4 7.5 9.6 7.4 9.6 9.4 9.4 HDT C. 105 116 112 120 132 137 137 144 138 134 CV . . . content volatile TM . . . tensile modulus Bstress . . . tensile stress at break Bstrain . . . tensile strain at break IS . . . Charpy impact strength (ISO 179-1eU) at 23 C. NIS . . . Charpy notched impact strength (ISO 179-1eA) at 23 C. HDT . . . Heat deflection temperature n.d.not determined

(58) As can be seen from FIGS. 1 and 2 the compositions of the Inventive Examples show much better impact/stiffness balance as the compositions of the Comparative Examples CE1 to CE4.

(59) Additionally the compositions of the Inventive Examples have clearly lower emissions.