Reinforced polyproylene composition

Abstract

Reinforced polypropylene composition comprising a heterophasic polypropylene copolymer, a polar modified polypropylene and carbon fibers.

Claims

1. A polypropylene composition (C) comprising: (a) 55 to 92 parts per weight of a heterophasic propylene copolymer (HECO); (b) 1.0 to 10 parts per weight of a polar modified polypropylene (PMP); (c) 7.0 to 35 parts per weight of carbon fibers (CF); based on the total parts by weight of compounds (a), (b) and (c), wherein the intrinsic viscosity (IV) of the xylene soluble (XCS) fraction of the heterophasic propylene copolymer (HECO) is in the range of 3.0 to 4.0 dl/g, wherein the polypropylene composition (C) has: (d) a tensile modulus measured according to ISO 527-2 of at least 2500 MPa; (e) a tensile strength measured according to ISO 527-2 of at least 25 MPa; and (f) a Charpy Impact Strength measured according to ISO 179-1eU:2000 at 23° C. of at least 35 kJ/m.sup.2.

2. The polypropylene composition (C) according to claim 1, wherein the polypropylene composition (C) comprises the heterophasic propylene copolymer (HECO) in an amount of at least 55 wt. %, based on the total weight of the polypropylene composition (C).

3. The polypropylene composition (C) according to claim 1, wherein the heterophasic propylene copolymer (HECO) has: (a) a melt flow rate MFR.sub.2 (230° C., 2.16 kg) measured according to ISO 1133 of not more than 60 g/10 min; and/or (b) a comonomer content of not more than 35 mol %; and/or (c) a xylene cold solubles (XCS) fraction of not more than 55 wt. %, based on the total weight of the heterophasic propylene copolymer (HECO); and/or (d) an intrinsic viscosity (IV) of the xylene soluble (XCS) fraction of the heterophasic propylene copolymer (HECO) in the range of 3.0 to 3.5 dl/g; and/or (e) a comonomer content of the xylene soluble (XCS) fraction of the heterophasic propylene copolymer (HECO) of not more than 65 mol %.

4. The polypropylene composition (C) according to claim 1, wherein the polypropylene composition (C) comprises the polar modified polypropylene (PMP) in an amount of at least 1.0 wt. %, based on the total weight of the polypropylene composition (C).

5. The polypropylene composition (C) according to claim 1, wherein the polar modified polypropylene (PMP) comprises groups derived from polar groups selected from the group consisting of acid anhydrides, carboxylic acids, carboxylic acid derivatives, primary and secondary amines, hydroxyl compounds, oxazoline, epoxides, and ionic compounds.

6. The polypropylene composition (C) according to claim 1, wherein the polar modified polypropylene (PMP) is a propylene polymer grafted with maleic anhydride.

7. The polypropylene composition (C) according to claim 1, wherein the polypropylene composition (C) comprises the carbon fibers (CF) in an amount of at least 7.0 wt. %, based on the total weight of the polypropylene composition (C).

8. The polypropylene composition (C) according to claim 1, wherein the heterophasic propylene copolymer (HECO) and the polar modified polypropylene (PMP) are comprised in an amount of at least 57.5 wt. %, based on the total weight of the polypropylene composition (C).

9. The polypropylene composition (C) according to claim 1, wherein the heterophasic propylene copolymer (HECO), the polar modified polypropylene (PMP) and the carbon fibers (CF) are comprised in an amount of at least 60 wt. %, based on the total weight of the polypropylene composition (C).

10. The polypropylene composition (C) according to claim 1, wherein the heterophasic propylene copolymer (HECO) comprises: (a) a polypropylene matrix (M) and (b) an elastomeric copolymer (E) comprising units derived from propylene and ethylene and/or C.sub.4 to C.sub.20 alpha-olefins.

11. The polypropylene composition (C) according to claim 1, wherein the polypropylene composition (C) has a tensile elongation at break measured according to ISO 527-2 of at least 6.0%.

12. The polypropylene composition (C) according to claim 1, wherein the polypropylene composition (C) does not comprise: (a) any other fibers besides the carbon fibers (CF); and/or (b) any other polymers besides the heterophasic propylene copolymer (HECO) and the polar modified polypropylene (PMP).

13. An article comprising the polymer composition (C) according to claim 1.

14. The article according to claim 13, wherein the article is a molded article or an extruded article.

15. The article according to claim 13, wherein the article is an automotive article.

Description

EXAMPLES

1. Definitions/Measuring Methods

(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.

(2) Quantification of Microstructure by NMR Spectroscopy

(3) Quantitative nuclear-magnetic resonance (NMR) spectroscopy is used to quantify the isotacticity and regio-regularity of the polypropylene homopolymers.

(4) 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.

(5) For polypropylene homopolymers approximately 200 mg of material was dissolved in 1,2-tetrachloroethane-d.sub.2 (TCE-d.sub.2). 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 needed for tacticity distribution quantification (Busico, V., Cipullo, R., Prog. Polym. Sci. 26 (2001) 443; Busico, V.; Cipullo, R., Monaco, G., Vacatello, M., Segre, A. L., Macromolecules 30 (1997) 6251). Standard single-pulse excitation was employed utilising the NOE and 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, 11289). A total of 8192 (8k) transients were acquired per spectra.

(6) Quantitative .sup.13C {.sup.1H} NMR spectra were processed, integrated and relevant quantitative properties determined from the integrals using proprietary computer programs.

(7) For polypropylene homopolymers all chemical shifts are internally referenced to the methyl isotactic pentad (mmmm) at 21.85 ppm.

(8) Characteristic signals corresponding to regio defects (Resconi, L., Cavallo, L., Fait, A., Piemontesi, F., Chem. Rev. 2000, 100, 1253;; Wang, W-J., Zhu, S., Macromolecules 33 (2000), 1157; Cheng, H. N., Macromolecules 17 (1984), 1950) or comonomer were observed.

(9) The tacticity distribution was quantified through integration of the methyl region between 23.6-19.7 ppm correcting for any sites not related to the stereo sequences of interest (Busico, V., Cipullo, R., Prog. Polym. Sci. 26 (2001) 443; Busico, V., Cipullo, R., Monaco, G., Vacatello, M., Segre, A. L., Macromolecules 30 (1997) 6251).

(10) Specifically the influence of regio-defects and comonomer on the quantification of the tacticity distribution was corrected for by subtraction of representative regio-defect and comonomer integrals from the specific integral regions of the stereo sequences.

(11) The isotacticity was determined at the pentad level and reported as the percentage of isotactic pentad (mmmm) sequences with respect to all pentad sequences:
[mmmm] %=100*(mmmm/sum of all pentads)

(12) The presence of 2,1 erythro regio-defects was indicated by the presence of the two methyl sites at 17.7 and 17.2 ppm and confirmed by other characteristic sites. Characteristic signals corresponding to other types of regio-defects were not observed (Resconi, L., Cavallo, L., Fait, A., Piemontesi, F., Chem. Rev. 2000, 100, 1253).

(13) The amount of 2,1 erythro regio-defects was quantified using the average integral of the two characteristic methyl sites at 17.7 and 17.2 ppm:
P.sub.21e=(I.sub.e6+I.sub.e8)/2

(14) The amount of 1,2 primary inserted propene was quantified based on the methyl region with correction undertaken for sites included in this region not related to primary insertion and for primary insertion sites excluded from this region:
P.sub.12=I.sub.CH3+P.sub.12e

(15) The total amount of propene was quantified as the sum of primary inserted propene and all other present regio-defects:
P.sub.total=P.sub.12+P.sub.21e

(16) The mole percent of 2,1- erythro regio-defects was quantified with respect to all propene:
[21e] mol.-%=100*(P.sub.21e/P.sub.total)

(17) 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.

(18) 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.

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

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

(21) The xylene Cold Solubles (XCS) are measured at 25° C. according ISO 16152; first edition; 2005-07-01.

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

(23) The Tensile Modulus; is 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).

(24) Tensile strength; Tensile Elongation at Break are measured according to ISO 527-2 (cross head speed=50 mm/min; 23° C.) using injection molded specimens as described in EN ISO 1873-2 (dog bone shape, 4 mm thickness).

(25) The Charpy Impact Strength is determined according to ISO 179 1eU at 23° C. by using an 80×10×4 mm.sup.3 test bars injection molded in line with EN ISO 1873-2.

(26) The Average Fiber Diameter is determined according to ISO 1888:2006(E), Method B, microscope magnification of 1000.

(27) The Melt Flow Rate (MFR.sub.2) is measured according to ISO 1133 at the temperature and load given.

(28) The Melt Flow Volume Rate (MVI) is measured according to ISO 1133 at the temperature and load given.

(29) The Density is measured according to ISO 1183-187. Sample preparation is done by compression molding in accordance with ISO 1872-2:2007.

(30) The DSC Analysis, Melting Temperature (Tm) and Melting Enthalpy (Hm), Crystallization Temperature (Tc) and Crystallization Enthalpy (Hc) are 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 C2 in a heat/cool/heat cycle with a scan rate of 10° C./min in the temperature range of −30 to +225° C. Crystallization temperature and crystallization enthalpy (Hc) are determined from the cooling step, while melting temperature and melting enthalpy (Hm) are determined from the second heating step.

2. Examples

(31) The present invention is illustrated by the following examples:

(32) Production of the Heterophasic Propylene Copolymer (HECO)

(33) Catalyst Preparation:

(34) 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 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 WO 87/07620, WO 92/19653, WO 92/19658 and EP 0 491 566, EP 591224 and EP 586390. 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. As external donor di(cyclopentyl) dimethoxy silane (donor D) was used.

(36) HECO Preparation

(37) The HECO is prepared in a slurry and multiple gas phase reactors connected in series. The conditions applied and the properties of the products obtained are summarized in Table 1.

(38) TABLE-US-00001 TABLE 1 Preparation of the HECO Prepolymerization TEAL/Ti [mol/mol] 220 TEAL/Do [mol/mol] 7.3 Temperature [° C.] 30 Residence time [h] 0.08 Loop Temperature [° C.] 72 Split [%] 35 H2/C3 [mol/kmol] 15 C2/C3 [mol/kmol] 0 MFR.sub.2 [g/10 min] 55 XCS [wt.-%] 2.0 C2 [mol-%] 0 1.sup.st GPR Temperature [° C.] 80 Pressure [kPa] 2231 Split [%] 30 H2/C3 [mol/kmol] 150 C2/C3 [mol/kmol] 0 MFR.sub.2 [g/10 min] 55 XCS [wt.-%] 2.0 C2 [mol-%] 0 2.sup.nd GPR Temperature [° C.] 70 Pressure [kPa] 2291 Split [%] 19 C2/C3 [mol/kmol] 584 H2/C2 [mol/kmol] 117 MFR.sub.2 [g/10 min] 11 XCS [wt.-%] 18 IV (XCS) [dl/g] nd C2 (XCS) [mol-%] nd C2 [mol-%] 18 3.sup.rd GPR Temperature [° C.] 85 Pressure bar 1421 Split [%] 16 C2/C3 [mol/kmol] 585 H2/C2 [mol/kmol] 93 MFR.sub.2 [g/10 min] 11 XCS [wt.-%] 32 IV (XCS) [dl/g] 3.1 C2 (XCS) [mol-%] 48 C2 [mol-%] 19 C2 ethylene content H2/C3 hydrogen/propylene ratio C2/C3 ethylene/propylene ratio H2/C2 hydrogen/ethylene ratio 1.sup.st 2.sup.nd 3.sup.rd GPR 1.sup.st 2.sup.nd 3.sup.rd gas phase reactor Loop loop reactor TEAL/Ti TEAL/Ti ratio TEAL/Do TEAL/Donor ratio MFR.sub.2 melt flow rate XCS xylene cold soluble fraction C2 (XCS) ethylene content of the xylene cold soluble fraction IV (XCS) intrinsic viscosity of the xylene cold soluble fraction

(39) The properties of the products obtained from the individual reactors naturally are not determined from homogenized material but from reactor samples (spot samples). The properties of the final resin are measured on homogenized material.

(40) The Inventive Example IE1 and the Comparative Examples CE1 and CE 2 are prepared by melt blending with a twin-screw extruder such as the Coperion STS-35 twin-screw extruder from the Coperion (Nanjing) Corporation, China. The twin-screw extruder runs at an average screw speed of 400 rpm with a temperature profile of zones from 180 to 250° C. The Inventive Example IE1 and the Comparative Examples CE1 and CE 2 are based on the recipe summarized in Table 2.

(41) TABLE-US-00002 TABLE 2 The recipe for preparing the inventive and comparative compositions Example CE1 CE2 IE1 PPH-1 [wt %]* 78.85 74.85 Elastomer [wt %]* 10 10 HECO [wt %]* 84.85 PMP [wt %]* 5.0 5.0 5.0 CF [wt %]* 6.0 10.0 10.0 *rest to 100 wt.-% are additives in regular levels, including polymeric carrier material, antioxidants, and UV-stabilizer, such as pentaerythrityl-tetrakis(3-(3′,5′-di-tert. butyl-4-hydroxyphenyl)-propionate in form of the commercial antioxidant “Irganox 1010” of BASF, Germany, CAS-no. 6683-19-8; and tris(2,4-di-t-butylphenyl) phosphite in form of the commercial antioxidant “Irgafos 168 FF” of BASF, Germany, CAS-no. 31570-04-4.

(42) “PPH-1” is the commercial product HF955MO of Borealis AG, which is a propylene homopolymer having a melt flow rate MFR.sub.2 (230° C., 2.16 kg) of 20 g/10 min and a density of 908 kg/m.sup.3. The propylene homopolymer HF955MO is α-nucleated with polyvinyl cyclohexane.

(43) “Elastomer” is the commercial product Queo8201 of Borealis AG, which is an ethylene/1-octene copolymer having a melt flow rate MFR2 (190° C., 2.16 kg) of 1.1 g/10 min and a density of 883 kg/m.sup.3.

(44) “PMP” is the commercial product SCONA TSPP10213GB of Co. Ltd, Germany, which is a polypropylene functionalized maleic acid anhydride having an MVR (170° C., 1.2 kg) of 40 to 100 cm.sup.3/10 min and a maleic acid anhydride content of 2.0 wt.-%.

(45) “CF” is the commercial product RECATEX C90 of SGL Carbon SE, which is a non-woven fabric comprising 90 wt.-% carbon fiber having a density determined according to ISO 10119:2002 of 1.8 g/m.sup.3 and a tensile strength determined according to ISO 10618:2004 of 4400.

(46) The properties of the Inventive Example IE1 and the Comparative Examples CE1 and CE 2 are summarized in Table 3.

(47) TABLE-US-00003 TABLE 3 The recipe for preparing the inventive and comparative compositions Example CE1 CE2 IE1 Tensile Modulus (TM) [MPa] 3839 5631 3555 Tensile Strength (TS) [MPa] 52 66 44 Tensile Elongation [%] 5.6 4.4 8.7 at Break (TEB) Charpy Impact Strength (IS) [kJ/m.sup.2] 31 32 47 Melt Flow Rate (MFR.sub.2) [g/10 min] 14.0 12.9 10.0 *based on the total weight of the composition