Extrudable polypropylene copolymer compostion having high impact resistance

Abstract

Heterophasic polypropylene polymer compositions are disclosed that have very high impact strength and are very flexible. The polypropylene polymer compositions are formulated such that the compositions can be extruded and molded into various different products and articles. The polypropylene polymer composition, for instance, can have a melt flow rate of less than about 10 g / 10 min, can have a melting temperature of greater than about 120°C, can contain ethylene in an amount from about 5% by weight to about 43% by weight, can have a xylene-soluble content of greater than about 30% by weight, and can have a relatively low molecular weight distribution.

Description

EXTRUDABLE POLYPROPYLENE COPOLYMER COMPOSITION HAVING HIGH IMPACT RESISTANCECROSS-REFERENCE TO RELATED APPLICATION

[0001] The present application is related to and has right of priority to U.S. Provisional Patent Application No. 63 / 760,378 filed on February 19, 2025, which is incorporated by reference in its entireties for all purposes.BACKGROUND

[0002] Propylene impact copolymers are commonly used in a variety of applications where strength and impact resistance are desired such as in producing household appliances, luggage, furniture, containers, and the like.Propylene homopolymers or propylene-based random copolymers having high crystallinity are often unsuitable for the applications above because they are too brittle and have low impact resistance. In order to increase the impact resistance, propylene impact copolymers are formulated to contain a rubber phase that is contained within a matrix polymer phase.

[0003] In one aspect, when producing polypropylene impact copolymer products, a second reactor is used in series with a first reactor. In the first reactor, typically a polypropylene homopolymer or copolymer is formed that forms the matrix material. The matrix material is then loaded into a second reactor where propylene and a comonomer are added to produce a rubber phase dispersed within the matrix material. The resulting impact copolymer can be formed with good impact resistance properties while maintaining its stiffness modulus.

[0004] In the past, it was observed that the properties of stiffness and impact resistance trend in opposite directions such that as stiffness increases, impact resistance decreases and vice versa. Further, when efforts have been undertaken to increase impact resistance, processing problems have been encountered. For instance, increasing the rubber content of the polypropylene impact copolymer in order to increase impact resistance can result in particle stickiness. Greater amounts of the rubber material, for instance, can cause the surface of the powdery particles to become sticky causing the formation of agglomerates and preventing the reactors from operating in a continuous fashion.

[0005] In view of the above, problems have been experienced in being able to produce a polypropylene impact copolymer with increased impact resistance in which the polymer resin can be handled and fed into molding operations including extrusion processes and injection molding.SUMMARY

[0006] In general, the present disclosure is directed to an impact polypropylene polymer composition and to a process for making the composition. Polypropylene compositions made according to the present disclosure, for instance, can offer very high flexibility and very high impact resistance properties while still being capable of being fed through molding processes, such as extrusion and injection molding. In one aspect, the polypropylene polymer composition includes a polypropylene polymer combined with a propylene and alpha-olefin copolymer containing relatively high amounts of alpha-olefin producing a polypropylene composition with a significant amount of rubber phase while maintaining a relatively low melt flow rate. In one embodiment, the polymer phases that are blended together are both made using a Ziegler-Natta catalyst system that can enable careful control over the different parameters and variables during polymer processing.

[0007] In one embodiment, for instance, the present disclosure is directed to a polypropylene composition comprising a first polymer phase that includes a polypropylene random copolymer. The first polymer phase, for instance, can comprise a propylene and ethylene copolymer, a propylene and butene copolymer, or a propylene, ethylene, and butene copolymer. The polypropylene polymer can have a xylene soluble content of greater than about 5% by weight and less than about 32% by weight and can display a melt flow rate of from about 0.1 g / 10 min to about 10 g / 10 min, such as from about 0.2 g / 10 min to about 5 g / 10 min, such as from about 0.5 g / 10 min to about 3 g / 10 min.

[0008] The polypropylene composition further comprises a second polymer phase combined with the first polymer phase. The second polymer phase comprises a propylene and alpha-olefin copolymer, such as a propylene and ethylene copolymer. The resulting heterophasic polypropylene composition has a melt flow rate of about 10 g / 10 min or less. The polypropylene composition has axylene soluble portion and a xylene insoluble portion. The polypropylene composition can have a total xylene soluble content of from about 10% to about 60% by weight, such as from about 12% to about 60% by weight, such as from about 25% to about 60% by weight. The polypropylene composition can contain ethylene in an amount from about 5% by weight to about 43% by weight, such as from about 12% by weight to about 40% by weight, such as from about 20% by weight to about 40% by weight. The xylene insoluble portion of the polymer composition can contain ethylene in an amount of greater than about 5% by weight, such as greater than about 8% by weight, such as greater than about 10% by weight, and in an amount of less than about 45% by weight, such as less than about 35% by weight, such as less than about 30% by weight, such as less than about 25% by weight.

[0009] The polypropylene composition can display excellent physical properties and high impact resistance. For instance, the polypropylene composition can display an Izod notched impact strength of greater than about 400 J / m, such as greater than about 500 J / m, such as greater than about 550 J / m, such as greater than about 600 J / m, such as greater than about 650 J / m, such as greater than about 700 J / m, such as greater than about 750 J / m (and up to specimens that do not break during the test) In addition, the polypropylene composition can display a flexural modulus of less than about 600 MPa, such as less than about 500 MPa, such as less than about 400 MPa, and greater than about 50 MPa.

[0010] In one aspect, the polypropylene random copolymer contained in the first polymer phase can comprise a polypropylene random copolymer containing ethylene and / or butylene. When containing ethylene, ethylene can be present in the first polymer phase in an amount from about 2% by weight to about 7% by weight. When containing butylene, butylene can be present in the first polymer phase in an amount from about 6% to about 12% by weight. The second polymer phase, on the other hand, can comprise a propylene ethylene copolymer. The second polymer phase can be present in the polypropylene composition in an amount from about 25% by weight to about 45% by weight, such as in an amount from about 30% by weight to about 40% by weight.

[0011] As described above, the polypropylene polymer in the first polymer phase can be Ziegler-Natta catalyzed and the propylene and alpha-olefincopolymer in the second polymer phase can also be Ziegler-Natta catalyzed. The Ziegler-Natta catalyst used for producing the polypropylene polymer of the first phase and the propylene and alpha-olefin copolymer of the second phase can include an internal electron donor comprising a substituted phenylene aromatic diester. The second polymer phase can be formed in the presence of the first polymer phase. In one aspect, the second polymer phase is in the form of polymer particles that are dispersed within the first polymer phase.

[0012] The polypropylene composition of the present disclosure is particularly well suited for molding and extrusion processes. In one aspect, for instance, the polypropylene composition can be extruded into a film to form various articles, such as mats. The polypropylene composition can also be injection molded in order to form all different types of articles, including automotive parts.

[0013] In another aspect, the present disclosure is directed to a polymerization process for producing a polypropylene polymer composition. The process includes contacting propylene and optionally at least one other olefin with a catalyst composition in a first polymerization reactor under gas phase polymerization conditions. In one aspect, for instance, propylene is fed to the first polymerization reactor in combination with ethylene and / or butylene. The catalyst composition comprises an internal electron donor, a co-catalyst, and optionally an external electron donor. A first polymer phase is formed in the first polymerization reactor comprising a propylene-based polymer having a melt flow rate of from about 0.1 g / 10 min to about 10 g / 10 min. The first polymer phase can have a xylene-soluble content of greater than about 5% by weight and less than about 32% by weight.

[0014] The process further includes the step of contacting the propylene-based polymer with propylene and ethylene in a second reactor under polymerization conditions. A second polymer phase is formed combined with the first polymer phase. The resulting polypropylene composition has a melt flow rate of about 10 g / 10 min or less. The polypropylene composition has a xylene-soluble portion and a xylene-insoluble portion. The xylene-soluble portion of the polypropylene composition is from about 10% by weight to about 60% by weight. The polypropylene composition can contain ethylene in an amount from about 5% to about 43% by weight, such as in an amount from about 15% to about 40% by weight. The xylene insoluble portion of the polymer composition can containethylene in an amount of greater than about 5% by weight, such as greater than about 8% by weight, such as greater than about 10% by weight, and in an amount of less than about 45% by weight, such as less than about 35% by weight, such as less than about 30% by weight, such as less than about 25% by weight.

[0015] The resulting polypropylene composition can display a notched Izod impact strength at 23°C of greater than about 500 J / m, can display a flexural modulus of less than about 500 MPa, and can have a melt flow rate of from about 0.1 g / 10 min to about 10 g / 10 min. The polypropylene composition can have a molecular weight distribution (Mw / Mn) of less than about 9 and can be greater than about 3.

[0016] Other features and aspects of the present disclosure are discussed in greater detail below.DEFINITIONS AND TESTING PROCEDURES

[0017] The term “propylene-ethylene copolymer”, as used herein, is a copolymer containing a propylene monomer with an ethylene monomer. One type of a propylene-ethylene copolymer is referred to (as a polypropylene random copolymer having individual repeating units of the ethylene monomer present in a random or statistical distribution in the polymer chain.

[0018] Melt flow rate (MFR), as used herein, is measured in accordance with the ASTM D 1238 test method at 230° C with a 2.16 kg weight for propylene-based polymers.

[0019] Xylene solubles (XS) is defined as the weight percent of resin that remains in solution after a sample of a composition resin is dissolved in hot xylene and the solution is allowed to cool to 25° C. This is also referred to as the gravimetric XS method according to ASTM D5492-06 and is also referred to herein as the “wet method”.

[0020] The ASTM D5492-06 method mentioned above may be adapted to determine the xylene soluble portion. In general, the procedure consists of weighing 2 g of sample and dissolving the sample in 200 ml o-xylene in a 400 ml flask with 24 / 40 joint. The flask is connected to a water cooled condenser and the contents are stirred and heated to reflux under nitrogen (N2), and then maintained at reflux for an additional 30 minutes. The solution is then cooled in a temperature controlled water bath at 25° C for 90 minutes to allow the crystallization of thexylene insoluble fraction. Once the solution is cooled and the insoluble fraction precipitates from the solution, the separation of the xylene soluble portion (XS) from the xylene insoluble portion (XI) is achieved by filtering through 25 micron filter paper. One hundred ml of the filtrate is collected into a pre-weighed aluminum pan, and the o-xylene is evaporated from this 100 ml of filtrate under a nitrogen stream. Once the solvent is evaporated, the pan and contents are placed in a 100° C vacuum oven for 30 minutes or until dry. The pan is then allowed to cool to room temperature and weighed. The xylene soluble portion is calculated as XS(wt %)=[(m3-m2)*2 / mi]*100, where rm is the original weight of the sample used, m2 is the weight of empty aluminum pan, and m3 is the weight of the pan and residue (the asterisk, *, here and elsewhere in the disclosure indicates that the identified terms or values are multiplied).

[0021] The ethylene content of the xylene soluble (XS) portion and the xylene insoluble (XI) are measured by13C-NMR. The samples are prepared by adding approximately 2.7 g of a 50 / 50 mixture of tetrachloroethane-d2 / orthodichlorobenzene containing 0.025 M Cr(AcAc)3 to 0.20 g sample in a Norell 1001-7 10 mm NMR tube. The samples are dissolved and homogenized by heating the tube and its contents to 150° C using a heating block. Each sample is visually inspected to ensure homogeneity. The data are collected using a Bruker 400 MHz spectrometer equipped with a Bruker Dual DUL high-temperature CryoProbe. The data are acquired using 500 transients per data file, a 6 sec pulse repetition delay, 90 degree flip angles, and inverse gated decoupling with a sample temperature of 120° C. All measurements are made on non-spinning samples in locked mode. Samples are allowed to thermally equilibrate for 10 minutes prior to data acquisition.Ethylene content was calculated based on the triads distribution. The assignment of chemical shift of triads is shown in Table 1.PPP=(F+A-0.5D) / 2PPE=DEPE=CEEE=(E-0.5G) / 2PEE=GPEP=HThe ethylene content is based on the following calculations:mols P= sum P centered triadsmols E= sum E centered triadsTable 1 Assignment of chemical shift to triad for ethylene propylene copolymer

[0022] Flexural modulus is determined in accordance with ASTM D790-10 Method A at 1.3 mm / min, using a Type 1 specimen per ASTM 3641 and molded according to ASTM D4101.

[0023] Mw / Mn (also referred to as “MWD”) and Mz / Mw are measured by GPC according to the Gel Permeation Chromatography (GPC) Analytical Method for Polypropylene. The polymers are analyzed on a PL-220 series high temperature gel permeation chromatography (GPC) unit equipped with a refractometer detector and four PLgel Mixed A (20 pm) columns (Polymer Laboratory Inc.). The oven temperature is set at 150° C. and the temperatures of autosampler's hot and the warm zones are at 135° C. and 130° C. respectively. The solvent is nitrogen purged 1 ,2,4-trichlorobenzene (TCB) containing ~200 ppm 2,6-di-t-butyl~4-methylphenol (BHT). The flow rate is 1.0 mL / min and the injection volume was 200 pl. A 2 mg / mL sample concentration is prepared by dissolving the sample in N2 purged and preheated TCB (containing 200 ppm BHT) for 2.5 hrs at 160° C. with gentle agitation.

[0024] The GPC column set is calibrated by running twenty narrow molecular weight distribution polystyrene standards. The molecular weight (MW) of the standards ranges from 580 to 8,400,000 g / mol, and the standards were contained in 6 “cocktail” mixtures. Each standard mixture has at least a decade of separation between individual molecular weights. The polystyrene standards are prepared at 0.005 g in 20 mL of solvent for molecular weights equal to or greater than1 ,000,000 g / mol and 0.001 g in 20 mL of solvent for molecular weights less than 1 ,000,000 g / mol. The polystyrene standards are dissolved at 150° C. for 30 min under stirring. The narrow standards mixtures are run first and in order of decreasing highest molecular weight component to minimize degradation effect. A logarithmic molecular weight calibration is generated using a fourth-order polynomial fit as a function of elution volume. The equivalent polypropylene molecular weights are calculated by using following equation with reported Mark-Houwink coefficients for polypropylene (Th. G. Scholte, N. L. J. Meijerink, H. M. Schoffeleers, and A. M. G. Brands, J. Appl. Polym. Sci. , 29, 3763-3782 (1984)) and polystyrene(E. P. Otocka, R. J. Roe, N. Y. Hellman, P. M. Muglia, Macromolecules, 4, 507 (1971)):where Mppis PP equivalent MW, Mps is PS equivalent MW, log K and a values of Mark-Houwink coefficients for PP and PS are listed below in Table 2.

[0025] Notched IZOD impact strength is measured in accordance with ASTM D 256. Samples used to measure the notched IZOD impact strength were injection molded following ASTM D4101 method.

[0026] The rubber particle size is measured by a scanning electronic microscope (SEM) machine Hitachi Tabletop Microscope TM3030Plus. The sample is firstly cut from the center of the IZOD testing bards (ASTM D4101) along the flow direction, and then cryo-microtomed at -20 °C and stained with RuO4 and further cryo-microtomed at -20 °C. The SEM images are observed under backscattering (BSE) mode where the highly stained region (EPR rubber) is the lighter phase and the slightly stained region is the darker phase. The particle size is captured and analyzed by the software of Image-Pro® Premier. D50 is calculated with the meaning of the particle size at 50% accumulative volume fraction.DETAILED DESCRIPTION

[0027] It is to be understood by one of ordinary skill in the art that the present discussion is a description of exemplary embodiments only and is not intended as limiting the broader aspects of the present disclosure.

[0028] In general, the present disclosure is directed to a polypropylene polymer composition and to a process for producing the composition. Polypropylene polymer compositions made in accordance with the present disclosure have high impact strength characteristics in combination with relatively low stiffness. In addition, the polypropylene polymer composition can be produced so as to have flow characteristics that make the composition well suited for producing all different types of molded and extruded products, including extruded films. All different types of articles can be made from the polypropylene polymer composition including geomembranes, mats, automotive parts, and the like.

[0029] In general, the polypropylene composition of the present disclosure comprises a heterophasic composition. In particular, the polypropylene composition includes a first polymer phase blended with a second polymer phase. Both polymer phases can be formed from a polypropylene copolymer containing controlled amounts of an alpha-olefin, such as ethylene and / or butylene. In accordance with the present disclosure, the polypropylene polymer composition is formed with a crystalline matrix containing an amorphous rubber wherein the finalcomposition contains a fraction of xylene insolubles with relatively high amount of ethylene.

[0030] In one embodiment, the first polymer phase comprises a polypropylene random copolymer containing ethylene and / or butylene. The first polymer phase can be present in the polymer composition in an amount greater than the second polymer phase and can form a matrix polymer. The second polymer phase, on the other hand, comprises a polypropylene copolymer having elastomeric or rubberlike properties. In accordance with the present disclosure, the second polymer phase contains significant amounts of an alpha-olefin monomer, such as ethylene. Substantially increasing the Xylene solubles level in the second polymer phase, for instance, can dramatically improve the impact resistant properties of the polymer composition at lower temperatures.

[0031] For example, when tested according to the notched Izod impact test, the polymer composition can display an impact resistance at 23°C of greater than about 400 J / m, such as greater than about 500 J / m, such as greater than about 550 J / m, such as greater than about 600 J / m, such as greater than about 650 J / m, such as greater than about 700 J / m, such as greater than about 750 J / m (and up to specimens that do not break during the test).

[0032] The flexible nature of the polymer composition can vary depending upon various factors including the relative amounts of the first polymer phase and the second polymer phase and the amount of comonomers in the first and second phases. In one aspect, the polypropylene polymer composition of the present disclosure has an extremely low stiffness while still being capable of being molded into shapes. For example, the polymer composition of the general disclosure can have a flexural modulus of less than about 600 MPa, such as less than about 550 MPa, such as less than about 500 MPa, such as less than about 450 MPa, such as less than about 400 MPa, such as less than about 300 MPa, such as less than about 200 MPa, such as less than about 150 MPa, such as less than about 100 MPa, such as less than about 90 MPa, such as less than about 80 MPa, such as less than about 70 MPa.

[0033] As described above, the polypropylene polymer composition of the present disclosure can have increased impact strength and low stiffness while still being capable of being extruded into shapes or otherwise molded into shapes.The polymer composition, for instance, can be extruded into films and fibers and / or molded into various articles and parts using, for instance, injection molding or the like. In one aspect, for instance, the polypropylene polymer composition is formulated so as to have a relatively low melt flow rate. For example, the polymer composition of the present disclosure can have a melt flow rate of less than about 10 g / 10 min, such as less than about 8 g / 10 mins, such as less than about 5 g / 10 mins, such as less than about 3 g / 10 mins, such as less than about 2.5 g / 10 min, such as less than about 2 g / 10 min, such as less than about 1.5 g / 10 min, such as less than about 1.2 g / 10 min, such as less than about 1 g / 10 min. The melt flow rate of the polymer composition is generally greater than about 0.1 g / 10 min, such as greater than about 0.2 g / 10 min, such as greater than about 0.3 g / 10 min, such as greater than about 0.4 g / 10 min, such as greater than about 0.5 g / 10 min.

[0034] As described above, the polypropylene composition of the present disclosure generally includes a first phase polymer combined with a second phase polymer. The first phase polymer comprises a polypropylene polymer, such as a random copolymer of polypropylene (including terpolymers). The random copolymer, for instance, can be a copolymer of propylene and one or more alphaolefins, such as ethylene and / or butylene. The polypropylene random copolymer can form the matrix polymer in the polypropylene composition and can contain the alpha-olefin (ethylene, butene or a combination of ethylene and butene) in an amount up to about 15% by weight. For instance, when the comonomer is ethylene, the polypropylene random copolymer can contain ethylene in an amount greater than about 2% by weight, such as in an amount greater than about 3% by weight, such as in an amount greater than about 4% by weight, and in an amount less than about 7% by weight, such as in an amount less than about 6% by weight, such as in an amount less than about 5% by weight. When the comonomer is butylene, on the other hand, the polypropylene random copolymer can contain butylene in an amount greater than about 6% by weight, such as in an amount greater than about 7% by weight, such as in an amount greater than about 8% by weight, such as in an amount greater than about 9% by weight, and in an amount less than about 12% by weight, such as in an amount less than about 11 % by weight, such as in an amount less than about 10% by weight.

[0035] The first phase polymer can have a xylene-soluble content of up to about 32% by weight. For instance, the first phase polymer can have a xylene-soluble content of greater than about 5% by weight, such as greater than about 8% by weight, such as greater than about 10% by weight, such as greater than about 13% by weight, such as greater than about 15% by weight, such as greater than about 18% by weight, such as greater than about 20% by weight, such as greater than about 22% by weight, such as greater than about 25% by weight, such as greater than about 28% by weight. The first phase polymer can have a xylene-soluble content of less than about 30% by weight, such as less than about 28% by weight, such as less than about 25% by weight, such as less than about 23% by weight, such as less than about 20% by weight, such as less than about 18% by weight. The xylene soluble content is typically greater when butene is used as a monomer and less when ethylene is used. For instance, in one aspect, ethylene is the co-monomer and the xylene soluble content is from about 5% by weight to about 20% by weight.

[0036] As will be described in greater detail below, the first phase polymer can comprise a Ziegler-Natta catalyzed polymer and can have a relatively broad molecular weight distribution. For instance, the molecular weight distribution (Mw / Mn) can be greater than about 3, such as greater than about 4, such as greater than about 4.2, such as greater than about 4.4, such as greater than about 4.6, such as greater than about 4.8, such as greater than about 5, such as greater than about 5.2, such as greater than about 5.5, such as greater than about 5.7, such as greater than about 6, such as greater than about 6.4, such as greater than about 6.8, such as greater than about 7.2, such as greater than about 7.4, such as greater than about 7.8, and generally less than about 9, such as less than about 8.5, such as less than about 8. The weight average molecular weight (determined by GPC) of the first phase polymer is generally greater than about 100,000, such as greater than about 120,000.

[0037] The polypropylene random copolymer that makes up the first phase polymer, in one embodiment, has a melt flow rate of less than about 10 g / 10 min. For instance, the first phase polymer can have a melt flow rate of less than about 8 g / 10 min, such as less than about 6 g / 10 min, such as less than about 4 g / 10 min, such as less than about 3 g / 10 min, such as less than about 2 g / 10 min, such asless than about 1 g / 10 min, and greater than about 0.1 g / 10 min, such as greater than about 0.3 g / 10 min, such as greater than about 0.4 g / 10 min, such as greater than about 1 g / 10 min, such as greater than about 2 g / 10 min, such as greater than about 3 g / 10 min.

[0038] The second phase polymer is a propylene and alpha-olefin copolymer, particularly a propylene ethylene copolymer. In addition, the second phase polymer has elastomeric or rubber-like properties.

[0039] In accordance with the present disclosure, the second phase polymer contains relatively high amounts of ethylene in relation to the amount of propylene contained in the second polymer phase. Increasing the ethylene content of the second polymer phase dramatically improves the impact resistance properties of the polymer composition at subzero temperatures.

[0040] The polypropylene composition of the present disclosure can have a total xylene soluble content of generally greater than about 8% by weight, such as greater than about 10% by weight, such as greater than about 12% by weight, such as greater than about 14% by weight, such as greater than about 35% by weight, such as greater than about 40% by weight, such as greater than about 45% by weight and generally less than about 60% by weight, such as less than about 55% by weight, such as less than about 53% by weight, such as less than about 50% by weight, such as less than about 45% by weight, such as less than about 40% by weight.

[0041] As described above, the polypropylene polymer composition contains two polymer phases that are formed from propylene and one or more alpha-olefin comonomers. In one aspect, the comonomer present in the polypropylene polymer composition comprises ethylene alone or can comprise a combination of butylene and ethylene. The polypropylene polymer composition can contain one or more comonomers in an amount of greater than about 14% by weight, such as in an amount greater than about 15% by weight, such as in an amount greater than about 18% by weight, such as in an amount greater than about 20% by weight, such as in an amount greater than about 25% by weight, such as in an amount greater than about 30% by weight, and in an amount less than about 80% by weight, such as in an amount less than about 70% by weight, such as in anamount less than about 60% by weight, such as in an amount less than about 50% by weight, such as in an amount less than about 40% by weight.

[0042] In one aspect, the polypropylene polymer composition only contains ethylene as a comonomer. In this embodiment, ethylene can be contained in the final polymer composition in an amount greater than about 5% by weight, such as in an amount greater than about 8% by weight, such as in an amount greater than about 10% by weight, such as in an amount greater than about 15% by weight, such as in an amount greater than about 18% by weight, such as in an amount greater than about 20% by weight, such as in an amount greater than about 23% by weight, such as in an amount greater than about 25% by weight, such as in an amount greater than about 28% by weight, such as in an amount greater than about 30% by weight, such as in an amount greater than about 33% by weight, such as in an amount greater than about 35% by weight,. Ethylene can be contained in the polypropylene polymer composition in an amount less than about 43% by weight, such as in an amount less than about 40% by weight, such as in an amount less than about 38% by weight, such as in an amount less than about 35% by weight, such as in an amount less than about 33% by weight, such as in an amount less than about 30% by weight.

[0043] The xylene insoluble portion of the polymer composition can contain ethylene in an amount of greater than about 5% by weight, such as greater than about 8% by weight, such as greater than about 10% by weight, and in an amount of less than about 45% by weight, such as less than about 35% by weight, such as less than about 30% by weight, such as less than about 25% by weight.

[0044] The second phase polymer can have a weight average molecular weight of at least about 130,000 g / mol, such as at least about 140,000 g / mol, such as at least about 150,000 g / mol and generally less than about 800,000 g / mol.

[0045] The heterophasic polypropylene polymer composition made in accordance with the present disclosure can generally have a relatively narrow molecular weight distribution. For instance, the molecular weight distribution of the polypropylene polymer composition can be less than about 9, such as less than about 8, such as less than about 7.5, such as less than about 7, and greater than about 3.51 , such as greater than about 4, such as greater than about 5, such as greater than about 5.5.

[0001] In one aspect, the heterophasic polypropylene polymer can be subjected to a post treatment process in order to further narrow the molecular weight distribution and / or increase the melt flow rate. For example, once the polypropylene copolymer is produced, the polymer can optionally be subjected to a visbreaking process by being contacted with a peroxide in a molten state.

[0002] The peroxide can be hydrogen peroxide, 2,5-dimethyl-2,5-bis(tert.butyl-peroxyjhexane (DHBP), 2,5-dimethyl-2,5-bis(tert.butyl-peroxy)hexyne-3 (DYBP), dicumyl-peroxide (DCLIP), di-tert.butyl-peroxide (DTBP), tert.butyl-cumyl-peroxide (BCLIP) and bis (tert.butylperoxy-isopropyl)benzene (DIPP). The above peroxides can be used alone or in a blend. The polypropylene copolymer can be contacted with the peroxide during melt processing in an extruder. For instance, the random polypropylene copolymer can be fed through an extruder and the peroxide can be added to the extruder once the polymer is in a molten state. Alternatively, the peroxide can be preblended with the polypropylene polymer. The extruder can be a single-screw extruder, a contra-rotating twin-screw extruder, a co-rotating twin-screw extruder, a planetary-gear extruder, a ring extruder, or any suitable kneading apparatus.

[0003] The amount of peroxide added to the polypropylene copolymer can depend upon various factors. For instance, the peroxide can be added to the polypropylene copolymer in an amount greater than about 0.001% by weight, such as greater than about 0.005% by weight, such as greater than about 0.01% by weight, such as greater than about 0.015% by weight, such as greater than about 0.02% by weight, such as greater than about 0.04% by weight, such as greater than about 0.1% by weight, such as greater than about 0.2% by weight, and in an amount less than about 1% by weight, such as in an amount less than about 0.5%by weight, such as in an amount less than about 0.3% by weight.

[0046] The melting temperature of the heterophasic polypropylene polymer composition can be sufficient in order to extrude and mold the composition into various different articles and products. For instance, the melting temperature can be greater than about 120°C, such as greater than about 123°C, such as greater than about 125°C, such as greater than about 128°C, such as greater than about 130°C, such as greater than about 133°C, such as greater than about 135°C, andless than about 180°C, such as less than about 160°C, such as less than about 150°C.

[0047] In addition to the first phase polymer and the second phase polymer, the polypropylene composition of the present disclosure can contain various other additives and ingredients. For instance, the polypropylene composition can contain nucleators, mold release agents, slip agents, antiblocks, UV stabilizers, heat stabilizer (e.g. DSTDP), flame retardants, colorants / tints, and the like. In one embodiment, the polymer composition can contain an antioxidant, such as a hindered phenolic antioxidant. The polymer composition can also contain an acid scavenger. Each of the additives can be present in the polymer composition generally in an amount less than about 3% by weight, such as in an amount less than about 2% by weight, such as in an amount less than about 1 % by weight, such as in an amount less than about 0.5% by weight, and generally in an amount greater than about 0.001 % by weight.

[0048] The first phase polymer and the second phase polymer can be produced using various different polymerization methods and procedures. In one embodiment, a Ziegler-Natta catalyst is used to produce the polymer composition. For example, the olefin polymerization can occur in the presence of a catalyst system that includes a catalyst, an internal electron donor, a cocatalyst, and optionally an external electron donor. Olefins of the formula CH2=CHR, where R is hydrogen or a hydrocarbon radical with 1 to 12 atoms, can be contacted with the catalyst system under suitable conditions to form the polymer products.Copolymerization may occur in a method-step process in order to generate the heterophasic composition of the present disclosure. The polymerization process can be carried out using known techniques in the gas phase using fluidized bed or stir bed reactors or in a slurry phase using an inert hydrocarbon solvent or diluent or liquid monomer.

[0049] In one embodiment, the first phase polymer and the second phase polymer can be produced in a two-stage process that includes a first stage, in which the propylene random copolymer of the continuous polymer phase is prepared, and a second stage, in which the propylene copolymer is produced. The first stage polymerization can be carried out in one or more bulk reactors or in one or more gas phase reactors. The second stage polymerization can be carried outin one or more gas phase reactors. The second stage polymerization is typically carried out directly following the first stage polymerization. For example the polymerization product recovered from the first polymerization stage can be conveyed directly to the second polymerization stage. In this regard, the polymerization may be performed according to a sequential polymerization process. A heterophasic copolymer composition is produced.

[0050] In one embodiment of the present disclosure, the polymerizations are carried out in the presence of a stereoregular olefin polymerization catalyst. For example, the catalyst may be a Ziegler-Natta catalyst. For instance, in one embodiment, a catalyst sold under the trade name CONSISTA and commercially available from W. R. Grace & Company can be used. In one embodiment, electron donors are selected that do not contain phthalates.

[0051] In one embodiment, the catalyst includes a procatalyst composition that contains a titanium moiety such as titanium chloride, a magnesium moiety such as magnesium chloride, and at least one internal electron donor.

[0052] The procatalyst precursor can include (i) magnesium, (ii) a transition metal compound from Periodic Table groups IV-VII, (iii) a halide, an oxylahilde, and or an alkoxide, and / or an alkoxide of (i) or (i) and / or (ii), and (iv) combination of (i), (ii), and (iii). Non limiting examples of suitable procatalyst precursors include halides, oxyhalides, alkoxides of magnesium, manganese, titanium, vanadium, chromium, molybdenum, zirconium, hafnium, and combinations thereof.

[0053] In one embodiment, the procatalyst precursor contains magnesium as the sole metal component. Non-limiting examples include anhydrous magnesium chloride and / or its alcohol adduct, magnesium alkoxide, and or aryloxide, mixed magnesium alkoxy halide, and / or carboxylated magnesium dialkoxide or aryloxide.

[0054] In one embodiment, the procatalyst precursor is an alcohol adduct of anhydrous magnesium chloride. The anhydrous magnesium chloride adduct is generally defined as MgC -nROH where n has a range of 1.5-6.0, preferably 2.5-4.0, and most preferably 2.8-3.5 moles total alcohol. ROH is a C1-C4 alcohol, linear or branched, or mixture of alcohol. Preferably ROH is ethanol or a mixture of ethanol and a higher alcohol. If ROH is a mixture, the mole ratio of ethanol to higher alcohol is at least 80:20, preferably 90:10, and most preferably at least 95:5.

[0055] In one embodiment, a substantially spherical MgC -nEtOH adduct may be formed by a spray crystallization process. In one, embodiment the spherical MgC precursor has an average particle size (Malvern dso) of between about 15-150 microns, preferably between 20-100 microns, and most preferably between 35-85 microns.

[0056] In one embodiment, the procatalyst precursor contains a transition metal compound and a magnesium metal compound. The transition metal compound has the general formula TrXxwhere Tr is the transition metal, X is a halogen or a C1-10 hydrocarboxyl or hydrocarbyl group, and x is the number of such X groups in the compound in combination with a magnesium metal compound. Tr may be a Group IV, V or VI metal. In one embodiment, Tr is a Group IV metal, such as titanium. X may be chloride, bromide, C1-4 alkoxide or phenoxide, or a mixture thereof. In one embodiment, X is chloride.

[0057] The precursor composition may be prepared by the chlorination of the foregoing mixed magnesium compounds, titanium compounds, or mixtures thereof.

[0058] In one embodiment, the precursor composition is a mixed magnesium / titanium compound of the formula MgdTi(ORe)fXgwherein Reis an aliphatic or aromatic hydrocarbon radical having 1 to 14 carbon atoms or COR' wherein R' is an aliphatic or aromatic hydrocarbon radical having 1 to 14 carbon atoms; each ORegroup is the same or different; X is independently chlorine, bromine or iodine; d is 0.5 to 56; or 2-4, or 3; f is 2 to 116, or 5 to 15; and g is 0.5 to 116, or 1 to 3.

[0059] In accordance with the present disclosure, the above described procatalyst precursor is combined with at least one internal electron donor. The internal electron donor can comprise a substituted phenylene aromatic diester.

[0060] In one embodiment, the first internal electron donor comprises a substituted phenylene aromatic diester having the following structure (I):wherein R1-R14 are the same or different. Each of R1-R14 is selected from hydrogen, a substituted hydrocarbyl group having 1 to 20 carbon atoms, an unsubstituted hydrocarbyl group having 1 to 20 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, a heteroatom, and combinations thereof. At least one R1-R14 is not hydrogen.

[0061] In one embodiment, the substituted phenylene aromatic diester may be any substituted phenylene aromatic diester as disclosed in U.S. Patent Application Serial No. 61 / 141 ,959 filed on December 31, 2008, the entire content of which is incorporated by reference herein.

[0062] In one embodiment, the substituted phenylene aromatic diester may be any substituted phenylene aromatic diester disclosed in WO12088028, filed on December 20, 2011 , the entire content of which is incorporated by reference herein.

[0063] In one embodiment, at least one (or two, or three, or four) R group(s) of R1-R4 is selected from a substituted hydrocarbyl group having 1 to 20 carbon atoms, an unsubstituted hydrocarbyl group having 1 to 20 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, a heteroatom, and combinations thereof.

[0064] In one embodiment, at least one (or some, or all) R group(s) of R5-R14 is selected from a substituted hydrocarbyl group having 1 to 20 carbon atoms, an unsubstituted hydrocarbyl group having 1 to 20 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, a heteroatom, and combinations thereof. In another embodiment, at least one of Rs-Rgand at least one of R10-R14 is selected from a substituted hydrocarbyl group having 1 to 20 carbon atoms, an unsubstitutedhydrocarbyl group having 1 to 20 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, a heteroatom, and combinations thereof.

[0065] In one embodiment, at least one of R1-R4 and at least one of R5-R14 is selected from a substituted hydrocarbyl group having 1 to 20 carbon atoms, an unsubstituted hydrocarbyl group having 1 to 20 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, a heteroatom, and combinations thereof. In another embodiment, at least one of R1-R4, at least one of R5-R9 and at least one of R10-R14 is selected from a substituted hydrocarbyl group having 1 to 20 carbon atoms, an unsubstituted hydrocarbyl group having 1 to 20 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, a heteroatom, and combinations thereof.

[0066] In one embodiment, any consecutive R groups in R1-R4, and / or any consecutive R groups in R5-R9, and / or any consecutive R groups in R10-R14 may be linked to form an inter-cyclic or an intra-cyclic structure. The inter- / intra-cyclic structure may or may not be aromatic. In one embodiment, the inter-Zintra-cyclic structure is a Csor a Ce membered ring.

[0067] In one embodiment, at least one of R1-R4 is selected from a substituted hydrocarbyl group having 1 to 20 carbon atoms, an unsubstituted hydrocarbyl group having 1 to 20 carbon atoms, and combinations thereof. Optionally, at least one of R5-R14 may be a halogen atom or an alkoxy group having 1 to 20 carbon atoms. Optionally, R1-R4, and / or R5-R9, and / or R10-R14 may be linked to form an inter-cyclic structure or an intra-cyclic structure. The inter-cyclic structure and / or the intra-cyclic structure may or may not be aromatic.

[0068] In one embodiment, any consecutive R groups in R1-R4, and / or in R5-R9, and / or in R10-R14, may be members of a Cs-Ce-membered ring.

[0069] In one embodiment, structure (I) includes R1, R3 and R4 as hydrogen. R2 is selected from a substituted hydrocarbyl group having 1 to 20 carbon atoms, an unsubstituted hydrocarbyl group having 1 to 20 carbon atoms, and combinations thereof. R5-R14 are the same or different and each of R5-R14 is selected from hydrogen, a substituted hydrocarbyl group having 1 to 20 carbon atoms, an unsubstituted hydrocarbyl group having 1 to 20 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, a halogen, and combinations thereof.

[0070] In one embodiment, R2 is selected from a Ci-Cs alkyl group, a C3-C6 cycloalkyl, or a substituted C3-C6 cycloalkyl group. R2 can be a methyl group, anethyl group, a n-propyl group, an isopropyl group, a t-butyl group, an isobutyl group, a sec-butyl group, a 2,4,4-trimethylpentan-2-yl group, a cyclopentyl group, and a cyclohexyl group.

[0071] In one embodiment, structure (I) includes R2 that is methyl, and each of R5-R14 is hydrogen.

[0072] In one embodiment, structure (I) includes R2 that is ethyl, and each of R5-R14 is hydrogen.

[0073] In one embodiment, structure (I) includes R2 that is t-butyl, and each of R5-R14 is hydrogen.

[0074] In one embodiment, structure (I) includes R2 that is ethoxycarbonyl, and each of R5-R14 is hydrogen.

[0075] In one embodiment, structure (I) includes R2, R3 and R4 each as hydrogen and R1 is selected from a substituted hydrocarbyl group having 1 to 20 carbon atoms, an unsubstituted hydrocarbyl group having 1 to 20 carbon atoms, and combinations thereof. R5-R14 are the same or different and each is selected from hydrogen, a substituted hydrocarbyl group having 1 to 20 carbon atoms, an unsubstituted hydrocarbyl group having 1 to 20 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, a halogen, and combinations thereof.

[0076] In one embodiment, structure (I) includes R1 that is methyl, and each of R5-R14 is hydrogen.

[0077] In one embodiment, structure (I) includes R2 and R4 that are hydrogen and R1 and R3 are the same or different. Each of R1 and R3 is selected from a substituted hydrocarbyl group having 1 to 20 carbon atoms, an unsubstituted hydrocarbyl group having 1 to 20 carbon atoms, and combinations thereof. R5-R14 are the same or different and each of R5-R14 is selected from a substituted hydrocarbyl group having 1 to 20 carbon atoms, an unsubstituted hydrocarbyl group having 1 to 20 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, a halogen, and combinations thereof.

[0078] In one embodiment, structure (I) includes R1 and R3 that are the same or different. Each of R1 and R3 is selected from a Ci-Cs alkyl group, a C3-C6 cycloalkyl group, or a substituted C3-C6 cycloalkyl group. R5-R14 are the same or different and each of R5-R14 is selected from hydrogen, a Ci-Cs alkyl group, and ahalogen. Nonlimiting examples of suitable Ci-Cs alkyl groups include methyl, ethyl, n-propyl, isopropyl, n-butyl, i-butyl, t-butyl, n-pentyl, i-pentyl, neopentyl, t-pentyl, n-hexyl, and 2,4,4-trimethylpentan-2-yl group. Nonlimiting examples of suitable C3-C6 cycloalkyl groups include cyclopentyl and cyclohexyl groups. In a further embodiment, at least one of R5-R14 is a Ci-Cs alkyl group or a halogen.

[0079] In one embodiment, structure (I) includes R1 that is a methyl group and R3 that is a t-butyl group. Each of R2, R4 and R5-R14 is hydrogen.

[0080] In one embodiment, structure (I) includes R1 and R3 that is an isopropyl group. Each of R2, R4 and R5-R14 is hydrogen.

[0081] In one embodiment, structure (I) includes each of R1, R5, and R10 as a methyl group and R3 is a t-butyl group. Each of R2, R4, R6-R9 and R11-R14 is hydrogen.

[0082] In one embodiment, structure (I) includes each of R1, R7, and R12 as a methyl group and R3 is a t-butyl group. Each of R2, R4, Rs, Re, Rs, R9, R10, R11 , R13, and R14 is hydrogen.

[0083] In one embodiment, structure (I) includes R1 as a methyl group and R3 is a t-butyl group. Each of R7 and R12 is an ethyl group. Each of R2, R4, Rs, Re, Rs, R9, R10, R11, R13, and R14 is hydrogen.

[0084] In one embodiment, structure (I) includes each of R1, R5, R7, R9, R10, R12, and R14 as a methyl group and R3 is a t-butyl group. Each of R2, R4, Re, Rs, R11, and R13 is hydrogen.

[0085] In one embodiment, structure (I) includes R1 as a methyl group and R3 is a t-butyl group. Each of R5, R7, R9, R10, R12, and R14 is an i-propyl group. Each of R2, R4, Re, Rs, R11, and R13 is hydrogen.

[0086] In one embodiment, the substituted phenylene aromatic diester has a structure (II) which includes R1 that is a methyl group and R3 is a t-butyl group. Each of R2 and R4 is hydrogen. Rs and R9 are members of a Cs membered ring to form a 1 -naphthoyl moiety. R13 and R14 are members of a Cs membered ring to form another 1 -naphthoyl moiety. Structure (II) is provided below.

[0087] In one embodiment, the substituted phenylene aromatic diester has a structure (III) which includes Ri that is a methyl group and R3 is a t-butyl group. Each of R2and R4 is hydrogen. Re and R7 are members of a Ce membered ring to form a 2-naphthoyl moiety. R12 and R13 are members of a Ce membered ring to form a 2-naphthoyl moiety. Structure (III) is provided below.

[0088] In one embodiment, structure (I) includes R1 that is a methyl group and R3 is a t-butyl group. Each of R7 and R12 is an ethoxy group. Each of R2, R4, Rs, Re, Rs, R9, R10, R11, R13, and R14 is hydrogen.

[0089] In one embodiment, structure (I) includes R1 that is a methyl group and R3 is a t-butyl group. Each of R7 and R12 is a fluorine atom. Each of R2, R4, Rs, Re, Rs, R9, R10, R11, R13, and R14 is hydrogen.

[0090] In one embodiment, structure (I) includes R1 that is a methyl group and R3 is a t-butyl group. Each of R7 and R12 is a chlorine atom. Each of R2, R4, Rs, Re, Rs, R9, R10, R11, R13, and R14 is hydrogen.

[0091] In one embodiment, structure (I) includes R1 that is a methyl group and R3 is a t-butyl group. Each of R7 and R12 is a bromine atom. Each of R2, R4, Rs, Re, Rs, R9, R10, R11, R13, and R14 is hydrogen.

[0092] In one embodiment, structure (I) includes Ri that is a methyl group and R3 is a t-butyl group. Each of R7 and R12 is an iodine atom. Each of R2, R4, Rs, Re, Rs, R9, R10, R11, R13, and R14 is hydrogen.

[0093] In one embodiment, structure (I) includes R1 that is a methyl group and R3 is a t-butyl group. Each of Re, R7, R11 , and R12 is a chlorine atom. Each of R2, R4, Rs, Rs, R9, R10, R13, and R14 is hydrogen.

[0094] In one embodiment, structure (I) includes R1 that is a methyl group and R3 is a t-butyl group. Each of Re, Rs, R11 , and R13 is a chlorine atom. Each of R2, R4, Rs, R7, R9, R10, R12, and R14 is hydrogen.

[0095] In one embodiment, structure (I) includes R1 that is a methyl group and R3 is a t-butyl group. Each of R2, R4 and R5-R14 is a fluorine atom.

[0096] In one embodiment, structure (I) includes R1 that is a methyl group and R3 is a t-butyl group. Each of R7 and R12 is a trifluoromethyl group. Each of R2, R4, Rs, Rs, Rs, R9, R10, R11, R13, and R14 is hydrogen.

[0097] In one embodiment, structure (I) includes R1 that is a methyl group and R3 is a t-butyl group. Each of R7 and R12 is an ethoxycarbonyl group. Each of R2, R4, Rs, Rs, Rs, R9, R10, R11, R13 and R14 is hydrogen.

[0098] In one embodiment, R1 is a methyl group and R3 is a t-butyl group. Each of R7and R12 is an ethoxy group. Each of R2, R4, Rs, Rs, Rs, R9, R10, R11 , R13, and R14 is hydrogen.

[0099] In one embodiment, structure (I) includes R1 that is a methyl group and R3 is a t-butyl group. Each of R7 and R12 is a diethylamino group. Each of R2, R4, Rs, Rs, Rs, R9, R10, R11, R13, and R14 is hydrogen.

[0100] In one embodiment, structure (I) includes R1 that is a methyl group and R3 is a 2,4,4-trimethylpentan-2-yl group. Each of R2, R4and R5-R14 is hydrogen.

[0101] In one embodiment, structure (I) includes R1 and R3, each of which is a sec-butyl group. Each of R2, R4 and R5-R14 is hydrogen.

[0102] In one embodiment, the substituted phenylene aromatic diester has a structure (IV) whereby R1 and R2 are members of a Cs membered ring to form a 1 ,2-naphthalene moiety. Each of R5-R14 is hydrogen. Structure (IV) is provided below.

[0103] In one embodiment, the substituted phenylene aromatic diester has a structure (V) whereby R2 and R3 are members of a Ce membered ring to form a 2,3-naphthalene moiety. Each of R5-R14 is hydrogen. Structure (V) is provided below.

[0104] In one embodiment, structure (I) includes R1 and R4 that are each a methyl group. Each of R2, R3, R5-R9 and R10-R14 is hydrogen.

[0105] In one embodiment, structure (I) includes R1 that is a methyl group. R4 is an i-propyl group. Each of R2, R3, R5-R9 and R10-R14 is hydrogen.

[0106] In one embodiment, structure (I) includes R1, R3, and R4, each of which is an i-propyl group. Each of R2, R5-R9 and R10-R14 is hydrogen.

[0107] In one embodiment, each of R1 and R4 is selected from a methyl group, an ethyl group, and a vinyl group. Each of R2 and R3 is selected from hydrogen, a secondary alkyl group, or a tertiary alkyl group, with R2 and R3 not concurrently being hydrogen. Stated differently, when R2 is hydrogen, R3 is not hydrogen (and vice versa).

[0108] In one embodiment, a second internal electron donor may be used that generally comprises a polyether that can coordinate in bidentate fashion. In oneembodiment the second internal electron donor is a substituted 1 ,3-diether of structure VI:Where R1 and R2 are the same or different, methyl, C2-C18 linear or branched alkyls, C3-C18 cycloalkyl, C4-C18 cycloalkyl-alky I, C4-C18 alkyl-cycloalkyl, phenyl, organosilicon, C7-C18 arylalkyl, or C7-C18 alkylaryl radicals; and R1 or R2 may also be a hydrogen atom.

[0109] In one embodiment the second internal electron donor may comprise a 1 ,3-diether with cyclic or polycyclic structure VII:Where R1, R2, R3, and R4 are as described for R1 and R2 of structure VI or may be combined to form one or more C5-C7 fused aromatic or non-aromatic ring structures, optionally containing an N,O, or S heteroatom. Particular examples of the second internal electron donor include4,4-bis(methoxymethyl)-2,6-dimethyl heptane, 9,9-bis(methoxymethyl)fluorene, or mixtures thereof.

[0110] The precursor is converted to a solid procatalyst by furtherreaction (halogenation) with an inorganic halide compound, preferably a titanium halide compound, and incorporation of the internal electron donors.

[0111] One suitable method for halogenation of the precursor is by reacting the precursor at an elevated temperature with a tetravalent titanium halide, optionallyin the presence of a hydrocarbon or halohydrocarbon diluent. The preferred tetravalent titanium halide is titanium tetrachloride.

[0112] The resulting procatalyst composition can generally contain titanium in an amount from about 0.5% to about 6% by weight, such as from about 1.5% to about 5% by weight, such as from about 2% to about 4% by weight. The solid catalyst can contain magnesium generally in an amount greater than about 5% by weight, such as in an amount greater than about 8% by weight, such as in an amount greater than about 10% by weight, such as in an amount greater than about 12% by weight, such as in an amount greater than about 14% by weight, such as in an amount greater than about 16% by weight. Magnesium is contained in the catalyst in an amount less than about 25% by weight, such as in an amount less than about 23% by weight, such as in an amount less than about 20% by weight. The internal electron donor can be present in the catalyst composition in an amount less than about 30% by weight, such as in an amount less than about 25% by weight, such as in an amount less than about 22% by weight, such as in an amount less than about 20% by weight, such as in an amount less than about 19% by weight. The internal electron donor is generally present in an amount greater than about 5% by weight, such as in an amount greater than about 9% by weight.

[0113] In one embodiment, the procatalyst composition is combined with a cocatalyst to form a catalyst system. A catalyst system is a system that forms an olefin-based polymer when contacted with an olefin under polymerization conditions. The catalyst system may optionally include an external electron donor, an activity limiting agent, and / or various other components.

[0114] As used herein, a "cocatalyst" is a substance capable of converting the procatalyst to an active polymerization catalyst. The cocatalyst may include hydrides, alkyls, or aryls of aluminum, lithium, zinc, tin, cadmium, beryllium, magnesium, and combinations thereof. In one embodiment, the cocatalyst is a hydrocarbyl aluminum cocatalyst represented by the formula R3AI wherein each R is an alkyl, cycloalkyl, aryl, or hydride radical; at least one R is a hydrocarbyl radical; two or three R radicals can be joined in a cyclic radical forming a heterocyclic structure; each R can be the same or different; and each R, which is a hydrocarbyl radical, has 1 to 20 carbon atoms, and preferably 1 to 10 carbonatoms. In a further embodiment, each alkyl radical can be straight or branched chain and such hydrocarbyl radical can be a mixed radical, i.e., the radical can contain alkyl, aryl, and / or cycloalkyl groups. Nonlimiting examples of suitable radicals are: methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, n-pentyl, neopentyl, n-hexyl, 2-methylpentyl, n-heptyl, n-octyl, isooctyl, 2-ethylhexyl, 5,5-dimethylhexyl, n-nonyl, n-decyl, isodecyl, n-undecyl, n-dodecyl.

[0115] Nonlimiting examples of suitable hydrocarbyl aluminum compounds are as follows: triisobutylaluminum, tri-n-hexylaluminum, diisobutylaluminum hydride, di-n-hexylaluminum hydride, isobutylaluminum dihydride, n-hexylaluminum dihydride, diisobutylhexylaluminum, isobutyldihexylaluminum, trimethylaluminum, triethylaluminum, tri-n-propylaluminum, triisopropylaluminum, tri-n-butylaluminum, tri-n-octylaluminum, tri-n-decylaluminum, tri-n-dodecylaluminum. In one embodiment, preferred cocatalysts are selected from triethylaluminum, triisobutylaluminum, tri-n-hexylaluminum, diisobutylaluminum hydride, and di-n-hexylaluminum hydride, and most preferred cocatalyst is triethylaluminum.

[0116] In one embodiment, the cocatalyst is a hydrocarbyl aluminum compound represented by the formula RnAIX3-nwherein n = 1 or 2, R is an alkyl, and X is a halide or alkoxide. Nonlimiting examples of suitable compounds are as follows: methylaluminoxane, isobutylaluminoxane, diethylaluminum ethoxide, diisobutylaluminum chloride, tetraethyldialuminoxane, tetraisobutyldialum inoxane, diethylaluminum chloride, ethylaluminum dichloride, methylaluminum dichloride, and dimethylaluminum chloride.

[0117] In one embodiment, the catalyst composition includes an external electron donor. As used herein, an "external electron donor" is a compound added independent of procatalyst formation and contains at least one functional group that is capable of donating a pair of electrons to a metal atom. Bounded by no particular theory, it is believed that the external electron donor enhances catalyst stereoselectivity, (i.e., to reduces xylene soluble material in the formant polymer).

[0118] In one embodiment, the external electron donor may be selected from one or more of the following: an alkoxysilane, an amine, an ether, a carboxylate, a ketone, an amide, a carbamate, a phosphine, a phosphate, a phosphite, a sulfonate, a sulfone, and / or a sulfoxide.

[0119] In one embodiment, the external electron donor is an alkoxysilane. The alkoxysilane has the general formula: SiRm(OR')4-m (I) where R independently each occurrence is hydrogen or a hydrocarbyl or an amino group optionally substituted with one or more substituents containing one or more Group 14, 15, 16, or 17 heteroatoms, said R' containing up to 20 atoms not counting hydrogen and halogen; R' is a C1-4 alkyl group; and m is 0, 1 , 2 or 3. In an embodiment, R is Ce-12 aryl, alkyl or aralkyl, C3-12 cycloalkyl, 03-12 branched alkyl, or C3-12 cyclic or acyclic amino group, R' is C1-4 alkyl, and m is 1 or 2. Nonlimiting examples of suitable silane compositions include dicyclopentyldimethoxysilane, di-tert-butyldimethoxysilane, methylcyclohexyldimethoxysilane, methylcyclohexyldiethoxysilane, ethylcyclohexyldimethoxysilane, diphenyldimethoxysilane, diisopropyldimethoxysilane, di-n-propyldimethoxysilane, diisobutyldimethoxysilane, diisobutyldiethoxysilane, isobutylisopropyldimethoxysilane, di-n-butyldimethoxysilane, cyclopentyltrimethoxysilane, isopropyltrimethoxysilane, n-propyltrimethoxysilane, n-propyltriethoxysilane, ethyltriethoxysilane, tetramethoxysilane, tetraethoxysilane, diethylaminotriethoxysilane, cyclopentylpyrrolidinodimethoxysilane, bis(pyrrolidino)dimethoxysilane, bis(perhydroisoquinolino)dimethoxysilane, and dimethyldimethoxysilane. In one embodiment, the silane composition is dicyclopentyldimethoxysilane (DCPDMS), methylcyclohexyldimethoxysilane (MChDMS) , diisopropyldimethoxysilane (DIPDMS), n-propyltrimethoxysilane (NPTMS), diethylaminotriethoxysilane (DATES), or n-propyltriethoxysilane (PTES), and any combination of thereof.

[0120] In one embodiment, the external donor can be a mixture of at least 2 alkoxysilanes. In a further embodiment, the mixture can be dicyclopentyldimethoxysilane and methylcyclohexyldimethoxysilane, dicyclopentyldimethoxysilane and tetraethoxysilane, or dicyclopentyldimethoxysilane and n-propyltriethoxysilane.

[0121] In one embodiment, the external electron donor is selected from one or more of the following: a benzoate, and / or a diol ester. In another embodiment, the external electron donor is 2,2,6,6-tetramethylpiperidine. In still another embodiment, the external electron donor is a diether.

[0122] In one embodiment, the catalyst composition includes an activity limiting agent (ALA). As used herein, an "activity limiting agent" ("ALA") is a material that reduces catalyst activity at elevated temperature (i.e., temperature greater than about 85°C). An ALA inhibits or otherwise prevents polymerization reactor upset and ensures continuity of the polymerization process. Typically, the activity of Ziegler-Natta catalysts increases as the reactor temperature rises. Ziegler-Natta catalysts also typically maintain high activity near the melting point temperature of the polymer produced. The heat generated by the exothermic polymerization reaction may cause polymer particles to form agglomerates and may ultimately lead to disruption of continuity for the polymer production process. The ALA reduces catalyst activity at elevated temperature, thereby preventing reactor upset, reducing (or preventing) particle agglomeration, and ensuring continuity of the polymerization process.

[0123] The activity limiting agent may be a carboxylic acid ester, a diether, a poly(alkene glycol), poly(alkene glycol)ester, a diol ester, and combinations thereof. The carboxylic acid ester can be an aliphatic or aromatic, mono-or polycarboxylic acid ester. Nonlimiting examples of suitable monocarboxylic acid esters include ethyl and methyl benzoate, ethyl p-methoxybenzoate,methyl p-ethoxybenzoate, ethyl p-ethoxybenzoate, ethyl acrylate, methyl methacrylate, ethyl acetate, ethyl p-chlorobenzoate, hexyl p-aminobenzoate, isopropyl naphthenate, n-amyl toluate, ethyl cyclohexanoate and propyl pivalate.

[0124] In one embodiment, the external electron donor and / or activity limiting agent can be added into the reactor separately. In another embodiment, the external electron donor and the activity limiting agent can be mixed together in advance and then added into the reactor as a mixture. In the mixture, more than one external electron donor or more than one activity limiting agent can be used. In one embodiment, the mixture is dicyclopentyldimethoxysilane and isopropyl myristate, dicyclopentyldiniethoxysilane and poly(ethylene glycol) laurate, dicyclopentyldimethoxysilane and isopropyl myristate and poly(ethylene glycol) dioleate, methylcyclohexyldimethoxysilane and isopropyl myristate, n-propyltrimethoxysilane and isopropyl myristate, dimethyldimethoxysilane and methylcyclohexyldimethoxysilane and isopropyl myristate, dicyclopentyldimethoxysilane and n-propyltriethoxysilane and isopropyl myristate,and dicyclopentyldimethoxysilane and tetraethoxysilane, isopropyl myristate, pentyl valerate, and combinations thereof.

[0125] In one embodiment, the catalyst composition includes any of the foregoing external electron donors in combination with any of the foregoing activity limiting agents.

[0126] The catalyst system as described above has been found to be particularly well suited for producing the heterophasic polymer composition of the present disclosure.

[0127] Due to the physical properties of the polypropylene composition of the present disclosure, especially the flow properties of the composition, the composition is well suited to producing molded articles. The polypropylene composition, for instance, can be used in extrusion, injection molding, and rotational molding applications.

[0128] The present disclosure may be better understood with reference to the following example.Example

[0129] Heterophasic polypropylene copolymers were produced generally in a gas phase pilot polymerization unit set up with two reactors in series. A catalyst, a co-catalyst, and an external donor and monomers were fed to the first reactor. In these particular examples, CONSISTA® C601 catalyst from W.R. Grace, a Ziegler Natta type of catalyst was used as the catalyst, tri-ethyl aluminum (Teal) was used as the cocatalyst, CONSISTA® D8700 donor from W.R. Grace was used as the external donor and propylene and ethylene were used the monomer and comonomer. The first reactor also had hydrogen feed for all samples which was used to control the polymer first phase melt flow rate. The reactor total pressure was maintained constant with nitrogen feed. In the first reactor, the polymer phase ethylene content was controlled by adjustment of the ethylene / propylene gas phase molar ratio and the melt flow rate was controlled by the hydrogen / propylene gas phase molar ratio, and the cold xylene solubles was controlled by the cocatalyst / external donor molar ratio.

[0130] The first polymer phase powder was transferred from the first gas phase reactor to the second gas phase reactor. The second reactor had ethylene and propylene feed to control the second phase composition by controlling thepropylene / ethylene gas phase molar ratio and hydrogen feed to control the melt flow rate by controlling the hydrogen / ethylene gas phase molar ratio. As with the first reactor, nitrogen was fed to maintain constant reactor pressure.

[0131] A twin screw extruder was used to mix in an additive package containing an antioxidant with the net polymer produced in the reactor.

[0132] Polymer pellet samples were injected molded into specimens. For instance, the specimens were made according to ASTM Test D4101 to produce specimens for flexural modulus and notched IZOD strength Testing.

[0133] The following polypropylene compositions were produced and the following results were obtained:> >

[0134] Sample Nos. 2 through 4 above were made in accordance with the present disclosure. These samples displayed a low melt flow rate, a high impact resistance, in combination with low stiffness. Example 1 was produced with less ethylene. As shown by Sample No. 1, when containing a lower overall ethylene content (especially in the xylene insoluble phase), the balance between the impact performance and the flexural modulus is lost, as the material retains a high rigidity. As shown in Sample Nos. 2 through 4, even while maintaining the final xylene soluble content relatively high, by increasing the xylene soluble of the first phase(XS1) and increasing the overall ethylene content of the composition results in a significant reduction of flexural modulus without losing impact performance, a much desired property balance in certain applications.

[0135] These and other modifications and variations to the present invention may be practiced by those of ordinary skill in the art, without departing from the spirit and scope of the present invention, which is more particularly set forth in the appended claims. In addition, it should be understood that aspects of the various embodiments may be interchanged both in whole or in part. Furthermore, those of ordinary skill in the art will appreciate that the foregoing description is by way of example only and is not intended to limit the invention so further described in such appended claims.

Claims

Claims1. A polypropylene composition comprising:a first polymer phase comprising a polypropylene polymer, the polypropylene polymer comprising a propylene and alpha olefin random copolymer, the alpha olefin comprising ethylene and / or butene, the polypropylene polymer having a xylene soluble content of greater than about 5% by weight and less than about 32% by weight and having a melt flow rate of from about 0.1 g / 10 min to about 10 g / 10 min;a second polymer phase combined with the first polymer phase, the second polymer phase comprising a propylene and ethylene copolymer; andwherein the polypropylene composition has a melt flow rate of 10 g / 10 min or less, the polypropylene composition having a xylene soluble portion and a xylene insoluble portion, the polypropylene composition having a total xylene soluble content of from about 10%% to about 60% by weight, the polypropylene composition containing ethylene in an amount from about 5% to about 43% by weight, the xylene insoluble portion containing ethylene in an amount of from about 5% to about 30% by weight, the polypropylene composition displaying a notched Izod impact strength at 23°C of greater than about 500 J / m, and displaying a flexural modulus of less than about 550 MPa.

2. A polypropylene composition as defined in claim 1 , wherein the composition displays a notched Izod impact strength of greater than about 600 J / m.

3. A polypropylene composition as defined in claim 1 or 2, wherein the second polymer phase is in the form of polymer particles dispersed within the first polymer phase.

4. A polypropylene composition as defined in claim 1 , 2 or 3, wherein the polypropylene polymer contained in the first polymer phase comprises a propylene and ethylene copolymer.

5. A polypropylene composition as defined in claim 1 , 2 or 3, wherein the polypropylene polymer contained in the first polymer phase comprises a propylene copolymer with butene and optionally ethylene.

6. A polypropylene composition as defined in claim 4, wherein the ethylene content of the xylene insoluble content is from about 8% to about 25% by weight.

7. A polypropylene composition as defined in any of the preceding claims, wherein the composition has a flexural modulus of less about 450 MPa.

8. A polypropylene composition as defined in any of the preceding claims, wherein the composition has a notched Izod impact strength of greater than about 650 J / m.

9. A polypropylene composition as defined in claim 4, wherein the propylene and ethylene random copolymer in the first polymer phase contains ethylene in an amount from about 2% to about 7% by weight.

10. A polypropylene composition as defined in claim 5, wherein the propylene and ethylene and / or butylene random copolymer in the first polymer phase contains butylene and / or ethylene in an amount from about 6% to about 12% by weight.

11. A polypropylene composition as defined in any of the preceding claims, wherein the polypropylene composition has a melt flow rate of from about 0.1 g / 10 min to about 5 g / 10 min, such as from about 0.1 g / 10 min to about 3 g / 10 min.

12. A polypropylene composition as defined in any of the preceding claims, wherein the polypropylene polymer in the first polymer phase has been Ziegler-Natta catalyzed and wherein the propylene and ethylene copolymer in the second polymer phase has also been Ziegler-Natta catalyzed.

13. A polypropylene composition as defined in claim 13, wherein the Ziegler-Natta catalyst used for producing the polypropylene polymer of the first polymer phase and the propylene and ethylene copolymer of the second polymer phase include an internal electron donor comprising a substituted phenylene aromatic diester.

14. A polypropylene composition as defined in claim 13 or 14, wherein the second polymer phase is formed in the presence of the first polymer phase.

15. A polypropylene composition as defined in any of the preceding claims, wherein the composition has a total xylene soluble content of greater than about 10% by weight and less than about 50% by weight.

16. A polypropylene composition as defined in any of the preceding claims, wherein the composition has a molecular weight distribution (Mw / Mn) of less than about 9 and greater than about 3.5.

17. A molded article formed from the polypropylene composition as defined in any of the preceding claims.

18. A molded article as defined in claim 18, wherein the molded article is an injection molded article.

19. A molded article as defined in claim 18, wherein the molded article is an extruded film.

20. A mat formed from the polypropylene composition as defined in any of claims 1-17.

21. An automotive part formed from the polypropylene composition as defined in any of claims 1 -17.

22. A polymerization process comprising:contacting propylene and at least one other olefin with a catalyst composition in a first polymerization reactor under gas phase polymerization conditions, the catalyst composition comprising an internal electron donor, a cocatalyst and optionally an external electron donor, the other olefin comprising ethylene or butylene;forming, in the first polymerization reactor a first polymer phase comprising a propylene-based polymer having a melt flow rate of from about 0.1 g / 10 min. to about 10 g / 10 min. as measured in accordance with ASTM D1238-01 (230° C., 2.16 kg) and having a xylene soluble content of greater than about 5% by weight and less than about 32% by weight;contacting the propylene-based polymer with propylene and ethylene in a second reactor under polymerization conditions; andforming a second polymer phase combined with the first polymer phase comprising a polypropylene composition having a melt flow rate of 10 g / 10 min or less, the polypropylene composition having a xylene soluble portion and a xylene insoluble portion, the polypropylene composition having a total xylene soluble content of from about 10% to about 60% by weight, the polypropylene composition containing ethylene in an amount from about 5% to about 43% by weight, the polypropylene composition displaying a notched Izod impact strength at 23°C ofgreater than about 600 J / m and displaying a flexural modulus of less than about 300 MPa.

23. A process as defined in claim 23, wherein the polypropylene composition has a melt flow rate of from about 0.1 g / 10 min to about 5 g / 10 min, such as from about 0.1 g / 10 min to about 3 g / 10 min., the xylene insoluble portion containing ethylene in an amount of from about 5% to about 30% by weight and the polypropylene composition having a total xylene soluble content of greater than about 10% by weight and less than about 60% by weight, and wherein the polypropylene composition has a molecular weight distribution (Mw / Mn) of less than about 9 and greater than about 3.

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