High melt strength polypropylene with improved processability

Abstract

1. A polypropylene composition suitable for foam molding, having improved processability while maintaining process hardening, and a process for producing the polypropylene composition, comprising the steps of: combining a linear polypropylene having a melt strength (190°C) in the range of 10 to 40 cN with an organic peroxide to obtain a branched polypropylene having a melt strength (190°C) in the range of 20 to 80 cN, wherein the melt strength of the branched polypropylene exceeds the melt strength of the linear polypropylene; and combining the branched polypropylene having a melt flow rate in the range of 0.1 to 20 g / 10 min and a Mw / Mn of at least 5 with 5% to 40% by weight of a low molecular weight polyolefin having a melt flow rate of at least 50 g / 10 min and a Mw / Mn of less than 5 to obtain the polypropylene composition. [Selected Figure] Figure 1

Description

[Technical field]

[0001] (Priority Claim) This application claims the benefit of Provisional Application No. 62 / 455,707, filed February 7, 2017, and European Application No. 17160477.0, filed March 13, 2017, the disclosures of which are incorporated herein by reference. The present disclosure relates to improved processing of branched polypropylene, and in particular to blends of branched polypropylene and low molecular weight polyolefins. [Background technology]

[0002] The applicability of polypropylene in industrial extrusion processes involving both shear and extensional flow has been limited, due in part to its low melt strength and distortion Several efforts have been made to improve the melt strength and hardening of polypropylene. distortion Attempts in the industry to improve cure include increasing the molecular weight, broadening the molecular weight distribution (Mw / Mn), adding ultra-high molecular weight tails, and / or adding long chain branches (LCB). Melt strength and distortion Polypropylenes with improved cure have been produced, but these tend to have very high shear viscosities, making them difficult to process. High melt strength and distortion It would be beneficial to find a polypropylene that has a wide processing window for applications such as foam molding and thermoforming while still having a high hardness. One way this could be accomplished is by lowering the processing temperature through the addition of low molecular weight additives to reduce the viscosity. However, the challenge with this approach is that at higher concentrations of low molecular weight additives, distortion The goal is to reduce sclerosis. Better approaches are needed. Relevant publications include U.S. Patent Application Publication No. 2015 / 0018463; U.S. Patent Application Publication No. 2010 / 222470; U.S. Patent Application Publication No. 2003 / 0119996; U.S. Patent No. 4,897,452; U.S. Patent No. 6,103,833; U.S. Patent No. 9,410,034; EP 1159,309 B1; EP 2325248; EP 2386601; EP 2433982; WO 2010 / 049371; WO 2014 / 070384; WO 2015 / 200586; WO 2016 / 053468; and JP 2010-043162; as well as M.E. Shivokhin, L. Urbanczyk, J. Michel, and C. Bailly, in "The influence of molecular weight distribution of industrial polystyrene on its melt extensional and ultimate properties", 56(9) POLYMER ENGINEERING & SCIENCE, 1012-1020 (September 2016). Summary of the Invention

[0003] Described herein is a process for producing a polypropylene composition, comprising (or consisting of, or consisting essentially of) combining a branched polypropylene with a low molecular weight polyolefin having a melt flow rate of at least 50 g / 10 min (ASTM D1238, 230° C. / 2.16 kg) to obtain a polypropylene composition. a linear polypropylene having a melt strength (190°C) in the range of 10 to 40 cN with an organic peroxide to obtain a branched polypropylene having a melt strength (190°C) in the range of 20 to 80 cN, wherein the melt strength of the branched polypropylene exceeds the melt strength of the linear polypropylene; and a branched polypropylene having a melt flow rate in the range of 0.1 to 20 g / 10 min and a Mw / Mn of at least 5 with a polypropylene homopolymer having a melt flow rate of at least 50 g / 10 min and a Mw / Mn of less than 5, in the range of 5 to 40% by weight, based on the weight of the branched polypropylene and the polypropylene homopolymer, to obtain a polypropylene composition, wherein the polypropylene composition has a melt flow rate in the range of 0.5 to 40 g / 10 min, a melt strength (190°C) in the range of 20 to 80 cN and a melt strength (190°C) in the range of distortion Shows at least 90% cure.

[0004] Also described are polypropylene compositions comprising (or consisting essentially of) branched polypropylene and low molecular weight polyolefins having a melt flow rate of at least 50 g / 10 min. In particular, foam molded, thermoformed, and / or extruded articles are described that comprise (or consist essentially of) a polypropylene composition comprising (or consisting essentially of) a branched polypropylene having a melt strength (190°C) in the range of 20 to 80 cN and a melt flow rate in the range of 0.1 to 20 g / 10 min, in the range of 95 to 60% by weight, based on the weight of the branched polypropylene and polypropylene homopolymer; and a polypropylene homopolymer having a melt flow rate of at least 50 g / 10 min, in the range of 5 to 40% by weight, based on the weight of the branched polypropylene and polypropylene homopolymer, where the polypropylene composition has a melt flow rate in the range of 0.5 to 40 g / 10 min, a melt strength (190°C) in the range of 20 to 80 cN, and the branched polypropylene composition exhibits a melt flow rate of at least 50 g / 10 min. distortion Shows at least 90% cure. [Brief description of the drawings]

[0005] [Figure 1] 1 is an extensional rheology trace of a comparative blend and two inventive blends showing viscosity as a function of time at a strain rate of 1 sec −1 . [Diagram 2] 1 is an extensional rheology trace of a comparative blend and two inventive blends showing viscosity as a function of time at a strain rate of 5 sec −1 . [Diagram 3] 1 is an extensional rheology trace of a comparative blend and two inventive blends showing viscosity as a function of time at a strain rate of 10 sec −1 . [Figure 4] 1 is a trace of SAOS for a comparative blend and two inventive blends showing angular frequency as a function of shear viscosity. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0006] Judicious selection of the molecular weight and concentration of the low molecular weight additive, low molecular weight polyolefins used herein, provides high melt strength and distortion While reducing the shear viscosity of the cured polypropylene, distortion It was discovered that the level of stiffening (elongational thickening) could be simultaneously maintained, a behavior that is unique and has not been previously demonstrated in polypropylene. distortion Curing is important for industrial applications involving extensional flow such as in thermoforming, fiber pultrusion / spinning, blown film, foam molding, and other industrial applications involving both shear and extensional flow deformation. The invention is described in more detail below and is ordered based on a description of the starting materials and processes that result in the desired terminal polypropylene composition. (Linear polypropylene) Herein, and throughout this specification, the term "linear polypropylene" refers to reactor grade polypropylene homopolymers or copolymers useful for forming "branched polypropylene" having a branching index g'(vis) of greater than 0.98. The most preferred linear polypropylene in any embodiment of the present invention has the properties described herein and can be made by any means known to those skilled in the art, but is most preferably produced using a Ziegler-Natta succinate-containing catalyst. The properties referred to here are those of the reactor grade material before or after melt mixing with non-peroxide "additives", such as antioxidants, alkyl radical scavengers, and the like. In any embodiment, the desired linear polypropylene is a homopolymer of propylene-derived units or a copolymer of ethylene or C4-C 2 -C 1 - ... 12 It is a copolymer that contains α-olefin derived units, most preferably ethylene, 1-butene, or 1-hexene derived units, with the remainder being propylene derived units.

[0007] Suitable Ziegler-Natta catalysts for producing useful linear polypropylenes include solid titanium supported catalyst systems such as those described in U.S. Patent Nos. 4,990,479, 5,159,021, and WO 00 / 63261. Briefly, Ziegler-Natta catalysts can be obtained by: (1) suspending a dialkoxymagnesium compound in an aromatic hydrocarbon that is liquid at 20-25° C.; (2) contacting the dialkoxymagnesium hydrocarbon composition with a titanium halide, and a diester of an aromatic dicarboxylic acid; and (3) contacting the resulting functional dialkoxymagnesium hydrocarbon composition of step (2) with additional titanium halide. A "catalyst system" typically includes a solid titanium catalyst component that includes titanium, magnesium, a halogen, at least one non-aromatic "internal" electron donor, and at least one, preferably two or more, "external" electron donors. The solid titanium catalyst component, also referred to as a Ziegler-Natta catalyst, can be prepared by contacting a magnesium compound, a titanium compound, and at least an internal electron donor. Examples of titanium compounds used in the preparation of the solid titanium catalyst component include those represented by the formula (I): Ti(OR n )X 4-n (I) where R is a hydrocarbyl radical, X is a halogen atom, and n is 0-4.

[0008] The terms "hydrocarbyl radical", "hydrocarbyl", and "hydrocarbyl group" are used interchangeably throughout the present specification, unless otherwise noted. For purposes of this disclosure, a hydrocarbyl radical is a C1-C6 alkyl group, which may be linear, branched, or cyclic (aromatic or non-aromatic), where appropriate. 20 Radical, or C1-C 10 Radical, or C6-C 20 Radical, or C7-C 20and includes hydrocarbyl radicals substituted with one or more functional groups including other hydrocarbyl radicals and / or elements from Groups 13-17 of the Periodic Table of the Elements. In addition, two or more such hydrocarbyl radicals may together form fused ring systems, including partially or fully hydrogenated fused ring systems, and may include heterocyclic radicals.

[0009] Preferably, the halogen-containing titanium compound is titanium tetrahalide or titanium tetrachloride. The titanium compounds may be used alone or in combination with each other. The titanium compounds may be diluted with a hydrocarbon compound or a halogenated hydrocarbon compound. Non-limiting examples include titanium tetrahalides such as TiCl4, TiBr4, and / or TiI4; alkoxy titanium trihalides including Ti(OCH3)Cl3, Ti(OC2H5)Cl3, Ti(On-C4H9)Cl3, Ti(OC2H5)Br3, and / or Ti(O-iso-C4H9)Br3; dialkoxy titanium dihalides including Ti(OCH3)2Cl2, Ti(OC2H5)2Cl2, Ti(On-C4H9)2Cl2, and / or Ti(OC2H5)2Br2; trialkoxy titanium monohalides including Ti(OCH3)3Cl, Ti(OC2H5)3Cl, Ti(On-C4H9)3Cl, and / or Ti(OC2H5)3Br; and / or tetraalkoxy titanium including Ti(OCH3)4, Ti(OC2H5)4, and / or Ti(On-C4H9)4. Preferably, the magnesium compounds used in the preparation of the solid titanium catalyst component include reducible and / or non-reducible magnesium compounds. Suitable reducible magnesium compounds may be, for example, magnesium compounds having magnesium-carbon or magnesium-hydrogen bonds. Suitable examples of such reducible magnesium compounds include dimethylmagnesium, diethylmagnesium, dipropylmagnesium, dibutylmagnesium, diamylmagnesium, dihexylmagnesium, didecylmagnesium, ethylmagnesium chloride, propylmagnesium chloride, butylmagnesium chloride, hexylmagnesium chloride, amylmagnesium chloride, butylethoxymagnesium, ethylbutylmagnesium, and / or butylmagnesium halide. These magnesium compounds may be used alone or may be complexed with an organoaluminum cocatalyst as described herein. These magnesium compounds may be liquid or solid.

[0010] Suitable examples of non-reducible magnesium compounds include magnesium halides, such as magnesium chloride, magnesium bromide, magnesium iodide, and magnesium fluoride; alkoxy magnesium halides, such as methoxy magnesium chloride, ethoxy magnesium chloride, isopropoxy magnesium chloride, phenoxy magnesium chloride, and methylphenoxy magnesium chloride; alkoxy magnesium, such as ethoxy magnesium, isopropoxy magnesium, butoxy magnesium, n-octaoxy magnesium, and 2-ethylhexoxy magnesium; aryloxy magnesium, such as phenoxy magnesium and dimethylphenoxy magnesium; and / or magnesium carboxylates, such as magnesium laurate and magnesium stearate. The non-reducible magnesium compound may be a compound derived from a reducible magnesium compound or a compound derived at the time of preparing the catalyst component. The non-reducible magnesium compound may be derived from a reducible compound, for example, by contacting a reducible magnesium compound with a polysiloxane compound, a halogen-containing silane compound, a halogen-containing aluminum compound, an ester, an alcohol, or the like.

[0011] The reducible and / or non-reducible magnesium compounds may be complexes of the above magnesium compounds with other metals or mixtures of the compounds with other metal compounds. They may also be mixtures of two or more types of the above compounds. Additionally, halogen-containing magnesium compounds may be used, including magnesium chloride, alkoxy magnesium chlorides, and aryloxy magnesium chlorides. The supported Ziegler-Natta catalyst may be used in combination with a cocatalyst, also referred to herein as a Ziegler-Natta cocatalyst. Compounds containing at least one aluminum-carbon bond in the molecule may be utilized as cocatalysts, also referred to herein as organoaluminum cocatalysts. Suitable organoaluminum compounds have the general formula (II): R 1 m Al(OR 2 ) n H p X q (II) wherein R 1 and R 2 are the same or different and each represents a hydrocarbyl radical containing from 1 to 15 carbon atoms, or 1-4 carbon atoms; X represents a halogen atom; m is 1, 2, or 3; n is 0, 1, or 2; p is 0, 1, 2, or 3; and q is 0, 1, or 2; and where m+n+p+q=3.

[0012] Other suitable organoaluminum compounds include those of the general formula (III): M 1 AlR 1 4(III) The alkylated compounds include aluminum complexes of Group I metals (such as lithium in the Periodic Table) represented by the formula: 1 is a group I metal such as Li, Na, or K, and R 1 is as defined in formula (II). Suitable examples of organoaluminum compounds include trialkylaluminums, such as trimethylaluminum, triethylaluminum, and tributylaluminum; trialkenylaluminums, such as triisophenylaluminum; dialkylaluminum alkoxides, such as diethylaluminum ethoxide and dibutylaluminum ethoxide; alkylaluminum sesquialkoxides, such as ethylaluminum sesquiethoxide and butylaluminum sesquibutoxide; 1 2.5 Al(OR 2 ) 0.5 partially halogenated alkylaluminums such as alkylaluminum dihalides, e.g., ethylaluminum dichloride, propylaluminum dichloride, and butylaluminum dibromide; partially hydrogenated alkylaluminum dihydrides, e.g., ethylaluminum dihydrogenide and propylaluminum dihydrogenide; and partially alkoxylated and halogenated alkylaluminums such as ethylaluminum ethoxychloride, butylaluminum butoxychloride, and ethylaluminum ethoxybromide.

[0013] The electron donor is present with the metal component described above in forming a catalyst suitable for producing the linear polypropylene described herein. Both "internal" and "external" electron donors are desirable in forming a catalyst suitable for making the linear polypropylene described herein. More specifically, the internal electron donor may be used in the catalyst formation reaction in which a transition metal halide is reacted with a metal hydride or metal alkyl. Examples of suitable internal electron donors include amines, amides, ethers, esters, ketones, nitriles, phosphines, stilbenes, arsines, phosphoramides, thioethers, thioesters, aldehydes, alcoholates, and salts of organic acids.

[0014] More preferably, the one or more internal donors are non-aromatic. Non-aromatic internal electron donors may include aliphatic amines, amides, esters, ethers, ketones, nitriles, phosphines, phosphoramides, thioethers, thioesters, aldehydes, alcoholates, carboxylic acids, or combinations thereof. Even more preferably, the non-aromatic internal electron donor includes a substituted or unsubstituted C2-C 10 Dicarboxylic acids C1-C 20 The non-aromatic internal electron donor includes a diester. [ka] (IV) wherein R 1 and R 2 But independently, C1-C 20 is a linear or branched alkyl, alkenyl, or cycloalkyl hydrocarbyl radical of the formula: 3 ~R 6 are independently hydrogen, halogen, or C1-C 20 is a linear or branched alkyl, alkenyl, or cycloalkyl hydrocarbyl radical of the formula: 3 ~R 6 The radicals are not bonded together, where R3 ~R 6 At least two of the radicals are linked to form a cyclic divalent radical, or a combination thereof.

[0015] R in formula (IV) 3 ~R 5 The group may be hydrogen, R 6 may be a radical selected from the group consisting of primary branched, secondary, or tertiary alkyl, or cycloalkyl radicals having 3 to 20 carbon atoms.

[0016] The internal donor may be a mono-substituted non-aromatic succinate compound. Suitable examples include diethyl-sec-butylsuccinate, diethylhexyl succinate, diethyl-cyclopropyl succinate, diethyl-trimethylsilyl succinate, diethyl-methoxysuccinate, diethyl-cyclohexyl succinate, diethyl-(cyclohexylmethyl) succinate, diethyl-t-butylsuccinate, diethyl-isobutylsuccinate, diethyl-isopropylsuccinate, diethyl-ter ... diisobutyl-neopentylsuccinate, diethyl-isopentylsuccinate, diethyl-(1,1,1-trifluoro-2-propyl)succinate, diisobutyl-sec-butylsuccinate, diisobutylhexylsuccinate, diisobutyl-cyclopropylsuccinate, diisobutyl-trimethylsilylsuccinate, diisobutyl-methoxysuccinate, diisobutyl-cyclohexylsuccinate, diisobutyl-(cyclohexylmethyl)succinate, Diisobutyl t-butylsuccinate, diisobutyl isobutylsuccinate, diisobutyl isopropylsuccinate, diisobutyl neopentylsuccinate, diisobutyl isopentylsuccinate, diisobutyl (1,1,1-trifluoro-2-propyl)succinate, dineopentyl sec-butylsuccinate, dineopentyl hexylsuccinate, dineopentyl cyclopropylsuccinate, dineopentyl trimethylsilylsuccinate dineopentyl methoxysuccinate, dineopentyl cyclohexylsuccinate, dineopentyl (cyclohexylmethyl)succinate, dineopentyl t-butylsuccinate, dineopentyl isobutylsuccinate, dineopentyl isopropylsuccinate, dineopentyl neopentyl succinate, dineopentyl isopentyl succinate, and / or dineopentyl (1,1,1-trifluoro-2-propyl)succinate.

[0017] The internal electron donor having a structure consistent with formula (IV) is R 3 From R 6wherein the radicals are different from hydrogen and are selected from the group consisting of C1-C 20 and optionally containing heteroatoms. Two radicals different from hydrogen may be linked to the same carbon atom. Suitable examples include diethyl-2,2-dimethylsuccinate, diethyl-2-ethyl-2-methylsuccinate, diethyl-2-(cyclohexylmethyl)-2-isobutylsuccinate, diethyl-2-cyclopentyl-2-n-propylsuccinate, diethyl-2,2-diisobutylsuccinate, diethyl-2-cyclohexyl-2-ethylsuccinate, diethyl-2-isopropyl-2-methylsuccinate, diethyl-2,2-diisopropyl-diethyl-2-isobutyl-2-ethylsuccinate, diethyl-2-(1,1,1-trifluoro-2-propyl)-2-methylsuccinate, diethyl-2-isopentyl-2-isobutylsuccinate, diisobutyl-2,2-dimethylsuccinate,

[0018] Diisobutyl-2-ethyl-2-methylsuccinate, diisobutyl-2-(cyclohexylmethyl)-2-isobutylsuccinate, diisobutyl-2-cyclopentyl-2-n-propylsuccinate, diisobutyl-2,2-diisobutylsuccinate, diisobutyl-2-cyclohexyl-2-ethylsuccinate, diisobutyl-2-isopropyl-2-methylsuccinate, diisobutyl-2-isobutyl-2-ethylsuccinate, diisobutyl-2-(1,1,1-trifluoro-2-propyl)-2-methylsuccinate, diisobutyl-2-isopentyl-2-isobutylsuccinate, diisobutyl-2,2-diisopropylsuccinate, dineopentyl-2,2-dimethylsuccinate, dineopentyl and 2,2-disubstituted succinates including dineopentyl-2-ethyl-2-methylsuccinate, dineopentyl-2-(cyclohexylmethyl)-2-isobutylsuccinate, dineopentyl-2-cyclopentyl-2-n-propylsuccinate, dineopentyl-2,2-diisobutylsuccinate, dineopentyl-2-cyclohexyl-2-ethylsuccinate, dineopentyl-2-isopropyl-2-methylsuccinate, dineopentyl-2-isobutyl-2-ethylsuccinate, dineopentyl-2-(1,1,1-trifluoro-2-propyl)-2-methylsuccinate, dineopentyl 2,2-diisopropylsuccinate, and / or dineopentyl 2-isopentyl-2-isobutylsuccinate.

[0019] At least two radicals different from hydrogen are R 3 From R 6 Examples include R 3 and R 5 , or R 4 and R 6Such suitable non-aromatic succinate compounds include: diethyl-2,3-bis(trimethylsilyl)succinate, diethyl-2,2-sec-butyl-3-methylsuccinate, diethyl-2-(3,3,3-trifluoropropyl)-3-methylsuccinate, diethyl-2,3-bis(2-ethylbutyl)succinate, diethyl-2,3-diethyl-2-isopropylsuccinate, diethyl-2,3-diisopropyl-2-methylsuccinate, diethyl-2,3-dicyclohexyl-2-methylsuccinate. , diethyl-2,3-diisopropylsuccinate, diethyl-2,3-bis(cyclohexylmethyl)succinate, diethyl-2,3-di-t-butylsuccinate, diethyl-2,3-diisobutylsuccinate, diethyl-2,3-dineopentylsuccinate, diethyl-2,3-diisopentylsuccinate, diethyl-2,3-(1-trifluoromethyl-ethyl)succinate, diethyl-2-isopropyl-3-isobutylsuccinate, diethyl-2-t-butyl-3-isopropylsuccinate,

[0020] Diethyl-2-isopropyl-3-cyclohexyl succinate, diethyl-2-isopentyl-3-cyclohexyl succinate, diethyl-2-cyclohexyl-3-cyclopentyl succinate, diethyl-2,2,3,3-tetramethyl succinate, diethyl-2,2,3,3-tetraethyl succinate, diethyl-2,2,3,3-tetrapropyl succinate, diethyl-2,3-diethyl-2,3-diisopropyl succinate, diisobutyl-2,3-bis(trimethylsilyl) succinate, diisobutyl-2,2-sec-butyl-3-methyl succinate, diisobutyl-2-(3,3,3-trifluoropropyl)-3-methyl succinate, diisobutyl- 2,3-bis(2-ethylbutyl)succinate, diisobutyl-2,3-diethyl-2-isopropyl succinate, diisobutyl-2,3-diisopropyl-2-methyl succinate, diisobutyl-2,3-dicyclohexyl-2-methyl succinate, diisobutyl-2,3-diisopropyl succinate, diisobutyl-2,3-bis(cyclohexylmethyl)succinate, diisobutyl-2,3-di-t-butyl succinate, diisobutyl-2,3-diisobutyl succinate, diisobutyl-2,3-dineopentyl succinate, diisobutyl-2,3-diisopentyl succinate, diisobutyl-2,3-(1,1,1-trifluoro-2-propyl) succinate,

[0021] Diisobutyl-2,3-n-propyl succinate, diisobutyl-2-isopropyl-3-isobutyl succinate, diisobutyl-2-tert-butyl-3-isopropyl succinate, diisobutyl-2-isopropyl-3-cyclohexyl succinate, diisobutyl-2-isopentyl-3-cyclohexyl succinate, diisobutyl-2-n-propyl-3-(cyclohexylmethyl) succinate, diisobutyl-2- Cyclohexyl-3-cyclopentylsuccinate, diisobutyl-2,2,3,3-tetramethylsuccinate, diisobutyl-2,2,3,3-tetraethylsuccinate, diisobutyl-2,2,3,3-tetrapropylsuccinate, diisobutyl-2,3-diethyl-2,3-diisopropylsuccinate, dineopentyl-2,3-bis(trimethylsilyl)succinate, dineopentyl-2,2-di-sec-butyl -3-methylsuccinate, dineopentyl 2-(3,3,3-trifluoropropyl)-3-methylsuccinate, dineopentyl-2,3-bis(2-ethylbutyl)succinate, dineopentyl 2,3-diethyl-2-isopropylsuccinate, dineopentyl-2,3-diisopropyl-2-methylsuccinate, dineopentyl-2,3-dicyclohexyl-2-methylsuccinate, dineopentyl-2,3-diisopropyl propyl succinate, dineopentyl-2,3-bis(cyclohexylmethyl)succinate, dineopentyl-2,3-di-t-butylsuccinate, dineopentyl-2,3-diisobutylsuccinate, dineopentyl-2,3-dineopentyl succinate, dineopentyl-2,3-diisopentyl succinate, dineopentyl 2,3-(1,1,1-trifluoro-2propyl)succinate, dineopentyl-2,3-n-propyl succinate, dineopentyl-2-isopropyl-3-isobutyl succinate, dineopentyl-2-t-butyl-3-isopropyl succinate, dineopentyl-2-isopropyl-3-cyclohexyl succinate, dineopentyl-2-isopentyl-3-cyclohexyl succinate, dineopentyl-2-n-propyl-3-(cyclohexylmethyl) succinate, dineopentyl 2-cyclohexyl-3-cyclopentyl succinate, dineopentyl-2,2,3,3-tetramethyl succinate, dineopentyl 2,2,3,3-tetraethyl succinate, dineopentyl-2,2,3,3-tetrapropyl succinate, and / or dineopentyl-2,3-diethyl-2,3-diisopropyl succinate.

[0022] The electron donor of formula (IV) is a cyclic polyvalent radical having two or four R 3 ~R 6 Examples of suitable compounds include 1-(ethoxycarbonyl)-1-(ethoxyacetyl)-2,6-dimethylcyclohexane, 1-(ethoxycarbonyl)-1-(ethoxyacetyl)-2,5-dimethyl-cyclopentane, 1-(ethoxycarbonyl)-1-(ethoxyacetylmethyl)-2-methylcyclohexane, and / or 1-(ethoxycarbonyl)-1-(ethoxy(cyclohexyl)acetyl)cyclohexane.

[0023] Preferably, the internal electron donor may be selected from the group consisting of diethyl-2,3-diisopropylsuccinate, diisobutyl-2,3-diisopropylsuccinate, di-n-butyl-2,3-diisopropylsuccinate, diethyl-2,3-dicyclohexyl-2-methylsuccinate, diisobutyl-2,3-dicyclohexyl-2-methylsuccinate, diisobutyl-2,2-dimethylsuccinate, diethyl-2,2-dimethylsuccinate, diethyl-2-ethyl-2-methylsuccinate, diisobutyl-2-ethyl-2-methylsuccinate, diethyl-2-(cyclohexylmethyl)-3-ethyl-3-methylsuccinate, diisobutyl-2-(cyclohexylmethyl)-3-ethyl-3-methylsuccinate, and combinations thereof.

[0024] In conjunction with the internal donor, two or more external electron donors may also be used in combination with the catalyst. The external electron donors have the general formula (V): R 1 n Si(OR 2 ) 4-n (V) wherein R 1 and R 2 independently represents a hydrocarbyl radical, and n is 1, 2, or 3. Examples of suitable organosilicon compounds include trimethylmethoxysilane, trimethylethoxysilane, dimethyldimethoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane, diisopropyldiethoxysilane, t-butylmethyl-n-diethoxysilane, t-butylmethyldiethoxysilane, t-amylmethyldiethoxysilane, diphenyldimethoxysilane, phenylmethyldimethoxysilane, diphenyldiethoxysilane, bis-o-tolyldimethoxysilane, bis-m-tolyldimethoxysilane, bis-p-tolyldimethoxysilane, bis-p-tolyldimethoxysilane, bisethylphenyldimethoxysilane, dicyclohexyldiethoxysilane, cyclohexylmethyldimethoxysilane, cyclohexylmethyldiethoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, vinyltrimethoxysilane, methyltrimethoxysilane, n-propyltrimethoxysilane, ethoxysilane, decyltrimethoxysilane, decyltriethoxysilane, phenyltrimethoxysilane, [γ]-chloropropyltri-methoxysilane, methyltriethoxysilane, ethyltriethoxysilane, vinyltriethoxysilane, t-butyltriethoxysilane, n-butyltriethoxysilane, iso-butyltriethoxysilane, phenyltriethoxysilane, γ-aminopropyltriethoxysilane, chlorotriethoxysilane, vinyltributoxysilane, cyclohexyltrimethoxysilane, cyclohexyltriethoxysilane, 2-norbornanetriethoxysilane, 2-norbornanemethyldimethoxysilane, ethylsilicate, butylsilicate, trimethylphenoxysilane, methylallyloxysilane, vinyltris(β-methoxyethoxysilane), vinyltriacetoxysilane, and / or dimethyltetraethoxydisiloxane.

[0025] Suitable examples of organosilicon compounds where n is 0, 1, or 3 include trimethylmethoxysilane, trimethylethoxysilane, methyl-phenyldimethoxysilane, methyltrimethoxysilane, t-butyl-methyldimethoxysilane, t-butylmethyldiethoxysilane, t-amylmethyldimethoxysilane, phenylmethyldimethoxysilane, cyclohexylmethyldimethoxysilane, cyclohexylmethyldiethoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, vinyltriethoxysilane, methyltrimethoxysilane, methyltriethoxysilane, propyltrimethoxysilane, decyl-trimethoxysilane, decyltriethoxysilane, phenyltri-methoxysilane, propyltriethoxysilane, butyltriethoxysilane, phenyltriethoxysilane, vinyltrimethoxysilane, vinyltributoxysilane, cyclohexyltrimethoxysilane, 2-norbornanetrimethoxysilane, and / or 2-norbornanetriethoxysilane.

[0026] Preferably, the external electron donor is selected from any one or more of methyltrimethoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, vinyltriethoxysilane, propyltrimethoxysilane, decyltrimethoxysilane, decyltriethoxysilane, propyltriethoxysilane, butyltriethoxysilane, phenyltriethoxysilane, vinyltrimethoxysilane, vinyltributoxysilane, and / or cyclohexyltrimethoxysilane. The external electron donor acts to control the stereoregularity, thereby affecting the amount of isotactic versus atactic polymer produced in a given system. More stereoregular isotactic polymers are more crystalline, which results in materials with higher flexural modulus. Highly crystalline isotactic polymers also exhibit lower melt flow rates (MFR) as a result of reduced hydrogen response during polymerization. The stereoregularity performance and hydrogen response of a given external electron donor are typically directly and inversely related.

[0027] The organosilicon compounds disclosed above can be used such that a compound convertible to such an organosilicon compound is added at the time of polymerization or prepolymerization of the olefin, such that the organosilicon compound may be formed in situ during the polymerization or prepolymerization of the olefin. In any embodiment, the production of linear polypropylene may include the use of two external electron donors. The two external electron donors may be selected from any of the external electron donors described herein. However, in certain embodiments, the first external electron donor is a compound represented by the formula R 1 2Si(OR 2 ) 2, wherein each R 1 is independently a hydrocarbyl radical containing from 1 to 10 carbon atoms, in which the carbon adjacent to Si is a secondary or tertiary carbon atom, 2 is independently a hydrocarbyl radical containing from 1 to 10 carbon atoms; and the second external electron donor is a group of formula R 3 n Si(OR 4 ) 4-n wherein each R 3 and R 4 is independently a hydrocarbyl radical containing from 1 to 10 carbon atoms, and n is 1, 2, or 3; and wherein the second external electron donor is different from the first external electron donor.

[0028] In any embodiment, the first external electron donor and the second external electron donor may be selected from the group consisting of tetraethoxysilane, methylcyclohexyldimethoxysilane, propyltriethoxysilane, dicyclopentydimethoxysilane, and combinations thereof. The Ziegler-Natta catalyst system may include from 2.5 mol% to less than 50 mol% of the first external electron donor and more than 50 mol% of the second external electron donor, based on the total mol% of the external electron donors. In any embodiment, a method for making linear polypropylene comprises contacting propylene monomer (and optionally a comonomer) with a catalyst system under propylene polymerization conditions as described herein to produce a linear polypropylene comprising at least 94.0, or 96.0, or 98.0, or 99.0, or 99.2, or 99.6, or 99.8, or 100% by weight of propylene derived units based on the weight of the linear polypropylene, a Mw / Mn greater than 5 (or as described herein), and a melt strength (described further below) of at least 10 cN determined using an extensional rheometer at 190° C., where the optional comonomer may be selected from ethylene, butene, hexene, octene, and combinations thereof.

[0029] The polymerization process may also include a prepolymerization step, which may include utilizing a Ziegler-Natta catalyst system that includes a non-aromatic internal electron donor in combination with at least a portion of an organoaluminum cocatalyst, where at least a portion of an external electron donor is present, and where the catalyst system is utilized in a higher concentration than is utilized in the subsequent "main" polymerization process. The concentration of the catalyst system in the main polymerization and / or prepolymerization steps may be from 0.01 to 200 mM, or more preferably from 0.05 to 100 mM, calculated as titanium atoms per liter of inert hydrocarbon medium. The organoaluminum cocatalyst may be present in an amount sufficient to produce from 0.1 to 500 g of polymer, or more preferably from 0.3 to 300 g of polymer, per gram of titanium catalyst present, and may be present from 0.1 to 100 mol, or more preferably from 0.5 to 50 mol, per mole of titanium atoms present in the catalyst component.

[0030] Prepolymerization, if carried out, may be carried out under mild conditions in an inert hydrocarbon medium in the presence of olefin and catalyst components. Examples of inert hydrocarbon medium used include aliphatic hydrocarbons such as propane, butane, pentane, hexane, heptane, octane, decane, dodecane, and kerosene; alicyclic hydrocarbons such as cyclopentane, cyclohexane, and methylcyclopentane; aromatic hydrocarbons such as benzene, toluene, and xylene; halogenated hydrocarbons such as chloroethylene and chlorobenzene; and mixtures thereof. Such inert hydrocarbons can be used in the present polymerization process as well. Also, the olefin used in the prepolymerization may be the same as the olefin to be used in the present polymerization. The reaction temperature for the prepolymerization may be a temperature at which the resulting prepolymer is substantially insoluble in the inert hydrocarbon medium, and may be from -20 to +100°C, or from -20 to +80°C, or from 0 to 40°C. During the prepolymerization, a molecular weight control agent such as hydrogen may be used. The molecular weight control agent may be used desirably in an amount such that the polymer resulting from the prepolymerization has properties consistent with the intended product. The prepolymerization is carried out so that 0.1 to 1000 g of polymer, or more preferably 0.3 to 300 g of polymer, is formed per gram of titanium catalyst. The polymerization of propylene and optional comonomers may be carried out in gas phase, liquid phase, bulk phase, slurry phase, or any combination thereof. In particular, the polymerization may be carried out by slurry polymerization, in which an inert hydrocarbon may be used as the reaction solvent or an olefin liquid may be used as the solvent under the reaction conditions. The polymerization process includes contacting a titanium catalyst component, one or more internal electron donors, an organoaluminum cocatalyst, and two external electron donors with each other at the time of the main polymerization, before the main polymerization, e.g., at the time of prepolymerization, or a combination thereof. Any two or more of these components may be freely selected and contacted when contacting them before the main polymerization. Two or more of the components may be contacted individually or partially and then contacted together to produce the catalyst system. In any case, hydrogen may be used during the polymerization to control the molecular weight and other properties of the resulting polymer.

[0031] In any embodiment, the polymerization conditions include a polymerization temperature ranging from 20, or 40, or 60° C. to 120, or 140, or 160, or 180, or 200° C., and a pressure ranging from atmospheric up to 100 kg / cm 2 up to 2 or 6 kg / cm 2 20, 50, or 100 kg / cm 2 The polymerization process may be carried out batchwise, semi-continuously or continuously, and / or in two or more reactors in series. When carried out in more than one reactor, the conditions in each reactor may be the same or different. The reaction slurry (homopolymer granules in bulk propylene) may then be removed from the reactor, and the polymer granules are continuously separated from the liquid propylene. The polymer granules may then be separated from the unreacted monomers to produce a granular product for compounding and / or mechanical properties.

[0032] In any case, the linear polypropylene has desirable properties as described herein. The melt flow rate (MFR) of the linear polypropylene in any embodiment is in the range of 0.1, or 0.2, or 0.5 g / 10 min to 4, or 8, or 10, or 20 g / 10 min. In any embodiment, the weight average molecular weight (Mw) of the linear polypropylene by GPC-3D analysis is in the range of 100,000, or 150,000, or 200,000, or 250,000 g / mol to 500,000, or 550,000, or 600,000, or 800,000 g / mol. In any embodiment, the linear polypropylene has a molecular weight distribution (Mw / Mn) of at least 5, or 6, or 8, or in the range of 5, or 6, or 8, to 9, or 10, or 12, or 16. In any embodiment, the z-average molecular weight (Mz) by GPC-3D analysis of the desirable linear polypropylene useful in the present invention is in the range of 800,000, or 1,000,000, or 1,100,000 g / mol to 1,300,000, or 1,400,000, or 1,500,000, or 1,800,000, or 2,000,000 g / mol, and the ratio of z-average molecular weight to weight average molecular weight (Mz / Mw) is greater than 2.8, or 2.9, or 3.0, or in the range of 2.8, or 2.9, or 3.0, or 3.5 to 4.0, or 4.5, or 5.0, with values ​​greater than 2.8 indicating a high molecular weight portion relative to the linear polyethylene.

[0033] Useful linear polypropylenes may also have other desirable properties. In any embodiment, the linear polypropylene has a tensile at yield of 20, or 25, or 30, or 25 MPa, or a tensile at yield in the range of 40, or 45, or 50, or 55, or 80 MPa (ASTM D638 using an Instron Machine with a crosshead speed of 50.8 mm / min (2.0 in / min) and a gauge length of 50.8 mm (2.0 in)). In any embodiment, the linear polypropylene has a 1% secant flexural modulus in the range of 1800, or 1900, or 2000 MPa, or a 1% secant flexural modulus in the range of 2100, or 2200, or 2400, or 2600 MPa (ASTM D790A using an Instron Machine with a crosshead speed of 1.27 mm / min (0.05 in / min) and a support span of 50.8 mm (2.0 in). In any embodiment, the linear polypropylene has a melt strength (as determined by extensional rheology as described below) of at least 10, or 15, or 20 cN, or in the range of 10, or 15, or 20, or 30 cN, to 35, or 40 cN at 190° C. In any embodiment, the melt strength of the branched polypropylene described below exceeds the melt strength of the linear polypropylene, preferably at least 5, or 10, or 15, or 20 cN higher than the melt strength of the linear polypropylene.

[0034] (Branched Polypropylene) Here, and throughout the specification, the term "branched polypropylene" refers to a homopolymer or copolymer of polypropylene having a branching index g'(vis) of less than 0.98, or 0.97, or 0.96. Branched polypropylene can be formed by any means, such as catalytic production or reactive extrusion to form reactor grade branched polypropylene, among other means. Preferred branched polypropylenes may also have other characteristics as further described below.

[0035] In any embodiment, the branched polypropylene is formed by combining, under suitable conditions, a linear polypropylene and an organic peroxide, where "organic peroxide" is any organic compound containing at least one -(O)COO- group and / or -OO- group, and preferably has a one hour half-life temperature (H2O) of less than 100°C, determined in an aromatic and / or halogenated aromatic hydrocarbon solvent. 1 T 1 / 2 ), preferably in the range of 25, 35, or 45° C. to 65, 75, or 85, or 100° C. ( 1 T 1 / 2 ).

[0036] In any embodiment, the organic peroxide is selected from compounds having one or more structures selected from (a) and (b): [ka] wherein each "R" group is independently selected from the group consisting of hydrogen, C1 or C5-C24 or C30 linear alkyl, C1 or C5-C24 or C30 secondary alkyl, C1 or C5-C24 or C30 tertiary alkyl, C7-C34 alkylaryl, C7-C34 arylalkyl, and substituted forms thereof. Most preferably, the organic peroxide is selected from the structure represented by formula (a). By "substituted" is meant hydrocarbon "R" groups having substituents such as halogens, carboxylates, hydroxyl groups, amines, mercaptans, and phosphorus-containing groups. In certain embodiments, each "R" group is independently selected from the group consisting of C8-C alkyl, such as octyl, decyl, lauryl, mythrityl, cetyl, arachidyl, behenyl, erucyl, and seryl groups, and linear, secondary, and tertiary forms thereof. 20or C24 linear, secondary, tertiary alkyl. Specific non-limiting examples of suitable organic peroxides include di-sec-butyl peroxydicarbonate, diisopropyl peroxydicarbonate, dicyclohexyl peroxydicarbonate, di(4-tert-butylcyclohexyl)peroxydicarbonate, dicetyl peroxydicarbonate, dibutyl peroxydicarbonate, di(2-ethylhexyl)peroxydicarbonate, didodecyl peroxydicarbonate, diicosyl peroxydicarbonate, and ditetracosyl peroxydicarbonate. The formation of branched polypropylene as described herein is accomplished in any embodiment by melt mixing linear polypropylene with organic peroxide, particularly by applying shear forces and radiant heating during mixing / extrusion up to at least the melting temperature of the linear polypropylene, for example, at least 140, or 150, or 160° C., or from 140, or 150, or 160° C. to 180, or 200, or 220, or 240, or 260, or 280, or 300° C. Suitable means include single or twin screw extruders, or Brabender type equipment. Most preferably, an organic peroxide in the range of 0.1, or 0.5, or 1, to 2, or 3, or 4, or 5% by weight based on the weight of organic peroxide and linear polypropylene is combined with the linear polypropylene.

[0037] In an optional embodiment, the branched polypropylene is formed into reactor flakes and / or granules, or extruded pellets directly from the extrusion process without treatment under vacuum and / or solvent washing. In any embodiment, it is preferred that the peroxide melts before reacting with the linear polypropylene so that the granules are uniformly coated and the high specific surface area is utilized prior to the branching and / or crosslinking reactions. In any embodiment, the reactor granules of linear polypropylene used herein are preferred over extrusion pellets. Such linear polypropylene granules are preferably dry mixed with the organic peroxide before "combining", e.g., melt mixing in a single or twin screw extruder ("melt extrusion").

[0038] In any embodiment, the products of the reaction between the organic peroxide and the linear polypropylene may include decomposition products consisting of carbon dioxide and an alcohol, preferably a C8-C24 alcohol, and most preferably an alcohol that is the hydroxyl equivalent of the organic peroxide used in the reaction. The alcohol is typically present, if at all, at only 2, or 1, or 0.5% by weight based on the weight of the branched polypropylene. Thus described, the branched polypropylene may have any of the properties described herein with respect to the composition. The branched polypropylene thus formed and described herein can be transported, shipped, and / or stored as is without further processing and used in blending with low molecular weight polyolefins to make any number of articles, both foamed and non-foamed. In any embodiment, a blowing agent may be added during the heating / extrusion process described above so that it is not activated until after shipping and can be used to make foamed articles as is. Preferably, the low molecular weight polyolefin is also blended into the branched polypropylene before foaming. As mentioned, the composition may be heated / extruded again later to form articles and achieve foaming, if so desired.

[0039] The branched polypropylene will have the same level of propylene and comonomer derived units as its linear precursor polypropylene. In any embodiment, diene monomers (linear, branched, or cyclic C4-C20 alkenes with at least two conjugated or non-conjugated carbon-carbon double bonds), such as butadiene, isoprene, norbornene, and 1,9-decadiene, are absent in the branched polypropylene and / or are absent in all process steps in the formation of the branched polypropylene. The polypropylene useful in the composition of the present invention is characterized by any number of parameters as different from its linear polypropylene precursor. In any embodiment, the branched polypropylene has a melt strength of at least 20, or 30, or 40 cN, or a melt strength within the range of 20, or 30, or 40, or 45 cN to 60, or 65, or 80 cN. In any embodiment, the branched polypropylene has a MFR in the range of from 0.1, or 0.2, or 0.5 g / 10 min to 4, or 8, or 10, or 20 g / 10 min.

[0040] In any embodiment, the branched polypropylene has a number average molecular weight (Mn) by GPC-3D analysis in the range of 18,000, or 20,000, or 24,000, or 28,000 g / mol to 40,000, or 44,000, or 48,000, or 50,000 g / mol, and in any embodiment, the polypropylene has a weight average molecular weight (Mw) by GPC-4D analysis in the range of 250,000, or 300,000, or 350,000 g / mol to 450,000, or 500,000, or 550,000, or 600,000 g / mol. Also in any embodiment, the branched polypropylene has a z-average molecular weight (Mz) by GPC-4D analysis in the range of 1,000,000, or 1,100,000, or 1,200,000 g / mol to 1,500,000, or 1,600,000, or 1,700,000, or 1,800,000 g / mol. As an indication of its high molecular weight component or "tail", the branched polypropylene in any embodiment has a Mz / Mw value of greater than 3.0, or 3.2, or 3.6, or a Mz / Mw value in the range of 3.0, or 3.2, or 3.6 to 4.0, or 4.5, or 5.0, or 6.0. The branched polypropylene also has a Mz / Mn of greater than 30, or 35, or 40, or in the range of 30, or 35, or 40 to 44, or 48, or 50, or 55, or 60. The branched polypropylene also has a Mz / Mn of at least 5, or 6, or 8, or 10, or in the range of 5, or 6, or 8, or 10 to 16, or 18, or 20, in any embodiment.

[0041] Branched polypropylenes provide improved polymeric properties as evidenced by increased peak extensional viscosity. distortionhardening (relative to linear polypropylene). In any embodiment, the branched polypropylene has a peak extensional viscosity (annealed) of greater than 50, or 55, or 60 kPa·s, or a peak extensional viscosity (annealed) in the range of 50, or 55, or 60 kPa·s to 500, or 550, or 600 kPa·s at a strain rate of 0.01 / sec (190° C.). In any embodiment, the branched polypropylene has a peak extensional viscosity (annealed) of greater than 500, or 550, or 600 kPa·s, or a peak extensional viscosity (annealed) in the range of 500, or 550, or 600 kPa·s to 2000, or 2500, or 3000 kPa·s at a strain rate of 0.01 / sec (190° C.).

[0042] (Polypropylene composition) In an optional embodiment, a polypropylene composition is disclosed that comprises (or consists essentially of) a branched polypropylene as described above, and a low molecular weight polyolefin. In an optional embodiment, the composition comprises in the range of 5 or 10% by weight, to 15, or 20, or 25, or 30, or 35, or 40% by weight of the low molecular weight polyolefin, based on the weight of the low molecular weight polyolefin and the branched polypropylene. Most preferably, the remainder of the composition is the branched polypropylene and additives. In any embodiment, the polypropylene composition has a viscosity index greater than that of the branched polypropylene alone when measured by extensional rheology at 190° C. at the same strain rate. distortionIt exhibits at least 90% or 95% cure. In any embodiment, the polypropylene composition also exhibits at least 10% or 5% lower complex viscosity at 500 rad / sec compared to the branched polypropylene alone as determined by small-amplitude oscillatory spectroscopy at 190° C. In any embodiment, the composition may be formed into foam molded, thermoformed, and / or extruded articles. Desirable articles include cups, plates, food containers, and insulating containers. A "low molecular weight polyolefin" is a polyolefin polymer having a weight average molecular weight of 80,000 or 100,000 g / mol or less, preferably comprising ethylene and C4-C10 derived units, most preferably comprising propylene derived units, and optionally comprising ethylene derived units. In any embodiment, the low molecular weight polyolefin has a melt flow rate (230°C / 2.16 kg) of at least 50, or 100, or 200, or 500 g / 10 min, or a melt flow rate (230°C / 2.16 kg) within the range of 50, or 100, or 200, or 500 g / 10 min to 1500, or 2000, or 5000 g / 10 min.

[0043] In any embodiment, the low molecular weight polyolefin is selected from the group consisting of polypropylene homopolymer, polypropylene copolymer, polyethylene homopolymer, polyethylene copolymer, and mixtures thereof. Most preferably, the low molecular weight polyolefin is a polypropylene homopolymer, meaning that it contains less than 1 or 2% by weight of ethylene or C4-C10 derived units. In any embodiment, the low molecular weight polyolefin has a Mw / Mn of less than 5, or 4, or 3. The composition is more processable than branched polypropylene alone, but does not contain the desired level of branched polypropylene to form a closed cell structure. distortionSince the composition maintains its hardening, it is suitable for thermoformed articles, and particularly foam molded articles. Thus, in any embodiment, the foam molded article, thermoformed article, and / or extruded article comprises a polypropylene composition comprising a branched polypropylene and a minor amount of additive, the branched polypropylene and the polypropylene homopolymer having a melt strength (190°C) in the range of 20 to 80 cN and a melt flow rate in the range of 0.1 to 20 g / 10 min, in the range of 95 to 60% by weight based on the weight of the branched polypropylene and the polypropylene homopolymer; and a polypropylene homopolymer having a melt flow rate of at least 50 g / 10 min, in the range of 5 to 40% by weight based on the weight of the branched polypropylene and the polypropylene homopolymer, wherein the polypropylene composition has a melt flow rate in the range of 0.5 to 40 g / 10 min, a melt strength (190°C) in the range of 20 to 80 cN, and the branched polypropylene and a minor amount of additive. distortion Shows at least 90% cure.

[0044] Nearly any mixing technique can be used to combine the ingredients and produce the polypropylene composition. Desirably, the process of the present invention includes combining a linear polypropylene with an organic peroxide to obtain a branched polypropylene; and combining the branched polypropylene with a low molecular weight polyolefin to obtain a polypropylene composition. Desirably, a range of 5 or 10% by weight to 15, or 20, or 25, or 30, or 35, or 40% by weight of the low molecular weight polyolefin and the branched polypropylene is combined. The remainder is the branched polypropylene with or without additives such as antioxidants, fillers, and other additives known in the art. The ingredients are most preferably melt mixed using a single or twin screw extruder operating at a temperature that melts the polymeric raw materials but below their decomposition temperatures, preferably in the range of 190 to 260°C.

[0045] In any embodiment, the low molecular weight polyolefin is combined with the other ingredients by feeding it directly to the extruder, preferably in its solid form, or by first forming a masterblend of the low molecular weight polyolefin with the higher molecular weight polyolefin. In an optional embodiment, a process for producing a polypropylene composition includes the steps of combining a linear polypropylene having a melt strength (190°C) in the range of 10 to 40 cN with an organic peroxide to obtain a branched polypropylene having a melt strength (190°C) in the range of 20 to 80 cN, where the melt strength of the branched polypropylene exceeds the melt strength of the linear polypropylene; and combining the branched polypropylene having a melt flow rate in the range of 0.1-20 g / 10 min and a Mw / Mn of at least 5 with a polypropylene homopolymer having a melt flow rate of at least 50 g / 10 min and a Mw / Mn of less than 5, in the range of 5 to 40% by weight based on the weight of the branched polypropylene and the polypropylene homopolymer, to obtain a polypropylene composition, where the polypropylene composition has a melt flow rate in the range of 0.5 to 40 g / 10 min, a melt strength (190°C) in the range of 20 to 80 cN, and distortion Shows at least 90% cure.

[0046] The various descriptive elements and numerical ranges disclosed herein for and for obtaining the inventive polypropylene compositions and processes can be combined with other descriptive elements and numerical ranges to describe the invention, and further, for a given element, any numerical upper limit can be combined with any numerical lower limit described herein, including examples in jurisdictions that allow such combinations. EXAMPLES

[0047] Features of the present invention are demonstrated in the following non-limiting examples. First, test methods and experimental procedures are described. MFR: 230°C with a load of 2.16 kg, ASTM D1238.

[0048] Molecular weight determination using DRI (GPC-3D). This method describes the first of two different methods used to determine the moments of molecular weight of the polymers described herein, the so-called "GPC-3D" method and the "GPC-4D" method, as indicated, each based on gel permeation chromatography (GPC), but using different detection methods. In the GPC-3D method, number average molecular weight (Mn) values ​​were determined by using a high temperature gel permeation chromatograph (Agilent PL-220) equipped with three in-line detectors: a differential refractive index detector (DRI), a light scattering (LS) detector, and a viscometer. Three Agilent PLgel 10 μm Mixed-B LS columns were used. The nominal flow rate was 0.5 mL / min, and the nominal injection volume was 300 μL. The various transfer lines, columns, viscometer, and differential refractometer (DRI detector) were housed in an oven maintained at 145 °C. The experimental solvent is prepared by dissolving 6 grams of butylated hydroxytoluene (BHT) as an antioxidant in 4 liters of Aldrich reagent grade 1,2,4-trichlorobenzene (TCB). The TCB mixture is then filtered through a 0.1 μm Teflon filter. The TCB is then degassed with an online degasser before entering the GPC-3D. Polymer solutions were prepared by placing dry polymer in a glass container, adding the desired amount of TCB, and then heating the mixture at 160° C. with continuous shaking for about 2 hours. All quantities were measured by mass spectrometry. The TCB density used to represent the polymer concentration in mass / volume units was 1.463 g / ml at 23° C. and 1.284 g / ml at 145° C. Injection concentrations ranged from 0.5 to 2.0 mg / ml, with lower concentrations being used for higher molecular weight samples. The DRI detector and viscometer were purged before each sample was run. The flow rate in the instrument is then increased to 0.5 ml / min and the DRI is allowed to stabilize for 8 hours before injecting the first sample. The LS laser is turned on at least 1-1.5 hours before running the sample. The concentration "c" of each point in the chromatogram is calculated using the formula: c = (K DRI / IDRI ) / (dn / dc) Using the baseline-subtracted DRI signal, I DRI In the formula, K DRI is a constant determined by DRI calibration, and (dn / dc) is the refractive index increment of the system. The refractive index of TCB at 145° C. is n=1.500, and λ=690 nm. The units of parameters throughout this description of the GPC-3D method are concentration, g / cm 3 where the molecular weight is expressed in g / mol and the intrinsic viscosity is expressed in dL / g. Unless otherwise stated, all concentrations are in g / cm 3 All molecular weights are expressed in g / mol, and all intrinsic viscosities are expressed in dL / g. For GPC-3D or GPC-4D data processing, the Mark-Houwink constants used were K=0.000229 and a=0.705, and dn / dc=0.1048 mL / mg. A2 (input value)=0.0006.

[0049] Molecular weight determination using an Ir detector (GPC-4D). Weight-average and z-average molecular weight (Mw, Mz) distributions and moments were determined using GPC-4D or using a method very similar to that performed by GPC-3D, using a high-temperature GPC (Polymer Char GPC-IR) equipped with a multichannel band filter-based infrared detector IR5, an 18-angle light scattering detector, and a viscometer. Three Agilent PLgel 10 μm Mixed-B LS columns were used to effect separation of the polymers. Aldrich reagent grade TCB containing 300 ppm of the antioxidant BHT was used as the mobile phase. The TCB mixture is filtered through a 0.1 μm Teflon filter and degassed with an online degasser before entering the GPC instrument. The nominal flow rate is 1.0 mL / min and the nominal injection volume is 200 μL. The entire system, including the transfer line, column, and detector, was housed in an oven maintained at 145°C. A predetermined amount of polymer sample was weighed and sealed in a standard vial with 80 μL of flow marker (heptane) added. After loading the vial into the autosampler, the polymer was dissolved automatically in the instrument with 8 mL of added TCB solvent. The polymer was dissolved at 160°C with continuous shaking for about 2 hours. The TCB densities used in the concentration calculations were 1.463 g / ml at 23°C and 1.284 g / ml at 145°C. Sample solution concentrations ranged from 0.2 to 2.0 mg / ml, with lower concentrations being used for higher molecular weight samples.

[0050] The concentration "c" of each point in the chromatogram is calculated using the following formula: c = βI The mass recovery is calculated from the baseline subtracted IR5 broadband signal intensity "I" using the formula: where β is a mass constant determined using a polypropylene standard. The mass recovery is calculated from the ratio of the concentration chromatographic integrated area to the elution volume and the injected mass equal to the predetermined concentration multiplied by the injection loop volume. The conventional molecular weight (IR MW) is determined by combining the universal calibration relationship with a column calibration performed with a series of monodisperse polystyrene (PS) standards ranging from 700 g / mol to 10,000,000 g / mol. The MW of each elution volume is calculated according to the following formula:

number

[0051] (branching index) The specific viscosity of the eluting polymer from the GPC was determined using a high temperature Viscotek viscometer with four capillaries arranged in a Wheatstone bridge configuration with two pressure transducers. One transducer measures the total pressure drop across the detector, and the other transducer, located between the sides of the bridge, measures the differential pressure. The specific viscosity, ηs, of the solution flowing through the viscometer is calculated from their outputs. The intrinsic viscosity [η] of each point in the chromatogram is calculated using the following equation: η s =c[η]+0.3(c[η]) 2 where c is the concentration, determined from the DRI output.

[0052] Branching index (g' vis ) is calculated using the output of the GPC-DRI-LS-VIS method as follows: avg of,

number

number

[0053] SAOS. Small Angle Oscillatory Spectroscopy was used to determine the viscosity at low shear rates. Polymer samples were prepared using a heated press (either Carver Press or Wabash Press) to produce disks with a diameter of 25 mm and a thickness of 2.5 mm. To characterize the shear thinning behavior, small angle oscillatory shear measurements were performed at angular frequencies ranging from 0.01 to 500 rad / s at a temperature of 190° C. and a fixed strain of 10% using a rheometer ARES-G2 (TA Instruments). The data were then converted to viscosity as a function of shear rate. Strain sweep measurements were performed (at an angular frequency of 100 Hz) to ensure that the selected strain provided measurements within the linear change range. Data were processed using Trios software.

[0054] Extensional rheology of polypropylene distortion To characterize the cure behavior, the annealed samples were tested using a DHR-3 rheometer (TA Instruments) with a SER fixture attached to measure stress in extension. Samples were prepared using the procedure described above (SAOS) and then cut into a rectangular shape with dimensions of approximately 18 mm in length and 12.7 mm in width. Measurements were taken at 1, 5, and 10 seconds. -1The Hencky strain rate was 100 s and a temperature of 190°C. Data was processed using Trios software. The sample was annealed by heating to approximately 200°C for 3 minutes to melt the polypropylene pellets without the use of pressure. A pressure of 1500 psi was then applied while the sample continued to be heated between the two plates for an additional 3 minutes. Afterwards, the pressure applied to the sample was removed while the sample continued to be heated at 200°C for an additional 20 minutes. After 20 minutes, the sample was cooled with water circulation without any pressure for an additional 20 minutes. Melt strength values ​​reported herein have an accuracy of ±10%. Procedure for blending the ingredients. The ingredients listed in Table 1 were melt blended using a ZSK 30 mm extruder to produce each example blend, where 15-50% by weight (based on the weight of all ingredients in the blend), a low molecular weight polyolefin, in this case a 1550 MFR polypropylene homopolymer, was pre-blended with 50-85% by weight of a branched polypropylene in a Patterson Double Cone Blender. The dry blend was fed into a Coperion Werner and Pfleiderer ZSK 30 mm extruder (two co-rotating screws, L / D=36) with an output of about 10 kg / hr and nitrogen applied to the hopper. The extruder torque was about 50%, the die pressure was about 400 psi, and the screw speed was about 200 rpm. The melt temperature was about 435°F (222°C). Finally, an underwater pelletizer was used to produce pellets for each of the example blends.

[0055] Branched polypropylene (b-PP) was produced by melt extruding Ziegler-Natta produced linear polypropylene homopolymer, made as described above, with 1.5 wt. % Perkadox (Akzo Nobel) at temperatures ranging from 190 to 220° C. In all exemplary blends, the b-PP has a g'(vis) of less than 0.98, a melt strength of 40±5 cN, an MFR of 2.09 g / 10 min, an Mw / Mn of 15, and an Mz / Mw of 6. In all blends, the low molecular weight polyolefin (LMW-PO) was a polypropylene homopolymer (100% by weight propylene derived units) with a MFR of 1550 g / 10 min and a Mw / Mn of 2.5 (GPC-3D).

[0056] Summary of the polypropylene compositions of the present invention in Table 1: Example 1 was a 85:15 blend of branched polypropylene (polypropylene homopolymer, 100% by weight propylene derived units) and LMW-PO, the blend had a melt strength of 17.5 cN and a draw ratio close to 5. Example 2 is a 50:50 blend of branched polypropylene (100% by weight propylene derived units) and PolyOne mixed by a third party compounder; the blend had a melt strength of 2.5 cN and a draw ratio close to 12. Example 3 is a 50:50 blend, but the branched polypropylene has about 0.55% or less by weight of ethylene derived units based on the weight of the polymer. Example 4 is a 50:50 blend, where the branched polypropylene is a polypropylene homopolymer having 100% by weight of propylene derived units. Table 1. Polypropylene composition [Table 1]

[0057] While the SAOS data in Figure 4 demonstrates that the viscosity, and therefore processability, of the polypropylene composition is improved over the branched polypropylene alone, the data in Figures 1-3 demonstrates that the composition requires only desirable levels of branched polypropylene. distortion Thus, the polypropylene composition exhibits at least a 10% lower complex viscosity at 500 rad / sec compared to the branched polypropylene as determined by small amplitude vibrational spectroscopy at 190° C., while preferably the composition exhibits at least a 10% lower complex viscosity at 500 rad / sec compared to the branched polypropylene at the same strain rate. distortion Shows at least 90% cure.

[0058] As used herein, "consisting essentially of" means that the claimed polymer or polymer blend contains only the specified components and no additional components that alter its measured properties by more than 10 or 20%; most preferably, the additional components or "additives" are present at levels of less than 5, or 4, or 3, or 2% by weight based on the weight of the composition. Such additives include, for example, fillers, colorants, antioxidants, alkyl radical scavengers, anti-UV additives, acid scavengers, slip agents, curing and crosslinking agents, aliphatic and / or cyclic-containing oligomers or polymers (also referred to as "hydrocarbon resins"), and other additives known in the art.

[0059] When referring to a process, the phrase "consisting essentially of" means that there are no other process characteristics present that would alter the claimed properties of the polymer, polymer blend, or article produced from that process by more than 10 or 20%. For all jurisdictions where the doctrine of "incorporation by literature" applies, all test methods, patent publications, patents, and referenced articles are incorporated herein by reference either in their entirety or to the relevant portion to which they are referenced.

Claims

1. A polypropylene composition comprising: 95% to 60% by weight of a branched polypropylene, based on the weight of the composition; and in the range of 5% to 40% by weight of a low molecular weight polyolefin, based on the weight of the composition; the branched polypropylene has a branching index g'(vis) of less than 0.98; a melt flow rate (ASTM D1238, 230°C / 2.16 kg) in the range of 0.1 g / 10 min to 20 g / 10 min; a melt strength (190°C) of at least 20 cN; and a Mw / Mn of at least 5; The low molecular weight polyolefin has a weight average molecular weight of 100,000 g / mol or less; and a melt flow rate (ASTM D1238, 230° C. / 2.16 kg) of at least 50 g / 10 min; The polypropylene composition exhibits strain hardening, when measured by extensional rheology at 190°C at three strain rates, 1 sec-1, 5 sec-1, and 10 sec-1, that is at least 90% of the strain hardening exhibited by the branched polypropylene alone when measured by extensional rheology at 190°C at the same strain rates.

2. 2. The polypropylene composition of claim 1, wherein the low molecular weight polyolefin has a melt flow rate (230° C. / 2.16 kg) in the range of 50 g / 10 min to 5,000 g / 10 min.

3. 3. The polypropylene composition of claim 1 or 2, wherein the low molecular weight polyolefin is selected from the group consisting of polypropylene homopolymer, polypropylene copolymer, polyethylene homopolymer, polyethylene copolymer, and mixtures thereof.

4. 4. The polypropylene composition according to any one of claims 1 to 3, wherein the low molecular weight polyolefin has a Mw / Mn of less than 5.

5. 5. The polypropylene composition according to any one of claims 1 to 4, exhibiting at least a 10% lower complex viscosity at 500 rad / sec compared to the branched polypropylene alone as determined by small amplitude vibrational spectroscopy at 190°C.

6. 1. A process for producing a polypropylene composition comprising: combining in the range of 95% to 60% by weight of branched polypropylene with in the range of 5% to 40% by weight of low molecular weight polyolefin, based on the weight of the branched polypropylene and the low molecular weight polyolefin; the branched polypropylene has a branching index g'(vis) of less than 0.98; a melt flow rate (ASTM D1238, 230°C / 2.16 kg) in the range of 0.1 g / 10 min to 20 g / 10 min; a melt strength (190°C) of at least 20 cN; and a Mw / Mn of at least 5; a low molecular weight polyolefin having a weight average molecular weight of 100,000 g / mol or less; and a melt flow rate (ASTM D1238, 230° C. / 2.16 kg) of at least 50 g / 10 min; and recovering the polypropylene composition, The process wherein the polypropylene composition exhibits strain hardening, when measured by extensional rheology at 190°C at three strain rates, 1 sec-1, 5 sec-1, and 10 sec-1, that is at least 90% of the strain hardening exhibited by the branched polypropylene alone at 190°C at the same strain rates, respectively, as measured by extensional rheology.

7. 7. The process of claim 6, wherein the low molecular weight polyolefin is combined by feeding directly into the extruder or by first forming a masterblend of the low molecular weight polyolefin with the higher molecular weight polyolefin.

8. 8. The process of claim 6 or 7, comprising combining linear polypropylene with an organic peroxide to obtain branched polypropylene.

9. 9. The process of claim 8, combining the organic peroxide in the range of 0.1% to 5% by weight based on the weight of the polypropylene and the organic peroxide.

10. 10. The process of any one of claims 6 to 9, further comprising melt extruding the polypropylene composition to form a foam molded article, a thermoformed article, and / or an extruded article.

11. 6. A foam molded, thermoformed or extruded article comprising the polypropylene composition of any one of claims 1 to 5.

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