RU2841725C1 - Copolymer of propylene and butene and compositions made therefrom - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: group of inventions relates to a copolymer of propylene and butene, a polymer composition containing a copolymer of propylene and butene, as well as articles made therefrom. Random copolymers of propylene and butene have given stiffness properties, low content of xylene-soluble substance and excellent transparency characteristics, especially when combined with one or more nucleating agents.

EFFECT: copolymers of propylene and butene can be made with different melt flow characteristics, owing to which they can be used in injection moulding, blow moulding or thermoforming.

28 cl, 4 tbl, 2 ex

Description

RELATED APPLICATIONS

[0001] This application is based on and claims priority from U.S. Provisional Patent Application No. 63/050,770, filed July 11, 2020, the contents of which are incorporated herein by reference.

PREREQUISITES FOR THE CREATION OF THE INVENTION

[0002] Polypropylene polymers are extremely versatile thermoplastic polymers that can be used in a variety of different fields. For example, polypropylene polymers can be extruded into a variety of shapes, including films and fibers, and can be molded into articles with relatively simple or complex shapes. Polypropylene polymers are used to produce, for example, carpets, carpet backings, food packaging, rigid containers, technical parts such as automobile parts, drain and pressure pipes, etc., and various consumer products, including furniture parts, household utensils, and toys. Polypropylene polymers can, for example, have low density, high strength, heat resistance, chemical inertness, good transparency, and are also recyclable. The properties of polypropylene polymers can be modified and tailored to a specific application by combining propylene monomers with other monomers to impart different properties.

[0003] For example, copolymerization of propylene with small amounts of ethylene allows for the production of random copolymers with unique properties. The resulting copolymer, for example, may have a lower degree of crystallinity than a polypropylene homopolymer, resulting in increased transparency, impact resistance, and lower heat sealing temperatures. Transparency can be further enhanced by additives such as initiators for the formation of active centers and clarifiers. Polypropylene-ethylene random copolymers also have a substantially lower melting point, which may limit their use in applications requiring high temperatures. Under the influence of higher temperatures, the transparency of the polymers, as a rule, is further deteriorated. For example, during the aging process, not only additional crystallization is possible, but also clouding may occur, which leads to the formation of a matte surface layer.

[0004] Although significant advances have been made in the field of random copolymers of propylene and ethylene, as described above, these polymers have a number of disadvantages. When attempting to improve one property of a product, such as reducing haze, such improvement may additionally negatively affect another property, such as mechanical strength. Thus, there is a need for a propylene polymer with an improved combination of mechanical properties that has good optical properties. In addition, there is a need for a propylene polymer, as described above, that can be used to form a variety of articles by injection molding, blow molding and thermoforming.

SUMMARY OF THE INVENTION

[0005] The present disclosure generally relates to propylene copolymers, and in particular to random copolymers of propylene and butene, which have been found to have an excellent combination of properties. The propylene copolymers can further be made without the use of a phthalate-based catalyst. The propylene-butene copolymers of the present disclosure have excellent optical properties and can be used to form transparent articles. The polymer can further be compositionally tailored for any suitable molding technique, such as extrusion blow molding, thermoforming, and the like. For example, articles can be formed from a nucleated/clarified propylene-butene copolymer that has lower haze and higher stiffness than articles made in the past from nucleated/clarified random copolymers of propylene and ethylene.

[0006] In one embodiment, for example, the present disclosure relates to a copolymer of propylene and butene that comprises propylene as a primary monomer. The copolymer may comprise butene substantially in an amount of from about 1 wt. % to about 12 wt. %, such as from about 2 wt. % to about 10 wt. %, such as from about 5 wt. % to about 8 wt. %. The copolymer of propylene and butene may have a xylene soluble fraction in an amount of from about 1 wt. % to about 10 wt. %, such as from about 2 wt. % to about 8 wt. %. The xylene soluble fraction/butene content ratio of the polymer may be from about 0.3 to about 3.0, such as from about 0.3 to about 2.2, such as from about 0.5 to about 1.0. The propylene-butene copolymer can be prepared using a non-phthalate Ziegler-Natta catalyst comprising a substituted aromatic phenylene diester to produce a polymer having a molecular weight distribution greater than about 3.5, such as greater than about 4. The propylene-butene copolymer can further have a heat deflection temperature greater than about 70°C and even greater than about 75°C, particularly when the copolymer contains smaller amounts of butene.

[0007] The propylene-butene copolymers prepared according to the present description can be prepared using a particular melt flow index that corresponds to the subsequent melt molding conditions for producing polymeric articles. For example, in one embodiment, the propylene-butene copolymer can have a relatively low melt flow index, such as from about 0.2 g/10 min to about 4 g/10 min. In an alternative embodiment, the propylene-butene copolymer can have a melt flow index from about 4 g/10 min to about 220 g/10 min.

[0008] The propylene-butene copolymers prepared according to the present description may have relatively high stiffness values. For example, the polymer may have a flexural modulus of greater than about 1100 MPa, such as greater than about 1300 MPa, such as greater than about 1400 MPa, such as greater than about 1500 MPa. The polymer may have a relatively high melting point. For example, the primary melting point may be greater than about 135°C, such as from about 145°C to about 155°C.

[0009] The random propylene copolymer of the present disclosure can be used to form a polymer composition for molding various molded articles. The random copolymer of propylene and butene, for example, can be present in the composition in an amount greater than about 70 wt. %, such as greater than about 80 wt. %, such as greater than about 90 wt. %, such as greater than about 95 wt. %, such as greater than about 98 wt. %, such as greater than about 99 wt. %. The composition can contain various other additives and ingredients, including an antioxidant, a deoxidizer, and/or an antistatic agent. In one embodiment, the polymer composition can contain a nucleating agent. The nucleating agent, for example, can contain nonite.

[0010] The polymer composition can be formulated to have excellent transparency properties. For example, the composition can exhibit a haze at 0.7 mm of about 15% or less, such as less than about 8%.

[0011] The present disclosure also relates to molded articles made from the polymer composition described above. For example, the polymer composition of the present disclosure can be formulated to be used to produce injection molded articles, and in particular blow molded articles and thermoformed articles. For example, the present disclosure can be used to produce blow molded bottles, thermoformed cups and thermoformed containers. The polymer of the present disclosure is also particularly suitable for the production of packaging, including food packaging. For example, the propylene-butene copolymer of the present disclosure can be used to produce an insulating film. The polymer composition can also be used to produce fibers.

DETAILED DESCRIPTION

[0012] The present disclosure relates to propylene-alpha-olefin copolymer compositions and methods for producing propylene copolymer compositions. The compositions may include a random copolymer of propylene and butene. For example, a polymer of the present disclosure may be made from only propylene and butene monomers, or may be made from propylene, butene monomers, and relatively small amounts of one or more other alpha-olefin monomers.

[0013] It has been found that the propylene-butene copolymers prepared according to the present disclosure have an excellent combination of properties. For example, such copolymers can exhibit improved rigidity, high deformation heat resistance and good optical properties, especially when compared to many traditional propylene-ethylene copolymers. For example, the propylene-butene copolymers of the present disclosure can be formed with additives that impart excellent optical properties, exhibiting very low levels of haze even at a thickness of 0.7 mm. The propylene-butene copolymer is also very versatile and can be formed over a wide range of melt flow rates, making the polymer suitable for use in all different types of molding processes, such as injection molding, extrusion blow molding or thermoforming.

[0014] The propylene-butene copolymers of the present disclosure can also be prepared using Ziegler-Natta catalysts that provide a polymer with a relatively broad molecular weight distribution. In one aspect, a non-phthalate catalyst comprising a substituted aromatic phenylene diester can be used, making the polymer more suitable for contact with food and beverages. The polymer is also well suited for use in medical devices.

[0015] The propylene-butene copolymer of the present disclosure can be incorporated into various polymer compositions containing other additives and nucleating agents, including clarifying agents. The polymer composition can then be used to produce various and numerous articles. For example, the polymer composition of the present disclosure can be used to produce all different types of packaging products, including food packaging. For example, in one aspect, the polymer composition comprising the propylene-butene copolymer can be used to produce low haze polymer films for food packaging elements. The polymer composition can further be used to produce all different types of rigid containers with excellent rigidity properties combined with excellent optical properties. The polymer composition of the present disclosure comprising the propylene-butene copolymer can also be used to produce blow molded bottles, thermoformed cups, fibers, and the like.

I. Definitions and Test Procedures

[0016] As used herein, the term "propylene-butene copolymer" means a copolymer comprising a propylene monomer in a predominant weight percentage relative to butene monomer as a secondary constituent. A "propylene-butene copolymer" (which is also sometimes referred to as a random copolymer of polypropylene and butene) is a polymer having individual repeating units of butene monomer present in the polymer chain in a random or random distribution.

[0017] The melt flow index (MFI) in the context of the present description is measured in accordance with the test method described in ASTM D 1238 at 230 °C with a load of 2.16 kg for propylene-based polymers. The melt flow index can be measured on the polymer in the form of pellets or on the powder exiting the reactor. When measuring the powder exiting the reactor, a stabilizing complex can be added that includes 2000 ppm of the antioxidant CYANOX 224 6 (methylene bis (4-methyl-6-tert-butylphenol)), 2000 ppm of the antioxidant IR ₈ AFOS 168 (tris (2,4-di-tert-butylphenyl) phosphite) and 1000 ppm of the deoxidizer ZnO.

[0018] Xylene solubles (XS) are determined as the weight percent of resin remaining in solution after a polypropylene random copolymer resin sample is dissolved in hot xylene and the solution is cooled to 25°C. This method is also referred to as the gravimetric XS method according to ASTM D5492-06 using a 60-minute settling time, and is also referred to herein as the "wet method."

[0019] The above method according to ASTM D5492-06 can be adapted to determine the xylene soluble fraction. In general, the procedure involves weighing 2 g of sample and dissolving the sample in 200 mL of o-xylene in a 400 mL flask with a 24/40 joint. The flask is connected to a water-cooled condenser and the contents are stirred and heated to boiling under nitrogen (N2) atmosphere and subsequently maintained at reflux for an additional 30 minutes. The solution is subsequently cooled in a water bath maintained at 25°C for 60 minutes to allow the xylene insoluble fraction to crystallize. After cooling the solution and precipitating the insoluble fraction from the solution, separation of the xylene-soluble portion (XS) from the xylene-insoluble portion (XI) is achieved by filtration through 25 micron filter paper. One hundred milliliters of the filtrate are collected in a pre-weighed aluminum crucible, and the o-xylene is evaporated from this 100 milliliters of the filtrate under a stream of nitrogen. After evaporation of the solvent, the crucible and contents are placed in a vacuum oven at 100°C for 30 minutes or until a dry residue is obtained. Subsequently, the crucible is allowed to cool to room temperature and weighed. The content of the xylene-soluble fraction is calculated using the formula: XS (wt.%) = [(m3 - m2) * 2/m1] * 100, where m1 is the initial mass of the sample used, m2 is the mass of the empty aluminum cup, and m3 is the mass of the cup with the residue (here and throughout the description, the asterisk (*) symbol means the product of the terms or values given).

[0020] XS can also be measured according to the Viscotek method as follows: 0.4 g of polymer is dissolved in 20 ml of xylenes with stirring at 130°C for 60 minutes. The solution is then cooled to 25°C and after 60 minutes the insoluble polymer fraction is filtered off. The resulting filtrate is analyzed by flow injection polymer analysis using a Viscotek ViscoGEL H-100-3078 column with a THF mobile phase flowing at 1.0 ml/min. The column is coupled to a Viscotek Model 302 TR ₁ ple Detector Array module equipped with light scattering, viscometer and refractometer detectors operating at 45°C. The instrument was calibrated using Viscotek PolyCAL™ polystyrene standards. A polypropylene homopolymer (PPH), such as Dow 5D98 biaxially oriented polypropylene (BOPP), is used as a reference material to ensure that the Viscotek instrument and sample preparation procedures provide consistent results. The value for the PPH reference polymer is initially obtained from testing using the ASTM method described above.

[0021] The term "tacticity" generally refers to the relative stereochemical structure of adjacent chiral centers located within a macromolecule or polymer. For example, in a propylene-based polymer, the chirality of adjacent monomers, such as two propylene monomers, may have the same or opposite configuration. The term "dyad" is used to refer to two adjacent monomers, and three adjacent monomers are called a "triad." If the chirality of adjacent monomers has the same relative configuration, the dyad is said to be isotactic; if it is opposite in configuration, it is called syndiotactic. Another way to describe the configurational relationship is that adjacent pairs of monomers having the same chirality are called meso (m), and pairs with opposite configurations are called racemic (r).

[0022] The tacticity or stereochemistry of macromolecules in general, and in particular polypropylene or random copolymers of polypropylene, can be described or quantified in terms of the concentration of triads. An isotactic triad, which is typically abbreviated mm, consists of two adjacent meso-dyads that have the same configuration, and therefore the stereoregularity of the triad is denoted as mm. If two adjacent monomers in a sequence of three monomers have the same chirality that is different from the relative configuration of the third unit, the triad has a tacticity of mr. An rr triad has a middle monomer unit that has a configuration opposite to that of both neighbors. The fractions of each type of triad in a polymer can be determined and multiplied by 100 to obtain the percentage of that type of triad in the polymer. In this document, the parameter "percent mm" is used to identify and characterize polymers.

[0023] The distribution of monomers in the order of arrangement in the polymer can be determined by the ^13C NMR method, which can also determine the arrangement of butene residues in relation to adjacent propylene residues. The ^13C NMR method can be used to determine the butene content, the distribution of triads and the tacticity of triads, and is performed as follows:

[0024] 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 of sample in a 10 mm Norell 1001-7 NMR tube. Samples are dissolved and homogenized by heating the tube and its contents to 150°C using a heating set. Each sample is visually inspected to ensure homogeneity.

[0025] Data were collected using a Bruker 400 MHz spectrometer equipped with a Bruker Dual DUL high temperature cryoprobe. Data were collected using 512 transitions per data file, a pulse repetition delay of 6 s, a magnetization vector flip angle of 90 degrees, inverse suppression mode, and a sample temperature of 120 °C. All measurements were performed on non-rotating samples in a fixed mode. Samples were allowed to stabilize at the temperature for 10 minutes prior to data collection. Tacticity in percent mm and mass percentage butene were calculated using methods commonly used in the art, which are briefly described below.

[0026] Regarding the measurement of the chemical shifts of the resonance frequencies, a value of 21.83 ppm is adopted for the methyl group of the third unit in a sequence of 5 adjacent propylene units consisting of head-to-tail bonds and having the same relative chirality. The chemical shift of other resonance frequencies of carbon is determined using the above-mentioned value as a standard. The spectrum related to the region of carbon in the methyl group (17.0-23 ppm) can be divided into the first region (21.1-21.9 ppm), the second region (20.4-21.0 ppm), the third region (19.5-20.4 ppm), and the fourth region (17.0-17.5 ppm). Each peak in the spectrum is interpreted using a literature source such as articles in, for example, Polymer, T. Tsutsui et al., Vol.30, Issue 7, (1989) 1350-1356 and/or Macromolecules, H. N. Cheng, 17 (1984) 1950-1955, the contents of which are incorporated herein by reference.

[0027] For convenience, the butene content was also measured by Fourier transform infrared spectroscopy (FTIR), the results of these measurements correlate with the butene content values determined by the above-mentioned ^13C NMR as the primary method. The relationship and agreement between measurements made using these two methods are described, for example, in the work of J. R. Paxson, J. C. Randall, Quantitative Measurement of Ethylene Incorporation into Propylene Copolymers by Carbon-13 Nuclear Magnetic Resonance and Infrared Spectroscopy, Analytical Chemistry, Vol. 50, No. 13, Nov. 1978, 1777-1780.

[0028] The flexural modulus is determined in accordance with ASTM D790-10 Method A at 1.3 mm/min using an ASTM 3641 Type 1 specimen cast in accordance with ASTM D4101.

[0029] Izod impact strength is measured in accordance with ASTM D 256 and D4101.

[0030] Turbidity is determined in accordance with ASTM D1003 Procedure A based on the latest test revision. Turbidity may be measured on a test panel or on a molded article such as a bottle, cup, container, or film. Turbidity may be measured before and after heat aging. Turbidity may be measured using a BYK Gardner Haze-Gard Plus 4725. The injection molded test specimens used in the turbidity measurements may be injection molded at 200 to 230°C in the presence of nonite as a nucleating agent, at 250 to 260°C in the presence of sorbitol as a nucleating agent, or at 200 to 260°C in the presence of an insoluble particulate nucleating agent. Thermal aging is accomplished by placing the specimens in an oven at the required temperature (e.g. 121°C) and for the required time (e.g. 30 min) and subsequently re-testing for turbidity.

[0031] The heat distortion temperature (HDT) is determined in accordance with the procedure of ASTM D648 entitled Deflection temperature of plastics under flexural load, 66 psi on samples prepared/aged according to D4101.

[0032] The melting point or melting point and the crystallization temperature are determined using differential scanning calorimetry (DSC). The melting point is the major peak that forms during the test and is typically the second peak that forms. The term "crystallinity" refers to the regularity of the arrangement of atoms or molecules that form a crystalline structure. The crystallinity of a polymer can be examined using DSC. T _me is the final melting temperature and T _max is the peak melting temperature as determined by one of ordinary skill in the art from DSC analysis using data obtained at the end of the heating stage. One suitable method for DSC analysis uses a Q1000™ DSC from TA Instruments, Inc. Calibration of the DSC is performed as follows. First, a baseline value is obtained by heating the cell from -90°C to 290°C with no sample in the aluminum DSC crucible. Subsequently, a 7 milligram sample of fresh indium was analyzed by heating the sample to 180 °C, cooling the sample to 140 °C at a cooling rate of 10 °C/min, then holding the sample at 140 °C for 1 minute, then heating the sample from 140 °C to 180 °C at a heating rate of 10 °C/min. The heat of fusion and the onset of melting point of the indium sample were determined and verified, the onset of melting point should be within 0.5 °C of 156.6 °C and the heat of fusion should be within 0.5 J/g of 28.71 J/g. Deionized water was subsequently analyzed by cooling a small drop of fresh sample in a DSC crucible from 25 °C to -30 °C at a cooling rate of 10 °C/min. The sample is kept under isothermal conditions at -30°C for 2 minutes and heated to 30°C at a heating rate of 10°C/min. The melting onset temperature is determined and checked; it should be within 0.5°C of 0°C.

[0033] 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 Polymer Char High Temperature GPC with an IRS MCT (thermoelectrically cooled IR detector based on mercury cadmium telluride, CMT), a Polymer Char viscometer with four capillaries, a Wyatt 8-detector multi-angle light scattering analyzer and three Agilent Plgel Oexis columns (13 μm). The oven temperature is set at 150 °C. The solvent is nitrogen-purged 1,2,4-trichlorobenzene (TCB) containing 200 ppm 2,6-di-tert-butyl-4-methylphenol (BHT). The flow rate is 1.0 mL/min and the injection volume is 200 µL. A sample concentration of 2 mg/mL is obtained by dissolving the sample in N2-purged and preheated TCB (containing 200 ppm BHT) for 2 h at 160°C with gentle stirring.

[0034] A set of GPC columns is calibrated with twenty polystyrene standards with a narrow molecular weight distribution. The molecular weight (MW) of the standards ranges from 266 to 12,000,000 g/mol and the standards are contained in six "cocktail" mixtures. Each standard mixture differs by at least one order of magnitude between the individual molecular weights. The polystyrene standards are prepared at 0.005 g in 20 mL of solvent for molecular weights equal to or greater than 1,000,000 g/nil 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 160 °C for 60 min with stirring. Narrow mixtures of standards are run first and in decreasing order from the component with the highest molecular weight to minimize the effects of degradation. A logarithmic molecular weight calibration is generated using a fourth-order polynomial fit to the elution volume. Equivalent molecular weights of polypropylene are calculated using the following equation with reduced Mark-Houwink coefficients for polypropylene (Th. G. Scholte, N. L. J. Meijeuink, H. M. Schof f eleers, and A. M. G. Brands, J. Appl. Polym. Sci., 29, 3763-3782 (1934)) and polystyrene (E. P. Otocka, R. J. Roe, N. Y. Hellman, and E. M. Muglia, Macromolecules, 4, 507 (1971)):

where M _pp is the equivalent PP Ml, M _PS is the equivalent PS MM, log K and the values of the Mark-Houwink coefficients for PP and PS are given below.

II. Random copolymer of propylene and butene and its compositions

[0035] The propylene-butene copolymers of the present disclosure may comprise a predominant weight percentage of propylene monomer with butene monomer as a secondary constituent. The butene content of the propylene-butene copolymer of the present disclosure may be from about 1 wt. % to about 12 wt. %, including all 0.1 wt. % increments therebetween. For example, the propylene-butene copolymer may comprise butene in an amount greater than about 1.5 wt. %, such as greater than about 2 wt. %, such as greater than about 2.3 wt. %, such as greater than about 3 wt. %, such as greater than about 4 wt. %, such as greater than about 4.5 wt. %, such as greater than about 5 wt. %. The butene content of the propylene-butene copolymer is substantially less than about 11 wt. %, such as less than about 10 wt. %, such as less than about 9 wt. %, such as less than about 8 wt. %, such as less than about 7.8 wt. %, such as less than about 7 wt. %, such as less than about 6 wt. %, such as less than about 5 wt. The amount of butene included in the copolymer can be varied to alter various physical properties of the polymer.

[0036] The xylene soluble (XS) fraction for the copolymers of the present invention may be equal to copolymer or more preferable and even more preferable or less. The xylene soluble fraction is substantially greater than about 0.5 wt.%, such as greater than about 1 wt.%. The xylene soluble (XS) fraction content is preferably in the range of 1.0 wt.% to 8.0 wt.%, such as 2 wt.% to 7 wt.%. It is a particular advantage that the propylene and butene copolymers according to the present disclosure can have a xylene soluble content of greater than about 3 wt.% and still exhibit excellent low haze. The xylene soluble fraction/butene content ratio of the polymer can be from about 0.3 to about 3.0, such as from about 0.3 to about 2.0, such as from about 0.5 to about 1.0, or less than 1.0.

[0037] The melt flow index of the propylene-butene copolymers made according to the present description can vary. For example, the melt flow index can be from about 0.2 g/10 min to about 220 g/10 min, including all increments of 0.1 therebetween. The melt flow index of the polymer, for example, can be varied and adjusted based on various factors and the desired application. If the polymer is incorporated into a composition and, for example, is blow molded or thermoformed, lower melt flow values may be required. For example, in one aspect, the melt flow index of the propylene-butene copolymer can be less than about 20 g/10 min, such as less than about 15 g/10 min, such as less than about 10 g/10 min, such as 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, and substantially greater than about 1 g/10 min, such as greater than about 1.5 g/10 min. However, when using the polymer for injection molding, a higher melt flow index may be required. For example, in one aspect, the melt flow index of the polymer can be greater than about 10 g/10 min, such as greater than about 20 g/10 min, such as greater than about 30 g/10 min, such as greater than about 40 g/10 min, and substantially less than about 110 g/10 min, such as less than 80 g/10 min, such as less than about 60 g/10 min.

[0038] The copolymer of the present invention is substantially characterized by a relatively broad molecular weight distribution. For example, the molecular weight distribution (Mw/Mn) is substantially greater than about 3.5, such as greater than about 3.8, such as greater than about 4, such as greater than about 4.3, such as greater than about 4.5, 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, and substantially less than about 10, such as less than about 8, such as less than about 7.5. The weight average molecular weight is determined by gel permeation chromatography (GPC).

[0039] In one aspect, the propylene-butene copolymer can be formulated to have superior stiffness properties. For example, the copolymer can have a flexural modulus of greater than about 1100 MPa, such as greater than about 1150 MPa, such as greater than about 1200 MPa, such as greater than about 1250 MPa, such as greater than about 1300 MPa, such as greater than about 1350 MPa, such as greater than about 1400 MPa, such as greater than about 1450 MPa, such as greater than about 1500 MPa. The flexural modulus is substantially less than about 3000 MPa, such as less than about 2000 MPa.

[0040] A particular advantage is that the random copolymer of propylene and butene can have a high heat distortion resistance, especially when the polymer is formulated to contain butene in smaller amounts. In general, the polymer can have a heat distortion temperature (HDT) of greater than about 70°C. When the butene content is less than 8 wt.%, such as less than 6 wt.%, such as less than 5 wt.%, the HDT can be greater than about 75°C, such as greater than about 76°C, such as greater than about 77°C, and substantially less than about 90°C. The polymer can be further formulated to have a melting point of greater than about 135°C, such as greater than about 145°C, such as greater than about 147°C, such as greater than about 148°C, such as greater than about 149°C, such as greater than about 150°C, such as greater than about 151°C, and substantially less than about 165°C. In one aspect, the polymer can have a primary melting point of at least 147°C.

[0041] In addition to excellent stiffness and heat resistance properties, the propylene-butene copolymer may also have good strength properties. For example, the copolymer may have an Izod impact strength of greater than about 40 J/m, such as greater than about 45 J/m, such as greater than about 50 J/m, such as greater than about 55 J/m, such as greater than about 60 J/m, such as greater than about 65 J/m, such as greater than about 70 J/m, such as greater than about 75 J/m, such as greater than about 80 J/m, such as greater than about 85 J/m, such as greater than about 90 J/m. The impact strength is substantially less than about 200 J/m, such as less than about 150 J/m.

III. Obtaining a random copolymer of propylene and butene

[0042] In one aspect, the propylene-butene copolymers of the present disclosure can be prepared using non-phthalate Ziegler-Natta catalysts. The non-phthalate catalyst includes a catalyst system that is free of phthalate compounds, i.e., all of the catalyst support, internal electron donors, external electron donors, activity limiting agent, and activator are free of phthalates. Phthalates have previously been used as internal electron donors. Non-phthalate internal electron donors include diethers, succinates, ethyl benzoates, phenylenediethers, and the like. As a result of using the non-phthalate catalyst, the polymers are more suitable for food contact and medical device applications. Using a Ziegler-Natta catalyst further enables a broad molecular weight distribution, which can provide numerous benefits and advantages.

[0043] The propylene-butene copolymers can be substantially made in any suitable reactor using any suitable process for producing propylene-based polymers. Such processes include the UNIPOL® PP gas phase process using a supported Ziegler Natta catalyst. Particularly preferred are CONSISTA® catalysts available from W.R. Grace & Co., Columbia, Maryland. Suitable random copolymers of polypropylene can be made using a single reactor or multiple reactors. Examples of processes that can be used are described in U.S. Patent No. 9,624,323 and U.S. Patent Publication No. 2016/0289357, both of which are incorporated herein by reference.

[0044] Procatalyst compositions suitable for use in the preparation of random copolymers of polypropylene include Ziegler-Natta procatalyst compositions. In one embodiment, the Ziegler-Natta procatalyst composition comprises a titanium functional group, such as titanium chloride, a magnesium functional group, such as magnesium chloride, and an internal electron donor.

[0045] In one embodiment, the internal electron donor comprises a substituted phenylene aromatic diester. In one embodiment, a 1,2-phenylene aromatic diester is provided. The substituted 1,2-phenylene aromatic diester has the structure (I) shown below:

[0046] where R ₁ -R ₁₄ are the same or different. Each of R ₁ -R ₁₄ is selected from hydrogen, a substituted hydrocarbon group having from 1 to 20 carbon atoms, an unsubstituted hydrocarbon group having from 1 to 20 carbon atoms, an alkoxy group having from 1 to 20 carbon atoms, a heteroatom, and combinations thereof. At least one of R ₁ -R ₁₄ is not hydrogen.

[0047] As used herein, the terms "hydrocarbon group" and "hydrocarbon" refer to substituents containing only hydrogen and carbon atoms, including branched or unbranched, saturated or unsaturated, cyclic, polycyclic, fused or acyclic groups, and combinations thereof. Non-limiting examples of hydrocarbon groups include alkyl, cycloalkyl, alkenyl, alkadienyl, cycloalkenyl, cycloalkadienyl, aryl, aralkyl, alkylaryl, and alkynyl groups.

[0048] As used herein, the terms "substituted hydrocarbon group" and "substituted hydrocarbon" mean a hydrocarbon group that is substituted with one or more non-hydrocarbon substituent groups. A non-limiting example of a non-hydrocarbon substituent is a heteroatom. As used herein, the term "heteroatom" means an atom of any element other than carbon or hydrogen. A heteroatom may be an atom other than carbon from Groups IV, V, VI, and VII of the periodic table. Non-limiting examples of heteroatoms include: halogens (F, Cl, Br, I), N, O, P, B, S, and Si. Substituted hydrocarbon groups also include a halogen-containing hydrocarbon group and a silicon-containing hydrocarbon group. As used herein, the term "halogen-containing hydrocarbon" group means a hydrocarbon group that is substituted with one or more halogen atoms. As used herein, the term "silicon-containing hydrocarbon group" means a hydrocarbon group that is substituted with one or more silicon atoms. The silicon atom(s) may or may not be included in the carbon chain.

[0049] The procatalyst precursor may comprise (i) magnesium, (ii) a compound of a transition metal of an element from Groups IV through VIII of the periodic table, (iii) a halide, oxyhalide, and/or alkoxide of (i) and/or (ii), and (iv) combinations of (i), (ii), and (iii). Non-limiting examples of suitable procatalyst precursors include halides, oxyhalides, and alkoxides of magnesium, manganese, titanium, vanadium, chromium, molybdenum, zirconium, hafnium, and combinations thereof.

[0050] In one embodiment, the procatalyst precursor is a magnesium-functional compound (MagMo), a mixed magnesium-titanium compound (MagTi), or a benzoate-containing magnesium chloride compound (BenMag). In one embodiment, the procatalyst precursor is a magnesium-functional precursor (MagMo). The MagMo precursor comprises magnesium as the only metal component. The MagMo precursor comprises a magnesium functional group. Non-limiting examples of suitable magnesium functional groups include anhydrous magnesium chloride and/or an alcohol adduct thereof, a magnesium alkoxide or aryloxide, a mixed magnesium alkoxyhalide, and/or a carboxylated magnesium dialkoxide or aryloxide. In one embodiment, the MagMo precursor is magnesium di(C _1-4 )alkoxide. In a further embodiment, the MagMo precursor is diethoxymagnesium.

[0051] In one embodiment, the procatalyst precursor is a mixed magnesium/titanium compound (MagTi). The MagTi precursor has the formula Mg _d Ti(OR ^e ) _f X _g , wherein R ^e is an aliphatic or aromatic hydrocarbon radical having from 1 to 14 carbon atoms, or COR', wherein R' is an aliphatic or aromatic hydrocarbon radical having from 1 to 14 carbon atoms; all OR ^e groups are the same or different; X is independently chlorine, bromine, or iodine, preferably chlorine; d is from 0.5 to 56, or from 2 to 4; f is from 2 to 116, or from 5 to 15; and g is from 0.5 to 116, or from 1 to 3. The precursors are prepared by controlled precipitation by removing an alcohol from the reaction mixture used in their preparation. In one embodiment, the reaction medium comprises a mixture of a liquid aromatic compound, in particular a chlorinated aromatic compound, most preferably chlorobenzene, with an alkanol, in particular ethanol. Suitable halogenating agents include titanium tetrabromide, titanium tetrachloride or titanium trichloride, in particular titanium tetrachloride. Removal of the alkanol from the solution used in the halogenation results in the precipitation of a solid precursor having a particularly desirable morphology and surface area. Moreover, the precursors obtained are particularly uniform in particle size.

[0052] In one embodiment, the procatalyst precursor comprises magnesium as the only metal component. Non-limiting examples include anhydrous magnesium chloride and/or an alcohol adduct thereof, a magnesium alkoxide and/or aryloxide, a mixed magnesium alkoxyhalide, and/or a carboxylated magnesium dialoxide or aryloxide.

[0053] In one embodiment, the procatalyst precursor is an anhydrous magnesium chloride alcohol adduct. The anhydrous magnesium chloride adduct is generally defined as MgCl ₂ -nROH, where n is in the range of 1.5-6.0, preferably 2.5-4.0, and most preferably 2.8-3.5 moles of total alcohol. ROH is a C ₁ -C ₄ alcohol, linear or branched, or a mixture of alcohols. Preferably, ROH is ethanol or a mixture of ethanol and a higher alcohol. If ROH is a mixture, the molar ratio of ethanol to higher alcohol is at least 80:20, preferably 90:10, and most preferably at least 95:5.

[0054] In one embodiment, the substantially spherical MgCl ₂ -nEtOH adduct can be formed by a spray crystallization process. In one embodiment, the spherical MgCl ₂ precursor has an average particle size (Mav d ₅₀ ) of about 15-150 microns, preferably 20-100 microns, and most preferably 35-85 microns.

[0055] In one embodiment, the procatalyst precursor comprises a transition metal compound and a magnesium metal compound. The transition metal compound has the general formula TrX _x , where Tr is a transition metal, X is a halogen or a C _1-10 hydrocarboxyl or hydrocarbon group, and x is the number of such X groups in the compound in combination with the magnesium metal compound. Tr can be a Group IV, V, or VI metal. In one embodiment, Tr is a Group IV metal, such as titanium. X can be a chloride, a bromide, a C _1-4 alkoxide, or a phenoxide, or a mixture thereof. In one embodiment, X is a chloride.

[0056] The present procatalyst composition may also include an internal electron donor. As used herein, the term "internal electron donor" refers to a compound added during the formation of the procatalyst composition that donates a pair of electrons to one or more metals present in the resulting procatalyst composition. Without wishing to be bound by any particular theory, it is believed that internal electron donors help control the formation of active sites and thus enhance the stereoselectivity of the catalyst. In one embodiment, the internal electron donor comprises a substituted phenylene aromatic diester of structure (I) shown above.

[0057] In one embodiment, a procatalyst composition is provided that includes a combination of a magnesium functionality, a titanium functionality, and an internal electron donor. The internal electron donor includes a substituted phenylene aromatic diester. The procatalyst composition is prepared using a halogenation procedure described in detail in U.S. Patent No. 8,536,372, which is incorporated herein by reference in its entirety, wherein a procatalyst precursor and a substituted phenylene aromatic diester donor are converted to a combination of magnesium and titanium functionality that includes an internal electron donor. The procatalyst precursor from which the procatalyst composition is formed can be a magnesium functionality, a mixed magnesium/titanium compound, or a benzoate-containing magnesium chloride compound.

[0058] In one embodiment, the magnesium functional group is a magnesium halide. In another embodiment, the magnesium halide is magnesium chloride or an alcohol adduct of magnesium chloride. In one embodiment, the titanium functional group is a titanium halide, such as titanium chloride. In another embodiment, the titanium functional group is titanium tetrachloride. In another embodiment, the procatalyst composition includes a magnesium chloride support onto which titanium chloride is deposited and into which an internal electron donor is included.

[0059] In one embodiment, the internal electron donor of the procatalyst composition comprises a substituted phenylene aromatic diester of structure (I) above, wherein R ₁ -R ₁₄ are the same or different; wherein each of R ₁ -R ₁₄ is selected from hydrogen, a substituted hydrocarbyl group having from 1 to 20 carbon atoms, an unsubstituted hydrocarbyl group having from 1 to 20 carbon atoms, an alkoxy group having from 1 to 20 carbon atoms, a heteroatom, and combinations thereof; and at least one of R ₁ -R ₁₄ is not hydrogen.

[0060] In one embodiment, at least one (or two, or three, or four) R group(s) of R ₁ -R ₄ is(are) selected from a substituted hydrocarbyl group having from 1 to 20 carbon atoms, an unsubstituted hydrocarbyl group having from 1 to 20 carbon atoms, an alkoxy group having from 1 to 20 carbon atoms, a heteroatom, and combinations thereof.

[0061] In one embodiment, at least one (or some, or all) of the R group(s) of R ₅ -R ₁₄ is(are) selected from a substituted hydrocarbyl group having from 1 to 20 carbon atoms, an unsubstituted hydrocarbyl group having from 1 to 20 carbon atoms, an alkoxy group having from 1 to 20 carbon atoms, a heteroatom, and combinations thereof. In another embodiment, at least one of the R ₅ -R9 groups and at least one of the R ₁₀ -R ₁₄ groups are selected from a substituted hydrocarbyl group having from 1 to 20 carbon atoms, an unsubstituted hydrocarbyl group having from 1 to 20 carbon atoms, an alkoxy group having from 1 to 20 carbon atoms, a heteroatom, and combinations thereof.

[0062] In one embodiment, at least one of the R1-R4 groups and at least one of the _R5 - _R14 groups are selected from a substituted hydrocarbon group having from 1 to 20 carbon atoms, an unsubstituted hydrocarbon group having from 1 to 20 carbon atoms, an alkoxy _group having from 1 to 20 ^carbon atoms, a heteroatom, and combinations thereof. In another embodiment, at least one of the _{R1_R4} groups, at least one of the _R5 - _R9 groups, and at least one of the _R10 - _R14 groups are selected from a substituted hydrocarbon group having from 1 to 20 carbon atoms, an unsubstituted hydrocarbon group having from 1 to 20 carbon atoms, an alkoxy group having from 1 to 20 carbon atoms, a heteroatom, and combinations thereof.

[0063] In one embodiment, any consecutive R groups in R ₁ -R ₄ , and/or any consecutive R groups in R ₅ -R ₉ , and/or any consecutive R groups in R ₁₀ -R ₁₄ can be linked together to form an intermolecular cyclic or intramolecular cyclic structure. The inter-/intramolecular cyclic structure may or may not be aromatic. In one embodiment, the inter- or intramolecular cyclic structure is a C ₅ - or C ₆ -membered ring.

[0064] In one embodiment, at least one of the R ₁ -R ₄ groups is selected from a substituted hydrocarbon group having from 1 to 20 carbon atoms, an unsubstituted hydrocarbon group having from 1 to 20 carbon atoms, and combinations thereof. At least one of the R ₅ -R ₁₄ groups can optionally be a halogen atom or an alkoxy group having from 1 to 20 carbon atoms. The R ₁ -R ₄ groups and/or R ₅ -R ₉ and/or R ₁₀ -R ₁₄ groups can optionally be bonded to each other to form an intermolecular cyclic or an intramolecular cyclic structure. The intermolecular cyclic structure and/or the intramolecular cyclic structure can be or not be aromatic.

[0065] In one embodiment, any consecutive R groups in R ₁ -R ₄ , and/or in R ₅ -R ₉ , and/or in R ₁₀ -R ₁₄ can be included in a C ₅ -C ₆ -membered ring.

[0066] In one embodiment, structure (I) includes R ₁ , R ₃ and R ₄ groups that are hydrogen. The R ₂ group is selected from a substituted hydrocarbon group having from 1 to 20 carbon atoms, an unsubstituted hydrocarbon group having from 1 to 20 carbon atoms, and combinations thereof. The R ₅ -R ₁₄ groups may be the same or different, and each of the R ₅ -R ₁₄ groups is selected from hydrogen, a substituted hydrocarbon group having from 1 to 20 carbon atoms, an unsubstituted hydrocarbon group having from 1 to 20 carbon atoms, an alkoxy group having from 1 to 20 carbon atoms, a halogen, and combinations thereof.

[0067] In one embodiment, the R ₂ group is selected from a C ₁ -C ₈ alkyl group, a C ₃ -C ₆ cycloalkyl group, or a substituted C ₃ -C ₆ cycloalkyl group. R ₂ can be a methyl group, an ethyl group, an n-propyl group, an isopropyl group, a tert-butyl group, an isobutyl group, a sec-butyl group, a 2,4,4-trimethylpentan-2-yl group, a cyclopentyl group, and a cyclohexyl group.

[0068] In one embodiment, structure (I) includes an R ₂ group that is methyl, and each of the R ₅ -R ₁₄ groups is hydrogen. In one embodiment, structure (I) includes an R ₂ group that is ethyl, and each of the R ₅ -R ₁₄ groups is hydrogen. In one embodiment, structure (I) includes an R ₂ group that is tert-butyl, and each of the R ₅ -R ₁₄ groups is hydrogen. In one embodiment, structure (I) includes an R ₂ group that is ethoxycarbonyl, and each of the R ₅ -R ₁₄ groups is hydrogen.

[0069] In one embodiment, structure (I) includes _R2 , _R3 , and _R4 groups, each of which is hydrogen, and the _R1 group is selected from a substituted hydrocarbon group having from 1 to 20 carbon atoms, an unsubstituted hydrocarbon group having from 1 to 20 carbon atoms, and combinations thereof. The _R5 - _R14 groups may be the same or different, and each of them is selected from hydrogen, a substituted hydrocarbon group having from 1 to 20 carbon atoms, an unsubstituted hydrocarbon group having from 1 to 20 carbon atoms, an alkoxy group having from 1 to 20 carbon atoms, a halogen, and combinations thereof.

[0070] In one embodiment, structure (I) includes a group R ₁ that is methyl and each of the groups R ₅ -R ₁₄ is hydrogen.

[0071] In one embodiment, structure (I) includes _R2 and _R4 groups that are hydrogen, and _R1 and _R3 groups may be the same or different. Each of _R1 and _R3 groups is selected from a substituted hydrocarbon group having from 1 to 20 carbon atoms, an unsubstituted hydrocarbon group having from 1 to 20 carbon atoms, and combinations thereof. _R5 - _R14 groups may be the same or different, and each of _R5 - _R14 groups is selected from a group of substituted hydrocarbons having from 1 to 20 carbon atoms, a group of unsubstituted hydrocarbons having from 1 to 20 carbon atoms, an alkoxy group having from 1 to 20 carbon atoms, a halogen, and combinations thereof.

[0072] In one embodiment, structure (I) includes R ₁ and R ₃ groups, which may be the same or different. Each of the R ₁ and R ₃ groups is selected from a C ₁ -C ₈ alkyl group, a C ₃ -C ₆ cycloalkyl group, or a substituted C ₃ -C ₆ cycloalkyl group. The R ₅ -R ₁₄ groups may be the same or different, and each of the R ₅ -R ₁₄ groups is selected from hydrogen, a C ₁ -C ₈ alkyl group, and halogen. Non-limiting examples of suitable _C1 - _C8 alkyl groups include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, n-pentyl, isopentyl, neopentyl, tert-pentyl, n-hexyl and 2,4,4-trimethylpentan-2-yl group. Non-limiting examples of suitable _C3 - _C6 cycloalkyl groups include cyclopentyl and cyclohexyl groups. In a further embodiment, at least one of the _R5 - _R14 groups is a _C1 - _C8 alkyl group or a halogen.

[0073] In one embodiment, structure (I) includes an R ₁ group that is a methyl group and an R ₃ group that is a tert-butyl group. Each of the R ₂ , R ₄ , and R ₅ -R ₁₄ groups is hydrogen.

[0074] In one embodiment, structure (I) includes R ₁ and R ₄ as methyl groups, wherein one of R ₃ or R ₂ is hydrogen and the other is a cycloalkyl group, such as a cyclohexyl group.

[0075] In one embodiment, structure (I) includes R ₁ and R ₃ groups, each of which is an isopropyl group. Each of the R ₂ , R ₄ , and R ₅ -R ₁₄ groups is hydrogen.

[0076] In one embodiment, structure (I) includes R ₁ , R ₅ , and R ₁₀ groups, each of which is a methyl group, and an R ₃ group, which is a tert-butyl group. Each of the R ₂ , R ₄ , R ₆ -R ₉ , and R ₁₁ -R ₁₄ groups is hydrogen.

[0077] In one embodiment, structure (I) includes groups R ₁ , R ₇ , and R ₁₂ , each of which is a methyl group, and a group R ₃ , which is a tert-butyl group. Each of the groups R ₂ , R ₄ , R ₅ , R ₆ , R ₈ , R ₉ , R ₁₀ , R ₁₁ , R ₁₃ , and R ₁₄ is hydrogen.

[0078] In one embodiment, structure (I) includes an R ₁ group that is a methyl group and an R ₃ group that is a tert-butyl group. Each of the R ₇ and R ₁₂ groups is an ethyl group. Each of the R ₂ , R ₄ , R ₅ , R ₆ , R ₈ , R ₈ , R ₁₀ , R ₁₁ , R ₁₃ and R ₁₄ groups is hydrogen.

[0079] In one embodiment, structure (I) includes groups R ₁ , R ₅ , R ₇ , R ₉ , R ₁₀ , R ₁₂ and R ₁₄ , each of which is a methyl group, and a group R ₃ , which is a tert-butyl group. Each of the groups R ₂ , R ₄ , R ₆ , R ₈ and R ₁₃ is hydrogen.

[0080] In one embodiment, structure (I) includes an R ₁ group that is a methyl group and an R ₃ group that is a tert-butyl group. Each of the R ₅ , R ₇ , R ₉ , R ₁₀ , R ₁₂ and R ₁₄ groups is an isopropyl group. Each of the R ₂ , R ₄ , R ₆ , R ₈ , R ₁₁ and R ₁₃ groups is hydrogen.

[0081] In one embodiment, the substituted phenylene aromatic diester has a structure selected from the group consisting of structures (II)-(V) including alternatives for each of the R ₁ -R ₁₄ groups, as described in detail in U.S. Patent No. 8,536,372, which is incorporated herein by reference.

[0082] In one embodiment, structure (I) includes an R ₁ group that is a methyl group and an R ₃ group that is a tert-butyl group. Each of the R ₇ and R ₁₂ groups is an ethoxy group. Each of the R ₂ , R ₄ , R ₅ , R ₆ , R ₈ , R ₈ , R ₁₀ , R ₁₁ , R ₁₃ and R ₁₄ groups is hydrogen.

[0083] In one embodiment, structure (I) includes an R ₁ group that is a methyl group and an R ₃ group that is a tert-butyl group. Each of the R ₇ and R ₁₂ groups is a fluorine atom. Each of the R ₂ , R ₄ , R ₅ , R ₆ , R ₈ , R ₉ , R ₁₀ , R ₁₁ , R ₁₃ and R ₁₄ groups is hydrogen.

[0084] In one embodiment, structure (I) includes an R ₁ group that is a methyl group and an R ₃ group that is a tert-butyl group. Each of the R ₇ and R ₁₂ groups is a chlorine atom. Each of the R ₂ , R ₄ , R ₅ , R ₆ , R ₈ , R ₉ , R ₁₀ , R ₁₁ , R ₁₃ and R ₁₄ groups is hydrogen.

[0085] In one embodiment, structure (I) includes an R ₁ group that is a methyl group and an R ₃ group that is a tert-butyl group. Each of the R ₇ and R ₁₂ groups is a bromine atom. Each of the R ₂ , R ₄ , R ₅ , R ₆ , R ₈ , R ₉ , R ₁₀ , R ₁₁ , R ₁₃ and R ₁₄ groups is hydrogen.

[0086] In one embodiment, structure (I) includes an R ₁ group that is a methyl group and an R ₃ group that is a tert-butyl group. Each of the R ₇ and R ₁₂ groups is an iodine atom. Each of the R ₂ , R ₄ , R ₅ , R ₆ , R ₈ , R ₉ , R ₁₀ , R ₁₁ , R ₁₃ and R ₁₄ groups is hydrogen.

[0087] In one embodiment, structure (I) includes an R ₁ group that is a methyl group and an R ₃ group that is a tert-butyl group. Each of the R ₆ , R ₇ , R ₁₁ , and R ₁₂ groups is a chlorine atom. Each of the R ₂ , R ₄ , R ₅ , R ₈ , R ₈ , R ₁₀ , R ₁₃ , and R ₁₄ groups is hydrogen.

[0088] In one embodiment, structure (I) includes an R ₁ group that is a methyl group and an R ₃ group that is a tert-butyl group. Each of the R ₆ , R ₈ , R ₁₁ , and R ₁₃ groups is a chlorine atom. Each of the R ₂ , R ₄ , R ₅ , R ₇ , R ₈ , R ₁₀ , R ₁₂ , and R ₁₄ groups is hydrogen.

[0089] In one embodiment, structure (I) includes an R ₁ group that is a methyl group and an R ₃ group that is a tert-butyl group. Each of the R ₂ , R ₄ , and R ₅ -R ₁₄ groups is a fluorine atom.

[0090] In one embodiment, structure (I) includes an R ₁ group that is a methyl group and an R ₃ group that is a tert-butyl group. Each of the R ₇ and R ₁₂ groups is a trifluoromethyl group. Each of the R ₂ , R ₄ , R ₅ , R ₆ , R ₈ , R ₉ , R ₁₀ , R ₁₁ , R ₁₃ and R ₁₄ groups is hydrogen.

[0091] In one embodiment, structure (I) includes an R ₁ group that is a methyl group and an R ₃ group that is a tert-butyl group. Each of the R ₇ and R ₁₂ groups is an ethoxycarbonyl group. Each of the R ₂ , R ₄ , R ₅ , R ₆ , R ₈ , R ₉ , R ₁₀ , R ₁₁ , R ₁₃ and R ₁₄ groups is hydrogen.

[0092] In one embodiment, the R ₁ group is a methyl group and the R ₃ group is a tert-butyl group. Each of the R ₇ and R ₁₂ groups is an ethoxy group. Each of the R ₂ , R ₄ , R ₅ , R ₆ , R ₈ , R ₉ , R ₁₀ , R ₁₁ , R ₁₃ and R ₁₄ groups is hydrogen.

[0093] In one embodiment, structure (I) includes an R ₁ group that is a methyl group and an R ₃ group that is a tert-butyl group. Each of the R ₇ and R ₁₂ groups is a diethylamine group. Each of the R ₂ , R ₄ , R ₅ , R ₈ , R ₈ , R ₈ , R ₁₀ , R ₁₁ , R ₁₃ and R ₁₄ groups is hydrogen.

[0094] In one embodiment, structure (I) includes an R ₁ group that is a methyl group and an R ₃ group that is a 2,4,4-trimethylpentan-2-yl group. Each of the R ₂ , R ₄ , and R ₅ -R ₁₄ groups is hydrogen.

[0095] In one embodiment, structure (I) includes R ₁ and R ₃ groups, each of which is a sec-butyl group. Each of the R ₂ , R ₄ , and R ₅ -R ₁₄ groups is hydrogen.

[0096] In one embodiment, structure (I) includes R ₁ and R ₄ groups, each of which is a methyl group. Each of the R ₂ , R ₃ , R ₅ -R ₉ and R ₁₀ -R ₁₄ groups is hydrogen.

[0097] In one embodiment, structure (I) includes an R ₁ group that is a methyl group. The R ₄ group is an isopropyl group. Each of the R ₂ , R ₃ , R ₅ -R ₉ , and R ₁₀ -R ₁₄ groups is hydrogen.

[0098] In one embodiment, structure (I) includes R ₁ , R ₃ , and R ₄ groups, each of which is an isopropyl group. Each of the R ₂ , R ₅ -R ₉ , and R ₁₀ -R ₁₄ groups is hydrogen.

[0099] In one embodiment, another procatalyst composition is provided. This procatalyst composition includes a combination of a magnesium functional group, a titanium functional group, and a mixed internal electron donor. As used herein, the term "mixed internal electron donor" refers to (i) a substituted phenylene aromatic diester; (ii) an electron donor component that provides a pair of electrons to one or more metals present in the resulting procatalyst composition; and (iii) optionally other components. In one embodiment, the electron donor component is a diether, a benzoate, and combinations thereof. The mixed internal electron donor procatalyst composition can be prepared using the procatalyst preparation procedure described in the previously filed patents and publications referenced herein.

[0100] For example, suitable catalyst compositions comprise a procatalyst composition, a cocatalyst, and an external electron donor or a mixed external electron donor (M-EED) of two or more different components. Suitable external donors include one or more activity limiting agents (ALAs), one or more selectivity control agents (SCAs), or both ALAs and SCAs. As used herein, the term "external electron donor" means a component or composition comprising a mixture of components added independently of the formation of the procatalyst that modify the performance of the catalyst. As used herein, the term "activity limiting agent" means a composition that reduces the activity of the catalyst if the polymerization temperature exceeds a threshold temperature in the presence of the catalyst (e.g., a temperature greater than about 85°C). The term "selectivity control agent" means a composition that improves the tacticality of the polymer, wherein improving the tacticality essentially means increasing the tacticality and/or decreasing the content of xylene soluble fractions. It should be understood that the above definitions are not mutually exclusive and that one compound may be classified, for example, as both an activity limiting agent and a selectivity controlling agent.

[0101] In one embodiment, the external electron donor comprises an alkoxysilane. The alkoxysilane has the general formula:

wherein each of the R groups is independently hydrogen, or a hydrocarbon group, or an amino group, optionally substituted with one or more substituents containing one or more heteroatoms from Group 14, 15, 16 or 17, said R group containing up to 20 atoms, not counting hydrogen and halogen; R' is a C _1-4 alkyl group; and m is 0, 1, 2 or 3. In one embodiment, R is a C _6-12 arylalkyl or aralkyl, C _3-12 cycloalkyl, C _3-12 branched alkyl or C _3-12 cyclic or acyclic amino group, R' is C _1-4 alkyl, and m is 1 or 2.

[0102] Non-limiting 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; cyclopentylpyrrolidinedimethoxysilane; bis(pyrrolidine)dimethoxysilane; bis(perhydroisoquinoline)dimethoxysilane; and dimethyldimethoxysilane. In one embodiment, the silane composition is dicyclopentyldimethoxysilane (DCPDMS); methylcyclohexyldimethoxysilane (MChDMS); or n-propyltrimethoxysilane (NPTMS); and any combinations thereof.

[0103] In one embodiment, the selectivity control agent component may be a mixture of 2 or more alkoxysilanes. In a further embodiment, the mixture may be dicyclopentyldimethoxysilane and methylcyclohexyldimethoxysilane, dicyclopentyldimethoxysilane and tetraethoxysilane, or dicyclopentyldimethoxysilane and n-propyltriethoxysilane. In one embodiment, the mixed external electron donor may include a benzoate, a succinate, and/or a diol ester. In one embodiment, the mixed external electron donor includes 2,2,6,6-tetramethylpiperidine as the selectivity control agent (SCA). In another embodiment, the mixed external electron donor includes a diether as both the SCA and the ALA.

[0104] The mixed external electron donor system may also include an activity limiting agent (ALA). The 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 increases. Ziegler-Natta catalysts also typically maintain high activity near the melting point of the polymer being produced. The heat generated by the exothermic polymerization reaction can cause the formation of agglomerates of polymer particles and ultimately lead to disruption of the polymer production process. The ALA reduces the activity of the catalyst at elevated temperatures, thereby preventing reactor upset, reducing (or preventing) particle agglomeration, and ensuring continuity of the polymerization process.

[0105] The activity limiting agent can be a carboxylic acid ester, a diester, a poly(alkene glycol), a diol ester, and combinations thereof. The carboxylic acid ester can be an aliphatic or aromatic ester of a mono- or polycarboxylic acid. Non-limiting examples of suitable monocarboxylic acid esters include ethyl and methyl benzoate; ethyl p-methoxybenzoate; methyl p-ethoxybenzoate; ethyl p-ethoxybenzoate; ethyl p-isopropoxybenzoate; ethyl acrylate; methyl methacrylate; ethyl acetate; ethyl p-chlorobenzoate; hexyl p-aminobenzoate; isopropyl naphthenate; n-amyl toluate; ethyl cyclohexanoate and propyl pivalate.

[0106] The aliphatic carboxylic acid ester may be a C ₆ aliphatic acid ester, may be a mono- or poly- (di- or more) ester, may be straight-chain or branched, may be saturated or unsaturated, and may be any combination of these esters. The _C6 - _C30 aliphatic acid ester may also be substituted with one or more substituents containing heteroatoms from Group 14, 15 or 16. Non-limiting examples of suitable _C6 - _C30 aliphatic acid esters include Ci _-2O alkyl esters of aliphatic _C6-30 monocarboxylic acids, _C1-20 alkyl esters of aliphatic _C8-20 monocarboxylic acids, _C1-4 allyl esters of aliphatic _C4-20 monocarboxylic acids and dicarboxylic acids, _C1-4 alkyl esters of aliphatic _C8-20 monocarboxylic acids and dicarboxylic acids, and _C6-20 mono- or polycarboxylate derivatives of _C2-100 (poly)glycols or _C2-100 ethers (poly)glycols. In one further embodiment, the _C6 - _C30 aliphatic acid ester may be a laurate, myristate, palmitate, stearate, oleate, sebacate, (poly)(alkylene glycol) mono- or diacetates, (poly)(alkylene glycol) mono- or dimyristates, (poly)(alkylene glycol) mono- or dilaurates, (poly)(alkylene glycol) mono- or dioleates, glyceryl tri(acetate), glyceryl triester of _C2-40 aliphatic carboxylic acids, and mixtures thereof. In a further embodiment, the _C6 - _C20 aliphatic ester is isopropyl myristate or di-n-butyl sebacate.

[0107] In one embodiment, the activity limiting agent comprises a diether. The diether may be a 1,3-diether represented by the following structure (VI):

where R ₁ -R ₄ independently of one another represent an alkyl, aryl or aralkyl group having up to 20 carbon atoms, which may optionally contain a heteroatom from group 14, 15, 16 or 17, and R ₁ and R ₂ may represent a hydrogen atom. The dialkyl ether may be linear or branched and may include one or more of the following groups: alkyl, cycloaliphatic, aryl, alkylaryl or arylalkyl radicals with 1-18 carbon atoms and hydrogen. R ₁ and R ₂ may be linked to form a cyclic structure such as cyclopentadiene or fluorene.

[0108] In one embodiment, the activity limiting agent comprises a succinate composition having the following structure (VII):

wherein R and R' may be the same or different, wherein R and/or R' comprise one or more of the following groups: hydrogen, a linear or branched alkyl, alkenyl, cycloalkyl, aryl, arylalkyl or alkylaryl group, optionally containing heteroatoms. One or more cyclic structures may be formed using one or both carbon atoms in the 2- and 3-positions.

[0109] In one embodiment, the activity limiting agent comprises a diol ester represented by the following structure (VIII):

where n is an integer from 1 to 5. R ₁ and R ₂ may be the same or different, and each of them may be selected from hydrogen, a methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, allyl, phenyl or halophenyl group. R ₃ , R ₄ , R ₅ , R ₆ , R ₇ and R ₈ may be the same or different, and each of them may be selected from hydrogen, a halogen, a substituted or unsubstituted hydrocarbon group having 1-20 carbon atoms. The groups R ₁ -R ₆ may optionally contain one or more heteroatoms replacing carbon, hydrogen or both, wherein the heteroatom is selected from nitrogen, oxygen, sulfur, silicon, phosphorus and halogen. R ₇ and R ₈ may be the same or different and may be bonded to any carbon atom in the 2-, 3-, 4-, 5- and 6-positions of any of the phenyl rings.

[0110] The individual components of the external electron donor may be added to the reactor separately, or two or more components may be pre-mixed together and subsequently added to the reactor as a mixture. More than one selectivity controlling agent or more than one activity limiting agent may be used in the mixture. In one embodiment, the mixture is dicyclopentyl dimethoxysilane and isopropyl myristate; diisopropyl dimethoxysilane and isopropyl myristate; dicyclopentyl dimethoxysilane and poly(ethylene glycol) laurate; dicyclopentyl dimethoxysilane and isopropyl myristate and poly(ethylene glycol) dioleate; methylcyclohexyl dimethoxysilane and isopropyl myristate; n-propyl trimethoxysilane and isopropyl myristate; dimethyl dimethoxysilane and methylcyclohexyl dimethoxysilane and isopropyl myristate; dicyclopentyldimethoxysilane, and n-propyltriethoxysilane, and isopropyl myristate; diisopropyl dimethoxysilane, and n-propyltriethoxysilane, and isopropyl myristate; and dicyclopentyldimethoxysilane, and tetraethoxysilane, and isopropyl myristate; dicyclopentyldimethoxysilane, and diisopropyl dimethoxysilane, and n-propyltriethoxysilane, and isopropyl myristate; and their combinations.

[0111] The catalyst composition includes a cocatalyst. The cocatalyst for use with the Ziegler-Natta procatalyst composition can be an aluminum-containing composition. Non-limiting examples of suitable aluminum-containing compositions include organoaluminum compounds such as a trialkyl aluminum; a dialkyl aluminum hydride; an alkyl aluminum dihydride; a dialkyl aluminum halide; an alkyl aluminum dihalide; a dialkyl aluminum alkoxide; and an alkyl aluminum dialkoxide - compounds containing 1-10 or 1-6 carbon atoms in each alkyl or alkoxide group. In one embodiment, the cocatalyst is a C _1-4 trialkyl aluminum compound such as triethyl aluminum (TEA). The catalyst composition has a molar ratio of aluminum (Al) to (SCA+ALA) of 0.5-25:1; or 1.0-20:1; or 1.5-15:1; or less than about 6.0; or less than about 5; or less than 4.5. In one embodiment, the molar ratio of Al:(SCA+ALA) is 0.5-4.0:1. The total molar ratio of SCA and ALA is 0.01-20:1; 0.10-5.00:1; 0.43-2.33:1; or 0.54-1.85:1; or 0.67-1.5:1.

IV. Applications

[0112] The propylene and butene copolymers of the present invention can be used in a variety of different and numerous application fields. As described above, the nucleated/clarified propylene and butene copolymers have excellent rigidity properties and excellent transparency properties.

[0113] In one embodiment, the propylene-butene copolymers of the present invention can be included in a composition for forming injection molded articles, such as containers. When used for injection molding, the polymer can have a melt flow rate of greater than about 4 g/10 min, such as greater than about 10 g/10 min, such as greater than about 20 g/10 min, such as greater than about 30 g/10 min, such as greater than about 35 g/10 min. The containers can have a bottom portion that defines a hollow interior and an upper portion that includes a flange that is hermetically sealed with the bottom portion. In addition to containers, substantially any article suitable for injection molding can be formed according to the present disclosure, which must have a certain degree of rigidity in combination with good optical properties. For example, the propylene-butene copolymer of the present disclosure is particularly well suited for the production of packaging, including all various types of food packaging.

[0114] In addition to injection molded articles, the propylene-butene copolymer of the present disclosure can also be used in extrusion blow molding, thermoforming. When used for blow molding or thermoforming, the polymer can have a melt flow index of less than about 5 g/10 min, such as less than about 4.5 g/10 min, such as less than about 4 g/10 min, such as less than about 3.5 g/10 min. The polymer can have a melt flow index of greater than about 0.2 g/10 min, such as greater than about 1 g/10 min. In a composition with a relatively low melt flow index, the copolymer exhibits excellent melt strength, allowing the molding of various articles by blow molding having a relatively uniform wall thickness. For example, the propylene-butene copolymer can be used to produce all different types of plastic bottles for containing, for example, beverages. As described above, since the polymer can be formed using non-phthalate catalysts, the polymer is extremely well suited for use in food contact articles.

[0115] In another embodiment, the propylene-butene copolymer of the present disclosure can be used for thermoforming. For example, the polymer can be used to make thermoformed containers, including beverage cups. For example, beverage cups made in accordance with the present disclosure can exhibit less haze and greater rigidity compared to cups made from random ethylene copolymers.

[0116] The propylene-butene copolymers of the present disclosure can be combined with various other components and ingredients to formulate a polymer composition for making molded articles, as described above. For example, in one embodiment, the polymer composition can comprise antioxidants and deoxidizers, and in some applications can also advantageously comprise other additives such as nucleators, mold release agents, antistatic agents, slip agents, antiblocking agents, processing aids, UV stabilizers, and colorants (pigments). The antioxidant can be a hindered phenol, which can be used with a phosphite stabilizer. Deoxidizers that can be used include a metal stearate such as calcium stearate, hydrotalcite, or mixtures thereof. Each additive can be present in the composition in an amount of from about 0.01 wt. % to about 2 wt. %, such as from about 0.1 wt. % to about 1 wt. %.

[0117] In one embodiment, the copolymer composition may further comprise a nucleating agent. The nucleating agent may be added to further improve the transparency properties of the composition. In one aspect, the nucleating agent may be a clarifying agent, which may comprise a compound capable of producing a gel-forming system within the composition.

[0118] In one embodiment, the nucleating agent may comprise a sorbitol compound, such as a sorbitol acetal derivative. For example, in one embodiment, the nucleating agent may comprise dibenzyl sorbitol.

[0119] With respect to sorbitol acetal derivatives that can be used as an additive in some embodiments, a sorbitol acetal derivative is shown in formula (I):

where R1-R5 contain the same or different functional groups selected from hydrogen and C1-C3 alkyl.

[0120] In some embodiments, R1-R5 are hydrogen, such that the sorbitol acetal derivative is 2,4-dibenzylidene sorbitol (DBS). In some embodiments, R1, R4, and R5 are hydrogen and R2 and R3 are methyl groups, such that the sorbitol acetal derivative is 1,3:2,4-di-p-methyldibenzylidene-D-sorbitol (MDBS). In some embodiments, R1-R4 are methyl groups and R5 is hydrogen, such that the sorbitol acetal derivative is 1,3:2,4-bis(3,4-dimethylbenzylidene)sorbitol (DMDBS). In some embodiments, R2, R3, and R5 are propyl groups (-CH2-CH2-CH3), and R1 and R4 are hydrogen, such that the sorbitol acetal derivative is 1,2,3-trideoxy-4,6:5,7-bis-O-(4-propylphenylmethylene)nonitol (TBPMN).

[0121] Other embodiments of nucleating agents that can be used include:

1,3:2,4-dibenzylidene sorbitol;

1,3:2,4-bis(p-methylbenzylidene)sorbitol;

di(p-methylbenzylidene)sorbitol;

di(p-ethylbenzylidene)sorbitol; And

bis(5', 6', 7', 8'-tetrahydro-2-naphthylidene)sorbitol.

[0122] In one embodiment, the nucleating agent may also comprise a bisamide, such as benzene trisamide. The nucleating agents described above may be used individually or in combination.

[0123] One or more nucleating agents may be present in the polymer composition in an amount greater than about 100 ppm, such as in an amount greater than about 300 ppm, such as in an amount greater than about 1000 ppm, such as in an amount greater than about 2000 ppm, and substantially less than about 20,000 ppm, such as less than about 10,000 ppm, such as less than about 4000 ppm.

[0124] When one or more nucleating agents are clarifying agents, the clarifying agents can be added in an amount greater than about 1500 ppm, such as in an amount greater than about 1800 ppm, such as in an amount greater than about 2000 ppm, such as in an amount greater than about 2200 ppm. The one or more clarifying agents are typically present in an amount less than about 20,000 ppm, such as less than about 15,000 ppm, such as less than about 10,000 ppm, such as less than about 8,000 ppm, such as less than about 5,000 ppm.

[0125] As described above, the polymer compositions comprising the propylene-butene copolymer of the present disclosure have excellent low haze characteristics that can be improved by adding and combining with the polymer one or more nucleating agents. For example, when measured at a thickness of 0.7 mm, the propylene-butene copolymer or the polymer composition comprising the propylene-butene copolymer can have a haze of less than about 12%, such as less than about 10%, such as less than about 8%. Molded articles such as bottles, containers, films, and cups made from the polymer can have a haze of less than about 10%, such as less than about 7.5%, such as less than about 7%, such as less than about 6.5%, such as less than about 6%, such as less than about 5.5%. The haze is substantially greater than about 1%.

V. Examples

Set of examples #1

[0126] Samples of the random copolymer of propylene and butene were prepared and their properties were tested according to the procedures described above. The properties and experimental results are presented in Table 2 below.

[0127] Random copolymers of propylene and butene were prepared using a stereospecific 6th generation Ziegler-Natta titanium catalyst on a magnesium-containing support. The catalyst included a non-phthalate internal donor that provided polymers with a broader molecular weight distribution than those prepared using a metallocene catalyst. The process for preparing the polymers is described in the prior art as the UNIPOL gas phase process. The catalyst used to prepare the polymers included a substituted phenylene aromatic diester as an internal electron donor. The catalyst used is commercially available from W.R. Grace and Company and is sold under the trade name CONSISTA. All copolymers were prepared using an external electron donor and triethylaluminum as a cocatalyst.

[0128] The various random copolymers that were prepared were combined with a nucleating agent, except for Samples No. 1, 6, 10, and 14, to which no nucleating agent was added. Two different nucleating agents were used. The following nucleating agents were used: (1) TPBMN (clarifier) and (2) HYPERFORM HPN-600ei (active site initiator), both available from Milliken Chemical. Samples No. 2, 7, 11, and 15 contained HYPERFORM HPN-600ei at a concentration of 400 ppm. Samples 3, 8, 12, and 16 contained TPBMN at a concentration of 2000 ppm, and samples 4, 5, 9, 13, and 17 contained TPBMN at a concentration of 4000 ppm. Each sample also contained a hindered phenol antioxidant, a phosphite antioxidant, and a deoxidizer (hydrotalcite).

[0129] The following results were obtained:

Example set #2

[0130] Samples of the random copolymer of propylene and butene were prepared and their properties were tested according to the procedures described above. The properties and experimental results are presented in Tables 3 and 4 below.

[0131] Random copolymers of propylene and butene were prepared using a stereospecific 6th generation Ziegler-Natta titanium catalyst on a magnesium-containing support. The catalyst included a non-phthalate internal donor that provided polymers with a broader molecular weight distribution than those prepared using a metallocene catalyst. The process for preparing the polymers is described in the prior art as the UNIP0L gas phase process. The catalyst used to prepare the polymers included a substituted phenylene aromatic diester as an internal electron donor. The catalyst used is commercially available from W.R. Grace and Company and is sold under the trade name CONSISTA. All copolymers were prepared using an external electron donor and triethylaluminum as a cocatalyst.

[0132] In addition, random copolymers of propylene and ethylene were prepared. In the table below, for example, samples No. 20-28 and 32-36 are random copolymers of propylene and butene, while samples No. 18, 19, 29-31, and 37-40 are random copolymers of propylene and ethylene. Samples No. 18, 19, 37, and 38 were made using the same catalyst that was used to prepare the propylene and butene copolymers. Samples No. 29-31, 39, and 40 were made using a phthalate-based catalyst. Some of the polymers obtained were combined with 2000 ppm or 4000 ppm of a nucleating agent, namely TBPMN, while samples No. 20, 23, 26, 29 and 32 did not contain a nucleating agent. The polymer compositions were subsequently used to manufacture containers by injection molding or to manufacture bottles by blow molding. The following results were obtained (Table 3 below).

[0133] Samples #19 and 22 were also tested for haze on injection molded product after one year of production and compared to a random copolymer of propylene and ethylene suitable for the production of commercial grade goods and having the following characteristics.

[0134] The following results were obtained:

[0135] These and other modifications and variations of the present invention can be made by those skilled in the art without departing from the spirit and scope of the present invention, which are more particularly set forth in the appended claims. It should also be understood that aspects of the various embodiments may be interchanged in whole or in part. In addition, those skilled in the art will understand that the above description is merely exemplary and is not intended to limit the invention, which is further described in such appended claims.

Claims (39)

1. A copolymer of propylene and butene containing: propylene as a primary monomer; butene from 1 wt. % up to 12 wt. %; acid-soluble fraction from 1.0 wt.% to 8.0 wt.%; molecular weight distribution (Mw/Mn) greater than 3.5; and substituted phenylene aromatic diester. 2. A copolymer of propylene and butene according to claim 1, in which the butene content is from 2 wt.% to 8 wt.%, for example from 2 wt.% to 6 wt.%. 3. A copolymer of propylene and butene according to claim 2, which has a heat deformation temperature of more than 75°C. 4. A copolymer of propylene and butene according to any of the preceding claims, which has a melting point of from 147°C to 155°C. 5. A copolymer of propylene and butene according to any one of the preceding claims, wherein the content of xylene-soluble substance is from 2 wt.% to 7 wt.%. 6. A copolymer of propylene and butene according to any one of the preceding claims, wherein the melt flow index of the copolymer is from 0.2 g/10 min to 8 g/10 min. 7. A copolymer of propylene and butene according to any one of claims 1 to 3, wherein the melt flow rate of the copolymer is from 8 g/10 min to 220 g/10 min. 8. A copolymer of propylene and butene according to any one of the preceding claims, wherein the flexural modulus of the copolymer is greater than 1200 MPa, such as greater than 1300 MPa, such as greater than 1400 MPa, and substantially less than 2000 MPa. 9. A copolymer of propylene and butene according to any one of the preceding claims, wherein the polymer has been catalyzed using a Ziegler-Natta non-phthalate catalyst. 10. A copolymer of propylene and butene according to any one of the preceding claims, wherein the ratio of xylene soluble fractions/butene in the polymer is from 0.3 to 3.0, such as from 0.3 to 2.0 or from 0.5 to 1.0. 11. A polymer composition comprising a copolymer of propylene and butene according to any one of the preceding claims, wherein the copolymer of propylene and butene is present in the polymer composition in an amount of more than 70 wt.%, for example in an amount of more than 80 wt.%, for example in an amount of more than 90 wt.%, for example in an amount of more than 95 wt.%. 12. The polymer composition according to claim 11, additionally containing a nucleating agent. 13. The polymer composition according to claim 12, wherein the nucleating agent comprises nonite. 14. A polymer composition according to any one of claims 11 to 13, exhibiting a turbidity at 0.7 mm of 8% or less, such as 6% or less. 15. An article made from a polymer composition according to any one of paragraphs 11-14, which is an injection molded article, a blow molded article, a thermoformed article, a film or fiber. 16. An article that is a blow molded article, a thermoformed article, a film or a fiber made from a polymer composition containing a copolymer of propylene and butene containing: propylene as a primary monomer; butene from 1 wt. % up to 12 wt. %; xylene-soluble fraction from 1.0 wt.% to 8.0 wt.%; and molecular weight distribution (Mw/Mn) greater than 3.5; substituted phenylene aromatic diester; and antioxidant and antacid. 17. The product according to item 16, which is a cup, bottle or container. 18. The product according to item 16, which is packaging. 19. The article according to claim 16, wherein the butene content in the copolymer is from 2 wt.% to 8 wt.%, for example from 2 wt.% to 6 wt.%. 20. The product according to claim 19, wherein the copolymer has a heat deformation temperature of more than 75°C. 21. An article according to any one of claims 19 or 20, wherein the copolymer has a melting point of from 145°C to 155°C, for example from 147°C to 155°C. 22. An article according to any one of paragraphs 16-21, in which the content of the xylene-soluble substance is from 2 wt.% to 7 wt.%. 23. An article according to any one of paragraphs 16-22, wherein the melt flow rate of the copolymer is from 0.2 g/10 min to 4 g/10 min. 24. An article according to any one of paragraphs 16-23, in which the ratio of the content of xylene-soluble fractions/butene is from 0.3 to 3.0, for example from 0.3 to 2.0. 25. An article according to any one of paragraphs. 16-24, in which the copolymer of propylene and butene is present in the polymer composition in an amount of more than 70 wt.%, for example in an amount of more than 80 wt.%, for example in an amount of more than 90 wt.%, for example in an amount of more than 95 wt.%. 26. An article according to any one of paragraphs 16-25, wherein the composition additionally contains a nucleating agent. 27. The article according to claim 26, wherein the nucleating agent comprises nonite. 28. The article according to any one of claims 16 to 27, wherein the polymer composition exhibits a turbidity at 0.7 mm of 8% or less, such as 6% or less.