RU2802810C2 - Random copolymers of propylene and ethylene with a low xs/et ratio and a high mfr - Google Patents

Abstract

FIELD: polymer compositions.

SUBSTANCE: present invention relates to a group of inventions: a propylene-ethylene copolymer with high flow rates, a polymer composition for moulding moulded products, an injection moulded product, a film, a packaging container for hot products, a storage container. A propylene-ethylene copolymer with high flow rates contains more than 90 wt% of propylene, 2.0–5.0 wt% of ethylene (ET). The amount of xylene (XS) soluble fraction in the copolymer is such that the XS/ET ratio in the copolymer is less than 1.51. The melt flow index of the copolymer is greater than 45 g/10 min at a temperature of 230°C and a load of 2.16 kg, and the molecular weight distribution (Mw/Mn) of the copolymer is greater than 2.8. The polymer composition contains a copolymer of propylene and ethylene in an amount of more than 70 wt%. The injection moulded article, the hot product packaging container, and the storage container are made from this resin composition.

EFFECT: obtaining a static propylene copolymer with improved transparency.

29 cl, 2 tbl, 33 ex

Description

Related applications

This application is based upon and claims the benefit of U.S. Provisional Patent Application No. 62/683,124, filed June 11, 2018, the contents of which are incorporated herein by reference.

Prerequisites for creating the invention

Polypropylene polymers are extremely flexible thermoplastic polymers that can be used in a wide variety of applications. For example, polypropylene polymers can be extruded into a variety of forms, including films and fibers, and can be molded into products with relatively simple or complex shapes. Polypropylene polymers are used to produce, for example, carpeting, carpet backing, food packaging, rigid containers, technical parts such as automobile parts, drain and pressure pipes, etc., and various consumer products including parts furniture, 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 for a specific application by combining propylene monomers with other monomers to give them different properties.

For example, copolymerization of propylene with small amounts of ethylene allows one to obtain random copolymers with unique properties. The resulting copolymer, for example, may have a lower degree of crystallinity than the polypropylene homopolymer, resulting in improved clarity, impact resistance and lower heat sealing temperatures. Polypropylene-ethylene random copolymers also generally have a lower melting point, which may limit their use in applications requiring high temperatures. In addition, when exposed to higher temperatures, the transparency of polymers tends to deteriorate. For example, during the aging process, not only is additional crystallization possible, but clouding may also occur, which leads to the formation of a matte surface layer.

In light of the above, there is currently a need for a propylene random copolymer that is able to withstand higher temperatures. In particular, there is a need for a propylene random copolymer that has increased strength and therefore higher thermal resistance. In addition, there is a need for a random propylene copolymer with improved clarity characteristics, especially after aging. In addition, there is a need for an improved propylene copolymer that has one of the above characteristics as well as improved flow characteristics, making the polymer well suited for applications requiring injection molding.

Summary of the invention

The present invention generally relates to propylene copolymers, such as random copolymers of propylene and ethylene, which have been found to have an excellent combination of properties. The propylene copolymers according to the present disclosure are prepared using a Ziegler-Natta catalyst (without the use of metallocenes) so as to produce a random copolymer with a very small fraction or very low content of xylene solubles. Random copolymers also have relatively high strength and are resistant to thermal aging haze, resulting in excellent polymer clarity properties. Random copolymers can also be prepared in such a way that they have relatively higher thermal deformation resistance, making the polymers quite suitable for higher temperature applications than many copolymers produced in the past. It is a particular advantage that the propylene random copolymers of the present disclosure can be produced with the above properties while maintaining excellent flow characteristics. For example, the melt flow rate of copolymers can be greater than about 45 g/10 min, making the polymers well suited for applications requiring injection molding. For example, high melt flow rates allow the polymers to be used for injection molded parts and products with relatively thin walls and/or complex shapes.

For example, in one embodiment, the present disclosure relates to a high flow propylene copolymer that contains propylene as the primary monomer and has an alpha-olefin comonomer content of less than about 5 wt.%, such as from about 3% to about 5 wt. %, for example from 3.1% to about 4.7 wt.%. In one embodiment, the comonomer is ethylene. A copolymer of propylene is also formed with very little xylene soluble fraction, such that the ratio of xylene soluble fraction (XS) to comonomer or ethylene (ET) is less than or equal to about 1.51, such as about 1.2 to about 1.5. In addition, the melt flow rate of the copolymer is greater than about 45 g/10 min, for example from about 45 g/10 min to about 140 g/10 min, for example from about 45 g/10 min to about 120 g/10 min, for example from about 45 g/10 min to about 100 g/10 min. For example, in one embodiment, the copolymer may be formulated to have a melt flow rate of from about 50 g/min to about 80 g/10 min. In an alternative embodiment, the copolymer may be formulated to have a melt flow rate of from about 80 g/10 min to about 100 g/10 min.

Typically, the xylene-soluble fraction content of the copolymer is less than about 7%, such as less than about 6%, such as less than about 5%, and substantially more than about 1%, such as more than about 2%. To form a random propylene copolymer, a Ziegler-Natta catalytic system that includes an internal electron donor containing a substituted phenylene aromatic diester can be used. The catalyst system may further include other donors such as dicyclopentyldimethoxysilane or n-propyltrimethoxysilane.

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

The polymer composition can be formulated to have excellent clarity properties. For example, at 40 mils, the composition may exhibit a haze of less than about 15%, and after thermal aging for 24 hours at 55°C, the haze is reduced by no more than about 15%, such as by no more than about 14%, such as no more than about 13%, such as no more than about 12%.

The present description also applies to injection molded articles from the polymer composition described above. In one embodiment, the polymeric product is a hot food packaging container that is designed to hold hot food products, such as, for example, take-out foods. The polymer composition of the present disclosure can also be used to form storage containers, such as containers or trays for organized storage, suitable for use in non-air-conditioned areas such as garages, attics, warehouses and the like. A wide range of embodiments are contemplated, including storage media packaging (eg for DVDs).

Detailed description

The present disclosure includes propylene-alpha-olefin copolymer compositions and methods for preparing propylene copolymer compositions. The compositions may include a random copolymer of propylene and ethylene. Propylene-ethylene copolymer compositions are particularly suitable for hot food packaging. In particular, the propylene copolymer compositions of the present disclosure can be used to form rigid containers and films for packaging and sealing hot foods and beverages. The compositions of the present disclosure may be particularly preferred for use with foodstuffs that are subject to pasteurization during packaging.

In addition to hot food packaging containers, the present disclosure can be used in a variety of other applications. For example, propylene random copolymers and compositions containing such copolymers can be used to make other storage containers. For example, the polymer composition of the present disclosure can be used to produce clear or translucent long-term storage containers configured for use in non-air-conditioned areas, attics, garages, warehouses, or other storage areas where the containers may be exposed to temperature cycles, including relatively high temperatures and relatively low temperatures.

Advantages of the various propylene-ethylene copolymer compositions of the present invention include increased strength for container applications. The compositions may also exhibit reduced haze and reduced turbidity even at elevated temperatures and over extended periods of time. The compositions herein may feature reduced levels of xylene extractables and xylene solubles, making the polymer compositions safe for consumer use and more closely compliant with US Food and Drug Administration (FDA) standards. The propylene-ethylene copolymer compositions of the present disclosure may also be used for packaging intended to reheat stored food products in a microwave oven.

The propylene copolymer of the present disclosure can provide the above benefits and can be used in the above applications while maintaining excellent flow properties, making the polymer well suited for injection molding processes. For example, the flow properties of the polymer facilitate the molding of thin-walled products and products of complex shapes. For example, the melt flow rate of the propylene copolymer of the present invention may be greater than about 45 g/10 min, such as greater than about 50 g/10 min, such as greater than about 55 g/10 min, such as greater than about 60 g/10 min, for example more than about 65 g/10 min, for example more than about 70 g/10 min, for example more than about 75 g/10 min, for example more than about 80 g/10 min, for example more than about 85 g/10 min, and typically less than about 150 g/10 min, such as less than about 125 g/10 min, such as less than about 100 g/10 min.

I. Definitions and testing procedures

As used herein, the term “propylene-ethylene copolymer” means a copolymer containing propylene monomer at a predominant weight percentage relative to ethylene monomer as a secondary constituent. A "propylene-ethylene copolymer" (also sometimes called polypropylene random copolymer, PPR, PP-R, RCP, or RACO) is a polymer having individual repeating ethylene monomer units present in a random or random distribution throughout the polymer chain.

Melt Flow Index (MFR) as used herein is measured in accordance with the test method set forth in ASTM D 1238 at 230°C with a 2.16 kg load for propylene-based polymers. The melt flow index can be measured on the polymer in pellet form or on the powder exiting the reactor. When measuring the powder leaving the reactor, a stabilizing complex can be added, which includes 2000 ppm of the antioxidant CYANOX 2246 (methylene bis(4-methyl-6-tert-butylphenol)), 2000 ppm of the antioxidant IRGAFOS 168 (tris(2,4 -di-tert-butylphenyl)phosphite) and 1000 ppm ZnO deoxidizer.

Xylene solubles (XS) are defined as the percentage by weight of resin that remains in solution after dissolving a sample of polypropylene random copolymer resin in hot xylene and cooling the solution to 25°C. This method is also referred to as the gravimetric XS method according to ASTM D5492-98 using a 90 minute settling time and is also referred to herein as the "wet method". The amount of substances soluble in xylene is determined by the powder leaving the reactor, without introducing any other additives.

In the Viscotek method, calibration is carried out according to the ASTM gravimetric method, which is implemented as follows. Using a method adapted from the ASTM D5492-06 method, also sometimes referred to herein as the “wet method,” the xylene soluble portion content is determined. The procedure involves weighing a 2 g sample and dissolving the sample in 200 ml 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 under nitrogen (N ₂ ) until condensation appears, and then maintained at reflux for a further 30 minutes. The solution is then cooled in a water bath maintained at 25°C for 90 minutes to allow the xylene-insoluble fraction to crystallize. After the solution has cooled and the insoluble fraction has precipitated out of 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 is collected in a pre-weighed aluminum bowl and o-xylene is evaporated from the said 100 ml of filtrate under a stream of nitrogen. After the solvent has evaporated, the tray and contents are placed in a vacuum oven at 100°C for 30 minutes or until dry. The tray is then allowed to cool to room temperature and weighed. The content of the xylene-soluble part is calculated using the formula: XS (wt. %) = [(m ₃ ⁻ m ₂ ) * 2/m ₁ ] * 100, where m ₁ is the initial mass of the sample used, m ₂ is the mass of the empty aluminum pan, and m ₃ is the mass of the pallet and the remainder (here and throughout the description, the “asterisk” symbol (*) means the product of the given terms or meanings).

The term "regularity of molecular structure" generally refers to the relative stereochemical structure of adjacent chiral centers located within a polymer macromolecule. 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 considered isotactic; if it is opposite in configuration, it is called syndiotactic. Another way to describe the configuration relationship is that adjacent pairs of monomers having the same chirality are called meso- (m), and pairs with the opposite configuration are called racemic (r).

The regularity or stereochemistry of macromolecules in general and polypropylene or polypropylene random copolymers in particular can be described or quantified in terms of the concentration of triads. An isotactic triad, usually abbreviated "mm", consists of two adjacent meso-dyads that have the same configuration, and therefore the stereoregularity of the triad is denoted "mm". If two adjacent monomers in a three-monomer sequence have the same chirality that differs from the relative configuration of the third unit, the triad has molecular structure regularity "mr". The “mr” triad has a middle monomer unit that has a configuration opposite to that of both neighbors. It is possible to determine the content of triad fractions of each type in a polymer and, by multiplying them by 100, obtain the percentage of a given type of triad in the polymer. In this document, the percentage mm parameter is used to identify and characterize polymers.

The distribution of monomers according to the order of arrangement in the polymer can be determined by ¹³ C NMR, which also allows one to determine the arrangement of ethylene residues in relation to neighboring propylene residues. The ¹³ C NMR method can be used to determine ethylene content, Koenig B value, triad distribution and triad regularity and is performed as described below.

Samples are prepared by adding about 2.7 g of a 50/50 tetrachloroethane-d2/orthodichlorobenzene mixture 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 block and a heat gun. Each sample is inspected to ensure uniformity.

Data collection is carried out using a Bruker 400 MHz spectrometer equipped with a Bruker Dual DUL CryoProbe high temperature sensor. Data collection is carried out using 320 transitions per data file, a pulse repetition delay of 6 s, a magnetization vector deflection angle of 90 degrees, inverse suppression mode and a sample temperature of 120°C. All measurements are carried out on non-rotating samples in blocking mode. Samples were allowed to reach thermal equilibrium for 7 min before data collection. The regularity of the molecular structure in percentage mm and the mass percentage of ethylene were calculated using methods commonly used in the art, which are briefly described below.

With respect to the measurement of chemical shifts of resonance frequencies, the third methyl group in a sequence of 5 contiguous propylene units consisting of head-to-tail bonds and having the same relative chirality is assumed to be 21.83 ppm. The chemical shift of other carbon resonance frequencies is determined using the above 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 million), third region (19.5–20.4 ppm) and fourth region (17.0–17.5 ppm). Each peak in the spectrum is deciphered using a literary 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.

The first region contains the signal of the central methyl group in the PPP triad (mm). In the second region, the signal of the central methyl group in the PPP triad (mr) and the methyl group of the propylene unit, adjacent to which the units are a propylene unit and an ethylene unit (PPE-methyl group), resonate. In the third region, the signal of the central methyl group in the PPP triad (rr) and the methyl group of the propylene unit, adjacent to which the units are ethylene units (EPE-methyl group), resonate.

The PPP (mm), PPP (mr) and PPP (rr) groups have the following chain structure of three propylene units with head-to-tail bonds, respectively. This is shown in the Fischer projection formulas below.

The regularity of the molecular structure of the triad (mm fraction) of propylene random copolymer can be determined from the ¹³ C NMR spectrum of propylene random copolymer using the formula below:

The peak areas used in the above calculation are not measured directly from the triad regions in the ¹³ C NMR spectrum. From these, it is necessary to subtract the intensities of the mr and rr triad regions due to the order of the EPP and EPE groups, respectively. The EPP area can be determined from the signal at 30.8 ppm after subtracting from it half the area for the sum of the signals between 26 and 27.2 ppm and the signal at 30.1 ppm. The area due to EPE can be determined from the signal at 33.2 ppm.

For convenience, ethylene content was also measured by Fourier transform infrared spectroscopy (FTIR), the results of which correlated with the ethylene content values determined by the above-mentioned ¹³ C NMR as the primary method. The relationship and agreement between measurements made using these two methods are described, for example, in 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.

The "Koenig B value" or "B value" or "chi statistic" is one measure of disorder or blockiness in a propylene-ethylene random copolymer. A Koenig B value of 1.0 characterizes a random copolymer, and a value of zero indicates complete block polymerization of monomers A and B; in this description - propylene and ethylene. A Koenig B value of 2 indicates a perfectly alternating copolymer (that is, a polymer defined by the A-B-A-B-A-B structure). The Koenig B value can be calculated as follows: B = [EP]/(2[P][E]), where [EP] is the total mole fraction of EP dimers (EP + PE or (EEP + PPE + PEP + EPE) ), [E] is the mole fraction of ethylene, and [P] = 1 - [E]. For more information on determining and calculating the value of B, see Koenig, Jack L.; Spectroscopy of Polymers, 2nd ed., which describes in detail the determination and calculation of Koenig's B value.

II. Compositions of random copolymer of propylene and ethylene

The propylene-ethylene copolymer compositions of the present disclosure may include propylene monomer at a predominant percentage by weight with an alpha-olefin monomer, such as ethylene, as a secondary moiety. The ethylene (ET) content of the propylene-ethylene copolymer compositions of the present disclosure can range from about 2.0 to about 5.0 wt% of the copolymer, preferably from about 3.0 to about 5.0 wt%, and more preferably from about 3 .1 to about 4.7 wt.%.

The xylene soluble (XS) content of the copolymers of the present invention (measured by the wet method) may be less than or equal to ( )7.0 wt.% copolymer or 6.0 wt%, more preferably 5.0 wt.% and even more preferably 4 wt.%, for example 6.5 wt.%, 5.5 wt.%, 4.5 wt.% or 3.5 wt.%. The content of the xylene soluble (XS) fraction is preferably in the range of 2.0 mass% to 7.0 mass%, 3 mass% to 7 mass%.

The melt flow rate of the propylene-ethylene copolymer may be substantially greater than about 45 g/10 min, such as greater than about 55 g/10 min, such as greater than about 65 g/10 min, such as greater than about 75 g/10 min, for example more than about 85 g/10 min, for example more than about 95 g/10 min, for example more than about 105 g/10 min, for example more than about 115 g/10 min. The melt flow rate is typically less than about 145 g/10 min, such as less than about 120 g/10 min, such as less than about 100 g/10 min.

The weight ratio of xylene solubles (XS) to ethylene content (ET) is an important aspect of embodiments of the present disclosure and may be referred to as the xylene solubles to ethylene ratio or XS/ET ratio. The XS/ET ratio in the propylene-ethylene copolymer compositions of the present disclosure may be less than or equal to ( )1.5 or 1.4, more preferable 1.2 and even more preferably 1.0, for example 1.8, 1.4, 1.1 or 0.95. The XS/ET ratio may also range from 0.5 to 1.51, 1.0 to 1.5, or 1.2 to 1.5.

In one embodiment, the polymer composition may contain an active site initiator. For example, the active site initiator may be the active site initiator leading to the alpha form. Examples of site initiators and/or brighteners that can be used in the polymer composition include benzoamide derivatives, sorbitol derivatives, nonitol derivatives, and mixtures thereof. Specific examples of site initiators include the site initiator NA-11 from Adeka Palmarole SAS, such as sodium 2,2'-methylene-bis-(4,6-di-tert-butylphenyl)phosphate. Other active site initiators that may be used include HPN active site initiators manufactured by Milliken and Company, Spartanburg, South Carolina, including HPN-600ei. Other acceptable clarifiers from Milliken include Millad NX8000 and Millad 3988i.

The copolymer of the present disclosure is essentially 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 using gel permeation chromatography (GPC).

III. Preparation of a random copolymer of propylene and ethylene

Embodiments of the present invention can be prepared by any method for polymerizing propylene-based polymers known in the art. These methods include the gas-phase UNIPOL® process using a supported Ziegler-Natta catalyst. Particularly preferred are CONSISTA® catalysts from W.R. Grace & Co., Columbia, Maryland. Suitable polypropylene random copolymers can be produced using a single reactor or multiple reactors to produce a multimodal product. For some embodiments, it is preferable to use internal electron donors that do not contain phthalates.

Methods and catalyst compositions for producing useful PP-R copolymers are described, for example, in WO 2011/084628, and others are substantially described in US patent No. 7,381,779; 7,491,670; 7,678,868; 7,781,363; and 7,989,383. Random copolymers of propylene and ethylene, having high molecular weight and low MFR, are prepared using stereospecific catalysts, sometimes called 6th generation Ziegler-Natta catalysts, containing phthalate-free internal donors, as described in US patents No. 8,288,585; 8,536,372; 8,778,826; US 2013/0338321; and/or WO 2010/078494, etc. Also suitable are so-called 4th generation Ziegler-Natta catalysts, usually containing phthalate internal donors (eg diisobutyl phthalate, DIBP). Each of the patents mentioned above is incorporated herein by reference.

Procatalyst compositions suitable for use in the preparation of random (PP-R) polypropylene copolymers include Ziegler-Natta procatalyst compositions. As is well known in the art, any conventional Ziegler-Natta procatalyst can be used in the present catalyst composition as long as it is capable of producing the claimed PP-R copolymers. In one embodiment, the Ziegler-Natta procatalyst composition contains a titanium functional group such as titanium chloride, a magnesium functional group such as magnesium chloride, and an internal electron donor.

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

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

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.

As used herein, the terms “substituted hydrocarbyl group” and “substituted hydrocarbon” mean a hydrocarbyl group that is substituted with one or more substituent groups other than hydrocarbyl groups. A non-limiting example of a non-hydrocarbyl 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 hydrocarbyl groups also include a halohydrocarbyl group and a silicon-containing hydrocarbyl group. As used herein, the term “hydrocarbyl” group means a hydrocarbyl group that is substituted with one or more halogen atoms. As used herein, the term “silicon-containing hydrocarbyl group” means a hydrocarbyl group that is substituted by one or more silicon atoms. The silicon atom(s) may or may not be included in the carbon chain.

The procatalyst precursor may include (i) magnesium, (ii) a transition metal compound of an element from Groups IV to 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 the halides, oxyhalides and alkoxides of magnesium, manganese, titanium, vanadium, chromium, molybdenum, zirconium, hafnium and combinations thereof.

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 group precursor (MagMo). The MagMo precursor contains magnesium as the only metal component. The MagMo precursor includes 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 alkoxy halide, 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.

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 , where R ^e is an aliphatic or aromatic hydrocarbon radical having from 1 to 14 carbon atoms, or COR', where 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. Precursors are prepared by controlled precipitation by removing the alcohol from the reaction mixture used in their preparation. In one embodiment, the reaction medium contains 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, especially titanium tetrachloride. Removal of the alkanol from the solution used in halogenation results in the precipitation of a solid precursor having a particularly desirable morphology and surface area. Moreover, the resulting precursors are particularly uniform in particle size.

The present procatalyst composition may also include an internal electron donor. As used herein, the term “internal electron donor” means a compound added during the formation of a procatalyst composition that donates a pair of electrons to one or more metals present in the resulting procatalyst composition. Without being bound by any particular theory, the authors believe that internal electron donors help regulate the formation of active sites and thus increase the stereoselectivity of the catalyst. In one embodiment, the internal electron donor includes a substituted phenylene aromatic diester with structure (I) presented above.

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 the halogenation procedure detailed in U.S. Patent No. 8,536,372, which is incorporated herein by reference in its entirety, in which a procatalyst precursor and a substituted phenylene aromatic diester donor are converted to a combination of magnesium and titanium functional groups in which internal electron donor. The procatalyst precursor from which the procatalyst composition is formed may be a magnesium functional group, a mixed magnesium/titanium compound, or a benzoate-containing magnesium chloride.

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.

In one embodiment, the internal electron donor of the procatalyst composition includes a substituted phenylene aromatic diester with structure (I) presented above, wherein 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, and at least one of R ₁ – R ₁₄ is not hydrogen.

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

In one embodiment, at least one (or some or all) R group(s) of R ₅ -R ₁₄ 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, 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 -R ₉ groups and at least one of the R ₁₀ -R ₁₄ 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, an alkoxy group having from 1 to 20 carbon atoms, a heteroatom and combinations thereof.

In one embodiment, at least one of the R ₁ -R ₄ groups and at least one of the R ₅ -R ₁₄ 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, an alkoxy group having from 1 to 20 carbon atoms, a heteroatom and combinations thereof. In another embodiment, at least one of the R ₁ -R ₄ groups, at least one of the R ₅ -R ₉ groups and at least one of the R ₁₀ -R ₁₄ 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, an alkoxy group having from 1 to 20 carbon atoms, a heteroatom and combinations thereof.

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 intermolecular cyclic or intramolecular cyclic structure. Such inter- or 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.

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

In one embodiment, any successive R groups in R ₁ -R ₄ , and/or in R ₅ -R ₉ , and/or in R ₁₀ -R ₁₄ may be included in a C ₅ -C ₆ -membered ring.

In one embodiment, structure (I) includes the groups R ₁ , R ₃ and R ₄ , which represent hydrogen. The R ₂ group is selected from a substituted hydrocarbon group having 1 to 20 carbon atoms, an unsubstituted hydrocarbon group having 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, halogen and their combinations.

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 may represent a methyl group, ethyl group, n-propyl group, isopropyl group, tert-butyl group, isobutyl group, sec-butyl group, 2,4,4-trimethylpentan-2-yl group, cyclopentyl group and cyclohexyl group .

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

In one embodiment, structure (I) includes the groups R ₂ , R ₃ and R ₄ , each of which is hydrogen, and the group R ₁ 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 their combinations. The groups R ₅ -R ₁₄ 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, halogen and their combinations.

In one embodiment, structure (I) includes an _R1 group, which represents methyl, and each of the _R5 through _R14 groups represents hydrogen.

In one embodiment, structure (I) includes R ₂ and R ₄ groups, which represent hydrogen, and the R ₁ and R ₃ groups may be the same or different. Each of the groups R ₁ and R ₃ 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 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, halogen and their combinations.

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 C ₁ -C ₈ alkyl groups include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, t-butyl, n-pentyl, isopentyl, neopentyl, t-pentyl, n-hexyl and 2,4,4-trimethylpentan-2-yl group. Non-limiting examples of suitable C ₃ -C ₆ cycloalkyl groups include cyclopentyl and cyclohexyl groups. In a further embodiment, at least one of the R ₅ -R ₁₄ groups is a C ₁ -C ₈ alkyl group or a halogen.

In one embodiment, structure (I) includes an R ₁ group, which is a methyl group, and an R ₃ group, which is a tert-butyl group. The groups R ₂ , R ₄ and R ₅ –R ₁₄ each represent hydrogen.

In one embodiment, structure (I) includes R ₁ and R ₃ groups, each of which is an isopropyl group. The groups R ₂ , R ₄ and R ₅ –R ₁₄ each represent hydrogen.

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

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

In one embodiment, structure (I) includes an R ₁ group, which is a methyl group, and an R ₃ group, which is a tert-butyl group. The groups R ₇ and R ₁₂ each represent an ethyl group. The groups R ₂ , R ₄ , R ₅ , R _{6 ,} R ₈ , R ₉ , R ₁₀ , R ₁₁ , R ₁₃ and R ₁₄ are each hydrogen.

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

In one embodiment, structure (I) includes an R ₁ group, which is a methyl group, and an R ₃ group, which is a tert-butyl group. The groups R ₅ , R ₇ , R ₉ , R ₁₀ , R ₁₂ and R ₁₄ are each an isopropyl group. The groups R ₂ , R ₄ , R ₆ , R ₈ , R ₁₁ and R ₁₃ are each hydrogen.

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 detailed in US Pat. No. 8,536,372, which is included incorporated into this document by reference.

In one embodiment, structure (I) includes an R ₁ group, which is a methyl group, and an R ₃ group, which is a tert-butyl group. The groups R ₇ and R ₁₂ are each an ethoxy group. The groups R ₂ , R ₄ , R ₅ , R _{6 ,} R ₈ , R ₉ , R ₁₀ , R ₁₁ , R ₁₃ and R ₁₄ are each hydrogen.

In one embodiment, structure (I) includes an R ₁ group, which is a methyl group, and an R ₃ group, which is a tert-butyl group. The groups R ₇ and R ₁₂ each represent a fluorine atom. The groups R ₂ , R ₄ , R ₅ , R _{6 ,} R ₈ , R ₉ , R ₁₀ , R ₁₁ , R ₁₃ and R ₁₄ are each hydrogen.

In one embodiment, structure (I) includes an R ₁ group, which is a methyl group, and an R ₃ group, which is a tert-butyl group. The groups R ₇ and R ₁₂ each represent a chlorine atom. The groups R ₂ , R ₄ , R ₅ , R _{6 ,} R ₈ , R ₉ , R ₁₀ , R ₁₁ , R ₁₃ and R ₁₄ are each hydrogen.

In one embodiment, structure (I) includes an R ₁ group, which is a methyl group, and an R ₃ group, which is a tert-butyl group. The groups R ₇ and R ₁₂ each represent a bromine atom. The groups R ₂ , R ₄ , R ₅ , R _{6 ,} R ₈ , R ₉ , R ₁₀ , R ₁₁ , R ₁₃ and R ₁₄ are each hydrogen.

In one embodiment, structure (I) includes an R ₁ group, which is a methyl group, and an R ₃ group, which is a tert-butyl group. The groups R ₇ and R ₁₂ each represent an iodine atom. The groups R ₂ , R ₄ , R ₅ , R _{6 ,} R ₈ , R ₉ , R ₁₀ , R ₁₁ , R ₁₃ and R ₁₄ are each hydrogen.

In one embodiment, structure (I) includes an R ₁ group, which is a methyl group, and an R ₃ group, which is a tert-butyl group. The groups _R6 , _R7 , _R11 and _R12 each represent a chlorine atom. The groups R ₂ , R ₄ , R ₅ , R ₈ , R ₉ , R ₁₀ , R ₁₃ and R ₁₄ are each hydrogen.

In one embodiment, structure (I) includes an R ₁ group, which is a methyl group, and an R ₃ group, which is a tert-butyl group. The groups _R6 , _R8 , _R11 and _R13 each represent a chlorine atom. The groups R ₂ , R ₄ , R ₅ , R ₇ , R ₉ , R ₁₀ , R ₁₂ and R ₁₄ are each hydrogen.

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

In one embodiment, structure (I) includes an R ₁ group, which is a methyl group, and an R ₃ group, which is a tert-butyl group. The groups R ₇ and R ₁₂ are each a trifluoromethyl group. The groups R ₂ , R ₄ , R ₅ , R _{6 ,} R ₈ , R ₉ , R ₁₀ , R ₁₁ , R ₁₃ and R ₁₄ are each hydrogen.

In one embodiment, structure (I) includes an R ₁ group, which is a methyl group, and an R ₃ group, which is a tert-butyl group. The groups R ₇ and R ₁₂ are each an ethoxycarbonyl group. The groups R ₂ , R ₄ , R ₅ , R _{6 ,} R ₈ , R ₉ , R ₁₀ , R ₁₁ , R ₁₃ and R ₁₄ are each hydrogen.

In one embodiment, the group R ₁ is a methyl group and the group R ₃ is a tert-butyl group. The groups R ₇ and R ₁₂ are each an ethoxy group. The groups R ₂ , R ₄ , R ₅ , R _{6 ,} R ₈ , R ₉ , R ₁₀ , R ₁₁ , R ₁₃ and R ₁₄ are each hydrogen.

In one embodiment, structure (I) includes an R ₁ group, which is a methyl group, and an R ₃ group, which is a tert-butyl group. The groups R ₇ and R ₁₂ each represent a diethylamine group. The groups R ₂ , R ₄ , R ₅ , R _{6 ,} R ₈ , R ₉ , R ₁₀ , R ₁₁ , R ₁₃ and R ₁₄ are each hydrogen.

In one embodiment, structure (I) includes an R ₁ group, which is a methyl group, and an R ₃ group, which is a 2,4,4-trimethylpentan-2-yl group. The groups R ₂ , R ₄ and R ₅ –R ₁₄ each represent hydrogen.

In one embodiment, structure (I) includes R ₁ and R ₃ groups, each of which is a sec-butyl group. The groups R ₂ , R ₄ and R ₅ –R ₁₄ each represent hydrogen.

In one embodiment, structure (I) includes R ₁ and R ₄ groups, each of which is a methyl group. The groups R ₂ , R ₃ , R ₅ –R ₉ and R ₁₀ –R ₁₄ each represent hydrogen.

In one embodiment, structure (I) includes an R ₁ group, which is a methyl group. The R ₄ group represents an isopropyl group. The groups R ₂ , R ₃ , R ₅ –R ₉ and R ₁₀ –R ₁₄ each represent hydrogen.

In one embodiment, structure (I) includes the groups R ₁ , R ₃ and R ₄ , each of which is an isopropyl group. The groups R ₂ , R ₅ –R ₉ and R ₁₀ –R ₁₄ each represent hydrogen.

In one embodiment, a different procatalyst composition is provided. The 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 phthalate, diester, benzoate, and combinations thereof. The mixed internal electron donor procatalyst composition can be prepared using the procatalyst preparation procedure described in the previously reported patents and publications referenced herein.

For example, suitable catalyst compositions contain a procatalyst composition, a cocatalyst, and an external electron donor or 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 controlling agents (SCAs), or both ALA and SCA agents. As used herein, the term “external electron donor” means a component or composition containing a mixture of components added independently of the formation of the procatalyst that modify the effectiveness of the catalyst. As used herein, the term “activity limiting agent” means a composition that reduces the activity of a catalyst when the polymerization temperature exceeds a threshold temperature in the presence of the catalyst (eg, a temperature greater than about 85°C). The term “selectivity controlling agent” means a composition that improves the regularity of the molecular structure of a polymer, whereby improved regularity of the molecular structure essentially means increased regularity of the molecular structure or a reduced content of xylene-soluble fractions, or both. It should be understood that the above definitions are not mutually exclusive and that one compound may be classified, for example, as both a potency limiting agent and a selectivity modulating agent.

In one embodiment, the external electron donor includes an alkoxysilane. Alkoxysilane has the following general formula:

SiR _m (OR′) _4-m …(I),

wherein each of the R groups independently represents 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, and said R group contains up to 20 atoms, not counting hydrogen and halogen; R′ represents a C _1–4 alkyl group; and m is 0, 1, 2 or 3. In one embodiment, R is a _C6-12 arylalkyl or aralkyl, a _C3-12 cycloalkyl, a _C3-12 branched alkyl, or a _C3-12 cyclic or acyclic amino group, R' is _C1-4 alkyl, and m is 1 or 2.

Non-limiting examples of suitable silane compositions include dicyclopentyldimethoxysilane; di-tert-butyldimethoxysilane; methylcyclohexyldimethoxysilane; methylcyclohexyldiethoxysilane; ethylcyclohexyldimethoxysilane; diphenyldimethoxysilane; diisopropyldimethoxysilane; di-n-propyldimethoxysilane; diisobutyldimethoxysilane; diisobutyldiethoxysilane; isobutyl isopropyl dimethoxysilane; di-n-butyldimethoxysilane; cyclopentyltrimethoxysilane; isopropyltrimethoxysilane; n-propyltrimethoxysilane; n-propyltriethoxysilane; ethyltriethoxysilane; tetramethoxysilane; tetraethoxysilane; diethylaminotriethoxysilane; cyclopentylpyrrolidine dimethoxysilane; 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.

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

The mixed external electron donor system may also include an activity limiting agent (ALA). ALA inhibits or otherwise prevents disruption of the polymerization reactor and ensures continuity of the polymerization process. Typically, as the reaction temperature increases, the activity of Ziegler-Natta catalysts increases. Ziegler-Natta catalysts also typically retain high activity near the softening point temperature of the resulting polymer. The heat generated by the exothermic polymerization reaction can cause agglomerates to form from the polymer particles and ultimately disrupt the continuity of the polymer production process. ALA reduces the activity of the catalyst at elevated temperatures, thereby preventing disturbances in the operation of the reactor, reduces (or prevents) particle agglomeration and ensures continuity of the polymerization process.

The activity limiting agent may be a carboxylic acid ester, a diester, a poly(alkene glycol), a diol ester, and combinations thereof. The carboxylic acid ester may 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-amyltoluate; ethyl cyclohexanoate and propyl pivalate.

Non-limiting examples of suitable polycarboxylic acid esters include dimethyl phthalate; diethyl phthalate; di-n-propyl phthalate; diisopropyl phthalate; di-n-butyl phthalate; diisobutyl phthalate; di-tert-butyl phthalate; diisoamyl phthalate; di-tert-amyl phthalate; dineopentyl phthalate; di-2-ethylhexyl phthalate; di-2-ethyldecyl phthalate; diethyl terephthalate; dioctyl terephthalate and bis-[4-(vinyloxy)butyl] terephthalate.

An 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 or branched, may be saturated or unsaturated, and may be any combination of these ethers. A _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 _C1-20 alkyl esters esters of aliphatic C _6–30 monocarboxylic acids, C _1–20 alkyl esters of aliphatic C _8–20 monocarboxylic acids, C _1–4 allylic mono- and diesters of aliphatic C _4–20 monocarboxylic acids and dicarboxylic acids, C _1–4 alkyl esters of aliphatic C _8–20 monocarboxylic acids and dicarboxylic acids and C _6–20 mono- or polycarboxylate derivatives of C _2–100 (poly)glycols or ethers of C _2–100 (poly)glycols. In a further embodiment, the _C6 - _C30 aliphatic acid ester may be 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 triesters of C _2–40 aliphatic carboxylic acids and mixtures thereof. In a further embodiment, the C ₆ -C ₂₀ aliphatic ester is isopropyl myristate or di-n-butyl sebacate.

In one embodiment, the activity limiting agent includes a diester. The diester may be a 1,3-diester represented by the following structure (VI):

where R ₁ -R ₄ independently 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. A dialkyl ether may be straight or branched and may contain one or more of the following groups: alkyl, cycloaliphatic, aryl, alkylaryl or arylalkyl radicals of 1-18 carbon atoms and hydrogen. R ₁ and R ₂ may be coupled to form a cyclic structure such as cyclopentadiene or fluorene.

In one embodiment, the activity limiting agent includes a succinate composition having the following structure (VII):

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

In one embodiment, the activity limiting agent includes 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 may be selected from hydrogen, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert- butyl, allylic, 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 may be selected from hydrogen, halogen, a substituted or unsubstituted hydrocarbon group having 1 to 20 carbon atoms. The R ₁ -R ₆ groups may optionally contain one or more heteroatoms replacing carbon, hydrogen or both, the heteroatom being selected from nitrogen, oxygen, sulfur, silicon, phosphorus and halogen. R ₇ and R ₈ can be the same or different and can be linked at any carbon atom in the 2-, 3-, 4-, 5- and 6-positions of any of the phenyl rings.

The individual components of the external electron donor may be added to the reactor separately, or two or more components may be premixed together and then 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 dicyclopentyldimethoxysilane and isopropyl myristate; diisopropyl dimethoxysilane and isopropyl myristate; dicyclopentyldimethoxysilane and poly(ethylene glycol) laurate; dicyclopentyldimethoxysilane, isopropyl myristate and poly(ethylene glycol) dioleate; methylcyclohexyl dimethoxysilane and isopropyl myristate; n-propyltrimethoxysilane and isopropylmyristate; dimethyldimethoxysilane, methylcyclohexyldimethoxysilane and isopropyl myristate; dicyclopentyldimethoxysilane, n-propyltriethoxysilane and isopropyl myristate; diisopropyl dimethoxysilane, n-propyltriethoxysilane and isopropyl myristate; dicyclopentyldimethoxysilane, tetraethoxysilane and isopropyl myristate; dicyclopentyldimethoxysilane, diisopropyl dimethoxysilane, n-propyltriethoxysilane and isopropyl myristate and combinations thereof.

The catalyst composition includes a cocatalyst. The cocatalyst for use with the Ziegler-Natta procatalyst composition may be an aluminum-containing composition. Non-limiting examples of suitable aluminum-containing compositions include organoaluminum compounds such as trialkylaluminum; dialkylaluminum hydride; alkyl aluminum dihydride; dialkylaluminum halide; alkyl aluminum dihalide; dialkylaluminum alkoxide and alkyl aluminum dialkoxide are 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 trialkylaluminum compound such as triethylaluminum (TEA). The catalyst composition has a molar ratio of aluminum (Al) and (SCA + ALA) equal to 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 about 4.5. In one embodiment, the Al:(SCA + ALA) molar ratio is 0.5-4.0:1. The total SCA to ALA molar ratio 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

The propylene copolymers of the present disclosure can be used in a variety of different applications. As described above, propylene copolymers have excellent flow properties combined with relatively high strength, low xylene solutes content and excellent clarity characteristics, including retention of clarity characteristics over an extended period of time.

In one embodiment, the propylene copolymers of the present disclosure may be included in a composition for molding injection molded articles such as containers. For example, containers may have a bottom defining a hollow interior and a top including a flange that is sealed to the bottom. In one embodiment, the containers may include hot food packaging containers. For example, hot food packaging containers are quite suitable for filling the product at higher temperatures. Containers made in accordance with the present description are also quite suitable for heating stored foods in a microwave oven.

The propylene 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 may contain antioxidants and deoxidizing agents, and in some applications may also preferably contain other additives commonly used in PP, such as site initiators, brighteners, mold release agents, antistatic agents, antifriction agents, UV stabilizers and dyes (pigments).

In one embodiment, the copolymer composition may further comprise a type of site initiator called a brightening agent or brightening agent. A brightening agent can be added to further improve the clarity properties of the composition. For example, the brightening agent may contain a compound to form a gel-like network in the composition.

In one embodiment, the brightening agent may contain a sorbitol compound, such as a sorbitol acetal derivative. For example, in one embodiment, the brightening agent may contain dibenzylsorbitol.

With respect to sorbitol acetal derivatives that can be used as an additive in some embodiments, the 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.

In some embodiments, R1-R5 is 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 to R4 are methyl groups and R5 is hydrogen, such that the sorbitol acetal derivative is 1,3:2,4-bis(3,4-dimethylobenzylidene)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).

Other embodiments of brightening agents that may 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.

In one embodiment, the brightening agent may also contain a bisamide. The brightening agents described above can be used alone or in combination.

When brightening agents are present in the polymer composition, one or more brightening agents are substantially added in an amount greater than about 1500 ppm, such as greater than about 1800 ppm, such as greater than about 2000 ppm, e.g. amount of more than about 2200 ppm. The one or more brightening agents are typically present in an amount of 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 5000 ppm.

V. Examples

Example 1

Propylene-ethylene random copolymer samples were prepared and their properties were tested according to the procedures described above. Properties and experimental results are presented in Table 1.

Random copolymers of propylene and ethylene were prepared using a 6th generation stereospecific titanium Ziegler-Natta catalyst on a magnesium-containing support. The catalyst included a phthalate-free internal donor to produce polymers with a broader molecular weight distribution than polymers produced using a metallocene catalyst. The process for producing polymers is described in the prior art as the gas-phase UNIPOL 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 triethylaluminum as a cocatalyst.

Table 1. Examples of random copolymer of propylene and ethylene

Sample Ethylene, wt.% XS (wt.%) wet. XS/ET MFR (g/10 min) 1 4.44 6.61 1.49 87.00 2 4.47 6.61 1.48 88.70 3 3.9 5.42 1.39 50.29 4 4.2 5.42 1.30 62.28 5 4.54 5.81 1.28 59.71 6 4.57 5.81 1.27 66.80 7 4.39 6.28 1.43 81.63 8 4.37 6.28 1.44 94.40 9 4.39 6.10 1.39 95.81 10 4.41 6.10 1.38 96.09 eleven 4.45 6.15 1.38 95.53 12 4.47 6.15 1.38 91.69 13 4.20 5.70 1.36 88.64 14 4.26 5.70 1.34 88.16 15 4.21 6.18 1.47 89.63 16 4.19 6.18 1.47 91.69 17 4.25 6.25 1.47 91.95 18 4.24 6.25 1.47 91.69 19 4.23 6.16 1.46 89.39 20 4.23 6.16 1.46 88.64 21 4.14 6.04 1.46 81.63 22 4.15 6.04 1.46 83.11 23 3.29 4.74 1.44 50.19 24 3.27 4.74 1.45 52.47 25 3.26 4.89 1.50 49.28 26 3.22 4.80 1.49 49.23 27 3.18 4.80 1.51 49.10 28 3.22 4.41 1.37 49.40 29 3.20 4.41 1.38 49.16 thirty 3.25 4.18 1.29 48.26 31 3.17 4.04 1.27 45.89 32 3.21 4.42 1.38 47.90 33 3.15 4.42 1.40 45.20

Example 2

Another propylene-ethylene random copolymer was prepared as described herein using essentially the same method as described above and compared to a control which in all cases had an XS/ET ratio of 2. The propylene-ethylene random copolymers were cast molded under pressure into test plates and analyzed their turbidity. Turbidity was measured at the beginning and after thermal aging. The following statistical copolymers of propylene and ethylene were studied:

Table 2. Examples of random copolymer of propylene and ethylene

Sample Ethylene, wt.% XS (wt.%) wet. XS/ET MFR (g/10 min) Control 4.10 8.2 2.00 40.7 34 3.78 5.0 1.33 42.4

Turbidity was measured in accordance with Procedure A of ASTM D1003 based on the most recent revision of the test. Haze was measured before and after 24 hours of thermal aging at 55°C using a BYK Gardner Haze-Gard 4725. Thermal aging was performed by placing sample plates in an oven. During thermal aging, propylene polymer compositions showed a tendency to increase turbidity. Haze increases due to additional crystallization in the polymer and/or due to the formation of a dull surface layer, which is commonly referred to as haze.

When molding test plates, random copolymers of propylene and ethylene were mixed with various stabilizers. Specifically, the polymer compositions contained 500 ppm of a hindered phenolic antioxidant, pentaerythritol tetrakis (3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate). Phosphite stabilizer was added at 700 ppm. The phosphite stabilizer was tris(2,4-ditert-butylphenyl)phosphite. The deoxidizer was added at a concentration of 200 ppm. Hydrotalcite was used as a deoxidizer. The antistatic agent was added at a concentration of 500 ppm. The antistatic agent included distilled monoglyceride, in particular the deoxidizing agent DIMODAN HS K-A GMS90 manufactured by DuPont. A brightening agent was also added to the compositions at a concentration of 1800 ppm. 1,2,3-trideoxy-4,6:5,7-bis-O-[(4-propylphenyl)methylene]nonitol was used as a brightening agent.

The polymer compositions were injection molded into slabs of three different thicknesses: 40 mil, 80 mil and 125 mil. The turbidity of the plates was assessed before and after storage in the oven. The following results were obtained.

Turbidity measurement Before oven treatment % After oven treatment % Before after % increase Visually Blurring Control 9.5 22.4 42.6 15.0 26.0 49.6 5.5 3.6 7.0 36.7 13.9 14.2 4 4 Sample 34 10.3 24.0 44.2 11.6 25.9 46.4 1.3 1.9 2.2 11.4 7.3 4.7 N N

As shown above, the propylene-ethylene random copolymer of the present disclosure unexpectedly exhibited improved turbidity performance compared to similar conventional propylene-ethylene random copolymers. For example, one important result is the absence of visual haze or blurring even after heat treatment.

As shown above, polymer compositions formulated herein may exhibit a haze of less than about 15%, such as less than about 12%, such as less than about 11%, at 40 mils. In addition, after aging for 24 hours at 55°C, the increase in turbidity is less than about 15%, such as less than about 14%, such as less than about 13%, such as less than about 12%. When measuring an 80 mil thick sample, the initial haze is substantially less than about 35%, such as less than about 30%, such as less than about 25%. After thermal aging for 24 hours at 55°C, the percentage increase in turbidity is substantially less than about 12%, such as less than about 11%, such as less than about 10%, such as less than about 9%, such as less than about 8% , for example less than about 7.5%. When measuring a 125 mil thick sample, the initial haze is substantially less than about 50%, such as less than about 46%, such as less than about 45%. After thermal aging for 24 hours at 55°C, the percentage increase in turbidity is substantially less than about 10%, such as less than about 8%, such as less than about 6%, such as less than about 5%.

These and other modifications and variations of the present invention may be implemented by those skilled in the art without departing from the spirit and scope of the present invention, which are more specifically set forth in the appended claims. In addition, it should be understood that aspects of the various embodiments may be completely or partially interchangeable. Moreover, those skilled in the art will appreciate that the above description is provided by way of example only and is not intended to limit the invention, which is further described in the accompanying claims.

Claims (30)

1. A copolymer of propylene and ethylene with high fluidity rates, containing: the proportion of propylene is more than 90 wt.%, and the specified copolymer contains ethylene (ET) in an amount from 2.0 wt.% to 5.0 wt.%, and the amount of xylene soluble (XS) fraction in the copolymer is such that the ratio XS /ET in the copolymer is less than 1.51, and the melt flow rate of the copolymer is more than 45 g/10 min at a temperature of 230°C and a load of 2.16 kg, and the molecular weight distribution (Mw/Mn) of the copolymer is more than 2 ,8. 2. A copolymer of propylene and ethylene according to claim 1, in which the ethylene content is from 3.0 wt.% to 5.0 wt.%. 3. A copolymer of propylene and ethylene according to claim 1, in which the ethylene content ranges from 3.1 wt.% to 4.7 wt.%. 4. The propylene-ethylene copolymer according to any one of the preceding claims, wherein the ratio of xylene solutes to ethylene (XS/ET) is from 1.2 to 1.5. 5. A copolymer of propylene and ethylene according to any of the preceding paragraphs, wherein the copolymer has a melt flow rate of from 45 g/10 min to 140 g/10 min. 6. A copolymer of propylene and ethylene according to any of the preceding paragraphs, in which the content of the fraction of substances soluble in xylene is from 4 wt.% to 7 wt.%. 7. The propylene-ethylene copolymer of any one of the preceding claims, wherein the copolymer is prepared using a Ziegler-Natta catalyst system that includes an internal electron donor containing a substituted phenylene aromatic diester. 8. A copolymer of propylene and ethylene according to claim 7, in which the catalytic system additionally includes a donor based on dicyclopentyldimethoxysilane. 9. A copolymer of propylene and ethylene according to claim 7, in which the catalytic system additionally includes a donor based on n-propyltrimethoxysilane. 10. Copolymer of propylene and ethylene according to claims. 1-4, and the copolymer has a melt flow rate from 80 g/10 min to 100 g/10 min. 11. Copolymer of propylene and ethylene according to claims. 1-4, and the copolymer has a melt flow rate from 50 g/10 min to 80 g/10 min. 12. A copolymer of propylene and ethylene according to any of the preceding paragraphs, wherein the copolymer is obtained without the use of metallocenes. 13. A polymer composition for molding cast products, containing a copolymer of propylene and ethylene according to any of the preceding paragraphs, and the copolymer of propylene and ethylene is present in the polymer composition in an amount of more than 70 wt.%, 14. The polymer composition according to claim 13, in which the copolymer of propylene and ethylene is present in an amount of more than 80 wt.%. 15. The polymer composition according to claim 13, in which the copolymer of propylene and ethylene is present in an amount of more than 90 wt.%. 16. The polymer composition according to claim 13, in which the copolymer of propylene and ethylene is present in an amount of more than 95 wt.%. 17. Polymer composition according to claims. 13-16, wherein the polymer composition additionally contains an antioxidant, a deoxidizing agent or mixtures thereof. 18. Polymer composition according to claim 17, additionally containing a brightening agent. 19. The polymer composition according to claim 18, in which the brightening agent contains dibenzylsorbitol. 20. The polymer composition according to claim 18, in which the brightening agent contains nonitol. 21. The polymer composition according to claim 18 or 19, wherein at 40 mils the turbidity of the polymer composition is less than 15%, and after thermal aging for 24 hours at 55°C the turbidity is reduced by no more than 15%. 22. The polymer composition according to claim 18 or 19, wherein at 40 mils the turbidity of the polymer composition is less than 15%, and after thermal aging for 24 hours at 55°C the turbidity is reduced by no more than 14%. 23. The polymer composition according to claim 18 or 19, wherein at 40 mils the haze of the polymer composition is less than 15%, and after thermal aging for 24 hours at 55°C the haze is reduced by no more than 13%. 24. The polymer composition according to claim 18 or 19, wherein at 40 mils the haze of the polymer composition is less than 15%, and after thermal aging for 24 hours at 55°C the haze is reduced by no more than 12%. 25. An injection molded article formed from a polymer composition according to any one of claims. 13-24. 26. A film formed from a polymer composition according to any one of paragraphs. 13-24. 27. Packaging container for hot products, made of a polymer composition according to any one of paragraphs. 13-24. 28. The hot food packaging container according to claim 27, wherein the container is formed by injection molding. 29. A storage container formed from a polymer composition according to any one of paragraphs. 13-24.