Polymer compositions containing salts of cyclopentylphosphonic acid and articles made from such polymer compositions

Abstract

The polymer composition includes a polyolefin polymer and a salt of cyclopentylphosphonic acid. The polyolefin polymer may be a polypropylene polymer or a polyethylene polymer. The polymer composition exhibits a fast crystallization rate and is suitable for use in the manufacture of thin articles with low haze levels. Polymer compositions containing polyethylene polymer can exhibit preferential lateral crystalline lamellar growth, a desirable orientation in films and round, center-gate injection molded parts.

Description

[Technical Field]

[0001] This application relates to polymer compositions, such as polypropylene or polyethylene polymer compositions, containing salts of cyclopentylphosphonic acid, and to articles (e.g., injection molded articles) made from such polymer compositions. The salts of cyclopentylphosphonic acid are believed to function as nucleating agents for the polymer. [Background technology]

[0002] Polyolefins are a particularly versatile group of polymer resins. They are semicrystalline polymers. When cooled relatively slowly (such as occurs during the production of molded plastic parts), polyolefins contain amorphous regions where the polymer chains are randomly arranged and crystalline regions where the polymer chains are in an ordered configuration. In these crystalline regions of polyolefins, the polymer chains align into domains commonly referred to as "crystalline lamellae." Under normal processing conditions, as a polyolefin polymer cools from the molten state, the crystalline lamellae grow radially in all directions. This radial growth results in the formation of spherulites, which are spherical, semicrystalline regions composed of multiple crystalline lamellae interrupted by amorphous regions. The size of the spherulites is affected by several parameters and can range from hundreds of nanometers to millimeters in diameter. When the size of the spherulites is significantly larger than the wavelength of visible light, they scatter visible light passing through the polymer. This scattering of visible light results in a hazy appearance commonly referred to as "polymer haze" or simply "haze." While significant levels of polymer haze may be acceptable in some applications, there are certain applications (e.g., storage containers) where consumers desire relatively clear plastics and therefore require correspondingly low haze levels.

[0003]

[0003] Several nucleating agents for thermoplastic polymers are known in the art. These nucleating agents generally function by forming nuclei or providing sites for the formation and / or growth of crystals in the thermoplastic polymer as it solidifies from the molten state. The nuclei or sites provided by the nucleating agent allow crystals to form in the cooled polymer at higher temperatures and / or at a faster rate than crystals would form in a virgin, non-nucleated thermoplastic polymer. This effect may allow the processing of nucleated thermoplastic polymer compositions at shorter cycle times than virgin, non-nucleated thermoplastic polymers.

[0004]

[0004] Some nucleating agents are capable of reducing the spherulite size of certain polymers (e.g., polypropylene and polyethylene) to such an extent that the haze of the polymer is significantly and appreciably reduced (i.e., the scattering of visible light passing through the polymer is reduced). Such nucleating agents are highly beneficial because they allow the polymer to be used in applications where a lower haze level is required, or at least desired.

[0005] In addition to such optical property improvements, it is often desirable for a nucleating agent to improve the rate at which a polymer crystallizes (e.g., shorten the polymer's crystallization half-time). Faster crystallization rates can shorten cycle times, thereby increasing process throughput. Rapid crystallization rates are particularly desirable in processes for manufacturing relatively thin parts or articles (e.g., thicknesses of about 30 mils [0.762 mm] or less). When thin parts / articles are made, they cool rapidly due to their low mass and high surface area. Because nucleation occurs only when the polymer is molten, nucleating agents that induce rapid crystallization rates more effectively and completely nucleate the polymer from which the thin parts / articles are made.

[0006]

[0006] Therefore, in view of the above, there remains a need for nucleating agents for thermoplastic polymers, such as polypropylene and polyethylene, that provide a desirable combination of low haze and high crystallization rate (e.g., low polymer crystallization half-time). The additives and polymer compositions described herein are intended to address such a need. Summary of the Invention

[0007] In a first aspect, the present invention provides a polymer composition comprising: (a) a polyolefin polymer; and (b) a salt of cyclopentylphosphonic acid.

[0008] In a first aspect, the present invention provides a polymer composition comprising: (a) a polyolefin polymer; and (b) a salt of cyclopentylphosphonic acid.

[0009] The polymer composition can include any suitable polyolefin polymer. Suitable polyolefins include, but are not limited to, polypropylene, polyethylene, polybutylene, poly(4-methyl-1-pentene), and combinations or mixtures thereof. In a preferred embodiment, the polyolefin polymer is selected from the group consisting of polypropylene polymers, polyethylene polymers, and mixtures thereof. In one preferred embodiment, the polyolefin polymer is a polypropylene polymer. In another preferred embodiment, the polyolefin polymer is a polyethylene polymer.

[0010] The polymer composition can include any suitable polypropylene polymer. In a preferred embodiment, the polypropylene polymer is selected from the group consisting of polypropylene homopolymers (e.g., atactic polypropylene homopolymer, isotactic polypropylene homopolymer, and syndiotactic polypropylene homopolymer), polypropylene copolymers (e.g., polypropylene random copolymers), polypropylene impact copolymers, and mixtures thereof. Suitable polypropylene copolymers include, but are not limited to, random copolymers prepared from the polymerization of propylene in the presence of a comonomer selected from the group consisting of ethylene, but-1-ene (i.e., 1-butene), and hex-1-ene (i.e., 1-hexene), with ethylene being particularly preferred. In such polypropylene random copolymers, the comonomer can be present in any suitable amount, but is typically present in an amount of less than about 10% by weight (e.g., from about 0.5% to about 10% by weight, from about 1% to about 7% by weight, or from about 0.5% to about 4% by weight). Suitable polypropylene impact copolymers include, but are not limited to, those produced by the addition of a copolymer selected from the group consisting of ethylene-propylene rubber (EPR), ethylene propylene-diene monomer (EPDM), polyethylene, and plastomer to a polypropylene homopolymer or a polypropylene random copolymer. In such polypropylene impact copolymers, the copolymer can be present in any suitable amount, but is typically present in an amount of about 5 to about 25 weight percent. Suitable polypropylene impact copolymers also include, but are not limited to, copolymers made by the polymerization of propylene and ethylene using one or more Zeigler-Natta catalysts. Such polypropylene impact copolymers generally have a heterophase structure in which an amorphous ethylene-propylene copolymer is dispersed in a semi-crystalline polypropylene homopolymer or polypropylene copolymer (e.g., a polypropylene random copolymer) matrix.Suitable polypropylene impact copolymers are polypropylene homopolymers and propylene and up to 50% by weight ethylene and / or C4-C6. 10 a continuous phase comprising a polypropylene polymer selected from copolymers of α-olefins, and ethylene / C3-C 10 The polyolefin polymer may be characterized by a discontinuous phase comprising an elastomeric ethylene polymer selected from α-olefin monomers, the ethylene polymer having an ethylene content of 8 to 90 wt%. In various embodiments of the present invention in which the polyolefin polymer is a polypropylene impact copolymer, (i) the ethylene content of the discontinuous phase may be 8 to 80 wt% (based on the weight of the discontinuous phase), (ii) the ethylene content of the heterophasic composition may be 5 to 30 wt% based on the total weight of the impact copolymer, (iii) the propylene content of the continuous phase may be 80 wt% or more (based on the weight of the continuous phase), and / or (iv) the discontinuous phase may be 5 to 35 wt% based on the total weight of the impact copolymer. The polypropylene polymer may be branched or crosslinked, for example, resulting from the addition of an additive that increases the melt strength of the polymer.

[0011] As noted above, the polymer composition may comprise a polyethylene polymer. The polymer composition may comprise one polyethylene polymer or a mixture of two or more different polyethylene polymers, and the term "polyethylene polymer composition" is used herein broadly to refer to compositions comprising one polyethylene polymer or a mixture of two or more different polyethylene polymers. Suitable polyethylene polymers include, but are not limited to, low-density polyethylene, linear low-density polyethylene, medium-density polyethylene, high-density polyethylene, and combinations thereof. In certain preferred embodiments, the thermoplastic polymer is selected from the group consisting of linear low-density polyethylene, high-density polyethylene, and mixtures thereof. In another preferred embodiment, the thermoplastic polymer is high-density polyethylene.

[0012] High density polyethylene polymers suitable for use in the present invention generally have a density of about 930 kg / m 3 Over (for example, 940 kg / m 3 Super, about 941kg / m 3 Above, about 950kg / m 3 or more, or approximately 955 kg / m 3 Although there is no upper limit to the suitable density of the polymer, high density polyethylene polymers typically have a density of about 980 kg / m 3 Less than (for example, about 975 kg / m 3 Less than or about 970 kg / m 3 Thus, in a preferred embodiment, the high density polyethylene polymer has a density of about 930 kg / m 3 ~980kg / m 3 (For example, about 940 kg / m 3 ~980kg / m 3 , about 941kg / m 3 ~980kg / m 3 , about 950kg / m 3 ~980kg / m 3 , or approximately 955 kg / m 3 ~980kg / m 3 ), approx. 930kg / m 3 ~Approx. 975kg / m 3 (For example, about 940 kg / m 3 ~Approx. 975kg / m 3 , about 941kg / m 3 ~Approx. 975kg / m 3 , about 950kg / m 3 ~Approx. 975kg / m 3 , or approximately 955 kg / m 3 ~Approx. 975kg / m 3 ), or approximately 930 to 970 kg / m 3 (For example, about 940 kg / m 3 ~Approx. 970kg / m 3 , about 941kg / m 3 ~Approx. 970kg / m 3 , about 950kg / m 3 ~Approx. 970kg / m 3 , or approximately 955 kg / m 3 ~970kg / m 3) density.

[0013] High-density polyethylene polymers suitable for use in the present invention may be homopolymers or copolymers of ethylene and one or more α-olefins. Suitable α-olefins include, but are not limited to, 1-butene, 1-hexene, 1-octene, 1-decene, and 4-methyl-1-pentene. The comonomer may be present in the copolymer in any suitable amount, such as about 5 wt. % or less (e.g., about 3 mol. % or less). As will be appreciated by those skilled in the art, the amount of comonomer suitable for the copolymer will depend largely on the end use of the copolymer and the required or desired polymer properties dictated by that end use.

[0014] High-density polyethylene polymers suitable for use in the present invention may be produced by any suitable process. For example, the polymers may be produced by a free-radical process using very high pressures, as described, for example, in U.S. Pat. No. 2,816,883 (Larchar et al.), but the polymers are typically produced by "low-pressure" catalytic processes. In this context, the term "low-pressure" is used to indicate a process carried out at pressures below 6.9 MPa (e.g., 1,000 psig), e.g., 1.4 to 6.9 MPa (200 to 1,000 psig). Examples of suitable low-pressure catalytic processes include, but are not limited to, solution polymerization processes (i.e., processes in which the polymerization is carried out using a solvent for the polymer), slurry polymerization processes (i.e., processes in which the polymerization is carried out using a hydrocarbon liquid in which the polymer does not dissolve or swell), gas-phase polymerization processes (e.g., processes in which the polymerization is carried out without the use of a liquid medium or diluent), or staged reactor polymerization processes. Suitable gas-phase polymerization processes also include so-called "condensed mode" or "super-condensed mode" processes, in which liquid hydrocarbons are introduced into a fluidized bed to increase the absorption of heat generated during the polymerization process. In these condensed mode and super-condensed mode processes, the liquid hydrocarbons are typically condensed in a recycle stream and reused in the reactor. Staged reactor processes can utilize a combination of slurry process reactors (tanks or loops) connected in series, parallel, or series or parallel combinations so that the catalyst (e.g., chromium catalyst) is exposed to more than one set of reaction conditions. Staged reactor processes can also be implemented by combining two loops in series, combining one or more tanks and loops in series, using multiple gas-phase reactors in series, or using a loop-gas-phase configuration. Because the catalyst can be exposed to different sets of reactor conditions, staged reactor processes are often used to produce multimodal polymers, such as those discussed below. Suitable processes also include those in which a prepolymerization step is performed.In this prepolymerization step, the catalyst is typically exposed to a cocatalyst and ethylene under mild conditions in a separate, smaller reactor, and the polymerization reaction is allowed to proceed until the catalyst constitutes a relatively small amount of the resulting composition (e.g., about 5% to about 30% of the total weight). This prepolymerized catalyst is then introduced into the larger reactor where the polymerization will occur.

[0015] High-density polyethylene polymers suitable for use in the present invention may be produced using any suitable catalyst or combination of catalysts. Suitable catalysts include transition metal catalysts, such as supported reduced molybdenum oxide, cobalt molybdate on alumina, chromium oxide, and transition metal halides. Chromium oxide catalysts are typically produced by impregnating a porous, high-surface-area oxide support, such as silica, with a chromium compound and calcining at 500-900°C in dry air. This converts the chromium to a hexavalent surface chromate or dichromate. Chromium oxide catalysts can be used in conjunction with metal alkyl cocatalysts, such as alkylborons, alkylaluminums, alkylzincs, and alkyllithiums. Supports for chromium oxide include silica, silica-titania, silica-alumina, alumina, and aluminophosphates. Further examples of chromium oxide catalysts include low-valent organochromium compounds, such as bis(arene)Cr. 0 , Allyl Cr 2+ and Cr 3+ , Cr 2+ and Cr 4+ Beta-stabilized alkyls of , and bis(cyclopentadienyl)Cr 2+onto a chromium oxide catalyst, such as those described above. Suitable transition metal catalysts also include supported chromium catalysts, such as those based on chromocene or silylchromates (e.g., bis(trisphenylsilyl)chromate). These chromium catalysts may be supported on any suitable high surface area support, such as those described above for the chromium oxide catalysts; silica is typically used. Supported chromium catalysts can also be used with cocatalysts, such as the metal alkyl cocatalysts listed above for the chromium oxide catalysts. Suitable transition metal halide catalysts include titanium(III) halides (e.g., titanium(III) chloride), titanium(IV) halides (e.g., titanium(IV) chloride), vanadium halides, zirconium halides, and combinations thereof. These transition metal halides are often supported on high surface area solids, such as magnesium chloride. Transition metal halide catalysts are typically used with an aluminum alkyl cocatalyst, such as trimethylaluminum (i.e., Al(CH3)3) or triethylaluminum (i.e., Al(C2H5)3). These transition metal halides can also be used in a staged reactor process. Suitable catalysts also include metallocene catalysts, such as cyclopentadienyl titanium halides (e.g., cyclopentadienyl titanium chloride), cyclopentadienyl zirconium halides (e.g., cyclopentadienyl zirconium chloride), cyclopentadienyl hafnium halides (e.g., cyclopentadienyl hafnium chloride), and combinations thereof. Metallocene catalysts based on transition metals complexed with indenyl or fluorenyl ligands are also known and can be used to produce high-density polyethylene polymers suitable for use in the present invention. The catalyst typically contains multiple ligands, which may be substituted with various groups (e.g., n-butyl groups) or linked by bridging groups such as —CH2CH2— or >SiPh2. Metallocene catalysts usually contain a cocatalyst, such as methylaluminoxane (i.e., (Al(CH3) x O y ) nOther cocatalysts include those described in U.S. Patent No. 5,919,983 (Rosen et al.), U.S. Patent No. 6,107,230 (McDaniel et al.), U.S. Patent No. 6,632,894 (McDaniel et al.), and U.S. Patent No. 6,300,271 (McDaniel et al.). Other "single-site" catalysts suitable for use in the production of high-density polyethylene include diimine complexes, such as those described in U.S. Patent No. 5,891,963 (Brookhart et al.).

[0016] High-density polyethylene polymers suitable for use in the present invention may have any suitable molecular weight (e.g., weight average molecular weight). For example, the weight average molecular weight of the high-density polyethylene may be from 20,000 g / mol to about 1,000,000 g / mol or more. As will be appreciated by those skilled in the art, the suitable weight average molecular weight of the high-density polyethylene will depend, at least in part, on the particular application or end use for which the polymer is intended. For example, a high-density polyethylene polymer intended for blow molding applications may have a weight average molecular weight of from about 100,000 g / mol to about 1,000,000 g / mol. A high-density polyethylene polymer intended for pipe or film applications may have a weight average molecular weight of from about 100,000 g / mol to about 500,000 g / mol. A high-density polyethylene polymer intended for injection molding applications may have a weight average molecular weight of from about 20,000 g / mol to about 80,000 g / mol. High-density polyethylene polymers intended for wire insulation, cable insulation, tape, or filament applications may have a weight average molecular weight of about 80,000 g / mol to about 400,000 g / mol.High-density polyethylene polymers intended for rotational molding applications may have a weight average molecular weight of about 50,000 g / mol to about 150,000 g / mol.

[0017] High-density polyethylene polymers suitable for use in the present invention may also have any suitable polydispersity, defined as the value obtained by dividing the weight-average molecular weight of the polymer by the number-average molecular weight of the polymer. For example, high-density polyethylene polymers may have a polydispersity of greater than 2 to about 100. As will be appreciated by those skilled in the art, the polydispersity of a polymer is greatly influenced by the catalyst system used to produce the polymer, with metallocene and other "single-site" catalysts generally producing polymers with relatively low polydispersities and narrow molecular weight distributions, while other transition metal catalysts (e.g., chromium catalysts) produce polymers with higher polydispersities and broader molecular weight distributions. High-density polyethylene polymers suitable for use in the present invention may also have a multimodal (e.g., bimodal) molecular weight distribution. For example, the polymer may have a first fraction having a relatively low molecular weight and a second fraction having a relatively high molecular weight. The difference in weight-average molecular weight of the fractions in the polymer may be any suitable amount. In fact, the difference in weight-average molecular weight need not be large enough to allow separation of two different molecular weight fractions using gel permeation chromatography (GPC). However, for certain multimodal polymers, the difference in weight average molecular weight of the fractions may be large enough to separate two or more distinct peaks from the GPC curve of the polymer. In this context, the term "different" does not necessarily mean that the portions of the GPC curve corresponding to each fraction do not overlap, but merely indicates that distinct peaks (i.e., maxima) of each fraction can be separated from the GPC curve of the polymer. Multimodal polymers suitable for use in the present invention may be produced using any suitable process. As mentioned above, multimodal polymers may be produced using a staged reactor process. One suitable example is a staged solution process incorporating a series of stirred tanks. Alternatively, multimodal polymers may be produced in a single reactor using a combination of catalysts each designed to produce a polymer with a different weight average molecular weight.

[0018] The molecular weight distribution of a polymer may also be characterized by measuring and comparing the melt flow index (or melt flow rate) of the polymer under different conditions to obtain a flow rate ratio (FRR). This method is described, for example, in Procedure D of ASTM Standard D1238, entitled "Standard Test Method for Melt Flow Rates of Thermoplastics by Extrusion Plastometer." Preferably, the FRR is calculated by comparing the melt flow index (MFI) measured using the 21.6 kg load specified in the standard. 21.6 ), and the melt flow index (MFI) measured using the standard specified 2.16 kg load. 2.16 ), and both melt flow indices are measured at a temperature of 190°C as specified in the standard. The high density polyethylene polymer used in the polymer composition may have any suitable FRR. Preferably, the high density polyethylene polymer has an FRR (MFI) of about 65 or less. 21.6 / MFI 2.16 More preferably, the high density polyethylene polymer has an FRR (MFI) of about 40 or less, or about 20 or less. 21.6 / MFI 2.16 )

[0019] High-density polyethylene polymers suitable for use in the present invention may have any suitable melt flow index. For example, the high-density polyethylene polymer may have a melt flow index of from about 0.01 dg / min to about 50 dg / min (e.g., from about 0.01 dg / min to about 40 dg / min). As with the weight average molecular weight, those skilled in the art will understand that a suitable melt flow index for a high-density polyethylene polymer will depend, at least in part, on the particular application or end use for which the polymer is intended. Thus, for example, a high-density polyethylene polymer intended for blow molding applications may have a melt flow index of from about 0.01 dg / min to about 1 dg / min. A high-density polyethylene polymer intended for blown film applications may have a melt flow index of from about 0.5 dg / min to about 50 dg / min (e.g., from about 1 dg / min to about 10 dg / min, from about 1 dg / min to about 5 dg / min, or from about 0.5 dg / min to about 3 dg / min). High-density polyethylene polymers intended for cast film applications may have a melt flow index of about 2 dg / min to about 10 dg / min. High-density polyethylene polymers intended for pipe applications may have a melt flow index of about 2 dg / min to about 40 dg / min (measured at 190°C with a 21.6 kg load). High-density polyethylene polymers intended for injection molding applications may have a melt flow index of about 2 dg / min to about 80 dg / min. High-density polyethylene polymers intended for rotational molding applications may have a melt flow index of about 0.5 dg / min to about 10 dg / min. High-density polyethylene polymers intended for tape applications may have a melt flow index of about 0.2 dg / min to about 4 dg / min. High-density polyethylene polymers intended for filament applications may have a melt flow index of about 1 dg / min to about 20 dg / min. The melt flow index of the polymers is measured using ASTM standard D1238-04c.

[0020] High-density polyethylene polymers suitable for use in the present invention generally do not contain significant amounts of long-chain branching. The term "long-chain branching" is used to refer to branches of sufficient length (e.g., branches of about 130 carbons or more) that are attached to the polymer chain and affect the rheology of the polymer. If desired for the application in which the polymer is to be used, high-density polyethylene polymers may contain small amounts of long-chain branching. However, high-density polyethylene polymers suitable for use in the present invention typically contain little long-chain branching (e.g., less than about 1 long-chain branch per 10,000 carbons, less than about 0.5 long-chain branches per 10,000 carbons, less than about 0.1 long-chain branches per 10,000 carbons, or less than about 0.01 long-chain branches per 10,000 carbons).

[0021] The degree of long-chain branching in a polymer may also be characterized using rheological methods (see, for example, R.N. Shroff and H. Mavridis, "Long-Chain-Branching Index for Essentially Linear Polyethylenes," Macromolecules, Vol. 32(25), pp. 8454-8464 (1999)). In particular, the long-chain branching index (LCBI) is a rheological index used to characterize relatively low levels of long-chain branching and is defined as follows:

[0022]

number

[0023] (where η is the limiting zero shear viscosity at 190°C (expressed in poise) and [η] is the intrinsic viscosity in trichlorobenzene at 135°C (expressed in dL / g).) The LCBI is based on the observation that low levels of long chain branching in an otherwise linear polymer result in a large increase in melt viscosity η while the intrinsic viscosity [η] remains unchanged. A higher LCBI means a greater number of long chain branches per polymer chain. Preferably, the high density polyethylene polymer used in the polymer composition has an LCBI of about 0.5 or less, about 0.3 or less, or about 0.2 or less.

[0024] In one preferred embodiment, the polymer composition comprises a blend of two or more high density polyethylene polymer compositions. In one preferred embodiment comprising two high density polyethylene polymer compositions, the first high density polyethylene polymer composition has a viscosity of about 950 kg / m 3 ~Approx. 975kg / m 3 (Preferably 950 kg / min 3 ~960kg / min 3 ) and the second high-density polyethylene polymer composition has a density of about 950 kg / m 3 ~970kg / m 3 (preferably 955 kg / m 3 ~965kg / m 3The first high-density polyethylene polymer composition preferably has a melt flow index (determined in accordance with ASTM D 1238 at 190°C using a 2.16 kg load) of greater than 5 dg / min (more preferably from about 15 dg / min to about 30 dg / min). Furthermore, the melt flow index of the first high-density polyethylene polymer composition is preferably at least 10 times greater than the melt flow index of the second high-density polyethylene polymer composition. The second high-density polyethylene polymer composition preferably has a melt flow index (determined in accordance with ASTM D 1238 at 190°C using a 2.16 kg load) of from about 0.1 dg / min to about 2 dg / min (more preferably from about 0.8 dg / min to about 2 dg / min). The first high-density polyethylene polymer composition may have any suitable polydispersity, but preferably has a polydispersity (determined by gel permeation chromatography in accordance with ASTM D 6474-99) of from about 2 to about 20, more preferably from about 2 to about 4. Without wishing to be bound by theory, it is believed that a low polydispersity (e.g., 2 to 4) of the first high-density polyethylene polymer composition may improve the nucleation rate and overall barrier performance of blown films prepared from the polymer composition. The polydispersity of the second high-density polyethylene polymer composition is not believed to be critical to achieving the desired results, but the second high-density polyethylene polymer preferably has a polydispersity of about 2 to about 4. The above-mentioned first high-density polyethylene polymer composition may consist of a single high-density polyethylene polymer that provides the desired properties, or the first high-density polyethylene polymer composition may comprise a blend of two or more high-density polyethylene polymers having the desired properties. Similarly, the second high-density polyethylene polymer composition may consist of a single high-density polyethylene polymer or a blend of two or more high-density polyethylene polymers having the desired properties.

[0025] In the embodiment described in the preceding paragraph, the first and second high-density polyethylene polymer compositions can be present in the polymer composition in any suitable relative amounts. Preferably, the first high-density polyethylene polymer composition is present in an amount of about 5% to about 60% by weight of the total high-density polyethylene polymer present in the composition (with the second high-density polyethylene polymer composition making up the remainder). In other preferred embodiments, the first high-density polyethylene polymer composition is present in an amount of about 10% to about 40% by weight, or about 20% to about 40% by weight. In one particularly preferred embodiment, the polymer composition has (i) a melt flow index of about 15 to about 30 dg / min and a melt flow index of about 950 kg / m 3 ~960kg / m 3 and (ii) a melt flow index of about 0.8 to about 2 dg / min and a density of about 955 kg / m 3 ~Approx. 965kg / m 3 The blend of high-density polyethylene polymers described above may be made by any suitable process, such as (i) physical blending of particulate resins; (ii) co-feeding different high-density polyethylene resins into a common extruder; (iii) melt mixing (in any conventional polymer mixing equipment); (iv) solution blending; or (v) a polymerization process using two or more reactors. A highly preferred blend of high-density polyethylene polymer compositions is prepared by a solution polymerization process using two reactors operating under different polymerization conditions. This results in a homogeneous in situ blend of the first and second high-density polyethylene polymer compositions. An example of this process is described in published U.S. Patent Application Publication No. 2006 / 0047078 A1 (Swabey et al.), the disclosure of which is incorporated herein by reference. The overall blend of high-density polyethylene polymer compositions preferably has a polydispersity of about 3 to about 20.

[0026] Medium density polyethylene polymers suitable for use in the present invention generally have a density of about 926 kg / m3 ~Approx. 940kg / m 3 The term "medium density polyethylene" is used to refer to a polymer of ethylene having a density between that of high density polyethylene and that of linear low density polyethylene, and containing relatively short branches compared to the long branches present in low density polyethylene polymers produced by free radical polymerization of ethylene at at least high pressure.

[0027]

[0025] Medium-density polyethylene polymers suitable for use in the present invention are generally copolymers of ethylene and at least one α-olefin, such as 1-butene, 1-hexene, 1-octene, 1-decene, and 4-methyl-1-pentene. The α-olefin comonomer may be present in any suitable amount, but is typically present in an amount less than about 8 wt% (e.g., less than about 5 mol%). As will be appreciated by those skilled in the art, the amount of comonomer suitable for the copolymer will depend largely on the end use of the copolymer and the required or desired polymer properties dictated by that end use.

[0028]

[0026] Medium-density polyethylene polymers suitable for use in the present invention may be produced by any suitable process. Like high-density polyethylene polymers, medium-density polyethylene polymers are typically produced by "low-pressure" catalytic processes, such as any of the processes described above in connection with high-density polyethylene polymers suitable for use in the present invention. Examples of suitable processes include, but are not limited to, gas-phase polymerization processes, solution polymerization processes, slurry polymerization processes, and staged reactor processes. Suitable staged reactor processes can incorporate any suitable combination of the gas-phase, solution, and slurry polymerization processes described above. Like high-density polyethylene polymers, staged reactor processes are often used to produce multimodal polymers.

[0029]

[0027] Medium-density polyethylene polymers suitable for use in the present invention may be produced using any suitable catalyst or combination of catalysts. For example, the polymers may be produced using Ziegler catalysts, such as transition metal (e.g., titanium) halides or esters used in combination with organoaluminum compounds (e.g., triethylaluminum). These Ziegler catalysts may be supported on, for example, magnesium chloride, silica, alumina, or magnesium oxide. Medium-density polyethylene polymers suitable for use in the present invention may also be produced using so-called "dual Ziegler catalysts," which contain one catalyst species for the dimerization of ethylene to 1-butene (e.g., a combination of a titanium ester and triethylaluminum) and another catalyst for the copolymerization of ethylene and the resulting 1-butene (e.g., titanium chloride supported on magnesium chloride). Medium-density polyethylene polymers suitable for use in the present invention may also be produced using chromium oxide catalysts, such as those produced by depositing a chromium compound on a silica-titania support, oxidizing the resulting catalyst in a mixture of oxygen and air, and then reducing the catalyst with carbon monoxide. These chromium oxide catalysts are typically used in conjunction with a cocatalyst, such as a trialkylboron or trialkylaluminum compound. Chromium oxide catalysts can also be used in conjunction with Ziegler catalysts, such as titanium halide or titanium ester-based catalysts. Medium-density polyethylene polymers suitable for use in the present invention can also be produced using supported chromium catalysts, such as those described above in the discussion of catalysts suitable for making high-density polyethylene. Medium-density polyethylene polymers suitable for use in the present invention can also be produced using metallocene catalysts. Several different types of metallocene catalysts may be used. For example, the metallocene catalyst may contain a bis(metallocene) complex of zirconium, titanium, or hafnium having two cyclopentadienyl rings and methylaluminoxane. Similar to the catalysts used in the production of high-density polyethylene, the ligands may be substituted with various groups (e.g., n-butyl groups) or linked by bridging groups.Another class of usable metallocene catalysts consists of bis(metallocene) complexes of zirconium or titanium and the anions of perfluorinated boron aromatic compounds. A third class of usable metallocene catalysts, called constrained geometry catalysts, contains monocyclopentadienyl derivatives of titanium or zirconium, in which one of the carbon atoms of the cyclopentadienyl ring is linked to the metal atom by a bridging group. These complexes are reacted with methylaluminoxane or with non-coordinating anions, such as B(C6F5)4. - or B(C6F5)3CH3 - The catalysts are activated by forming an ionic complex with the metallocene complex. A fourth class of usable metallocene catalysts are transition metal, e.g., titanium, metallocene-based complexes containing one cyclopentadienyl ligand in combination with another ligand, e.g., a phosphinimine or —O—SiR3. This class of metallocene catalysts is also activated with methylaluminoxane or boron compounds. Other catalysts suitable for use in making medium-density polyethylene suitable for use in the present invention include, but are not limited to, those disclosed in U.S. Pat. No. 6,649,558.

[0030]

[0028] Medium-density polyethylene polymers suitable for use in the present invention may have any suitable compositional uniformity, which is a term used to describe the uniformity of branching in the copolymer molecules of the polymer. Many commercially available medium-density polyethylene polymers have relatively low compositional uniformity, in which the high molecular weight fraction of the polymer contains relatively small amounts of α-olefin comonomer and has relatively small amounts of branching, while the low molecular weight fraction of the polymer contains relatively large amounts of α-olefin comonomer and has relatively large amounts of branching. Alternatively, another set of medium-density polyethylene polymers has relatively low compositional uniformity, in which the high molecular weight fraction of the polymer contains relatively large amounts of α-olefin comonomer, while the low molecular weight fraction of the polymer contains relatively small amounts of α-olefin comonomer. The compositional uniformity of the polymer may be measured using any suitable method, for example, temperature rising elution fractionation.

[0031] Suitable medium-density polyethylene polymers for use in the present invention may have any suitable molecular weight. For example, the polymer may have a weight average molecular weight of from about 50,000 g / mole to about 200,000 g / mole. As will be appreciated by those skilled in the art, the suitable weight average molecular weight of the medium-density polyethylene will depend, at least in part, on the particular application or end use for which the polymer is intended.

[0032]

[0030] Medium-density polyethylene polymers suitable for use in the present invention may also have any suitable polydispersity index. Many commercially available medium-density polyethylene polymers have polydispersities of about 2 to about 30. Medium-density polyethylene polymers suitable for use in the present invention may also have a multimodal (e.g., bimodal) molecular weight distribution. For example, the polymer may have a first fraction having a relatively low molecular weight and a second fraction having a relatively high molecular weight. As with the high-density polyethylene polymers suitable for use in the present invention, the difference in weight-average molecular weight of the fractions in a multimodal medium-density polyethylene polymer may be any suitable amount. In fact, the difference in weight-average molecular weight need not be large enough to allow separation of two different molecular weight fractions using gel permeation chromatography (GPC). However, in certain multimodal polymers, the difference in weight-average molecular weight of the fractions may be large enough to allow separation of two or more distinct peaks from the GPC curve of the polymer. In this context, the term "different" does not necessarily mean that the portions of the GPC curve corresponding to each fraction do not overlap, but is intended simply to indicate that different peaks of each fraction can be separated from the GPC curve of the polymer. Multimodal polymers suitable for use in the present invention may be produced using any suitable process. As mentioned above, multimodal polymers may be produced using a staged reactor process. One suitable example is a staged solution process incorporating a series of stirred tanks. Alternatively, multimodal polymers may be produced in a single reactor using a combination of catalysts, each designed to produce a polymer with a different weight average molecular weight.

[0033]

[0031] Medium-density polyethylene polymers suitable for use in the present invention may have any suitable melt flow index. For example, medium-density polyethylene polymers may have a melt flow index of about 0.01 dg / min to about 200 dg / min. As with the weight average molecular weight, those skilled in the art will understand that the suitable melt flow index of a medium-density polyethylene polymer will depend, at least in part, on the particular application or end use for which the polymer is intended. Thus, for example, a medium-density polyethylene polymer intended for blow molding or pipe applications may have a melt flow index of about 0.01 dg / min to about 1 dg / min. A medium-density polyethylene polymer intended for blown film applications may have a melt flow index of about 0.5 dg / min to about 3 dg / min. A medium-density polyethylene polymer intended for cast film applications may have a melt flow index of about 2 dg / min to about 10 dg / min. A medium-density polyethylene polymer intended for injection molding applications may have a melt flow index of about 6 dg / min to about 200 dg / min. Medium density polyethylene polymers intended for rotational molding applications may have a melt flow index of about 4 dg / min to about 7 dg / min. Medium density polyethylene polymers intended for wire and cable insulation applications may have a melt flow index of about 0.5 dg / min to about 3 dg / min. The melt flow index of the polymers is measured using ASTM standard D1238-04c.

[0034]

[0032] Medium density polyethylene polymers suitable for use in the present invention generally do not contain significant amounts of long chain branching. For example, medium density polyethylene polymers suitable for use in the present invention generally contain less than about 0.1 long chain branches per 10,000 carbon atoms (e.g., less than about 0.002 long chain branches per 100 ethylene units), or less than about 0.01 long chain branches per 10,000 carbon atoms.

[0035] Linear low density polyethylene polymers suitable for use in the present invention generally have a viscosity of 925 kg / m 3or less (for example, about 910 kg / m 3 ~Approx. 925kg / m 3 The term "linear low density polyethylene" is used to refer to low density polymers of ethylene having relatively short branches compared to the long branches present in low density polyethylene polymers made by free radical polymerization of ethylene at at least high pressure.

[0036]

[0034] Linear low-density polyethylene polymers suitable for use in the present invention are generally copolymers of ethylene and at least one α-olefin, such as 1-butene, 1-hexene, 1-octene, 1-decene, and 4-methyl-1-pentene. The α-olefin comonomer may be present in any suitable amount, but is typically present in an amount less than about 6 mol % (e.g., from about 2 mol % to about 5 mol %). As will be appreciated by those skilled in the art, the amount of comonomer suitable for the copolymer will depend largely on the end use of the copolymer and the required or desired polymer properties dictated by that end use.

[0037] Linear low-density polyethylene polymers suitable for use in the present invention may be produced by any suitable process. Like high-density polyethylene polymers, linear low-density polyethylene polymers are typically produced by a "low-pressure" catalytic process, such as any of the processes described above in connection with the high-density polyethylene polymers suitable for use in the present invention. Suitable processes include, but are not limited to, gas-phase polymerization processes, solution polymerization processes, slurry polymerization processes, and staged reactor processes. Suitable staged reactor processes can incorporate any suitable combination of the gas-phase, solution, and slurry polymerization processes described above. Like high-density polyethylene polymers, staged reactor processes are often used to produce multimodal polymers.

[0038] Linear low-density polyethylene polymers suitable for use in the present invention may be produced using any suitable catalyst or combination of catalysts. For example, the polymers may be produced using Ziegler catalysts, such as transition metal (e.g., titanium) halides or esters used in combination with organoaluminum compounds (e.g., triethylaluminum). These Ziegler catalysts may be supported on, for example, magnesium chloride, silica, alumina, or magnesium oxide. Linear low-density polyethylene polymers suitable for use in the present invention may also be produced using so-called "dual Ziegler catalysts," which contain one catalyst species for the dimerization of ethylene to 1-butene (e.g., a combination of a titanium ester and triethylaluminum) and another catalyst for the copolymerization of ethylene and the resulting 1-butene (e.g., titanium chloride supported on magnesium chloride). Linear low-density polyethylene polymers suitable for use in the present invention may also be produced using chromium oxide catalysts, such as those produced by depositing a chromium compound on a silica-titania support, oxidizing the resulting catalyst in a mixture of oxygen and air, and then reducing the catalyst with carbon monoxide. These chromium oxide catalysts are typically used in conjunction with a cocatalyst, such as a trialkylboron or trialkylaluminum compound. Chromium oxide catalysts can also be used in conjunction with Ziegler catalysts, such as titanium halide or titanium ester-based catalysts. Linear low-density polyethylene polymers suitable for use in the present invention can also be produced using supported chromium catalysts, such as those described above in the discussion of catalysts suitable for making high-density polyethylene. Linear low-density polyethylene polymers suitable for use in the present invention can also be produced using metallocene catalysts. Several different types of metallocene catalysts may be used. For example, the metallocene catalyst may contain a bis(metallocene) complex of zirconium, titanium, or hafnium having two cyclopentadienyl rings and methylaluminoxane. Similar to the catalysts used in the production of high-density polyethylene, the ligands may be substituted with various groups (e.g., n-butyl groups) or linked by bridging groups.Another class of usable metallocene catalysts consists of bis(metallocene) complexes of zirconium or titanium and the anions of perfluorinated boron aromatic compounds. A third class of usable metallocene catalysts, called constrained geometry catalysts, contains monocyclopentadienyl derivatives of titanium or zirconium, in which one of the carbon atoms of the cyclopentadienyl ring is linked to the metal atom by a bridging group. These complexes are reacted with methylaluminoxane or with non-coordinating anions, such as B(C6F5)4. - or B(C6F5)3CH3 - The metallocene catalysts are activated by forming an ionic complex with the cyclopentadienyl ligand. A fourth class of usable metallocene catalysts are transition metal, e.g., titanium, metallocene-based complexes containing one cyclopentadienyl ligand in combination with another ligand, e.g., a phosphinimine or —O—SiR3. This class of metallocene catalysts is also activated with methylaluminoxane or boron compounds. Other catalysts suitable for use in making the linear low-density polyethylene suitable for use in the present invention include, but are not limited to, those disclosed in U.S. Pat. No. 6,649,558.

[0039]

[0037] Linear low-density polyethylene polymers suitable for use in the present invention may have any suitable compositional uniformity, which is a term used to describe the uniformity of branching in the copolymer molecules of the polymer. Many commercially available linear low-density polyethylene polymers have relatively low compositional uniformity, in which high molecular weight fractions of the polymer contain relatively small amounts of α-olefin comonomer and have relatively small amounts of branching, while low molecular weight fractions of the polymer contain relatively large amounts of α-olefin comonomer and have relatively large amounts of branching. Alternatively, another set of linear low-density polyethylene polymers have relatively low compositional uniformity, in which high molecular weight fractions of the polymer contain relatively large amounts of α-olefin comonomer, while low molecular weight fractions of the polymer contain relatively small amounts of α-olefin comonomer. The compositional uniformity of the polymer may be measured using any suitable method, for example, temperature rising elution fractionation.

[0040] Linear low density polyethylene polymers suitable for use in the present invention may have any suitable molecular weight. For example, the polymer may have a weight average molecular weight of from about 20,000 g / mole to about 250,000 g / mole. As will be appreciated by those skilled in the art, the suitable weight average molecular weight of the linear low density polyethylene will depend, at least in part, on the particular application or end use for which the polymer is intended.

[0041]

[0039] Linear low-density polyethylene polymers suitable for use in the present invention may also have any suitable polydispersity. Many commercially available linear low-density polyethylene polymers have a relatively narrow molecular weight distribution and therefore a relatively low polydispersity, for example, from about 2 to about 5 (e.g., from about 2.5 to about 4.5, or from about 3.5 to about 4.5). Linear low-density polyethylene polymers suitable for use in the present invention may also have a multimodal (e.g., bimodal) molecular weight distribution. For example, the polymer may have a first fraction having a relatively low molecular weight and a second fraction having a relatively high molecular weight. As with the high-density polyethylene polymers suitable for use in the present invention, the difference in weight-average molecular weight of the fractions in a multimodal linear low-density polyethylene polymer may be any suitable amount. Indeed, the difference in weight-average molecular weight need not be large enough to allow separation of two different molecular weight fractions using gel permeation chromatography (GPC). However, in certain multimodal polymers, the difference in weight-average molecular weight of the fractions may be large enough to allow separation of two or more distinct peaks from the GPC curve of the polymer. In this context, the term "different" does not necessarily mean that the portions of the GPC curves corresponding to each fraction do not overlap, but merely indicates that the different peaks of each fraction can be separated from the GPC curve of the polymer. Multimodal polymers suitable for use in the present invention may be produced using any suitable process. As noted above, multimodal polymers may be produced using a staged reactor process. One suitable example is a staged solution process incorporating a series of stirred tanks. Alternatively, multimodal polymers may be produced in a single reactor using a combination of catalysts each designed to produce a polymer with a different weight average molecular weight.

[0042] Linear low-density polyethylene polymers suitable for use in the present invention may have any suitable melt flow index. For example, linear low-density polyethylene polymers may have a melt flow index of about 0.01 dg / min to about 200 dg / min. As with the weight average molecular weight, those skilled in the art will understand that the suitable melt flow index of a linear low-density polyethylene polymer will depend, at least in part, on the particular application or end use for which the polymer is intended. Thus, for example, linear low-density polyethylene polymers intended for blow molding or pipe applications may have a melt flow index of about 0.01 dg / min to about 1 dg / min. Linear low-density polyethylene polymers intended for blown film applications may have a melt flow index of about 0.5 dg / min to about 3 dg / min. Linear low-density polyethylene polymers intended for cast film applications may have a melt flow index of about 2 dg / min to about 10 dg / min. Linear low density polyethylene polymers intended for injection molding applications may have a melt flow index of about 6 dg / min to about 200 dg / min. Linear low density polyethylene polymers intended for rotational molding applications may have a melt flow index of about 4 dg / min to about 7 dg / min. Linear low density polyethylene polymers intended for wire and cable insulation applications may have a melt flow index of about 0.5 dg / min to about 3 dg / min. The melt flow index of the polymers is measured using ASTM standard D1238-04c.

[0043]

[0041] Linear low density polyethylene polymers suitable for use in the present invention generally do not contain significant amounts of long chain branching. For example, linear low density polyethylene polymers suitable for use in the present invention generally contain less than about 0.1 long chain branches per 10,000 carbon atoms (e.g., less than about 0.002 long chain branches per 100 ethylene units) or less than about 0.01 long chain branches per 10,000 carbon atoms.

[0044] Low density polyethylene polymers suitable for use in the present invention generally have a viscosity of 935 kg / m 3 It has a density less than 1000 kJ / cm2 and, in contrast to high density polyethylene, medium density polyethylene and linear low density polyethylene, has a relatively large amount of long chain branching in the polymer.

[0045]

[0043] Low-density polyethylene polymers suitable for use in the present invention may be either ethylene homopolymers or copolymers of ethylene and a polar comonomer. Suitable polar comonomers include, but are not limited to, vinyl acetate, methyl acrylate, ethyl acrylate, and acrylic acid. These comonomers may be present in any suitable amount, with comonomer contents as high as 20% by weight being used for certain applications. As will be appreciated by those skilled in the art, the amount of comonomer suitable for a polymer will depend largely on the end use of the polymer and the required or desired polymer properties dictated by that end use.

[0046] Low-density polyethylene polymers suitable for use in the present invention may be produced using any suitable process, but typically the polymers are produced by the free-radical initiated polymerization of ethylene at high pressure (e.g., from about 81 to about 276 MPa) and high temperature (e.g., from about 130 to about 330°C). Any suitable free-radical initiator can be used in such processes, with peroxides and oxygen being the most common. The free-radical polymerization mechanism produces short-chain branching in the polymer, as well as the relatively high degree of long-chain branching that distinguishes low-density polyethylene from other ethylene polymers (e.g., high-density polyethylene and linear low-density polyethylene). The polymerization reaction is typically carried out in an autoclave reactor (e.g., a stirred autoclave reactor), a tubular reactor, or a combination of such reactors positioned in series.

[0047] Low-density polyethylene polymers suitable for use in the present invention may have any suitable molecular weight. For example, the polymer may have a weight average molecular weight of about 30,000 g / mol to about 500,000 g / mol. As will be appreciated by those skilled in the art, the suitable weight average molecular weight of the low-density polyethylene will depend, at least in part, on the particular application or end use for which the polymer is intended. For example, a low-density polyethylene polymer intended for blow molding applications may have a weight average molecular weight of about 80,000 g / mol to about 200,000 g / mol. A low-density polyethylene polymer intended for pipe applications may have a weight average molecular weight of about 80,000 g / mol to about 200,000 g / mol. A low-density polyethylene polymer intended for injection molding applications may have a weight average molecular weight of about 30,000 g / mol to about 80,000 g / mol. Low density polyethylene polymers intended for film applications may have a weight average molecular weight of from about 60,000 g / mole to about 500,000 g / mole.

[0048] Low density polyethylene polymers suitable for use in the present invention may have any suitable melt flow index. For example, the low density polyethylene polymer may have a melt flow index of about 0.2 to about 100 dg / min. As noted above, the melt flow index of a polymer is measured using ASTM standard D1238-04c.

[0049] As noted above, one of the primary differences between low-density polyethylene and other ethylene polymers is the relatively high degree of long-chain branching within the polymer. Low-density polyethylene polymers suitable for use in the present invention may exhibit any suitable amount of long-chain branching, such as, for example, about 0.01 or more long-chain branches per 10,000 carbon atoms, about 0.1 or more long-chain branches per 10,000 carbon atoms, about 0.5 or more long-chain branches per 10,000 carbon atoms, about 1 or more long-chain branches per 10,000 carbon atoms, or about 4 or more long-chain branches per 10,000 carbon atoms. While there is no strict limit to the maximum extent of long-chain branching that may be present in low-density polyethylene polymers suitable for use in the present invention, the long-chain branching in many low-density polyethylene polymers is less than about 100 long-chain branches per 10,000 carbon atoms.

[0050] The polyethylene polymer composition utilized in the composition can include any suitable polyethylene polymer or mixture of polyethylene polymers. However, it is believed that polyethylene polymer compositions exhibiting greater melt relaxivity are more effectively nucleated by the salt of cyclopentylphosphonic acid. During certain melt processing of polymers (e.g., blown film production), the polymer melt undergoes elongational thinning or strain as it is extruded through a die. The polymer melt can undergo further elongational thinning or strain as the extruded polymer melt is further processed, e.g., drawn and / or blown. The strain applied to the polymer melt causes the elongated polymer chains in the polymer melt to orient in the flow direction. As the processed polymer melt cools, these oriented elongated polymer chains can return to a less ordered state before the polymer melt crystallizes. This process is referred to herein as "melt relaxation." Alternatively, the oriented elongated polymer chains may crystallize while still oriented in the melt, forming fibrils. These fibrils provide sites where self-nucleation of the polymer can be initiated. If sufficient fibrils are formed in a polymer as it solidifies from the melt, the resulting strain-induced self-nucleation may become the dominant mode of nucleation in the polymer. While self-nucleation of a polymer may seem beneficial, the polymer structure produced by such self-nucleation is generally less favorable for certain desired physical properties. For example, self-nucleated polyethylene generally exhibits higher water vapor and oxygen permeability than polyethylene heterogeneously nucleated with, for example, a salt of cyclopentylphosphonic acid. Therefore, to maximize the degree of nucleation induced by the salt of cyclopentylphosphonic acid, the polymer composition preferably contains a polyethylene polymer composition that exhibits sufficient melt relaxation to ensure that strain-induced self-nucleation does not dominate.

[0051] The degree of melt relaxation exhibited by a polymer cannot be easily quantified directly. Furthermore, it is believed that melt relaxation can be influenced by many factors, such as molecular weight, the width of the molecular weight distribution, the relative amount of high molecular weight fraction in the molecular weight distribution, and branched or non-linear chains in the polymer. Due to the number of factors involved and the complex relationships between those factors, it is difficult to identify a range of respective values ​​sufficient to define a polyethylene polymer exhibiting sufficient melt relaxation. In other words, it is possible to attempt to define the molecular weight distribution of a polymer exhibiting sufficient melt relaxation, but the appropriate range may vary depending on the "shape" of the distribution (i.e., the relative amount of high molecular weight fraction). Therefore, while these factors may be taken into account when attempting to identify a polyethylene polymer exhibiting sufficient melt relaxation, a more direct and accurate quantification of melt relaxation may be desirable.

[0052]

[0050] The shear storage modulus (G') of a viscoelastic material (e.g., a polymer melt) relates to the stored energy (stress), e.g., that stored in the directionally oriented, elongated polymer chains described above. The shear loss modulus (G'') of a viscoelastic material relates to the energy loss or dissipation, e.g., that released by relaxation of the directionally oriented, elongated polymer chains in a polymer melt. The ratio of the shear loss modulus to the shear storage modulus (G'' / G'), defined as tan δ, is proportional to the energy loss versus storage at a given strain rate. For materials with tan δ less than 1, energy storage dominates at the measured strain rate. For materials with tan δ greater than 1, energy loss (dissipation) dominates at the measured strain rate. Furthermore, comparison of tan δ measured at different strain rates (e.g., the ratio of tan δ) can be used to quantify the extent to which the dominance of energy loss and energy storage in a material changes with changing strain rate.

[0053]

[0051] The shear storage modulus and shear loss modulus may be measured at various strain rates by various techniques. However, if the moduli are to be used to accurately quantify the melt relaxation of a polymer, both moduli should be measured at or near the strain rates to which the polymer melt is subjected during melt processing. To this end, the inventors believe that measurement of the shear storage modulus and shear loss modulus by parallel plate rheometry at angular frequencies of approximately 0.1 rad / s and approximately 10 rad / s provides a fair approximation of the strain rates to which polyethylene polymer composition melts are subjected during processing. As previously mentioned, the ratio of tan δ at these two strain rates may be used to indicate the change in energy loss and energy storage with a change in strain rate. After extensive experimentation with various polymers and polymer compositions, it is believed that polyethylene polymers that exhibit a significant increase in energy loss (i.e., a significant increase in tan δ) with decreasing strain rate (i.e., decreasing angular frequency) exhibit sufficient melt relaxation for heterogeneous nucleation by salts of cyclopentylphosphonic acid. In particular, the ratio of tan δ at approximately 0.1 rad / s to tan δ at approximately 10 rad / s is believed to be particularly useful in identifying polymers that exhibit a desirable level of melt relaxation. In particular, the ratio of tan δ at approximately 0.1 rad / s to tan δ at approximately 10 rad / s, hereinafter referred to as the "melt relaxation ratio," is believed to be 1.5 or greater. In other words, polyethylene polymer compositions preferably have a melt relaxation ratio of 1.5 or greater, more preferably 1.55 or greater.

[0054] As mentioned above, the melt relaxation ratio (MRR) is defined as the ratio of tan δ at approximately 0.1 rad / s to tan δ at approximately 10 rad / s:

[0055]

number

[0056] In this definition, the two angular frequencies are approximately equal to the given values. Thus, tan δ at approximately 0.1 rad / s can be measured at any angular frequency between 0.095 and 0.105 rad / s, and tan δ at approximately 10 rad / s can be measured at any angular frequency between 9.5 and 10.5 rad / s. The exact angular frequencies used to determine MRR may vary within the above range, but the ratio of the two angular frequencies must be 1:100 (i.e., there must be a 100-fold difference between the two angular frequencies).

[0057] The melt relaxation ratio may be measured by any suitable technique. Preferably, the shear loss modulus (G"), shear storage modulus (G'), and tan δ are determined by parallel plate rheometry at a temperature of 190°C using a rotational rheometer equipped with 25 mm parallel plates set at a 1.1 mm gap. The polymer sample used for the measurements is provided in the form of a compression-molded disk. During the measurements, the angular distance or strain is preferably kept low to remain in the non-hysteretic region, with a nominal strain of approximately 1 percent being preferred. Because these parameters are determined from the polymer melt, the presence of a nucleating agent does not significantly affect the shear loss modulus (G"), shear storage modulus (G'), and tan δ measured from the polyethylene polymer. Thus, these parameters (and the melt relaxation ratio) may be measured from the polyethylene polymer composition before it is combined with the salt of cyclopentylphosphonic acid, or the parameters may be measured from a polymer composition comprising the polyethylene polymer composition and the salt of cyclopentylphosphonic acid.

[0058] As noted above, the polyethylene polymer composition can comprise any suitable polyethylene polymer or mixture of polyethylene polymers that exhibits the desired melt relaxation ratio. Thus, the polyethylene polymer composition can comprise a single polyethylene polymer that exhibits the desired melt relaxation ratio. Alternatively, the polyethylene polymer composition can comprise a mixture of two or more polyethylene polymers that exhibit the desired melt relaxation ratio. In such a mixture, each polyethylene polymer can exhibit a melt relaxation ratio that falls within the desired range, although this is not required. For example, a polyethylene polymer that exhibits a relatively low melt relaxation ratio (e.g., less than 1.5) can be blended with an appropriate amount of another polyethylene polymer having a higher melt relaxation ratio (e.g., 1.55 or greater) to obtain a polyethylene polymer composition that exhibits the desired melt relaxation ratio.

[0059] The degree of melt relaxation of polyethylene polymers may alternatively be quantified by other means. For example, after extensive experimentation with various polymers and polymer compositions, it is believed that the ratio of tan δ values ​​at which sufficient melt relaxation occurs may be influenced by the molecular weight of the polymer, with polymers having higher molecular weights requiring a higher ratio to achieve sufficient melt relaxation. Therefore, the ratio between tan δ values ​​may benefit from an additional factor to account for the effect of polymer molecular weight. The molecular weight of a polymer is generally inversely proportional to the polymer's melt flow index. Furthermore, the relationship between molecular weight and melt flow index is not linear but is more typically logarithmic in nature. Therefore, the ratio between tan δ values ​​can be increased to account for the effect of molecular weight by multiplying the ratio by 1 plus the natural logarithm of the polymer's melt flow index. The resulting parameter, hereinafter referred to as the "melt relaxation index," should be 2 or greater. In other words, a polyethylene polymer composition preferably has a melt relaxation index of 2 or greater, more preferably 2.1 or greater.

[0060]

[0056] Thus, the melt relaxation index (MRI) is defined as the product of (i) the sum of 1 and the natural logarithm of the melt flow index of the polymer, and (ii) the ratio of tan δ at approximately 0.1 rad / s to tan δ at approximately 10 rad / s:

[0061]

number

[0062] In this definition, the two angular frequencies are approximately equal to the given values. Thus, tan δ at approximately 0.1 rad / s can be measured at any angular frequency between 0.095 and 0.105 rad / s, and tan δ at approximately 10 rad / s can be measured at any angular frequency between 9.5 and 10.5 rad / s. The exact angular frequencies used to determine MRR may vary within the ranges mentioned above, but the ratio of the two angular frequencies must be 0.01 (i.e., there must be a 100-fold difference between the two angular frequencies). The melt flow index of polymers, which can be reported in units of decigrams per minute (dg / min) or grams per 10 minutes (g / 10min), is measured according to ASTM standard D1238 at 190°C using a 2.16 kg load.

[0063] The melt relaxation index may be measured by any suitable technique. Preferably, the shear loss modulus (G"), shear storage modulus (G'), and tan δ are determined by parallel plate rheometry, as described above in connection with the melt relaxation ratio. As with the measurement of the melt relaxation ratio, the presence of a nucleating agent does not significantly affect the shear loss modulus (G"), shear storage modulus (G'), tan δ, or melt flow index measured from the polyethylene polymer composition. Thus, these parameters (and the melt relaxation index) may be measured from the polyethylene polymer composition before it is combined with the salt of cyclopentylphosphonic acid, or the parameters may be measured from a polymer composition comprising the polyethylene polymer composition and the salt of cyclopentylphosphonic acid.

[0064] As noted above, the polyethylene polymer composition can comprise any suitable polyethylene polymer or mixture of polyethylene polymers that exhibits the desired melt relaxation index. Thus, the polyethylene polymer composition can comprise a single polyethylene polymer that exhibits the desired melt relaxation index. Alternatively, the polyethylene polymer composition can comprise a mixture of two or more polyethylene polymers that exhibit the desired melt relaxation index. In such a mixture, each polyethylene polymer can exhibit a melt relaxation index that falls within the desired range, although this is not required. For example, a polyethylene polymer exhibiting a relatively low melt relaxation index (e.g., less than 2) can be mixed with an appropriate amount of another polyethylene polymer having a higher melt relaxation index (e.g., 2.1 or greater) to obtain a polyethylene polymer composition that exhibits the desired melt relaxation index.

[0065] As noted above, the polymer composition also includes a salt of cyclopentylphosphonic acid, which has the structure of formula (I):

[0066] [ka]

[0067] As can be seen from formula (I), cyclopentylphosphonic acid is a dibasic acid (i.e., the compound contains two acidic hydrogen atoms). Thus, cyclopentylphosphonic acid can provide two cyclopentylphosphonic acid anions: a first anion with only one acidic hydrogen removed and a charge of −1 (minus one), and a second anion with both acidic hydrogens removed and a charge of −2 (minus two). Preferably, the salt of cyclopentylphosphonic acid used in the polymer composition is a salt in which the cyclopentylphosphonic acid is fully deprotonated (i.e., both acidic hydrogen atoms of the cyclopentylphosphonic acid have been removed).

[0068] The salt of cyclopentylphosphonic acid used in the polymer composition may contain any suitable cation to balance the charge of the cyclopentylphosphonate anion. In a preferred embodiment, the salt of cyclopentylphosphonic acid contains one or more cations selected from the group consisting of Group 1 element cations, Group 2 element cations, and Group 12 element cations. Suitable Group 1 element cations include, but are not limited to, sodium and lithium cations. Thus, in a preferred embodiment, the salt of cyclopentylphosphonic acid is selected from the group consisting of disodium cyclopentylphosphonate, dilithium cyclopentylphosphonate, and mixtures thereof. Suitable Group 2 element cations include, but are not limited to, calcium and magnesium cations. Thus, in another preferred embodiment, the salt of cyclopentylphosphonic acid is selected from the group consisting of calcium cyclopentylphosphonate, magnesium cyclopentylphosphonate, and mixtures thereof. Suitable Group 12 element cations include, but are not limited to, zinc cations. Thus, in yet another preferred embodiment, the salt of cyclopentylphosphonic acid is zinc cyclopentylphosphonate.

[0069]

[0061] The salts of cyclopentylphosphonic acid suitable for use in the polymer composition are crystalline solids. Some of these crystalline solids may have water of crystallization or water of hydration incorporated into their crystal structure. Thus, the salts of cyclopentylphosphonic acid used in the polymer composition may be hydrates (i.e., salts of cyclopentylphosphonic acid containing water of crystallization / water of hydration in their crystal structure) or dehydrates (i.e., salts of cyclopentylphosphonic acid not containing water of crystallization / water of hydration in their crystal structure). For example, if the salt of cyclopentylphosphonic acid contains a calcium cation, the salt of cyclopentylphosphonic acid is preferably anhydrous calcium cyclopentylphosphonate (i.e., calcium cyclopentylphosphonate not containing water of crystallization / water of hydration in its crystal structure).

[0070] The salt of cyclopentylphosphonic acid can have any suitable specific surface area (e.g., BET specific surface area). In a preferred embodiment, the salt of cyclopentylphosphonic acid has a specific surface area of ​​about 20 m 2 In another preferred embodiment, the salt of cyclopentylphosphonic acid has a BET specific surface area of ​​about 30 m 2 The salts of cyclopentylphosphonic acid have a BET surface area of ​​1 / g or greater. The BET surface area of ​​the salts of cyclopentylphosphonic acid can be measured by any suitable technique. Preferably, the BET surface area of ​​the salts of cyclopentylphosphonic acid is measured according to ISO standard 9277:2010, entitled "Determination of the Specific Surface Area of ​​Solids by Gas Adsorption - BET method," using nitrogen as the adsorption gas. The salts of cyclopentylphosphonic acid disclosed herein generally have a layered structure that can be exfoliated using techniques known in the art. Exfoliation of such a layered structure increases the BET surface area of ​​the salts of cyclopentylphosphonic acid, thereby aiding dispersion. Physical methods for increasing the BET surface area of ​​the salts of cyclopentylphosphonic acid include air jet milling, pin milling, hammer milling, and grinding milling. Improved dispersion and surface area can also be achieved by more rigorous mixing and extrusion methods, such as high-intensity mixing and twin-screw extrusion. Thus, salts of cyclopentylphosphonic acid that do not have the desired BET specific surface area can be exfoliated using these and other known techniques until the desired BET specific surface area is achieved.

[0071] The polymer composition can contain any suitable amount of the salt of cyclopentylphosphonic acid. In a preferred embodiment, the salt of cyclopentylphosphonic acid is present in the polymer composition in an amount of about 50 parts per million (ppm) or greater, based on the total weight of the polymer composition. In another preferred embodiment, the salt of cyclopentylphosphonic acid is present in the polymer composition in an amount of about 75 ppm or greater, about 100 ppm or greater, about 150 ppm or greater, about 200 ppm or greater, or about 250 ppm or greater, based on the total weight of the polymer composition. The salt of cyclopentylphosphonic acid is preferably present in the polymer composition in an amount of about 10,000 ppm or less, based on the total weight of the polymer composition. In preferred embodiments, the salt of cyclopentylphosphonic acid is present in the polymer composition in an amount of about 5,000 ppm or less, about 4,000 ppm or less, about 3,000 ppm or less, about 2,000 ppm or less, about 1,500 ppm or less, about 1,250 ppm or less, or about 1,000 ppm or less, preferably based on the total weight of the polymer composition.Thus, in a series of preferred embodiments, the salt of cyclopentylphosphonic acid is present in an amount of from about 50 ppm to about 10,000 ppm (e.g., from about 50 ppm to about 5,000 ppm, from about 50 ppm to about 4,000 ppm, from about 50 ppm to about 3,000 ppm, from about 50 ppm to about 2,000 ppm, from about 50 ppm to about 1,500 ppm, from about 50 ppm to about 1,250 ppm, or from about 50 ppm to about 1,000 ppm), from about 75 ppm to about 10,000 ppm (e.g., from about 75 ppm to about 5,000 ppm, from about 75 ppm to about 10,000 ppm), based on the total weight of the polymer composition. about 4,000 ppm, about 75 ppm to about 3,000 ppm, about 75 ppm to about 2,000 ppm, about 75 ppm to about 1,500 ppm, about 75 ppm to about 1,250 ppm, or about 75 ppm to about 1,000 ppm), about 100 ppm to about 10,000 ppm (for example, about 100 ppm to about 5,000 ppm, about 100 ppm to about 4,000 ppm, about 100 ppm to about 3,000 ppm, about 100 ppm to about 2,000 ppm, about 100 ppm to about 1,500 ppm, about 100 ppm to about 1,250 ppm, or about 100 ppm to about 1 ,000 ppm), about 150 ppm to about 10,000 ppm (for example, about 150 ppm to about 5,000 ppm, about 150 ppm to about 4,000 ppm, about 150 ppm to about 3,000 ppm, about 150 ppm to about 2,000 ppm, about 150 ppm to about 1,500 ppm, about 150 ppm to about 1,250 ppm, or about 150 ppm to about 1,000 ppm), about 200 ppm to about 10,000 ppm (for example, about 200 ppm to about 5,000 ppm, about 200 ppm to about 4,000 ppm, about 200 ppm to about 3,000 ppm, about 2 The carboxylic acid or carboxylic acid salt is present in the polymer composition in an amount of from about 00 ppm to about 2,000 ppm, from about 200 ppm to about 1,500 ppm, from about 200 ppm to about 1,250 ppm, or from about 200 ppm to about 1,000 ppm, from about 250 ppm to about 10,000 ppm (e.g., from about 250 ppm to about 5,000 ppm, from about 250 ppm to about 4,000 ppm, from about 250 ppm to about 3,000 ppm, from about 250 ppm to about 2,000 ppm, from about 250 ppm to about 1,500 ppm, from about 250 ppm to about 1,250 ppm, or from about 250 ppm to about 1,000 ppm).When the polymer composition includes more than one salt of cyclopentylphosphonic acid, each salt of cyclopentylphosphonic acid can be present in the polymer composition in one of the amounts described above, or the total amount of all salts of cyclopentylphosphonic acid present in the polymer composition can fall within one of the ranges described above. Preferably, when the polymer composition includes more than one salt of cyclopentylphosphonic acid, the total amount of all salts of cyclopentylphosphonic acid present in the polymer composition falls within one of the ranges described above.

[0072]

[0064] Suitable salts of cyclopentylphosphonic acid for use in the compositions of the present invention can be prepared by any suitable process. For example, salts can be prepared by reacting cyclopentylphosphonic acid with a metal base, such as a metal hydroxide (e.g., calcium hydroxide, sodium hydroxide, potassium hydroxide, magnesium hydroxide) or a metal oxide (e.g., calcium oxide or zinc oxide), in an aqueous medium. Salts of cyclopentylphosphonic acid prepared by such processes can be hydrates (e.g., calcium cyclopentylphosphonate monohydrate). Such hydrate salts can be dehydrated by heating the salt to a sufficiently high temperature. Some such dehydrated salts may be sufficiently unstable to rehydrate upon exposure to atmospheric moisture, while other dehydrated salts, such as calcium cyclopentylphosphonate (i.e., anhydrous calcium cyclopentylphosphonate), remain dehydrated even when exposed to atmospheric moisture.

[0073] The polymer compositions of the present invention may contain other polymer additives in addition to the salts of cyclopentylphosphonic acid described above. Suitable additional polymer additives include antioxidants (e.g., phenolic antioxidants, phosphite antioxidants, and combinations thereof), antiblocking agents (e.g., amorphous silica and diatomaceous earth), pigments (e.g., organic and inorganic pigments) and other colorants (e.g., dyes and polymeric colorants), fillers and reinforcing agents (e.g., glass, glass fiber, talc, calcium carbonate [e.g., aragonite], and magnesium oxysulfate whiskers), nucleating agents, clarifying agents, acid scavengers (e.g., metal salts of fatty acids, such as metal salts of stearic acid, and hydrotalcite-like materials), polymer processing additives (e.g., fluoropolymer processing additives), polymer crosslinkers, slip agents (e.g., fatty acid amide compounds obtained from the reaction of fatty acids with ammonia or amine-containing compounds), fatty acid ester compounds (e.g., fatty acid ester compounds obtained from the reaction of fatty acids with hydroxyl-containing compounds, such as glycerol, diglycerol, and combinations thereof), polymer modifiers (e.g., hydrocarbon resin modifiers, such as ExxonMobil Corporation under the trade name Oppera™), and combinations of the foregoing.

[0074]

[0066] Polymer compositions comprising heterophasic polyolefin polymers (e.g., polypropylene impact copolymers) may also contain compatibilizers that form bonds between the polymers of each phase of the heterophasic polyolefin polymer (e.g., between the propylene polymer in the continuous phase and the ethylene polymer in the discontinuous phase of a polypropylene impact copolymer). These bonds between the polymers of each phase of the heterophasic polyolefin polymer are formed when the polymer composition is melt mixed / compounded in a manner that generates free carbon radicals in the polymer composition (e.g., when the polymer composition is melt mixed / compounded with an organic peroxide). Suitable examples of such compatibilizers include, but are not limited to, those described in U.S. Pat. Nos. 9,410,035; 9,879,134; 9,914,825; 10,100,187; 10,273,346; 10,400,096; 10,590,270; 10,745,538; and 11,248,114, and U.S. Patent Application Publication Nos. 2021 / 0108052 A1 and 2021 / 0108038 A1, with diphenylfulvene and trimethylolpropane trisorbate (2,2-bis[(1,3-pentadienylcarbonyloxy)methyl]butyl 2,4-hexadienoate) being particularly preferred.

[0075] In a preferred embodiment, the polymer composition further comprises one or more acid scavengers. As noted above, suitable acid scavengers include metal salts of fatty acids and hydrotalcite-like materials (e.g., synthetic hydrotalcites). Suitable metal salts of fatty acids include C 12 ~C 22 Fatty acids (e.g., saturated C 12 ~C 22Examples of suitable acid scavengers include, but are not limited to, metal salts of fatty acids, such as stearic acid. In a preferred embodiment, the acid scavenger is selected from the group consisting of calcium, zinc, potassium, and lanthanum stearates, with zinc stearate being particularly preferred. Suitable hydrotalcite-like materials for use as acid scavengers include, but are not limited to, the synthetic hydrotalcite materials (CAS No. 11097-59-9) sold by Kisuma Chemicals under the trade names "DHT-4A" and "DHT-4V."

[0076] The cyclopentylphosphonic acid salt and the acid scavenger can be present in the polymer composition in any suitable relative amounts. For example, the cyclopentylphosphonic acid salt and the acid scavenger can be present in the polymer composition in a ratio (cyclopentylphosphonic acid salt to acid scavenger) of about 10:1 to about 1:10, based on the weight of the cyclopentylphosphonic acid salt and the acid scavenger in the polymer composition. More preferably, the cyclopentylphosphonic acid salt and the acid scavenger are present in the polymer composition in a ratio of about 4:1 to about 1:4, about 3:1 to about 1:3 (e.g., about 3:1 to about 1:1 or about 3:1 to about 2:1), about 1:1 to about 1:4, or about 1:1 to about 1:3, based on the weight of the cyclopentylphosphonic acid salt and the acid scavenger in the polymer composition. In a particularly preferred embodiment, the salt of cyclopentylphosphonic acid and the acid scavenger are present in the polymer composition in a ratio of about 2:1 based on the weight of the salt of cyclopentylphosphonic acid and the acid scavenger in the polymer composition (e.g., about 2 parts by weight of anhydrous calcium cyclopentylphosphonate to 1 part by weight of zinc stearate). In another particularly preferred embodiment, the salt of cyclopentylphosphonic acid and the acid scavenger are present in the polymer composition in a ratio of about 3:1 based on the weight of the salt of cyclopentylphosphonic acid and the acid scavenger in the polymer composition (e.g., about 3 parts by weight of anhydrous calcium cyclopentylphosphonate to 1 part by weight of zinc stearate).

[0077] As mentioned above, the polymer composition of the present invention may contain, in addition to the salt of cyclopentylphosphonic acid described above, other nucleating agents. Suitable nucleating agents include 2,2'-methylene-bis-(4,6-di-tert-butylphenyl)phosphates (e.g., sodium 2,2'-methylene-bis-(4,6-di-tert-butylphenyl)phosphate or hydroxyaluminum bis(2,2'-methylene-bis-(4,6-di-tert-butylphenyl)phosphate), bicyclo[2.2.1]heptane-2,3-dicarboxylates (e.g., disodium bicyclo[2.2.1]heptane-2,3-dicarboxylate or calcium bicyclo[2.2.1]heptane-2,3-dicarboxylate), cyclohexane-1,2-dicarboxylates (e.g., calcium cyclohexane-1,2-dicarboxylate, monobasic cyclohexane-1,2 Examples of suitable carboxylic acids include, but are not limited to, aluminum cyclohexane-1,2-dicarboxylate, dilithium cyclohexane-1,2-dicarboxylate, or strontium cyclohexane-1,2-dicarboxylate, glycerolates (e.g., zinc glycerolate), phthalates (e.g., calcium phthalate), phenylphosphonates (e.g., calcium phenylphosphonate), salts of branched alkyl phosphonic acids (e.g., calcium t-butylphosphonate monohydrate), and combinations thereof. In the case of bicyclo[2.2.1]heptane-2,3-dicarboxylate and cyclohexane-1,2-dicarboxylate, the carboxylate moieties may be configured in either the cis or trans configuration, with the cis configuration being preferred.

[0078] As mentioned above, the polymer composition of the present invention can also contain a clarifying agent. Suitable clarifying agents include, but are not limited to, trisamides and acetal compounds, which are condensation products of polyhydric alcohols and aromatic aldehydes. Suitable trisamide clarifying agents include, but are not limited to, amide derivatives of benzene-1,3,5-tricarboxylic acid, derivatives of N-(3,5-bis-formylamino-phenyl)-formamide (e.g., N-[3,5-bis-(2,2-dimethyl-propionylamino)-phenyl]-2,2-dimethyl-propionamide), derivatives of 2-carbamoyl-malonamide (e.g., N,N'-bis-(2-methyl-cyclohexyl)-2-(2-methyl-cyclohexylcarbamoyl)-malonamide), and combinations thereof. As mentioned above, the clarifying agent can be an acetal compound, which is the condensation product of polyhydric alcohols and aromatic aldehydes. Suitable polyhydric alcohols include acyclic polyols such as xylitol and sorbitol, and acyclic deoxypolyols (e.g., 1,2,3-trideoxynonitol or 1,2,3-trideoxynon-1-enitol). Suitable aromatic aldehydes typically contain a single aldehyde group, with the remaining positions on the aromatic ring either unsubstituted or substituted. Thus, suitable aromatic aldehydes include benzaldehyde and substituted benzaldehydes (e.g., 3,4-dimethyl-benzaldehyde or 4-propyl-benzaldehyde). The acetal compounds produced by the above reaction may be monoacetal, diacetal, or triacetal compounds (i.e., compounds containing one, two, or three acetal groups, respectively), with diacetal compounds being preferred. Suitable acetal-based clarifying agents include, but are not limited to, those disclosed in US Pat. Nos. 5,049,605; 7,157,510; and 7,262,236.

[0079] The polymer compositions of the present invention can be produced by any suitable method or process. For example, the polymer compositions can be produced by simple mixing of the individual components of the polymer composition (e.g., polymer, salt of cyclopentylphosphonic acid, and other additives, if present). The polymer compositions can also be produced by mixing the individual components under high shear or high intensity mixing conditions. The polymer compositions of the present invention can be provided in any form suitable for use in further processing to produce articles of manufacture from the thermoplastic polymer composition. For example, the thermoplastic polymer compositions can be provided in the form of a powder (e.g., a free-flowing powder), flakes, pellets, prills, tablets, agglomerates, etc.

[0080] The polymer composition of the first aspect of the invention can take the form of a masterbatch composition designed for addition or dropwise addition to a new polymer (e.g., a non-nucleated polypropylene polymer). In such an aspect, the polymer composition generally contains a higher amount of the salt of cyclopentylphosphonic acid than a thermoplastic polymer composition intended for use in forming an article of manufacture without further dilution or addition to a new thermoplastic polymer. For example, the salt of cyclopentylphosphonic acid can be present in such a polymer composition in an amount of about 0.5 wt. % or more (e.g., about 1 wt. % or more or about 2 wt. % or more). The maximum amount of salt in the masterbatch is limited only by manufacturing and processing considerations, but the amount is typically about 50 wt. % or less. Thus, in a series of preferred embodiments, the salt of cyclopentylphosphonic acid is present in an amount of about 0.5 wt % to about 50 wt % (e.g., about 0.5 wt % to about 40 wt %, about 0.5 wt % to about 30 wt %, about 0.5 wt % to about 25 wt %, about 0.5 wt % to about 20 wt %, about 0.5 wt % to about 15 wt %, about 0.5 wt % to about 10 wt %, about 0.5 wt % to about 5 wt %, or about 0.5 wt % to about 4 wt %), about 1 wt % to about 50 wt % (e.g., about 1 wt % to about 40 wt %, about 1 wt % to about 30 wt %), based on the total weight of the polymer composition. The hydroxybenzoate may be present in the masterbatch in an amount of about 1 wt. % to about 25 wt. %, about 1 wt. % to about 20 wt. %, about 1 wt. % to about 15 wt. %, about 1 wt. % to about 10 wt. %, about 1 wt. % to about 5 wt. %, or about 1 wt. % to about 4 wt. %, or about 2 wt. % to about 50 wt. % (e.g., about 2 wt. % to about 40 wt. %, about 2 wt. % to about 30 wt. %, about 2 wt. % to about 25 wt. %, about 2 wt. % to about 20 wt. %, about 2 wt. % to about 15 wt. %, about 2 wt. % to about 10 wt. %, about 2 wt. % to about 5 wt. %, or about 2 wt. % to about 4 wt. %). If the masterbatch composition includes more than one salt of cyclopentylphosphonic acid, each salt of cyclopentylphosphonic acid may be present in the masterbatch composition in one of the amounts recited above, or the combined amount of all salts of cyclopentylphosphonic acid present in the masterbatch composition may fall within one of the ranges recited above.Preferably, when the masterbatch composition comprises more than one salt of cyclopentylphosphonic acid, the combined amount of all salts of cyclopentylphosphonic acid present in the masterbatch composition falls within one of the ranges mentioned above. In such masterbatch compositions, the additional additives contained in the composition are likewise present in higher amounts intended to provide the desired concentration upon lowering the masterbatch composition into fresh polymer in the desired / specified ratio.

[0081] The polymer compositions of the present invention are believed to be useful in the manufacture of thermoplastic polymer articles of manufacture. The polymer compositions of the present invention may be formed into desired thermoplastic polymer articles of manufacture by any suitable technique, such as injection molding (e.g., thin-wall injection molding, multi-component molding, overmolding, or 2K molding), blow molding (e.g., extrusion blow molding, injection blow molding, or injection stretch blow molding), extrusion (e.g., fiber extrusion, tape [e.g., slit tape] extrusion, sheet extrusion, film extrusion, cast film extrusion, pipe extrusion, extrusion coating, or foam extrusion), thermoforming, rotational molding, film blowing (blown film), film casting (cast film), compression molding, extrusion compression molding, extrusion compression blow molding, etc. Thermoplastic polymer articles made using the polymer compositions of the present invention may be composed of multiple layers (e.g., multilayer blown or cast film, or multilayer injection-molded article), with one or any suitable number of the multiple layers containing the polymer composition of the present invention.

[0082] The polymer compositions of the present invention can be used to manufacture any suitable article of manufacture, including, but not limited to, medical devices (e.g., pre-filled syringes for retort applications, intravenous supply containers, and blood collection devices), food packaging, liquid containers (e.g., containers for beverages, medicines, personal care compositions, shampoos, etc.), wardrobes, microwaveable items, shelving, cabinet doors, machine parts, automotive parts, sheet, pipe, tubing, rotational molded parts, blow molded parts, films, fibers, and the like.

[0083] Salts of cyclopentylphosphonic acid (e.g., anhydrous calcium cyclopentylphosphonate) have been observed to rapidly nucleate polyolefin polymers. Accordingly, the polymer compositions of the present invention, which contain a polyolefin and at least one salt of cyclopentylphosphonic acid, exhibit relatively high crystallization temperatures and relatively fast crystallization rates (e.g., low crystallization half-times). As such, the polymer compositions of the present invention are believed to be particularly well suited for use in producing relatively thin-walled articles, such as thin-walled injection-molded articles (i.e., injection-molded articles having a wall thickness of about 25 mils or less (0.62 mm or less)). In producing such articles, the molded articles, due to their low mass and high surface area, are rapidly cooled after formation. Many conventional nucleating agents, which nucleate polyolefin polymers at lower temperatures and significantly slower rates than salts of cyclopentylphosphonic acid, are unable to effectively nucleate the polymers from which these thin-walled articles are made (the polymer cools from the molten state before such conventional nucleating agents can completely and / or effectively nucleate the polymer). Thus, the polymer compositions of the present invention enable the production of highly nucleated thin-walled articles (eg, thin-wall injection molded parts).

[0084] Furthermore, salts of cyclopentylphosphonic acid (e.g., anhydrous calcium cyclopentylphosphonate) generally induce relatively low isotropic shrinkage when used to nucleate polyolefin polymers (e.g., polypropylene homopolymer, polypropylene random copolymer, and / or polypropylene impact copolymer). This low isotropic shrinkage, combined with very rapid polymer nucleation, is believed to make salts of cyclopentylphosphonic acid (e.g., anhydrous calcium cyclopentylphosphonate) very useful for nucleating polymer compositions containing fillers, reinforcing agents, and / or pigments, particularly fillers, reinforcing agents, and / or pigments that can also nucleate polyolefin polymers. In such polymer compositions, the salts of cyclopentylphosphonic acid act rapidly to nucleate the polyolefin polymer before the fillers / reinforcing agents / pigments can nucleate the polyolefin. This effect, commonly referred to as "leveling" or "pigment leveling," is particularly beneficial because many such fillers, reinforcing agents, and / or pigments induce non-uniform (anisotropic) and / or high shrinkage upon nucleating the polyolefin polymer, which can lead to warping of articles made from the polymer composition.

[0085]

[0077] Accordingly, in a preferred embodiment, the present invention provides a polymeric composition comprising a polyolefin polymer, a salt of cyclopentylphosphonic acid, and an additive selected from the group consisting of a filler, a reinforcing agent, and / or a pigment. In such an embodiment, the polyolefin polymer may be any of the polyolefin polymers described above, but is preferably a polypropylene polymer (e.g., a polypropylene homopolymer, a polypropylene random copolymer, and / or a polypropylene impact copolymer). In a particularly preferred embodiment of such a polymeric composition, the polyolefin polymer is a polypropylene impact copolymer, such as one of the polypropylene impact copolymers described above. The salt of cyclopentylphosphonic acid may be any of the salts described above, with anhydrous calcium cyclopentylphosphonate being particularly preferred. The salt of cyclopentylphosphonic acid may be present in any of the amounts described above, with a range of about 1,000 ppm to about 2,000 ppm being particularly preferred. The additive in this embodiment of the polymeric composition is preferably an additive that increases the stiffness of the polyolefin polymer, such as glass fiber, talc, calcium carbonate (e.g., aragonite), and magnesium oxysulfate whiskers. In a particularly preferred embodiment, the stiffness additive is talc. While the polymer composition may contain any suitable amount of such a stiffness additive, the stiffness additive is generally present in the polymer composition in an amount of about 1 wt % or greater (e.g., about 2 wt % or greater, about 3 wt % or greater, about 4 wt % or greater, or about 5 wt % or greater) based on the total weight of the polymer composition. The stiffness additive is preferably present in an amount of about 15 wt % or less (e.g., about 10 wt % or less) based on the total weight of the polymer composition. Thus, the stiffness additive is preferably present in the polymer composition in an amount of about 1 wt % to about 15 wt % (e.g., about 2 wt % to about 15 wt %, about 3 wt % to about 15 wt %, about 4 wt % to about 15 wt %, or about 5 wt % to about 15 wt %), or about 1 wt % to about 10 wt % (e.g., about 2 wt % to about 10 wt %, about 3 wt % to about 10 wt %, about 4 wt % to about 10 wt %, or about 5 wt % to about 10 wt %) based on the total weight of the polymer composition.In a particularly preferred embodiment of such a polymer composition, the polymer composition comprises a polypropylene polymer (more preferably a polypropylene impact copolymer), about 1,000 ppm to about 2,000 ppm of anhydrous calcium cyclopentylphosphonate, and about 1% to about 10% by weight of talc.

[0086] In addition to the rapid nucleation and desirable shrinkage properties described above, some salts of cyclopentylphosphonic acid (e.g., anhydrous calcium cyclopentylphosphonate) have been observed to induce a strong preference for transverse lamellar growth in articles made from polyolefin polymers (e.g., polyethylene). In this context, "transverse" refers to both the machine direction (i.e., the direction in which the molten polymer exits the die and / or flows into the mold cavity) and the thickness of the molded article. Preferential transverse lamellar growth results in a higher transverse modulus, which may be desirable in round, center-gated injection-molded articles. Therefore, embodiments of the polymer compositions of the present invention, e.g., embodiments comprising a polyethylene polymer and anhydrous calcium cyclopentylphosphonate, are believed to be particularly suitable for use in making injection-molded articles (e.g., round, center-gated injection-molded articles). Furthermore, preferential transverse lamellar growth results in improved gas barrier properties (e.g., water vapor and / or oxygen barrier properties) of polyolefins (e.g., polyethylene, more specifically, high-density polyethylene). Thus, the polymer compositions of the present invention, e.g., embodiments comprising a polyethylene polymer and anhydrous calcium cyclopentylphosphonate, are believed to be particularly suitable for use in making films and other articles with improved gas barrier properties (e.g., lower water vapor transmission rate and / or oxygen transmission rate).

[0087] Alternatively, some salts of cyclopentylphosphonic acid (e.g., dilithium cyclopentylphosphonate) have been observed to induce a strong preference for normal lamellar growth in articles made from polyolefin polymers (e.g., polyethylene). In this context, "normal" is perpendicular to the machine direction (i.e., the direction in which the molten polymer exits the die and / or flows into the mold cavity) and parallel to the thickness of the molded article. Preferential normal lamellar growth can be particularly beneficial in improving the crack resistance of pipe. Normal lamellar growth can also improve the drop impact resistance of injection-molded parts and films (e.g., blown films). Thus, the polymer compositions of the present invention, e.g., embodiments comprising a polyethylene polymer and dilithium cyclopentylphosphonate, are believed to be particularly suitable for use in making pipes (e.g., high-density polyethylene pipes), injection-molded articles, and films (e.g., blown films).

[0088] The following examples further illustrate the above subject matter but, of course, should not be construed as in any way limiting its scope.

[0089] Example 1 This example demonstrates the synthesis of salts of cyclopentylphosphonic acid suitable for use in the polymer compositions described herein.

[0090] Dichloromethane (DCM, 916 g), aluminum chloride powder (223.4 g, 1.67 mol), and PCl3 (230.4 g, 1.67 mol) were added to a 5 L round-bottom flask equipped with overhead stirring, a nitrogen bubbler, a reflux condenser, and an addition funnel. The resulting mixture was stirred and cooled with dry ice. Bromocyclopentane (250 g, 1.67 mol) was added dropwise via the addition funnel over a period of approximately 20 minutes. The dry ice bath was removed, a mantle was added, and the mixture was heated to 35°C and stirred for 2 hours. The reaction mixture was poured into a bucket of ice water (2 kg), resulting in the formation of some HCl vapor. The biphasic solution was separated in a 2 L separatory funnel, and the aqueous phase was extracted three times, using 100 mL of DCM for each extraction. The combined organic layers were dried over anhydrous magnesium sulfate. GC analysis of the recovered organic layer showed the reaction products to contain approximately 86.8% cyclopentylphosphonic acid dichloride, approximately 12.32% cyclopentylphosphonic acid bromide, and approximately 0.87% cyclopentylphosphonic acid dibromide.

[0091] To a 5 L, three-necked, round-bottom flask equipped with a mechanical stirrer, reflux condenser, and thermocouple was added 985.8 g of the recovered organic layer (approximately 21.88 wt. % solution containing 215.69 g of active dichloride and bromide, 1.116 moles). The contents of the flask were stirred, and a solution of NaOH (357.22 g of a 50% solution, 178.61 g of active NaOH, 4.46 moles) was added. The caustic solution was initially warm, and the mixture began to exotherm violently to 49°C. An ice bath was placed under the flask, and the temperature began to slowly decrease. After approximately 2 hours of stirring, the pH of the aqueous layer was 11, indicating complete hydrolysis.

[0092] The aqueous layer was separated using a funnel and added to a 10 L glass beaker equipped with a Teflon stirring paddle. A solution of calcium chloride (123.85 g, 1.116 mol) in water (4 L) was added portionwise to the stirred aqueous layer. A white precipitate appeared immediately, which was suction filtered, washed with plenty of hot water, and dried overnight at 110°C to give a fine white powder (162.1 g of calcium cyclopentylphosphonate monohydrate (CaCPP), 77% yield). FTIR and GC analyses confirmed complete conversion. The powder was crushed and further heated in an oven at 200°C to remove the bound water of hydration, thereby yielding anhydrous calcium cyclopentylphosphonate.

[0093] Example 2 This example demonstrates the synthesis of salts of cyclopentylphosphonic acid suitable for use in the polymer compositions described herein.

[0094] Cyclopentylphosphonic acid (20 g, 0.133 mol) and deionized water (250 mL) were added to a 500 mL beaker, and the resulting mixture was stirred until homogeneous. To this solution was added 50% NaOH solution in water (21.28 g, 10.64 g, 0.266 mol), resulting in a solution. The water was removed by rotary evaporation to give a white crystalline solid, disodium cyclopentylphosphonate (NaCPP) (22.63 g, 88.4% yield). FTIR was consistent with the expected product.

[0095] Example 3 This example demonstrates the synthesis of salts of cyclopentylphosphonic acid suitable for use in the polymer compositions described herein.

[0096] Cyclopentylphosphonic acid (10 g, 0.066 mol) and deionized water (100 mL) were added to a 250 mL beaker, and the resulting mixture was stirred until homogeneous. To this solution was added lithium hydroxide monohydrate (5.59 g, 0.133 mol), resulting in a solution. The water was evaporated at room temperature in a hood to give a white crystalline solid, dilithium cyclopentylphosphonate (LiCPP) (10.17 g, 95.1%). FTIR was consistent with the expected product.

[0097] Example 4 This example demonstrates the synthesis of salts of cyclopentylphosphonic acid suitable for use in the polymer compositions described herein.

[0098] Cyclopentylphosphonic acid (10 g, 0.066 mol) and deionized water (100 mL) were added to a 250 mL beaker, and the resulting mixture was stirred until homogeneous. To this solution was added magnesium hydroxide (3.84 g, 0.066 mol), resulting in a slurry. The solid slowly dissolved to give a solution. The water was allowed to evaporate in a hood at room temperature to give magnesium cyclopentylphosphonate (MgCPP) as a white crystalline solid (12.1 g, approximately 100% yield). FTIR was consistent with the expected product.

[0099] Example 5 This example demonstrates the synthesis of salts of cyclopentylphosphonic acid suitable for use in the polymer compositions described herein.

[0100] Cyclopentylphosphonic acid (10 g, 0.066 mol) and deionized water (100 mL) were added to a 250 mL beaker, and the resulting mixture was stirred until homogeneous. To this solution, a slurry of zinc oxide (5.37 g, 0.066 mol) in water (10 mL) was added, resulting in a slurry. The slurry was stirred overnight at room temperature. The temperature of the slurry was then raised to 60°C and stirred for an additional 5 hours, at which point a cloudy solution was obtained. The solution was suction filtered, and the filtrate was evaporated at room temperature to give a crystalline white solid, zinc cyclopentylphosphonate (ZnCPP) (13.8 g, 98% yield). FTIR was consistent with the expected product.

[0101] Example 6 This example demonstrates the preparation of a polymer composition in accordance with the present invention, the preparation of a thin-walled injection-molded article made from such a polymer composition, and certain physical properties of such a thin-walled injection-molded article.

[0102] Several polymer compositions were prepared using two commercially available polypropylene resins. The sample labeled "6A" was prepared using LyondellBasell's Pro-fax 6301 polypropylene homopolymer, reported to have a melt flow rate of 12 g / 10 min. The sample labeled "6B" was prepared using LyondellBasell's SA849 polypropylene random copolymer (RCP), also reported to have a melt flow rate of 12 g / 10 min. All samples were stabilized with 500 ppm Irganox® 1010 antioxidant and 1,000 ppm Irgafos® 168 antioxidant, both available from BASF. Some polymer compositions further contained calcium cyclopentylphosphonate ("CaCPP"), calcium t-butylphosphonate monohydrate ("CaTBP"), zinc stearate ("ZnSt"), and / or DHT-4A from Kisuma Chemicals. The amounts of these additional ingredients are set forth in the table below.

[0103] Each of the polymer compositions was prepared by high-intensity mixing of the polypropylene resin and additives and melt compounding the mixture using a Deltaplast single-screw extruder. The extruder screw speed was set at 126 rpm. The first zone of the extruder barrel was set at 200°C, the second zone of the extruder barrel was set at 215°C, and zones three through six of the extruder barrel were all set at 230°C. After melt compounding, each extrudate was chopped into pellets for further processing.

[0104] The extruded pellets of each polymer composition were then injection molded into 16 U.S. fluid ounce (470 mL) deli cups in a Husky injection molding machine with all barrels set at 220°C, an injection speed of 140 mm / s, a back pressure of 50 psi (0.14 MPa), and mold cooling water set at 45°C. The deli cups had a circular bottom with a diameter of 3.637 inches (92.38 mm), a circular opening at the top with a rim whose inner edge was 4.266 inches (108.4 mm) in diameter and whose outer edge was 4.612 inches (117.1 mm) in diameter. The deli cup wall thickness was 26 mils (0.66 mm).

[0105] After molding, the deli cups were tested to determine several physical properties. Compression topload was measured according to ASTM D2659. Haze was measured according to ASTM D1003. Thermal properties of the specimens were measured by differential scanning calorimetry using a Mettler Toledo differential scanning calorimeter (DSC) unit (DSC 3+STAR system) and analyzed by Mettler STARe evaluation software. For crystallization temperature measurements, the specimens were heated from 50°C to 220°C at a rate of 20°C / min to remove all thermal history. After holding the specimens at 220°C for 2 minutes to equilibrate, the specimens were cooled to 50°C at a rate of 20°C / min to study the crystallization behavior. The crystallization temperature (T c) is reported as the peak value on the cooling curve. For the crystallization half-time measurement, the specimen was heated from 50°C to 220°C at a rate of 20°C / min to remove all thermal history, held at 220°C for 2 minutes to equilibrate, then cooled at a rate of 300°C / min to 140°C and held at that temperature for 30 minutes. The crystallization half-time was calculated from the DSC curve using software. The results of these measurements are reported in Tables 1 and 2 below.

[0106] [Table 1]

[0107] [Table 2]

[0108] As can be seen from the data in Tables 1 and 2 above, anhydrous calcium cyclopentylphosphonate ("CaCPP") was the most effective at nucleating both polypropylene polymers, and was superior to branched alkyl calcium phosphonate ("CaTBP"). These nucleation effects are evident from the shorter crystallization half-times, higher crystallization temperatures, higher compressed top loads, and lower haze values ​​exhibited by all polymer compositions containing CaCPP compared to their respective control polymers (i.e., virgin polypropylene resins) and polymer compositions containing CaTBP.

[0109] Example 7 This example demonstrates the preparation of polymer compositions in accordance with the present invention, the preparation of thermoformed articles from such polymer compositions, and certain physical properties of such thermoformed articles.

[0110]

[0100] Polymer compositions were made using Total Energies' Polypropylene 3371 resin (a polypropylene homopolymer), which is reported to have a melt flow rate of 2.8 g / 10 min. Certain polymer compositions were nucleated with an acid scavenger, such as calcium t-butylphosphonate monohydrate ("CaTBP") and anhydrous calcium cyclopentylphosphonate ("CaCPP"), in conjunction with zinc stearate ("ZnSt") or calcium stearate ("CaSt"). The amounts of CaTBP, CaCPP, and acid scavenger used in each polymer composition are listed in the table below. The 3371 resin and additives were high-intensity mixed using a Henschel mixer prior to melt compounding, as described below.

[0111] The polymer composition was melt compounded in a Werner & Pfleiderer zsk-40 twin-screw extruder with a screw diameter of 40 mm and an L / D ratio of 37. The temperature of the first zone of the extruder barrel was set at 165°C, and the temperatures of the second to sixth zones of the extruder barrel and the die zone were set at 175°C. The extruder speed was set at 400 rpm, with a total output of approximately 55 kg / h. The polymer strands exiting the extruder die were cooled in a water bath and chopped into pellets using a pelletizer.

[0112] The pelletized polymer composition was then thermoformed into drinking cups using a Reifenhaeuser Model AT-20-G1 sheet line in conjunction with an iLLig RDM54K thermoformer. The extruder of the sheet line was set at 230°C, the die zone was set at 250°C, and the die gap was 1.5 mm. The screw speed was approximately 72 rpm. The sheet exiting the die was transferred to a set of three stacked chill rolls set at 65°C, 75°C, and 65°C. The sheet exiting the chill rolls was 1.9 mm thick. The sheet was then indexed through the heating section of the thermoformer, set at 165°C, where it was heated just below the melting temperature of the polymer composition. The sheet then passed through the forming section, where it was thermoformed into drinking cups, which were then trimmed from the sheet and ejected from the thermoformer. The resulting drinking cups had a base diameter of approximately 60 mm, a top edge diameter of approximately 94 mm, and a height of approximately 140 mm.

[0113] Specimens of the extruded sheets and thermoformed drinking cups were obtained for the optical and physical property testing described below. Haze and clarity were measured according to ASTM D1003 using a BYK Hazegard Haze Meter. For thermoformed drinking cups, haze measurements were taken in an area 76.2 mm from the bottom of the cup and 25.4 mm from the top edge. Gloss was measured using a BYK Single Angle Gloss Meter, Microgloss 20°. Measurements were taken from both sides of the specimen, and the results were averaged to obtain an average gloss, reported in gloss units.

[0114]

[0104] The thermal properties of the specimens were measured by differential scanning calorimetry as described in Example 6, except that the specimens were cooled to 135°C at a rate of 300°C / min when performing the crystallization half-time measurements.

[0115]

[0105] Test specimens for flexural modulus testing were cut from the extruded sheets using a Type 1 dogbone cutting die as described in ASTM D638-10. Test specimens were obtained from the machine and transverse directions. The specimens were then conditioned at approximately 23°C and approximately 50% relative humidity for at least 40 hours. Flexural modulus testing was performed in accordance with ASTM D790-10 using an MTS Criterion Model 43 electromechanical testing system equipped with a three-point flexure bending setup (Model 642.01A). The depth of beam movement was recorded to calculate strain. The 1% secant modulus was calculated based on the ratio of stress to strain when 1% strain was reached.

[0116] Cup ovality is a parameter that indicates the difference in cup diameter measured in the machine direction (parallel to the direction in which the sheet exits the die) and the cross direction (perpendicular to the direction in which the sheet exits the die). Thermoformed cups are measured using a vernier caliper to measure the difference in the cup diameter measured in the machine direction (D MD ) and transverse (D TD The cup ovality, reported in mils, was calculated using the following formula: Cup ovality = (D MD -D TD ) x 1000 Edge shrinkage is a parameter that indicates the difference between the diameter of the edge of a thermoformed cup and the diameter of the corresponding portion of the mold from which the cup was made. The diameter of the mold was 3.7427 inches. The average diameter of the cup edge (D avg ) was measured using a spring tension band (in inches). Cup lip shrinkage, reported in mils, was calculated using the following formula: Edge shrinkage = (3.7427-D avg )×1000.

[0117] The compressive strength of the sidewall of a thermoformed cup was measured using a probe to determine its resistance to deflection. The cup was positioned horizontally on its side using a cup fixture attached to the platen of an MTS Criterion Model 43 electromechanical testing system. The probe, moving at a constant vertical speed of 25 mm / min, pressed vertically downward against the sidewall of the cup to achieve a total wall deflection distance of 10 mm. Once the desired total wall deflection distance was reached, the resulting resistance was recorded as the sidewall force. Top-load compression (ASTM D2659) of a thermoformed cup was measured by inverting the cup and mechanically compressing it downward until resistance to buckling failure of the cup was detected. The cup was placed edge-down on the fixed base of the MTS Criterion Model 43 electromechanical testing system. A vented base allowed air to escape from the interior of the cup as it was compressed. The upper compression plate, moving at a constant speed of 50 mm / min, pressed down on the cup until collapse was detected. The peak force recorded at the time of collapse was reported as the top load.

[0118] [Table 3]

[0119] [Table 4]

[0120] [Table 5]

[0121] [Table 6]

[0122] As can be seen from the data in Tables 3-6, anhydrous calcium cyclopentyl phosphonate ("CaCPP") was particularly advantageous over calcium t-butyl phosphonate ("CaTBP") in improving the optical properties of both the extruded sheet and the thermoformed cups. While the physical properties of the formed cups were similar, CaCPP exhibited a higher polymer crystallization temperature (T c ) and shortened crystallization half-time (T 1 / 2 ), which was a significant advantage in terms of cycle time reduction not only in thermoforming but also in other processes.

[0123] Example 8

[0109] This example demonstrates the preparation of several polymer compositions in accordance with the present invention, the preparation of injection molded articles from such polymer compositions, and certain physical properties exhibited by such injection molded articles.

[0124] Seven polymer compositions were prepared for the injection molding runs described herein. Sample 8A was a non-nucleated Pro-fax 6301 polypropylene homopolymer manufactured by LyondellBasell. Samples 8B-8G were made from a mixture of Pro-fax 6301, 1,000 ppm of each nucleating agent, 500 ppm zinc stearate ("ZnSt"), 300 ppm Irganox® 1010 antioxidant, and 600 ppm Irgafos® 168 antioxidant. The nucleating agents used in each of Samples 8B-8G are identified in Table 7 below. Samples 8B-8G were separately mixed, melt compounded, and pelletized as described in Example 6.

[0125] A portion of each polymer composition was injection molded into ASTM bent bars according to ASTM D4101-11 using a 40 ton Arburg injection molding machine. Another portion of each polymer composition was injection molded into ISO shrink plaques according to ISO 294 using a 55 ton Arburg injection molding machine. Finally, another portion of each polymer composition was injection molded into 77 mm long, 50 mm wide, 1.27 mm (50 mil) thick plaques on the 40 ton Arburg injection molding machine.

[0126] Heat deflection temperatures (HDT) were measured according to ASTM D648-07 (using 0.4555 MPa stress) on the injection-molded ASTM flexural bars described above. Notched Izod impact was measured according to ASTM D256-10 on an Instron 9050 pendulum impact tester using injection-molded ASTM flexural bars trimmed and notched as specified in ASTM D256-10. Thermal properties of the specimens were measured by differential scanning calorimetry as described in Example 6, except that the specimens were cooled to 135°C at a rate of 300°C / min when performing the crystallization half-time measurements.

[0127] Flexural modulus was measured according to ASTM D790-10 using an MTS Criterion Model 43 electromechanical testing system equipped with a three-point flexure setup (Model 642.01A). The bending bars were conditioned for at least 40 hours at approximately 23°C and approximately 50% relative humidity prior to testing. Bidirectional flexural modulus (machine direction (MD) and transverse direction (TD)) was also measured according to ASTM D790-10. Specimens for bidirectional flexural modulus, conditioned as described above, were trimmed from injection-molded ISO shrink plaques. For MD measurements, 9.2 mm of material was trimmed from the TD axis (leaving 50.8 mm [2 inches] in the TD direction) and the load was applied perpendicular to the machine direction. For TD measurements, 9.2 mm of material was trimmed from the MD axis (leaving 50.8 mm [2 inches] in the MD direction) and the load was applied parallel to the machine direction.

[0128] Shrinkage of injection molded ISO shrinkage plaques was measured according to ISO 294, with the plaques conditioned for at least 48 hours at about 23°C and about 50% relative humidity before testing. Shrinkage in the machine and transverse directions was calculated using the following formulas:

[0129]

number

[0130] In the formula, MD mоld is the dimension of the die in the machine direction, MD specimen is the specimen dimension in the machine direction, and TD mоld is the horizontal dimension of the mold, and TD specimen is the specimen dimension in the cross direction. The isotropy index, a measure of how uniformly the part shrunk, was calculated by dividing the shrinkage in the machine direction by the shrinkage in the cross direction.

[0131]

number

[0132] The above measurement results are shown in Tables 7 to 12 below.

[0133] [Table 7]

[0134] [Table 8]

[0135] [Table 9]

[0136] The data in Tables 7-9 show that among the metal salts of cyclopentylphosphonic acid, the anhydrous calcium salt (CaCPP) stands out in nearly every category of nucleation performance. CaCPP induces physical property improvements to the same extent as branched alkyl phosphonates (specifically, calcium t-butyl phosphonate monohydrate ("CaTBP")), but at a significantly higher polymer crystallization temperature (T c ) and faster kinetics (lower T 1 / 2 ) may allow for greater actual cycle time reductions and a greater ability to "over-nucleate" or "pigment level" pigmented PP systems.

[0137] Example 9

[0116] This example demonstrates the preparation of polyethylene polymer compositions in accordance with the present invention and the improved properties exhibited by injection molded articles made from such polymer compositions.

[0138] Injection moulded parts were made using Sclair 2908 HDPE from Nova Chemicals. The polymer had a viscosity of 961 kg / m 3 and a melt flow index of 7.0 dg / min. The granular resin was ground to a powder before being compounded with the additives described below.

[0139]

[0118] Samples were made by mixing ground HDPE resin with 1000 ppm of the specified nucleating agent and 500 ppm of zinc stearate. The nucleating agent used in each of Samples 9B-9G is identified below in Table 10. The combined ingredients were mixed at high intensity in a Henschel mixer.

[0140] Each resulting mixture was compounded using a Leistritz ZSE-18 twin-screw extruder. The extruder was purged with Sclair 2908 HDPE resin before each sample. The temperature profile for all zones was set at 155°C to 165°C, with a die temperature of 155°C. The screw speed was set at 500 rpm, and the feed rate was 3.5 kg / hr. After the first 200 g of material was extruded, the polymer strand was transferred to a water bath. The cooled polymer strand was chopped to granular size using a standard pelletizer.

[0141] The thermal properties of the polymer specimens were measured by differential scanning calorimetry (DSC) in a manner similar to that described in Example 6. In particular, the T c was measured by DSC by heating the specimen from 30 °C to 220 °C at 20 °C / min, holding the specimen at 220 °C for 2 min, and then cooling the specimen to 30 °C at 20 °C / min. However, due to the inherent crystallization behavior of HDPE, the crystallization half-time was not measured in the kinetics measurements. Therefore, for relative comparison of nucleation kinetics, the "Peak T c The "time to peak T" was measured. This value was measured again by DSC by heating the specimen to 200°C at 20°C / min and holding the temperature for 2 minutes to remove the thermal history. The specimen was then cooled to 130°C at 35°C / min and then cooled back down to 100°C at 1°C / min. The time measurement started when the sample reached 130°C and was followed by the peak T c The test was terminated when the peak T c The time to

[0142] Each compounded sample was molded into ISO shrink plaques according to ISO 294 using a 55-ton Arburg injection molding machine. The mold had a dual cavity, and the plaque dimensions were 60.0 mm long, 60.0 mm wide, and 2.0 mm high. The throat temperature was 40°C. The first four barrel zones were set at 210°C, and the last zone was set at 230°C. The mold temperature was set at 40°C. The total cycle time was 40-45 seconds. The resulting ISO shrink plaques were subjected to measurements of plaque shrinkage in the machine direction (MD) and transverse direction (TD).

[0143] [Table 10]

[0144] [Table 11]

[0145] The results in Table 10 show that CaCPP provides the highest crystallization temperature and fastest crystallization kinetics for polyethylene in injection-molded parts, similar to the effects observed with polypropylene. In addition to the cycle-time benefit, a "leveling" effect can also be realized in the presence of nucleating pigments (e.g., talc), which can otherwise lead to problems due to differential shrinkage that such pigments can cause. Table 11 shows that anhydrous calcium cyclopentylphosphonate (CaCPP) results in preferential alignment of crystalline PE lamellae, as indicated by higher MD shrinkage compared to TD shrinkage. This orientation, in which PE crystalline lamellae grow preferentially in the TD direction of these parts, results in a very high TD modulus. This orientation may be desirable for round, center-gate injection-molded parts. CaCPP (Sample 9C) induces the highest TD modulus among the classes of metal salts of cyclopentylphosphonic acid tested.

[0146]

[0123] All references cited in this specification, including publications, patent applications, and patents, are hereby incorporated by reference to the same extent as if each reference was individually and specifically indicated to be incorporated by reference and was set forth in its entirety herein.

[0147]

[0124] In the context of describing the subject matter of this application (particularly in the context of the claims below), the use of the terms "a," "an," and "the," and similar referents, are to be construed to encompass both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. The terms "comprising," "having," "including," and "containing" are to be construed as open-ended terms (i.e., meaning "including, but not limited to"), unless otherwise stated. The recitation of ranges of values ​​herein is merely intended to be a shorthand method of referring individually to each separate value falling within the range, unless otherwise indicated, and each separate value is incorporated herein as if it were individually recited herein. All methods described herein can be performed in any suitable order unless otherwise indicated herein or clearly contradicted by context. The use of any and all examples or exemplary language (e.g., "for example") presented herein is intended merely to better clarify the subject matter of the present application and does not limit the scope of the subject matter unless otherwise claimed. No language herein should be construed as indicating any non-claimed element as essential to the practice of the subject matter described herein.

[0148] Preferred embodiments of the subject matter, including the best mode known to the inventors for carrying out the claimed subject matter, are described herein. Variations of the preferred embodiments may become apparent to those of skill in the art upon reading the foregoing description. The inventors anticipate that those of skill in the art will employ such variations as appropriate, and the inventors intend that the subject matter described herein may be practiced otherwise than as specifically described herein. Accordingly, this disclosure includes all modifications and equivalents of the subject matter recited in the claims appended hereto as permitted by applicable law. Moreover, any combination of the above-described elements in all possible variations thereof is encompassed by this disclosure unless otherwise indicated herein or clearly contradicted by context.

Claims

1. (a) a polyolefin polymer; and (b) Salts of cyclopentylphosphonic acid A polymer composition comprising:

2. 10. The polymer composition of claim 1, wherein the polyolefin polymer is selected from the group consisting of polypropylene polymers, polyethylene polymers, and mixtures thereof.

3. 3. The polymer composition of claim 2, wherein the polypropylene polymer is selected from the group consisting of polypropylene homopolymer, polypropylene random copolymer, polypropylene impact copolymer, and mixtures thereof.

4. 4. The polymer composition of claim 3, wherein the polypropylene polymer is selected from the group consisting of polypropylene homopolymer, polypropylene random copolymer, and mixtures thereof.

5. The polymer composition of claim 1 , wherein the polyolefin polymer is a polyethylene polymer.

6. The polyethylene polymer has a viscosity of about 930 kg / m ３ ~Approx. 970kg / m ３ 6. The polymer composition of claim 5, having a density of

7. 2. The polymer composition of claim 1, wherein the salt of cyclopentylphosphonic acid comprises one or more cations selected from the group consisting of Group 1 element cations, Group 2 element cations, and Group 12 element cations.

8. 8. The polymer composition of claim 7, wherein the salt of cyclopentylphosphonic acid comprises a Group 1 element cation.

9. 9. The polymer composition of claim 8, wherein the salt of cyclopentylphosphonic acid is dilithium cyclopentylphosphonate.

10. 9. The polymer composition of claim 8, wherein the salt of cyclopentylphosphonic acid is disodium cyclopentylphosphonate.

11. 8. The polymer composition of claim 7, wherein the salt of cyclopentylphosphonic acid comprises a Group 2 element cation.

12. 12. The polymer composition of claim 11, wherein the salt of cyclopentylphosphonic acid comprises calcium or magnesium cations.

13. 13. The polymer composition of claim 12, wherein the salt of cyclopentylphosphonic acid comprises a calcium cation.

14. 14. The polymer composition of claim 13, wherein said salt of said cyclopentylphosphonic acid is anhydrous calcium cyclopentylphosphonate.

15. 8. The polymer composition of claim 7, wherein the salt of cyclopentylphosphonic acid comprises a Group 12 cation.

16. 16. The polymer composition of claim 15, wherein the salt of cyclopentylphosphonic acid is zinc cyclopentylphosphonate.

17. 10. The polymer composition of claim 1, wherein the salt of cyclopentylphosphonic acid is present in the polymer composition in an amount of from about 50 parts per million to about 2,000 parts per million, based on the total weight of the polymer composition.

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