Bimodal HDPE and polyethylene blends containing raw and recycled HDPE materials

Abstract

A high density polyethylene blend containing (a) from 25% to 90% by weight of a recycled high density polyethylene; and (b) from 10% to 75% by weight of a raw bimodal HDPE polymer having a density of from 0.944 g / cc to 0.953 g / cc and a flow index (I21) of from 8 g / 10 min to 12 g / 10 min, and exhibiting good physical properties for blow molded articles, including good melt strength, physical properties, and crack resistance.

Description

Technical Field

[0001] The present application relates to the field of polyethylene polymers. Background Art

[0002] Plastic recycling is an important part of plastic waste management. Recycled plastics may not meet the physical property specifications required for common end uses. Therefore, recycled plastics are often blended with newly made ("virgin") plastics to provide a blend that can meet the specifications required for commercial use. Such blends ideally contain as much recycled plastic as possible to maximize the amount of recycled plastic used and minimize the amount of virgin plastic required.

[0003] Many common uses of high density polyethylene (HDPE) require good melt strength, good mechanical properties (tensile strength and flexural strength) and crack resistance. Crack resistance is usually measured by ASTM D1693, which measures environmental stress crack resistance (ESCR), and / or ASTM F2136, which measures notched constant ligament stress (NCLS) resistance. ESCR may be critical for some uses such as blow molded bottles, while NCLS may be more important for other uses such as corrugated tubing.

[0004] Recycled high density polyethylene polymers may have ESCR and / or NCLS that are too low for the desired use. This may be particularly true for post-consumer recycled ("PCR") high density polyethylene polymers. Some virgin polymers that may be blended to improve crack resistance may also have the effect of reducing other desired physical properties such as rigidity.

[0005] It is desirable to identify blends of virgin high density polyethylene polymers with high levels of recycled high density polyethylene polymers, especially PCR high density polyethylene polymers, that have a good balance of physical properties and high crack resistance. Summary of the invention

[0006] We have found that selecting a virgin bimodal HDPE with the appropriate density and flow index can provide a blend with recycled HDPE with good stiffness and good ESCR and NCLS, as well as other desirable properties. We have also developed a virgin bimodal HDPE material that is well suited for this application.

[0007] One aspect of the invention is a high density polyethylene (HDPE) blend comprising: (a) 25 wt% to 90 wt% recycled HDPE; and (b) 10 wt% to 75 wt% virgin bimodal high density polyethylene (virgin bimodal HDPE), the virgin bimodal HDPE having a density of 0.944 g / cc to 0.953 g / cc and a flow index (I) of 8 g / 10 min to 12 g / 10 min. 21). The HDPE blend is a post-reactor blend of recycled HDPE and virgin bimodal HDPE.

[0008] Another aspect of the present invention is a shaped article comprising the high density polyethylene blend of the present invention.

[0009] Another aspect of the present invention is a blow molding method comprising the steps of: (1) placing a certain amount of molten high-density polyethylene blend in a mold cavity, (2) blowing gas into the molten high-density polyethylene blend to cause it to expand and assume the approximate shape of the mold cavity, and (3) cooling the high-density polyethylene blend, wherein the high-density polyethylene blend is the high-density polyethylene blend of the present invention.

[0010] Another aspect of the present invention is a blow-molded product, which is produced by the blow-molding method.

[0011] Another embodiment is a raw bimodal high density polyethylene polymer comprising a higher molecular weight ethylene / 1-hexene copolymer component and a lower molecular weight ethylene / 1-hexene copolymer component, wherein: the raw bimodal HDPE polymer has a density of 0.944 g / cc to 0.953 g / cc; the raw bimodal HDPE polymer has a flow index (I 21 ) is 8 g / 10 min to 12 g / 10 min; and the melt flow ratio (I 21 / I2) is at least 125. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 The melt strength over a range of draw speeds from 1 millimeter per second (mm / s) to 120 mm / s is demonstrated for two virgin HDPE polymers: a virgin bimodal HDPE polymer within the scope of the present invention and a comparable virgin unimodal HDPE polymer. Figure 1 is the melt strength of virgin bimodal HDPE 1 (or simply "virgin HDPE 1" or "virgin 1") and a comparative HDPE (Marlex HXM50100P). Figures 2 to 5 The melt strength of blends of two virgin HDPE polymers with recycled HDPE (containing 25 wt%, 50 wt%, 75 wt% and 90 wt% recycled HDPE, respectively) under similar conditions is demonstrated. Figure 2 is the melt strength of a blend containing 25% post consumer recycled (PCR) HDPE and 75% virgin HDPE (virgin bimodal HDPE 1 or comparative Marlex HXM50100P). Figure 3is the melt strength of a blend containing 50% PCR HDPE and 50% virgin HDPE (virgin bimodal HDPE 1 or comparative Marlex HXM 50100P). Figure 4 is the melt strength of a blend containing 75% PCR HDPE and 25% virgin HDPE (virgin bimodal HDPE 1 or comparative Marlex HXM 50100P). Figure 5 is the melt strength of a blend containing 90% PCR HDPE and 10% virgin HDPE (virgin bimodal HDPE 1 or comparative Marlex HXM 50100P). Figure 6 The molecular weight distributions of a pristine bimodal HDPE polymer within the scope of the present invention and a comparable unimodal HDPE polymer as measured by gel permeation chromatography are illustrated. DETAILED DESCRIPTION

[0013] HDPE polymer - general properties

[0014] The present invention uses both virgin and recycled high density polyethylene (HDPE) polymers. Typically, HDPE is a polymer containing primarily repeating units derived from ethylene, optionally with repeating units derived from one or more unsaturated comonomers, and having a density of 0.93 g / cc to 0.98 g / cc. Both virgin and recycled HDPE are commercially available.

[0015] In some embodiments, the HDPE is a homopolymer that contains no measurable comonomer residues. In some embodiments, the HDPE is a copolymer in which a small number of repeating units are derived from unsaturated comonomers.

[0016] Examples of suitable comonomers for preparing HDPE may include α-olefins. Suitable α-olefins may include olefins containing 3 to 20 carbon atoms (C3 to C 20 For example, the α-olefin may be C4 to C 20 α-olefins, C4 to C 12 α-olefins, C3 to C 10 α-olefins, C3 to C8 α-olefins, C4 to C8 α-olefins or C6 to C8 α-olefins. In some embodiments, the α-olefin is selected from the group consisting of propylene, 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-heptene, 1-octene, 1-nonene and 1-decene. In other embodiments, the α-olefin is selected from the group consisting of propylene, 1-butene, 1-hexene and 1-octene. In other embodiments, the α-olefin is selected from the group consisting of 1-hexene and 1-octene.

[0017] In some embodiments, the HDPE copolymer contains at least 95 wt%, or at least 96 wt%, or at least 97 wt%, or at least 98 wt%, or at least 99 wt%, or at least 99.5 wt% of repeating units derived from ethylene, with the remaining repeating units derived from unsaturated comonomers. In some embodiments, the HDPE copolymer contains at least 4 wt%, or at least 3 wt%, or at least 2 wt%, or at least 1 wt%, or at least 99.5 wt% of repeating units derived from comonomers, with the remaining repeating units derived from ethylene monomers. It is well known how to select comonomers and comonomer content to obtain known molecular weights and other properties of HDPE copolymers. In some embodiments, where the comonomer is a higher molecular weight comonomer, such as 1-octene, the comonomer content can be in the higher part of the ranges listed above. In some embodiments, where the comonomer is a lower molecular weight comonomer, such as 1-butene, the comonomer content can be in the lower part of the ranges listed above.

[0018] Recycled HDPE

[0019] The HDPE blends of the present invention contain recycled HDPE. In some embodiments, the recycled HDPE is pre-consumer recycled polyethylene, such as scraps and waste from HDPE manufacturing facilities or from HDPE manufacturers. In some embodiments, the recycled HDPE polymer is post-consumer recycled (PCR) HDPE. In some embodiments, the recycled HDPE polymer is post-industrial recycled HDPE.

[0020] The terms "pre-consumer recycled polyethylene" and "post-industrial recycled HDPE" refer to polymers including blends of polyethylene polymers recovered from pre-consumer materials as defined by ISO-14021. Thus, the generic term pre-consumer recycled polyethylene includes blends of polyethylene and other polymers recovered from materials diverted from waste streams during the manufacturing process. The generic term pre-consumer recycled polyethylene does not include the reuse of polyethylene materials that are generated in a process and can be recovered in the same process in which they were generated, such as reprocessing, regrind, or scrap.

[0021] As used herein, the term "post-consumer recycled" (or "PCR") polyethylene refers to a polyethylene material, such as PCR HDPE, that includes materials that were previously used in consumer or industrial applications (i.e., pre-consumer recycled polyethylene and post-industrial recycled HDPE). PCR polyethylene is typically collected from recycling programs and recycling plants. PCR polyethylene may include one or more contaminants. Contaminants may be the result of the use of the polyethylene material before it is reused for reuse. For example, contaminants may include paper, ink, food scraps, or other recycled materials other than polymers that may result from the recycling process. PCR polyethylene is different from virgin polyethylene. Virgin polyethylene does not include materials that were previously used in consumer or industrial applications, while PCR polyethylene includes them. After the initial polymer manufacturing process, the virgin polyethylene material has not yet undergone or has not otherwise undergone a heating process or a molding process. When compared to virgin polyethylene, the physical, chemical, and flow properties of the PCR polyethylene polymer are different, which in turn may pose challenges for incorporating PCR polyethylene into commercial use blends.

[0022] As used in this disclosure, "PCR polyethylene" means a PCR ethylene / α-olefin copolymer, such as a PCR high density polyethylene; and optionally other components and additives.

[0023] It is contemplated that PCR polyethylene includes various polyethylene compositions. PCR polyethylene can be derived from HDPE packaging such as bottles (milk jugs, juice containers), LDPE / LLDPE packaging such as films. PCR polyethylene also includes residues from its original use, such as residues of paper, adhesives, inks, nylon, ethylene vinyl alcohol (EVOH), polyethylene terephthalate (PET), and other odor-causing agents. Sources of PCR polyethylene can include, for example, bottle caps and stoppers, milk, water or orange juice containers, detergent bottles, office automation equipment (printers, computers, copiers, etc.), white appliances (refrigerators, washing machines, etc.), consumer electronics (TVs, VCRs, stereos, etc.), car shredder residues (mixed materials remaining after most of the metals have been sorted out from shredded cars and other metal-rich products "shredded" by metal recyclers), packaging waste, household waste, rotomolded parts (kayaks / coolers), construction waste, and industrial molding and extrusion waste.

[0024] In an embodiment, the polyethylene of the PCR polyethylene comprises low density polyethylene, linear low density polyethylene, or a combination thereof. In an embodiment, the PCR polyethylene also comprises residues from its original use, such as paper, adhesives, inks, nylon, ethylene vinyl alcohol (EVOH), polyamide (PA), polyethylene terephthalate (PET), and other organic or inorganic materials. Examples of PCR polymers include KWR101-150 and KWR-102 from KW Plastics, and AVANGARD TM NATURA PCR-LDPCR-100(“AVANGARD TM 100”) and AVANGARD TM NATURA PCR-LDPCR-150(“AVANGARD TM 150″) (PCR polymers are commercially available from Avangard Innovative LP, Houston, Texas).

[0025] In some embodiments, the PCR polyethylene is a PCR HDPE available from KWR101-150 from KW Plastics. KWR101-150 has the DSC properties shown in the following table when measured using a "hot-cold-hot" temperature curve as described in the following test methods,

[0026]

[0027] Wherein: “1st Cool Delta H cryst” measures the crystallization enthalpy during the first cooling curve; “1st CoolTc1” measures the crystallization temperature during the first cooling cycle; “2nd Heat Delta H melt” measures the melting enthalpy during the second heating curve; and “2nd Heat Tm1” measures the melting temperature during the second heating curve.

[0028] In an embodiment, the PCR polyethylene has a heat of fusion in the range of 130 Joules / gram (J / g) to 170 J / g as measured according to the DSC test method described below. All individual values ​​and subranges from 130 J / g to 170 J / g are disclosed and included herein; for example, the heat of fusion of the PCR polyethylene can be 130 J / g to 170 J / g, 130 J / g to 160 J / g, 130 J / g to 150 J / g, 130 J / g to 140 J / g, 140 J / g to 170 J / g, 140 J / g to 160 J / g, 140 J / g to 150 J / g, 150 J / g to 170 J / g, or 155 J / g to 170 J / g when measured according to the DSC test method described below.

[0029] In an embodiment, the PCR polyethylene has a peak melting temperature (Tm) of 115°C to 137°C when measured according to the DSC test method described below. All individual values ​​and subranges from 115°C to 137°C are disclosed and included herein; for example, the peak melting temperature (Tm) of the PCR polymer can be 121°C to 135°C, 131°C to 135°C, 132°C to 135°C, or 133.0°C to 134.0°C when measured according to the DSC test method described below.

[0030] In some embodiments, the recycled HDPE has a density of at least 0.94 g / cc, or at least 0.95 g / cc, or at least 0.955 g / cc, or at least 0.958 g / cc. In some embodiments, the recycled HDPE has a density of at most 0.97 g / cc, or at most 0.965 g / cc.

[0031] In some embodiments, the melt index (I2) of recycled HDPE is in the range of 0.01 g / 10 min to 30 g / 10 min. All individual values ​​and subranges of 0.01 g / 10 min to 30 g / 10 min are included and disclosed herein. In some embodiments, the melt index (I2) of recycled HDPE is at least 0.1 g / 10 min or at least 0.3 g / 10 min or at least 0.4 g / 10 min or at least 0.5 g / 10 min or at least 0.55 g / 10 min. In some embodiments, the melt index (I2) of recycled HDPE is at most 2 g / 10 min or at least 1 g / 10 min or at most 0.8 g / 10 min or at most 0.7 g / 10 min or at most 0.65 g / 10 min.

[0032] In some embodiments, the melt index (I5) of recycled HDPE is at least 1 g / 10 min, or at least 2 g / 10 min, or at least 2.5 g / 10 min, or at least 2.75 g / 10 min. In some embodiments, the melt index (I5) of recycled HDPE is at most 5 g / 10 min, or at most 4 g / 10 min, or at most 3.5 g / 10 min, or at most 3.25 g / 10 min.

[0033] In some embodiments, the flow index (I) of the recycled HDPE is 21 ) is at least 30 g / 10 min or at least 40 g / 10 min or at least 45 g / 10 min or at least 50 g / 10 min. In some embodiments, the flow index (I) of the recycled HDPE is at least 30 g / 10 min or at least 40 g / 10 min or at least 45 g / 10 min or at least 50 g / 10 min. 21 ) is at most 100 g / 10 min, or at most 90 g / 10 min, or at most 80 g / 10 min, or at most 70 g / 10 min, or at most 60 g / 10 min.

[0034] In some embodiments, the melt flow ratio (I 21 / I5) is at least 10 or at least 15 or at least 17 or at least 18. In some embodiments, the melt flow ratio (I / I5) of the recycled HDPE is at least 10 or at least 15 or at least 17 or at least 18. 21 / I5) is at most 30 or at most 25 or at most 23 or at most 21 or at most 20.

[0035] In some embodiments, the recycled HDPE has a number average molecular weight (Mn) of at least 10,000 Da or at least 15,000 Da or at least 18,000 Da. In some embodiments, the recycled HDPE has a number average molecular weight (Mn) of at most 50,000 Da or at most 40,000 Da or at most 30,000 Da or at most 25,000 Da.

[0036] In some embodiments, the recycled HDPE has a weight average molecular weight (Mw) of at least 80,000 Da or at least 100,000 Da or at least 110,000 Da. In some embodiments, the recycled HDPE has a weight average molecular weight (Mw) of at most 200,000 Da or at most 160,000 Da or at most 130,000 Da or at most 120,000 Da.

[0037] In some embodiments, the molecular weight distribution (Mw / Mn) of the recycled HDPE is at least 3 or at least 4 or at least 5. In some embodiments, the molecular weight distribution (Mw / Mn) of the recycled HDPE is at most 10 or at most 8 or at most 7.

[0038] In some embodiments, the recycled HDPE has a tensile yield strength of at least 2500 psi, or at least 3000 psi, or at least 3500 psi. In some embodiments, the recycled HDPE has a tensile yield strength of at most 7000 psi, or at most 5000 psi, or at most 4000 psi.

[0039] In some embodiments, the flexural modulus of the recycled HDPE is at least 100 ksi or at least 130 ksi or at least 145 ksi. In some embodiments, the flexural modulus of the recycled HDPE is at most 200 ksi or at most 180 ksi or at most 170 ksi. (1 ksi = 1000 psi).

[0040] In some embodiments, the ESCR (time to 50% failure rate under the test conditions listed below) of recycled HDPE is at most 35 hours, or at most 30 hours, or at most 25 hours, or at most 22 hours, or at most 20 hours. In some embodiments, the ESCR (time to 50% failure rate under the test conditions listed below) of recycled HDPE is at least 10 hours, or at least 15 hours, or at least 18 hours.

[0041] Suitable recycled HDPE streams are commercially available, such as from Kavi Plastics. Other streams can be prepared by known methods, such as: (1) separating HDPE material having desired properties from a recycled waste stream; (2) washing the separated HDPE material; and (3) grinding the separated HDPE material. Examples of such methods are described in European Patent 2 697 025 B1.

[0042] Original Bimodal HDPE

[0043] The HDPE blends of the present invention also contain virgin bimodal high density polyethylene polymer (or "virgin bimodal HDPE"). "Virgin" means that the bimodal HDPE has not yet been made into or used to make shaped articles after being pelletized.

[0044] The density of the original bimodal HDPE is from 0.944 g / cc to 0.953 g / cc. In some embodiments, the density of the original bimodal HDPE is at least 0.946 g / cc or at least 0.947 g / cc or at least 0.948 g / cc. In some embodiments, the density of the original bimodal HDPE is at most 0.952 g / cc or at most 0.951 g / cc.

[0045] The flow index (I 21 ) is 8 g / 10 min to 12 g / 10 min. In some embodiments, the flow index (I 21) is at least 8.5 g / 10 min or at least 9 g / 10 min. In some embodiments, the flow index (I 21 ) is at most 11 g / 10 min or at most 10 g / 10 min.

[0046] In some embodiments, the melt index (I2) of the original bimodal HDPE is at least 0.01 g / 10 min, or at least 0.02 g / 10 min, or at least 0.03 g / 10 min, or at least 0.04 g / 10 min. In some embodiments, the melt index (I2) of the original bimodal HDPE is at most 0.1 g / 10 min, or at most 0.08 g / 10 min, or at most 0.06 g / 10 min, or at most 0.05 g / 10 min.

[0047] In some embodiments, the melt index (I5) of the original bimodal HDPE is at least 0.1 g / 10 min, or at least 0.2 g / 10 min, or at least 0.25 g / 10 min. In some embodiments, the melt index (I5) of the original bimodal HDPE is at most 0.8 g / 10 min, or at most 0.6 g / 10 min, or at most 0.5 g / 10 min, or at most 0.4 g / 10 min.

[0048] In some embodiments, the melt flow ratio (I 21 In some embodiments, the melt flow ratio (I / I2) of the original bimodal HDPE is at least 100 or at least 125 or at least 150 or at least 175 or at least 185 or at least 195. 21 / I2) is at most 400 or at most 300 or at most 250 or at most 225.

[0049] In some embodiments, the melt flow ratio (I 21 / I5) is at least 20 or at least 25 or at least 27 or at least 28. In some embodiments, the melt flow ratio (I / I5) of the original bimodal HDPE is at least 20 or at least 25 or at least 27 or at least 28. 21 / I5) is at most 50 or at most 40 or at most 35 or at most 32.

[0050] In some embodiments, the pristine bimodal HDPE has a melt strength of at least 10 cN or at least 12 cN or at least 15 cN at 190° C. In some embodiments, the pristine bimodal HDPE has a melt strength of at most 25 cN or at most 20 cN or at most 18 cN.

[0051] In some embodiments, the number average molecular weight (Mn) of the original bimodal HDPE is at least 20,000 Da or at least 24,000 Da or at least 26,000 Da or at least 28,000 Da or at least 29,000 Da. In some embodiments, the number average molecular weight (Mn) of the original bimodal HDPE is at most 40,000 Da or at most 37,000 Da or at most 35,000 Da or at most 33,000 Da or at most 31,000 Da.

[0052] In some embodiments, the weight average molecular weight (Mw) of the original bimodal HDPE is at least 350,000 Da or at least 375,000 Da or at least 400,000 Da or at least 420,000 Da. In some embodiments, the weight average molecular weight (Mw) of the original bimodal HDPE is at most 600,000 Da or at most 550,000 Da or at most 500,000 Da or at most 475,000 Da or at most 450,000 Da.

[0053] In some embodiments, the molecular weight distribution (Mw / Mn) of the original bimodal HDPE is at least 10 or at least 12 or at least 13 or at least 14. In some embodiments, the molecular weight distribution (Mw / Mn) of the original bimodal HDPE is at most 20 or at most 18 or at most 16 or at most 15.5 or at most 15 or at most 14.8.

[0054] The original bimodal HDPE has a bimodal molecular weight distribution, which means that it contains a higher molecular weight (HMW) component and a lower molecular weight (LMW) component. The weight average molecular weight (Mw) of the HMW component is higher than the weight average molecular weight (Mw) of the LMW component. In some embodiments, the molecular weight distribution of the bimodal HDPE can form two different peaks, as described in U.S. Patent 6,787,608 B2, column 4, lines 4-37 and Figure 1 C. In some embodiments, the molecular weight distribution of the bimodal HDPE may form a single peak with a shoulder peak, as described in U.S. Pat. No. 6,787,608 B2, column 4, lines 4-37 and Figure 1 B. In some embodiments, the molecular weight distribution of bimodal HDPE can form a single peak with a tail peak, as described in U.S. Patent No. 6,787,608 B2, column 4, lines 4-37 and Figure 1 As explained and illustrated in A.

[0055] In some embodiments of the invention, the LMW component comprises more than 50 wt. % or more than 60 wt. % or more than 70 wt. % or more than 75 wt. % of the original bimodal HDPE. In some embodiments of the invention, the molecular weight distribution (GPC) of the original bimodal HDPE shows the HMW component as a shoulder on the LMW component peak.

[0056] In some embodiments of the invention, the bimodal nature of the original bimodal HDPE is reflected in the higher molecular weight distribution (Mw / Mn) or Mz / Mw ratio compared to a similar unimodal HDPE.

[0057] In some embodiments, the tensile yield strength (also referred to as "yield stress") of the original bimodal HDPE is at least 3000 psi or at least 3200 psi or at least 3400 psi or at least 3500 psi. In some embodiments, the tensile yield strength of the original bimodal HDPE is at most 4500 psi or at most 4000 psi or at most 3750 psi.

[0058] In some embodiments, the strain at break of the pristine bimodal HDPE is at least 500% or at least 600% or at least 700% or at least 750% or at least 775%.In some embodiments, the strain at break of the pristine bimodal HDPE is at most 900% or at most 800%.

[0059] In some embodiments, the flexural modulus (2% secant modulus) of the pristine bimodal HDPE is at least 100 ksi or at least 120 ksi or at least 125 ksi. In some embodiments, the flexural modulus of the pristine bimodal HDPE is at most 160 ksi or at most 140 ksi or at most 130 ksi. (1 ksi = 1000 psi).

[0060] In some embodiments, the original bimodal HDPE has a -1 The melt viscosity at a shear rate of 100 °C and a temperature of 190 °C (“low shear viscosity” or “η 0.1 ”) is at least 90,000 Pa·s or at least 100,000 Pa·s or at least 120,000 Pa·s or at least 140,000 Pa·s. In some embodiments, the original bimodal HDPE has a relative humidity of at least 0.1 rad s -1 The melt viscosity at a shear rate of 100 °C and a temperature of 190 °C (“low shear viscosity” or “η 0.1 ”) is at most 200,000 Pa·s or at most 180,000 Pa·s or at most 160,000 Pa·s.

[0061] In some embodiments, the original bimodal HDPE has a -1 The melt viscosity at a shear rate of 100 °C and a temperature of 190 °C (“high shear viscosity” or “η 100 s) is at least 2000 Pa·s or at least 2100 Pa·s or at least 2200 Pa·s or at least 2250 Pa·s. In some embodiments, the original bimodal HDPE has a -1The melt viscosity at a shear rate of 100 °C and a temperature of 190 °C (“high shear viscosity” or “η 100 ”) is at most 3000 Pa·s or at most 2750 Pa·s or at most 2500 Pa·s.

[0062] The die swell of polymers can be compared using a "timed swell test" as described in PCT Publication WO 2020 / 223191, paragraph

[0074] . A polymer is extruded through a specific die with a set aperture under a specific set of conditions (temperature, extrusion rate, shear, etc.), and the time required for the extrudate to reach a specified length is recorded. Polymers that swell more from the die take longer to reach a specified length and therefore have more die swell. In this application, the specified length is 25.4 cm.

[0063] In some embodiments, the original bimodal HDPE has a strength of 300 s under the test conditions listed below. -1 The timed die swell at a shear rate of at least 22 seconds, or at least 23 seconds, or at least 24 seconds. In some embodiments, the original bimodal HDPE has a timed die swell at a shear rate of at least 22 seconds, or at least 23 seconds, or at least 24 seconds under the test conditions listed below. -1 The timed die swell at a shear rate of at most 30 seconds, or at most 28 seconds, or at most 26 seconds.

[0064] In some embodiments, the original bimodal HDPE has a strength of 1000 s under the test conditions listed below. -1 The timed die swell at a shear rate of at least 8.0 seconds, or at least 8.5 seconds, or at least 9.0 seconds. In some embodiments, the original bimodal HDPE has a timed die swell at a shear rate of at least 8.0 seconds, or at least 8.5 seconds, or at least 9.0 seconds under the test conditions listed below. -1 The timed die swell at a shear rate of at most 15 seconds, or at most 12 seconds, or at most 11 seconds.

[0065] In some embodiments, the Charpy impact resistance of the original bimodal HDPE is at least 8 kJ / m 2 or at least 10 kJ / m 2 or at least 12 kJ / m 2 or at least 14 kJ / m 2 or at least 16 kJ / m 2 There is no maximum expected Charpy impact resistance, but it exceeds 20kJ / m 2 performance may not be necessary.

[0066] In some embodiments, the strain hardening modulus of the original bimodal HDPE is at least 25 MPa or at least 30 MPa or at least 33 MPa or at least 35 MPa or at least 37 MPa. There is no maximum desired strain hardening modulus for the original bimodal HDPE, but in some embodiments, a strain hardening modulus above 45 MPa or 40 MPa may not be necessary.

[0067] In some embodiments, the ESCR (time to 50% failure rate under the test conditions listed below) of the pristine bimodal HDPE is at least 500 hours, or at least 600 hours, or at least 700 hours, or at least 800 hours, or at least 900 hours, or at least 1000 hours. There is no maximum desired ESCR performance, but ESCRs in excess of 1500 hours may not be necessary.

[0068] In some embodiments, the notched constant ligament stress (NCLS) of the pristine bimodal HDPE is at least 100 hours, or at least 200 hours, or at least 300 hours, or at least 400 hours, or at least 500 hours, or at least 600 hours, or at least 700 hours, or at least 800 hours, or at least 900 hours, or at least 1000 hours. There is no maximum desired NCLS performance, but NCLS in excess of 1500 hours may not be necessary.

[0069] Particularly useful virgin bimodal high density polyethylene polymers (virgin bimodal HDPE) comprise a higher molecular weight ethylene / 1-hexene copolymer component and a lower molecular weight ethylene / 1-hexene copolymer component, wherein (a) the virgin bimodal HDPE polymer has a density of 0.944 g / cc to 0.953 g / cc; (b) the virgin bimodal HDPE polymer has a flow index (I 21 ) is 8 g / 10 min to 12 g / 10 min; and (c) the melt flow ratio (I 21 / I5) is 25 to 35.

[0070] Another embodiment of the present invention is a virgin bimodal high density polyethylene polymer comprising a higher molecular weight ethylene / 1-hexene copolymer component ("HMW component" or "HMW PE") and a lower molecular weight ethylene / 1-hexene copolymer component ("LMW component" or "LMW PE"), wherein: the virgin bimodal HDPE polymer has a density of 0.944 g / cc to 0.953 g / cc; the virgin bimodal HDPE polymer has a flow index (I 21 ) is 8 g / 10 min to 12 g / 10 min; and the melt flow ratio (I 21 In some embodiments, the melt flow ratio (I / I5) of the original bimodal HDPE polymer is 25 to 35. 21 / I2) is at least 125. In some embodiments, the original bimodal high density polyethylene polymer itself, as well as when used in a blend, has a component distribution (also referred to as component weight fractions) in which the HMW component and the LMW component are 29.0 wt% to 36.0 wt% and 71.0 wt% to 64.0 wt%, respectively, based on the combined weight of the HMW component and the LMW component, alternatively, the HMW component and the LMW component are 30.1 wt% to 34.9 wt% and 69.9 wt% to 65.1 wt%, respectively. In some embodiments, the original bimodal high density polyethylene polymer itself, as well as when used in a blend, has an ESCR of 750 hours or more. In some embodiments, the original bimodal high density polyethylene polymer, by itself, and as used in a blend, has one of the following limits (i) to (x): (i) a density of 0.948 g / cc to 0.951 g / cc; (ii) a melt index (I5) of 0.29 g / 10 min to 0.42 g / 10 min; (iii) a flow index (I6) of 8.8 g / 10 min to 11.9 g / 10 min. 21 ); (iv) a melt flow ratio of 28 to 32 (I 21 / I5); (v) Abs M of 28,000 g / mol to 30,999 g / mol n (vi) Abs M of 250,000 g / mol to 340,000 g / mol w (vii) Abs M of 3,400,000 g / mol to 3,990,000 g / mol z (viii) Abs M 8.0 to 12.2 w / M n (ix) M of 11.0 to 14.0 z / M w ; or (x) any two or more of the limits (i) to (ix). "Abs" molecular weight is measured by the Absolute GPC test method described below.

[0071] The original bimodal high density polyethylene polymer is prepared in a single gas phase polymerization reactor by polymerizing ethylene and 1-hexene with a bimodal catalyst system. In some embodiments, the bimodal catalyst system comprises or is made of a zirconium-containing metallocene catalyst, a zirconium-containing post-metallocene catalyst, a silica support material, and an activator. Wherein the zirconium-containing metallocene catalyst is a bis(n-butylcyclopentadienyl)zirconium X2 of formula (I): Each R 1 is -CH2CH2CH2CH3 and each X is Cl or each X is methyl; wherein the zirconium-containing post-metallocene catalyst is dibenzylbis(2-(pentamethylphenylamido)ethyl)zirconium amine, which is a compound of formula (II) wherein M is Zr and each R is a benzyl group ("Bn"). The polymerization can be carried out under conditions including: a reactor bed temperature of about 100°C ± 2°C; a molar ratio of 1-hexene to ethylene (C6 / C2 mol / mol) of 0.0024 ± 0.0005; a molar ratio of hydrogen to ethylene (H2 / C2 mol / mol) of 0.0008 ± 0.0001; and an isopentane concentration of 12.5 mol% ± 0.5 mol%.

[0072] In some embodiments of the original bimodal HDPE polymer, the molecular weight distribution (Mw / Mn) is at most 16. Other possible embodiments within those limits are as previously described.

[0073] This original bimodal HDPE material can be used in the formulation of the present invention. It can also be used by itself for blow molding such as medium-sized parts. It has good impact strength and flexural modulus and has excellent ESCR and NCLS properties.

[0074] The original bimodal high density polyethylene and its production method are described in many references, such as the following patent applications: US2007 / 0043177 A1; US2009 / 0036610 A1; US2020 / 0071509A1, WO 2009 / 148487 A1, WO2019 / 241045 A1, WO 2020 / 046663 A1 and WO 2020 / 068413A1; and the following patents: US 5.539,076; US 5,882,750; US 6,403,181 B1; US ​​7,090,927; US 8,110,644 B2; and US 8,378,029 B2, and by Total Petrochemicals USA. USA, Inc) published publication B5845, Bimodal Molecular Weight Polyethylene for Blow Molding. Some production technologies use a dual sequence reactor, and some production technologies use a single reactor with a bimodal catalyst system. Suitable bimodal catalyst systems are commercially available from Univation Technologies, LLC.

[0075] An example of a suitable bimodal catalyst system is PRODIGY TM The bimodal catalyst system provided by the BMC 300 trademark may alternatively be produced as described in the aforementioned patents and in U.S. Application 2020 / 0024376A1. TMThe BMC 300 catalyst system comprises or is made of a zirconium-containing metallocene catalyst, a zirconium-containing post-metallocene catalyst, a support material and an activator. The zirconium-containing metallocene catalyst is a bis(n-butylcyclopentadienyl)zirconium X2 of formula (I): Each R 1 is -CH2CH2CH2CH3 and each X is a leaving group. In some embodiments of formula (I), each X is Cl or each X is methyl. The zirconium-containing post-metallocene catalyst is dibenzyl bis (2- (pentamethylphenylamido) ethyl) zirconium amine, which is sometimes referred to in the art as "HN5 dibenzyl" and is a compound of formula (II) Wherein M is Zr and each R is a benzyl ("Bn"). Both catalysts are well known in the art. For example, zirconium-containing post-metallocene catalysts can be prepared by procedures described in the art or obtained from Univision Technologies, LLC, a subsidiary of The Dow Chemical Company, Midland, Michigan, USA, in Houston, Texas, USA. Representative Group 15 metal-containing compounds, including dibenzylbis(2-(pentamethylphenylamido)ethyl)zirconium amine and their preparation can be discussed and described in U.S. Pat. Nos. 5,318,935; 5,889,128; 6,333,389; 6,271,325; 6,689,847; and 9,981,371; and WO Publications WO 99 / 01460; WO 98 / 46651; WO 2009 / 064404; WO 2009 / 064452; and WO 2009 / 064482.

[0076] PRODIGY OF BIMODAL CATALYST SYSTEM TM The BMC-300 embodiment was used to prepare virgin bimodal HDPE polymer No. 1 of the present invention, referred to as "virgin bimodal HDPE 1" in the examples.

[0077] Another suitable embodiment of the bimodal catalyst system is made from the same components as used to prepare the BMC-300 type catalyst system, except that the bis(n-butylcyclopentadienyl)zirconium X2 of formula (I) is replaced by (cyclopentadienyl)(1,5-dimethylindenyl)zirconium X2, which is a zirconium-containing metallocene of formula (III):

[0078] Wherein M is Zr and each X is a leaving group. In some embodiments of formula (III), each X is Cl or each X is methyl. This other suitable bimodal catalyst system therefore comprises or is made of a zirconium-containing metallocene of formula (III), HN5 dibenzyl, a support and an activator. For convenience, this other embodiment of the bimodal catalyst system is referred to as a "BMC analogue".

[0079] The BMC analogue embodiment of the bimodal catalyst system was used to prepare virgin bimodal HDPE polymer No. 2 of the present invention, referred to in the examples as "virgin bimodal HDPE 2".

[0080] The support material used in these bimodal catalyst systems can be an inorganic oxide material. As used herein, the terms "support" and "support material" are identical and refer to porous inorganic or organic substances. In some embodiments, the desired support material can be an inorganic oxide, which comprises a 2nd, 3rd, 4th, 5th, 13th or 14th family oxide, alternatively a 13th or 14th family atom. The example of an inorganic oxide type support material is a mixture of any two or more of silica, alumina, titania, zirconium oxide, thoria and such inorganic oxides. The example of such a mixture is silica-chromium, silica-alumina and silica-titania.

[0081] The inorganic oxide support material is porous and has variable surface area, pore volume, and average particle size. In some embodiments, the surface area is 50 square meters per gram (m 2 / g) to 1000m 2 / g, and an average particle size of 20 micrometers (μm) to 300 μm. Alternatively, the pore volume is 0.5 cubic centimeters per gram (cc / g) to 6.0 cc / g, and the surface area is 200m 2 / g to 600m 2 Alternatively, the pore volume is 1.1 cc / g to 1.8 cc / g and the surface area is 245 m 2 / g to 375m 2 Alternatively, the pore volume is 2.4 cc / g to 3.7 cc / g and the surface area is 410 m 2 / g to 620m 2 Alternatively, the pore volume is 0.9 cc / g to 1.4 cc / g and the surface area is 390 m 2 / g to 590m 2 Each of the above properties is measured using conventional techniques known in the art.

[0082] The support material may include silica, alternatively amorphous silica (not quartz), alternatively high surface area amorphous silica (e.g., 500 to 1000 m 2 / g). Such silicas are commercially available from several sources, including the Davison Chemical Division of WR Grace and Company (e.g., Davison 952 and Davison 955 products) and PQ Corporation (e.g., ES70 products). The silica can be in the form of spherical particles obtained by a spray drying process. Alternatively, the MS3050 product is a non-spray dried silica from PQ Corporation. As obtained, these silicas are not calcined (i.e., not dehydrated). Silica calcined before purchase can also be used as a support material.

[0083] The support material may be pretreated by heating the support material in air prior to contact with a catalyst such as HN5 dibenzyl and a zirconium-containing metallocene to obtain a calcined support material. The pretreatment comprises heating the support material at a peak temperature of 350°C to 850°C, alternatively 400°C to 800°C, alternatively 400°C to 700°C, alternatively 500°C to 650°C, and for a period of 2 hours to 24 hours, alternatively 4 hours to 16 hours, alternatively 8 hours to 12 hours, alternatively 1 hour to 4 hours, thereby preparing a calcined support material. The support material may be a calcined support material.

[0084] The process for preparing the original bimodal HDPE using the bimodal catalyst system may further employ a trimming catalyst, typically in the form of a trimming catalyst solution comprising a zirconium-containing metallocene of formula (I) or (III) above and an additional amount of an activator. For convenience, the trimming catalyst is fed as a solution in a hydrocarbon solvent (e.g., mineral oil, heptane, or isopentane). The trimming catalyst may be used to vary the amount of zirconium-containing metallocene used in the process relative to the amount of zirconium-containing post-metallocene (e.g., HN5 dibenzyl) of the bimodal catalyst system within limits in order to adjust the properties of the HDPE blends of the present invention.

[0085] Each catalyst of the bimodal catalyst system is activated by contacting it with an activator. Any activator can be the same or different from each other, and can independently be a Lewis acid, a non-coordinating ion activator or an ionizing activator or a Lewis base, an alkylaluminum or an alkylaluminoxane. The alkylaluminum can be a trialkylaluminum, an alkylaluminum halide or an alkylaluminum alkoxide (diethyl ethoxyaluminum). The trialkylaluminum can be trimethylaluminum, triethylaluminum ("TEAl"), tripropylaluminum or tri(2-methylpropyl)aluminum. The alkylaluminum halide can be diethylaluminum chloride. The alkylaluminum alkoxide can be diethyl ethoxyaluminum. The alkylaluminumoxane can be methylaluminoxane (MAO), ethylaluminoxane, 2-methylpropyl-aluminoxane or modified methylaluminoxane (MMAO). Each alkyl group of the alkylaluminum or alkylaluminoxane may independently be a (C1-C7)alkyl, alternatively a (C1-C6)alkyl, alternatively a (C1-C4)alkyl. The molar ratio of the metal (Al) of the activator to the metal (catalytic metal, such as Zr) of the specific catalyst compound may be from 1000:1 to 0.5:1, alternatively from 300:1 to 1:1, alternatively from 150:1 to 1:1. Suitable activators are commercially available.

[0086] Once the activator and catalyst of the bimodal catalyst system are in contact with each other, the catalyst of the bimodal catalyst system is activated, and the activator species can be prepared in situ. The activator species may have a different structure or composition from the catalyst and activator from which it is derived, and may be a byproduct of catalyst activation or may be a derivative of a byproduct. The corresponding activator species may be a derivative of a Lewis acid, a non-coordinating ion activator, an ionizing activator, a Lewis base, an alkyl aluminum or an alkyl aluminoxane, respectively. An example of a derivative of a byproduct is a methyl aluminoxane species formed by devolatilization during a bimodal catalyst system made with methyl aluminoxane in spray drying.

[0087] Each contacting step between the activator and the catalyst may be independently carried out in a separate vessel outside the gas phase polymerization (GPP) reactor, such as outside the floating bed gas phase polymerization (FB-GPP) reactor, or in a feed line to the GPP reactor. Once the catalyst of the bimodal catalyst system is activated, the bimodal catalyst system may be fed into the GPP reactor in dry powder form, alternatively in the form of a slurry in a non-polar, aprotic (hydrocarbon) solvent. The one or more activators may be fed into the GPP reactor in "wet mode" as a solution thereof in an inert liquid such as mineral oil or toluene, in slurry mode as a suspension, or in dry mode as a powder. Each contacting step may be carried out at the same or different times.

[0088] The gas phase polymerization reactor may be a fluidized bed gas phase polymerization (FB-GPP) reactor, and the effective polymerization conditions may include the following reaction conditions: the FB-GPP reactor has a fluidized bed, and the bed temperature is 80 degrees Celsius (° C.) to 110° C.; the FB-GPP reactor receives feeds of ethylene and 1-olefin in corresponding independently controlled amounts, characterized in that the 1-olefin and ethylene (C x / C2, where the subscript x represents the number of carbon atoms in the 1-olefin; for example, when the 1-olefin is 1-hexene, C x The C6 / C2 ratio is the ratio of 1-hexene to ethylene, which can be written as the C6 / C2 ratio) molar ratio, a bimodal catalyst system, optionally a trim catalyst solution, optionally hydrogen (H2), characterized by a hydrogen to ethylene (H2 / C2) molar ratio or a ratio of parts per million by weight of H2 to mole percent C2 (H 2ppm / C2 mol%), and optionally (C5-C 10 ) alkane, such as an induced condensing agent (ICA) of isopentane; wherein the (C6 / C2) molar ratio is from 0.0010 to 0.1; and wherein when ICA is fed, the concentration of ICA in the reactor is from 1 mole percent (mol%) to 20 mol%, based on the total moles of ethylene, 1-olefins and ICA in the reactor. The average residence time of the copolymer in the reactor can be from 1.0 hour to 4.0 hours. A continuity additive can be used in the FB-GPP reactor during polymerization. In some embodiments, the reaction conditions are those described in the Examples for preparing the original bimodal HDPE 1, plus or minus (±) 10%.

[0089] HDPE blends

[0090] The HDPE blend is a post-reactor blend of recycled HDPE and virgin bimodal HDPE.

[0091] In the HDPE blends of the present invention, recycled HDPE and virgin bimodal HDPE are melt blended together in relative amounts of 25 to 90 wt% recycled HDPE and 10 to 75 wt% virgin bimodal HDPE. Blending can be achieved by any known means, such as coextrusion of the two polymers in a known extruder or melt blending in a known mixer such as from Hakke, Brabender or Banbury.

[0092] In some embodiments, the HDPE blend contains at least 35 wt %, or at least 40 wt %, or at least 45 wt %, or at least 55 wt %, or at least 65 wt %, or at least 70 wt %, or at least 75 wt %, or at least 80 wt %, or at least 85 wt %, or at least 90 wt % recycled HDPE. In some embodiments, the HDPE blend contains up to 90 wt %, or up to 85 wt %, or up to 80 wt %, or up to 75 wt %, or up to 65 wt %, or up to 55 wt % recycled HDPE. For example, the HDPE blend may contain 45 wt % to 80 wt %, or 45 wt % to 65 wt %, or 65 wt % to 80 wt %, or 70 wt % to 90 wt % recycled HDPE.

[0093] In some embodiments, the HDPE blend contains up to 65 wt %, or up to 55 wt %, or up to 45 wt %, or up to 35 wt %, or up to 30 wt %, or up to 25 wt %, or up to 20 wt % of virgin bimodal HDPE. In some embodiments, the HDPE blend contains at least 15 wt %, or at least 20 wt %, or at least 25 wt %, or at least 35 wt %, or at least 45 wt % of virgin bimodal HDPE. For example, the HDPE blend may contain 20 wt % to 55 wt %, or 35 wt % to 55 wt %, or 20 wt % to 35 wt %, or 10 wt % to 30 wt % of virgin bimodal HDPE.

[0094] In some embodiments, the HDPE blend may contain additives. Additives for polyolefin polymers are described in many publications, such as the booklet published by Plastics Design Library in 2015: Tolinski, "Additives for Polyolefins. Getting the Most out of Polypropylene, Polyethylene and TPO (Second Edition)". Examples of common additives include antistatic agents, color enhancers, dyes, lubricants, fillers, pigments, primary antioxidants, secondary antioxidants, processing aids, UV stabilizers, nucleating agents, slip agents (such as erucamide), anti-blocking agents (such as talc), and combinations thereof. In some embodiments, the additives constitute no more than 5 weight % or no more than 4 weight % or no more than 3 weight % or no more than 2 weight % or no more than 1 weight % of the HDPE blend. In some embodiments, the additives constitute essentially 0 weight % of the HDPE blend.

[0095] In some embodiments, the density of the HDPE blend is at least 0.95 g / cc or at least 0.952 g / cc or at least 0.954 g / cc. In some embodiments, the density of the HDPE blend is at most 0.965 g / cc or at most 0.960 g / cc or at most 0.958 g / cc.

[0096] In some embodiments, the melt index (I2) of the HDPE blend is at least 0.06 g / 10 min, or at least 0.08 g / 10 min, or at least 0.1 g / 10 min. In some embodiments, the melt index (I2) of the HDPE blend is at most 2 g / 10 min, or at most 1 g / 10 min, or at most 0.5 g / 10 min, or at most 0.4 g / 10 min, or at most 0.3 g / 10 min, or at most 0.25 g / 10 min.

[0097] In some embodiments, the flow index (I 21 ) is at least 10 g / 10 min, or at least 12 g / 10 min, or at least 15 g / 10 min, or at least 17 g / 10 min, or at least 19 g / 10 min. In some embodiments, the flow index (I) of the HDPE blend is at least 10 g / 10 min, or at least 12 g / 10 min, or at least 15 g / 10 min, or at least 17 g / 10 min, or at 21 ) is at most 50 g / 10 min, or at most 45 g / 10 min, or at most 40 g / 10 min, or at most 35 g / 10 min, or at most 32 g / 10 min.

[0098] In some embodiments, the melt flow ratio (I 21 / I2) is at least 100 or at least 110 or at least 120 or at least 140. In some embodiments, the melt flow ratio (I2) of the HDPE blend is at least 100 or at least 110 or at least 120 or at least 140. 21 / I2) is at most 250 or at most 200 or at most 190 or at most 185.

[0099] In some embodiments, the tensile yield strength (yield stress) of the HDPE blend is at least 3200 psi or at least 3400 psi or at least 3600 psi or at least 3700 psi. In some embodiments, the tensile yield strength of the HDPE blend is at most 5000 psi or at most 4500 psi or at most 4200 psi.

[0100] In some embodiments, the strain at break of the HDPE blend is at least 500% or at least 600% or at least 700% or at least 800%.In some embodiments, the strain at break of the HDPE blend is at most 1000% or at most 900% or at most 850%.

[0101] In some embodiments, the flexural modulus (2% secant modulus) of the HDPE blend is at least 125 ksi or at least 130 ksi or at least 135 ksi or at least 140 ksi. In some embodiments, the flexural modulus of the HDPE blend is at most 175 ksi or at most 160 ksi or at most 155 ksi. (1 ksi = 1000 psi).

[0102] In some embodiments, the HDPE blend has a Charpy impact resistance of at least 3.5 J / m 2 or at least 4J / m 2 or at least 5J / m 2 or at least 6J / m 2 In some embodiments, the HDPE blend has a Charpy impact resistance of at most 12 J / m 2 or at least 4J / m 2 or up to 10J / m 2 or up to 9J / m 2 .

[0103] In some embodiments, the strain hardening modulus of the HDPE blend is at least 8 MPa or at least 10 MPa or at least 12 MPa or at least 13 MPa. There is no maximum desired strain hardening modulus for HDPE blends, but in some embodiments, a strain hardening modulus above 35 MPa or 25 MPa may not be necessary.

[0104] In some embodiments, the ESCR (time to 50% failure rate under the test conditions listed below) of a HDPE blend containing at least 20 wt% recycled HDPE is at least 500 hours, or at least 600 hours, or at least 700 hours, or at least 800 hours, or at least 900 hours, or at least 950 hours. In some embodiments, the ESCR (time to 50% failure rate under the test conditions listed below) of a HDPE blend containing at least 45 wt% recycled HDPE is at least 200 hours, or at least 250 hours, or at least 275 hours, or at least 300 hours, or at least 325 hours, or at least 350 hours. In some embodiments, the ESCR (time to 50% failure rate under the test conditions listed below) of a HDPE blend containing at least 70 wt% recycled HDPE is at least 200 hours, or at least 250 hours, or at least 275 hours, or at least 300 hours, or at least 325 hours. In some embodiments, the ESCR (time to 50% failure rate under the test conditions listed below) of a HDPE blend containing at least 85 wt.% recycled HDPE is at least 200 hours, or at least 250 hours, or at least 275 hours, or at least 300 hours, or at least 325 hours. There is no maximum desired ESCR, but performance in excess of 1500 hours or 2000 hours may not be necessary. For HDPE blends containing high levels of recycled HDPE, lower ESCRs such as 750 hours, or 500 hours, or 400 hours may be acceptable.

[0105] In some embodiments, the NCLS (time to reach 50% failure rate under the test conditions listed below) of a HDPE blend containing at least 20 wt% recycled HDPE is at least 100 hours or at least 200 hours or at least 300 hours or at least 400 hours or at least 500 hours or at least 600 hours or at least 700 hours or at least 750 hours. In some embodiments, the NCLS (time to reach 50% failure rate under the test conditions listed below) of a HDPE blend containing at least 45 wt% recycled HDPE is at least 15 hours or at least 25 hours or at least 35 hours or at least 45 hours or at least 55 hours or at least 65 hours or at least 75 hours. In some embodiments, the NCLS (time to reach 50% failure rate under the test conditions listed below) of a HDPE blend containing at least 70 wt% recycled HDPE is at least 11 hours or at least 13 hours or at least 15 hours or at least 16 hours. In some embodiments, the notched constant ligament stress (time to 50% failure rate under the test conditions listed below) of a HDPE blend containing at least 85 wt% recycled HDPE is at least 7 hours, or at least 8 hours, or at least 9 hours, or at least 10 hours. There is no maximum desired NCLS, but for HDPE blends containing at least 45 wt% recycled HDPE, performance in excess of 150 hours may not be necessary, and for HDPE blends containing at least 70 wt% recycled HDPE, performance in excess of 50 hours or 25 hours may not be necessary.

[0106] In some embodiments, the melt strength of HDPE blends containing at least 45 wt% recycled HDPE is at least 8 cN or at least 10 cN or at least 11 cN. In some embodiments, the melt strength of HDPE blends containing at least 45 wt% recycled HDPE is at most 16 cN or at most 15 cN.

[0107] In some embodiments, the melt strength of the HDPE blend containing at least 70 wt% recycled HDPE is at least 8 cN or at least 9 cN or at least 10 cN. In some embodiments, the melt strength of the HDPE blend containing at least 70 wt% recycled HDPE is at most 15 cN or at most 12 cN.

[0108] In some embodiments, the melt strength of a HDPE blend containing at least 85 wt% recycled HDPE is at least 6 cN or at least 7 cN or at least 8 cN. In some embodiments, the melt strength of a HDPE blend containing at least 70 wt% recycled HDPE is at most 12 cN or at most 10 cN.

[0109] Blow molded and manufactured products

[0110] The HDPE blends of the present invention can be used in common blow molding processes such as extrusion blow molding, injection blow molding, or injection stretch blow molding. All three processes use the following steps: (1) placing a certain amount of molten HDPE blend in a mold cavity, (2) blowing air or a neutral gas such as nitrogen into the molten HDPE blend to expand it and assume the approximate shape of the mold cavity, and (3) cooling the HDPE blend.

[0111] In the extrusion blow molding process, the HDPE blend is melted and extruded into a hollow tube, called a parison. The parison is enclosed in a cooled metal mold for molding articles such as bottles, containers, or parts. Air or a neutral gas such as nitrogen is then blown into the parison to expand it into the shape of the mold. After the HDPE blend has cooled sufficiently, the mold is opened and the part is removed.

[0112] In the injection blow molding process, the HDPE blend is melted and injected into a metal mold for forming an article such as a bottle, container or part. Air or a neutral gas such as nitrogen is then blown into the mold to expand the HDPE blend into the shape of the mold. After the HDPE blend has cooled sufficiently, the mold is opened and the part is removed.

[0113] In the injection stretch blow molding process, the preform of the HDPE blend is prepared by injection molding. In some embodiments, the final neck feature (such as the thread on the bottleneck) for the final molded article is made on the preform. Next, the molten preform is placed in the mold. Then air or a neutral gas such as nitrogen is blown into the preform to expand it into the shape of the mold. After the HDPE blend has been fully cooled, the mold is opened and the parts are taken out. The preform can be blown immediately after it is formed, or it can be cooled and then reheated and blown later.

[0114] In some embodiments, the temperature of the molten HDPE blend is at least 150°C, or at least 155°C, or at least 160°C. In some embodiments, the temperature of the molten HDPE blend is at most 210°C, or at most 190°C, or at most 180°C.

[0115] The product of blow molding is a molded article. In some embodiments, the molded article is a liquid container, such as a wide-mouth bottle or a bottle. In some embodiments, the liquid container has a capacity of at most 10L or at most 5L or at most 2L or at most 1L or at most 0.75L or at most 0.5L or at most 0.4L or at most 0.3L. In some embodiments, the liquid container has a capacity of at least 0.1L or at least 0.3L or at least 0.5L or at least 0.75L or at least 1L. In some embodiments, the liquid container is relatively small, with a capacity of 1mL to 100mL. In some embodiments, the HDPE blend with a flow index of at least 30g / 10min may be more useful for small parts such as small bottles, and the HDPE blend with a flow index lower than 30g / 10min may be more useful for large parts such as large bottles.

[0116] In some embodiments, the shaped article is a tube such as a corrugated tube.

[0117] The following blow molding process is well known and is described in many publications, such as by the Gemini Group in https: / / geminigroup.net / wp-content / uploads / 2018 / 06 / Blow- Molding-Design-Guide-by-Regency-Plastics.pdf "Blow Molding Design Guide", published by Industrial Quick Search, is available at https: / / www.iqsdirectory.com / articles / blow-molding.html "Blow-Molding" published by LyondellBasell Industries, "A Guide to Polyolefin Blow Molding", publication 6683 / 0715, and NCLee, Blow molding understanding (Understanding Blow Molding)" (Hanser Publications, 2007).

[0118] In some embodiments, the high density polyethylene blend comprises: (a) 25 wt% to 90 wt% recycled high density polyethylene; and (b) 10 wt% to 75 wt% virgin bimodal HDPE polymer having a density of 0.944 g / cc to 0.953 g / cc and a flow index (I) of 8 g / 10 min to 12 g / 10 min. 21 ).

[0119] In some embodiments, the recycled high density polyethylene is post-consumer recycled polymer.

[0120] In some embodiments, the melt flow ratio (I 21 / I2) is at least 125.

[0121] In some embodiments, the flow index (I 21 ) is 10g / 10min to 50g / 10min.

[0122] In some embodiments, the molecular weight distribution (Mw / Mn) of the pristine bimodal high density polyethylene polymer is at most 16.

[0123] In some embodiments, the melt flow ratio (I 21 / I2) is at least 140.

[0124] In some embodiments, the high density polyethylene blend contains at least 45 wt% PCR high density polyethylene and has a NCLS of at least 50 hours as measured according to ASTM F2136.

[0125] In some embodiments, the high density polyethylene blend contains at least 70 wt% PCR high density polyethylene and has a NCLS of at least 15 hours as measured according to ASTM F2136 or has a melt strength of at least 9 cN, or both.

[0126] In some embodiments, the high density polyethylene blend contains at least 85 wt% PCR high density polyethylene and has a NCLS of at least 8 hours or a melt strength of at least 8 cN, or both, as measured according to ASTM F2136.

[0127] In some embodiments, the high density polyethylene blend has an ESCR of at least 200 hours as measured according to ASTM D 1693-13, Condition A, with a 10% surfactant solution in water.

[0128] In some embodiments, the high density polyethylene blend has a notched constant ligament stress (NCLS) of at least 15 hours.

[0129] In some embodiments, the original bimodal high density polyethylene polymer component of the high density polyethylene blend comprises a higher molecular weight ethylene / 1-hexene copolymer component and a lower molecular weight ethylene / 1-hexene copolymer component, wherein: the density of the original bimodal HDPE polymer is from 0.944 g / cc to 0.953 g / cc; the flow index (I 21 ) is 8 g / 10 min to 12 g / 10 min; the melt flow ratio of the bimodal HDPE polymer (I 21 / I2) is at least 125.

[0130] In some embodiments are shaped articles comprising a high density polyethylene blend.

[0131] In some embodiments is a blow molding method comprising the steps of: (1) placing a certain amount of molten high-density polyethylene (HDPE) blend in a mold cavity, (2) blowing a gas into the molten HDPE blend to cause it to expand and take on the approximate shape of the mold cavity, and (3) cooling the HDPE blend, wherein the HDPE blend is a high-density polyethylene blend.

[0132] In some embodiments is a blow molded article, the blow molded article being prepared by a blow molding process.

[0133] Example

[0134] Test Method :

[0135] The following test methods are used to measure the properties described in this application:

[0136] The following test methods are used to measure the properties described in this application:

[0137] Density: Density is measured in accordance with ASTM D792-13, Standard Test Methods for Density and Specific Gravity (Relative Density) of Plastics by Displacement, Method B (for testing solid plastics in liquids other than water, such as liquid 2-propanol). Results are reported in grams per cubic centimeter (g / cc).

[0138] Differential Scanning Calorimetry (DSC): Differential Scanning Calorimetry (DSC) is a common technique that can be used to examine the melting and crystallization of semi-crystalline polymers. The general principles of DSC measurements and the application of DSC in studying semi-crystalline polymers are described in standard texts (e.g., EATuri, ed., Thermal Characterization of Polymeric Materials, Academic Press, 1981).

[0139] In preparation for differential scanning calorimetry (DSC) testing, the sample in pellet form was first loaded into a 1 inch diameter 0.13 mm thick slot and compression molded into a film at 190° C. under 25,000 pounds of pressure for approximately 10 seconds. The resulting film was then cooled to room temperature, after which the film was punched out to remove a disk that would fit into an aluminum pan supplied by TA Instrument. The disk was then weighed individually (note: sample weight was approximately 4 mg to 8 mg) and placed into an aluminum pan, and sealed prior to insertion into the DSC test chamber.

[0140] DSC testing was performed using a hot-cold-hot cycle according to ASTM standard D3418. First, the sample was equilibrated at 180°C and held isothermally for 5 min to remove heat and process history. The sample was then quenched to -40°C at a rate of 10°C / min and held isothermally for 5 min again during the cooling cycle. Finally, the sample was heated to 150°C at a rate of 10°C / min for a second heating cycle. For data analysis, the melting temperature and melting enthalpy were extracted from the second heating curve, while the crystallization enthalpy was extracted from the cooling curve. The melting enthalpy and crystallization enthalpy were obtained by integrating the DSC thermograms from -20°C to the end of melting and crystallization, respectively. TA Instruments Q2000 and Discovery DSC were used for testing, and data analysis was performed by TA Instruments Universal Analysis and TRIOS software packages.

[0141] Melt index, flow index and melt flow ratio: Flow index (I 21 ) is measured according to ASTM D1238-13, condition 190°C / 21.6 kg, and is reported in g / 10 min. Melt indexes I5 and I2 are measured using the same procedure using 5.0 kg and 2.16 kg load conditions, respectively. Based on the results, melt flow ratio (I 21 / I5).

[0142] Melt Strength: Melt strength tests were performed on a Rheotester 2000 or Rheograph 25 capillary rheometer paired with a Rheotens model 71.97, all of which are manufactured by Gottfort. The die used for the test had a diameter of 2 mm, a length of 30 mm, and an entry angle of 180 degrees. Each test was conducted isothermally at 190°C. Before starting the test, the sample pellets were loaded into the capillary barrel and allowed to equilibrate at the test temperature for 10 min. During the test, the piston in the barrel applied a steady force to the molten sample to achieve a 38.16 s -1The apparent wall shear rate was 2.4 mm / s and the melt was extruded through the die at an exit velocity of approximately 9.7 mm / s. Located 100 mm below the die exit, the extrudate in strand form was guided through a Rheotens wheel set that extruded the extrudate at a velocity of 2.4 mm / s. 2 The constant rate of acceleration and measurement of the extrudate response to the applied tensile force. It should be noted that the Rheotens wheel pair is usually serrated and spaced 0.4mm apart. The results of this test are recorded in the figure of force relative to the Rheotens wheel speed using the RtensEvaluations2007excel macro. In these figures, before the extrudate strand breaks, the force tends to be stable, i.e., the flat line area. For analysis, before the extrudate strand breaks, the melt strength is reported as the flat line area force in centinewtons (cN). The corresponding speed of the Rheotens wheel at the strand breaking point is recorded as the pullability limit.

[0143] Environmental Stress Crack Resistance (ESCR): ESCR measurements were made according to ASTM D1693-15, Standard Test Method for Environmental Stress Crack of Ethylene Plastics, Method B. ESCR (10% IGEPAL CO-630, F50) is the number of hours after 50% of the bent, notched, compression molded test specimens are immersed in a 10 wt. % solution of IGEPAL CO-630 in water at a temperature of 50°C to fail. IGEPAL CO-630 is a 4-(branched-C9H19)-phenyl-[OCH2CH2] n -OH, wherein the subscript n is a number such that the branched ethoxylated nonylphenol has a number average molecular weight of about 619 g / mole.

[0144] Notched Constant Ligament Stress (NCLS): NCLS was measured using ASTM F2136.

[0145] Charpy impact resistance: Charpy impact strength is tested at -40°C according to ISO 179, Plastics-Determination of Charpy Impact Properties. Specimens with dimensions of 80 mm x 10 mm x 4 mm are cut and machined from 4 mm compression molded plaques that have been cooled at 5°C / min. A notch having a half angle of 22.5 degrees and a radius of curvature of 0.25 at its tip is used to cut a notch with a depth of 2 mm on its long side in the thickness direction of the specimen. The specimen is cooled in a cold box for 1 hour, then removed and tested in less than 5 seconds. The impact testing machine meets the specifications described in ISO 179. The results are reported in units of kilojoules per square meter (kJ / m2).

[0146] 2% Secant Flexural Modulus: Measured according to ASTM D790-10, Procedure B, Standard Test Method for Flexural Properties of Unreinforced and Reinforced Plastics and Electrical Insulation Materials. Results are reported in megapascals (MPa). 1,000.0 pounds per square inch (psi) = 6.8948 MPa.

[0147] Tensile Strength: Tensile strength was measured using ASTM D638-14. The average of five specimens tested at a speed of 2 in / min is reported.

[0148] Strain hardening modulus: The strain hardening modulus ("SHM") is determined in accordance with ISO 18488. The polymer pellets are compression molded into 0.3 mm thick sheets according to the molding conditions described in Table 1 of ISO 18488. After molding, the sheets are conditioned at 120°C for one hour and then cooled to room temperature at a controlled rate of 2°C / min. Five tensile bars (dog bone shape) are punched out of the compression molded sheets. The tensile test is carried out in an 80°C temperature chamber. Before starting the test, each specimen is conditioned in the temperature chamber for at least 30 minutes. The specimen is clamped up and down and a preload of 0.4 MPa is applied at a speed of 5 mm / min. During the test, the load and elongation borne by the specimen are measured. The specimen is stretched at a constant speed of 20 mm / min, and data points are collected from a stretch ratio (λ) of 8.0 until λ=12.0 or breakage. As specified in ISO 18488, the slope between the stretch ratios of 8.0 and 12.0 is calculated using the true stress diagram versus the stretch ratio. If failure occurs before a stretch ratio of 12.0, the stretch ratio corresponding to the failure strain is considered to be the upper limit of the slope calculation. If failure occurs before a stretch ratio of 8.0, the test is considered invalid.

[0149] Die Swell: Polymer expansion is characterized by "timed swell" via capillary rheometry. In this method, the time required for an extruded polymer strand to travel a distance of 10 inches (25.4 cm) is measured. The more the polymer swells, the slower the free end of the strand travels and the longer it takes to cover the distance. A 12 mm barrel equipped with a 30 / 1 (mm / mm) L / D capillary die was used. The measurements were performed using a Rheotester 2000. The measurements were performed at 190 °C at two fixed shear rates: 300 s -1 and 1000s -1 The time measurements of the expansion are reported as t300 and t1000 values ​​respectively.

[0150] High shear and low shear viscosity: Dynamic oscillatory shear measurements were performed on a strain-controlled rheometer ARES / ARES-G2 of Thermal Analysis Instruments with 25 mm diameter stainless steel parallel plates at a temperature of 190°C and 10% strain in the range of 0.1 rad s-1 to 100 rad s-1. The rheometer was preheated at 190°C for at least 30 minutes. The disk prepared by the compression molded plate preparation method was placed between the "25 mm" parallel plates in the oven. The gap between the "25 mm" parallel plates was slowly reduced to 2.0 mm. The sample was kept under these conditions for exactly 5 minutes. The oven was turned on, and the excess sample was carefully trimmed from the edge of the plate. The oven was turned off. A delay of another 5 minutes was allowed to allow its temperature to equilibrate. The complex shear viscosity was then determined via small amplitude oscillatory shear, and the complex viscosity at 0.1 rad / s and 100 rad / s was obtained according to an increasing frequency scan from 0.1 rad / s to 100 rad / s. The shear viscosity ratio (SVR) is defined as the ratio of the complex shear viscosity in Pascal-seconds (Pa.s) at 0.1 rad / s to the complex shear viscosity in Pascal-seconds (Pa.s) at 100 rad / s.

[0151] Molecular weight (determined by gel permeation chromatography (GPC)):

[0152] The chromatographic system consisted of a PolymerChar GPC-IR (Valencia, Spain) high temperature GPC chromatograph equipped with an internal IR5 infrared detector (IR5) connected to a Precision Detectors (now Agilent Technologies) 2-angle laser scattering (LS) detector model 2040 and 4 capillary viscometers (DV). For all absolute light scattering measurements, a 15 degree angle was used for measurement. The autosampler oven chamber was set to 160 degrees Celsius, and the column and detector chambers were set to 150 degrees Celsius. The columns used were 4 Agilent "MixedA" 30 cm 20 micron linear mixed bed columns. The chromatographic solvent used was 1,2,4 trichlorobenzene and contained 200 ppm of butylated hydroxytoluene (BHT). The solvent source was nitrogen sparged. The injection volume used was 200 microliters, and the flow rate was 1.0 ml / min.

[0153] The GPC column set was calibrated with 21 narrow molecular weight distribution polystyrene standards ranging from 580 to 8,400,000 molecular weights and arranged in 6 "cocktail" mixtures with at least ten times intervals between individual molecular weights. The standards were purchased from Agilent Technologies. For molecular weights equal to or greater than 1,000,000, 0.025 grams of polystyrene standards were prepared in 50 milliliters of solvent, and for molecular weights less than 1,000,000, 0.05 grams of polystyrene standards were prepared in 50 milliliters of solvent. The polystyrene standards were pre-dissolved at 80°C under gentle stirring for 30 minutes, then cooled and the room temperature solution was transferred to a 160°C autosampler dissolution oven to cool for 30 minutes. The polystyrene standard peak molecular weights were converted to polyethylene molecular weights using Equation 1 (as described in Williams and Ward, J. Polym. Sci., Polym. Let., 6, 621 (1968)):

[0154] M polyethylene =A×(M polystyrene ) B (Equation 1)

[0155] Where M is the molecular weight, A has a value of 0.4389, and B equals 1.0.

[0156] A fifth-order polynomial was used to fit the calibration points to the corresponding polyethylene equivalents.

[0157] Total plate counts for the GPC column set were performed with decane, which was introduced into the blank sample via a micro pump controlled by the PolymerChar GPC-IR system. The plate count of the chromatography system should be greater than 18,000 for 4 Agilent "Mixed A" 30 cm 20 micron linear mixed bed columns.

[0158] The samples were prepared semi-automatically using the PolymerChar "Instrument Control" software, where the target weight of the sample was set to 2 mg / ml, and the solvent (containing 200 ppm BHT) was added to a septum-capped vial previously sparged with nitrogen via the PolymerChar high temperature autosampler. The samples were dissolved at 160 degrees Celsius for 2 hours under "slow" shaking.

[0159] Based on the GPC results, using the internal IR5 detector (measurement channel) of the PolymerChar GPC-IR spectrometer, according to equations 2 to 4, the PolymerChar GPCOne TMThe software was used to calculate the Mn value of the baseline-subtracted IR chromatogram at each equidistant data collection point (i) and the polyethylene equivalent molecular weight obtained from the narrow standard calibration curve at point (i) according to Equation 1. (GPC) 、Mw (GPC) and Mz (GPC) Calculation.

[0160]

[0161] To monitor deviations over time, a flow rate marker (decane) was introduced into each sample via a micropump controlled by the PolymerChar GPC-IR system. This flow rate marker (FM) was used to linearly correct the pump flow rate for each sample (Flow Rate (Nominal)) by comparing the RV of the corresponding decane peak in the sample (RV (FM Sample)) with the RV of the decane peak in the narrow standard calibration (RV (FM Calibrated)). Any changes in the decane marker peak time were then assumed to be related to a linear change in flow rate (Flow Rate (Effective)) throughout the run. After calibrating the system based on the flow marker peak, the effective flow rate (relative to the narrow standard calibration) was calculated as Equation 5. TM The software completes the processing of the flow marker peak. An acceptable flow rate correction is such that the effective flow rate should be within + / - 0.5% of the nominal flow rate. Flow Rate (Effective) = Flow Rate (Nominal) x (RV (FM Cal) / RV (FM Sample)) (Equation 5)

[0162] Triple Detector GPC (TDGPC)

[0163] To determine the offset of the viscometer and light scattering detectors relative to the IR5 detector, a systematic method for determining multi-detector offset was performed in a manner consistent with that published by Balke, Mourey et al. (Mourey and Balke, Chromatography Polym., Chapter 12, (1992)) (Balke, Thitiratsakul, Lew, Cheung, Mourey, Chromatography Polym., Chapter 13, (1992)) using the PolymerChar GPCOne TM The software optimizes triple detector log (MW and IV) results from linear homopolymer polyethylene standards in the molecular weight range of 115,000 g / mol to 125,000 g / mol (3.5>Mw / Mn>2.2) with narrow standards column calibration results from narrow standards calibration curves.

[0164] Absolute molecular weight data using PolymerChar GPCOneTM The software was obtained in a manner consistent with that published by Zimm (Zimm, BH, Chem. Phys., 16, 1099 (1948)) and Kratochvil (Kratochvil, P., Classical Light Scattering from Polymer Solutions, Elsevier, Oxford, NY (1987)). The total injected concentration used to determine the molecular weight is obtained from the mass detector area and the mass detector constant, which is derived from a suitable linear polyethylene homopolymer or one of the polyethylene standards of known weight average molecular weight. The calculated molecular weight (using GPCOne TM ) is obtained using the light scattering constants from one or more of the polyethylene standards mentioned below and a refractive index concentration coefficient dn / dc of -0.104. Typically, the mass detector response (IR5) and the light scattering constant (using GPCOne TM Viscometer calibration (using GPCOne TM The viscometer constant (measured using GPCOne TM The specific viscosity area (DV) and injected mass of the calibration standard are related to their intrinsic viscosity. The chromatographic concentration is assumed to be low enough to eliminate the effect of the 2nd Virial coefficient (the effect of concentration on molecular weight).

[0165] Absolute weight average molecular weight (MW (Abs) )Yes (Using GPCOne TM ) is obtained by dividing the area of ​​the light scattering (LS) integrated chromatogram (calculated from the light scattering constant) by the mass recovered from the mass constant and the mass detector (IR5) area. Molecular weight and intrinsic viscosity responses are at the end of the chromatogram where the signal-to-noise ratio becomes low (using GPCOne TM ) is linearly extrapolated. The other corresponding moments Mn are calculated according to equations 8 to 10 as follows (Abs) and Mz (Abs) :

[0166]

[0167]

[0168] The following working examples illustrate some specific embodiments of the invention but are not intended to limit the broad scope of the invention.

[0169] Production of virgin bimodal HDPE1

[0170] The original bimodal HDPE 1 of the present invention is prepared by using ethylene ("C2") monomer and 1-hexene ("C6") comonomer and PRODIGY TM Embodiment of the original bimodal HDPE polymer produced by the BMC-300 bimodal catalyst system. The original bimodal HDPE 1 comprises a higher molecular weight component and a lower molecular weight component, the higher molecular weight component is an ethylene / 1-hexene copolymer, and the lower molecular weight component is an ethylene / 1-hexene copolymer. The original bimodal HDPE 1 is produced in a gas phase fluidized bed reactor with isopentane ("iC5") feed under the conditions shown in Table 1.

[0171] Production of virgin bimodal HDPE2

[0172] The original bimodal HDPE 2 is an embodiment of the original bimodal HDPE polymer of the present invention prepared using ethylene ("C2") monomer and 1-hexene ("C6") comonomer and a BMC analog bimodal catalyst system. The original bimodal HDPE 2 comprises a higher molecular weight component and a lower molecular weight component, the higher molecular weight component being an ethylene / 1-hexene copolymer and the lower molecular weight component being an ethylene / 1-hexene copolymer. The original bimodal HDPE 2 is prepared in a gas phase fluidized bed reactor with an isopentane ("iC5") feed under the conditions shown in Table 1.

[0173] Table 1 :

[0174]

[0175] For comparison purposes, a virgin unimodal HDPE polymer, typically blended with recycled polyethylene (Marlex HXM 50100P polyethylene from Chevron Phillips Chemical Co.) was obtained. The properties of both polymers are reported in Table 2.

[0176] Table 2 :

[0177]

[0178] In Table 2, "GPC" molecular weight data is measured by conventional GPC, "Abs" molecular weight data is measured by the Absolute GPC test method, N / a means not applicable, and N / m means not measured.

[0179] In Table 2, the inventive pristine bimodal high density polyethylene polymer embodiments pristine bimodal HDPE 1 and pristine bimodal HDPE 2 and comparative Marlex HDPE each contain 0.06 wt% of Irganox 1010 antioxidant and 0.10 wt% of Irgafos 168 antioxidant.

[0180] Post-consumer recycled (PCR) HDPE homopolymer was obtained: KWR 101-150 natural homopolymer high density polyethylene polymer from KW Plastics. The PCR polymer was melt blended with virgin bimodal HDPE 1 in amounts of 25 wt % PCR polymer, 50 wt % PCR polymer, 75 wt % PCR polymer, and 90 wt % PCR polymer to form HDPE blends. Separately, the PCR polymer was melt blended with virgin bimodal HDPE 2 in amounts of 25 wt % PCR polymer, 50 wt % PCR polymer, 75 wt % PCR polymer, and 90 wt % PCR polymer to form HDPE blends.

[0181] Melt blending was performed on a Coperion ZSK 25mm twin screw extruder (11 barrels, 44L / D, electric heating and water cooling). The motor was rated at 40 horsepower. The gearbox ratio was 1:89, and the maximum screw speed was 1,200RPM. The maximum torque of the pipeline was 106Nm. Each barrel length was 1125mm, and 11 barrels comprised the entire process section. The screw diameter was 25.5mm. The extruder barrel inner diameter was 25mm. Nitrogen filling (9.5SCFH) was maintained at the feed throat during the entire compounding process. The screw design was a ZSK-25 mild screw. The screw RPM was 300.

[0182] The polymer was fed into the extruder using a single helical screw K-tron T-20 polymer feeder. The feed rate was 30 lbs / hr.

[0183] The compounded material was extruded through a 3 mm, 2 hole die into a 6 foot long cooling water bath. The strands were passed through a Huestis Air Block to remove excess water. The cooled and dried strands were pelletized using a Conair strand pelletizer.

[0184] The properties of each HDPE blend were measured. In addition, the properties of each virgin polymer were measured.

[0185] The measured properties are listed in Table 2. Examples listed as "IE" are inventive examples and examples listed as "CE" are comparative examples. The inventive HDPE blends have higher NCLS performance and substantially equivalent physical properties as compared to comparative HDPE blends containing the same level of virgin polymer.

[0186] The melt strength of the sample at 190°C is Figures 1 to 5 Shown in.

[0187] In Table 3a, the melt strength reported for each sample is the average melt strength observed over the speed range for which the samples exhibit a rough melt strength plateau. It can be observed that for HDPE blends containing at least 70 wt% PCR HDPE, the melt strength of the inventive HDPE blends is substantially equivalent to that of the comparative HDPE blends.

[0188] In Table 3b, the inventive blends are contemplated examples. Therefore, for these contemplated inventive blends, no properties can be reported, indicated by "N / a," which means not applicable.

[0189] In Tables 3a and 3b, cN is centinewton, ksi is kilopounds per square inch, psi is pounds per square inch, kJ / m 2 is kilojoule per square meter, MPa is megapascal, and hr is hour.

[0190] Table 3a. Properties of inventive examples and comparative examples with pristine bimodal HDPE 1 .

[0191]

[0192] Table 3a continued. Properties of inventive examples and comparative examples with pristine bimodal HDPE 1 .

[0193]

[0194]

[0195] Table 3b: Properties of envisioned inventive examples with pristine bimodal HDPE 2. Comparative examples see Table 3a .

[0196]

[0197] *Envisioned embodiments.

[0198] Table 3b continued: Properties of proposed inventive examples with pristine bimodal HDPE 2. Comparative examples see Table 3a .

[0199]

[0200]

[0201] *Envisioned embodiments.

Claims

1. A high density polyethylene blend comprising: (a) 25 wt% to 90 wt% recycled high density polyethylene; and (b) 10 wt% to 75 wt% virgin bimodal high density polyethylene polymer having a density of 0.944 g / cc to 0.953 g / cc and a flow index (I) of 8 g / 10 min to 12 g / 10 min. 21 ).

2. The high density polyethylene blend of claim 1, wherein the recycled high density polyethylene is a post-consumer recycled polymer.

3. The high density polyethylene blend according to claim 1 or claim 2, wherein the melt flow ratio (I 21 / I2) is at least 125.

4. The high density polyethylene blend according to any one of claims 1 to 3, wherein the flow index (I 21 ) is 10g / 10min to 50g / 10min.

5. The high density polyethylene blend according to any one of claims 1 to 4, wherein the molecular weight distribution (Mw / Mn) of the original bimodal high density polyethylene polymer is at most 16.

6. The high-density polyethylene blend according to claim 6, wherein the melt flow ratio (I 21 / I2) is at least 140.

7. The high density polyethylene blend of any one of claims 1 to 6, containing at least 45 wt% PCR high density polyethylene and having a NCLS of at least 50 hours as measured according to ASTM F2136.

8. The high density polyethylene blend according to any one of claims 1 to 6, containing at least 70 wt% PCR high density polyethylene and having a NCLS of at least 15 hours as measured according to ASTM F2136 or having a melt strength of at least 9 cN or both.

9. The high density polyethylene blend of any one of claims 1 to 6, containing at least 85 wt% PCR high density polyethylene and having a NCLS of at least 8 hours or a melt strength of at least 8 cN, or both, as measured according to ASTM F2136.

10. A high density polyethylene blend according to any one of claims 1 to 9, wherein the high density polyethylene blend has limitations (i), (ii) or (iii): (i) wherein the high density polyethylene blend has an ESCR of at least 200 hours as measured according to ASTM D 1693-13, Condition A, with a 10% surfactant solution in water; or (ii) wherein the high density polyethylene blend has a notched constant ligament stress (NCLS) of at least 15 hours; or (iii) both limitations (i) and (ii).

11. The high density polyethylene blend according to any one of claims 1 to 10, wherein the original bimodal high density polyethylene polymer comprises a higher molecular weight ethylene / 1-hexene copolymer component and a lower molecular weight ethylene / 1-hexene copolymer component, wherein: The density of the original bimodal HDPE polymer is 0.944 g / cc to 0.953 g / cc; the flow index (I 21 ) is 8 g / 10 min to 12 g / 10 min; and the melt flow ratio (I 21 / I2) is at least 125.

12. A shaped article comprising the high density polyethylene blend according to any one of claims 1 to 11.

13. A blow molding method, comprising the following steps: (1) placing a certain amount of molten high-density polyethylene (HDPE) blend in a mold cavity, (2) blowing gas into the molten HDPE blend to cause it to expand and assume an approximate shape of the mold cavity, and (3) cooling the HDPE blend, wherein the HDPE blend is the high-density polyethylene blend according to any one of claims 1 to 10.

14. A blow molded product prepared by the method according to claim 13.

15. A raw bimodal high density polyethylene polymer comprising a higher molecular weight ethylene / 1-hexene copolymer component and a lower molecular weight ethylene / 1-hexene copolymer component, wherein: The density of the original bimodal HDPE polymer is 0.944 g / cc to 0.953 g / cc; the flow index (I 21 ) is 8 g / 10 min to 12 g / 10 min; and the melt flow ratio (I 21 / I5) is 25 to 35.

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