Multimodal polyethylene composition

Patent metadata

Field	Value
Publication number	US-11827725-B2
Application number	US-201916976497-A
Country	US
Kind code	B2
Filing date	Mar 22, 2019
Priority date	Mar 28, 2018
Publication date	Nov 28, 2023
Grant date	Nov 28, 2023

Abstract

A bimodal polyethylene composition, products made therefrom, methods of making and using same, and articles, including bottle caps and closures, containing same.

First claim

The invention claimed is:

1. A bimodal polyethylene composition comprising a lower molecular weight (LMW) polyethylene component and a higher molecular weight (HMW) polyethylene component, wherein each of the LMW and HMW polyethylene components comprises ethylene-derived monomeric units and (C 3 -C 20 )alpha-olefin-derived comonomeric units; and wherein the bimodal polyethylene composition is characterized by each of limitations (a) to (e): (a) a resolved bimodality (resolved molecular weight distribution) showing in a chromatogram of gel permeation chromatography (GPC) of the bimodal polyethylene composition, wherein the chromatogram shows a peak representing the HMW polyethylene component, a peak representing the LMW polyethylene component, and a local minimum in a range of Log(molecular weight) (“Log(MW)”) 3.5 to 5.5 between the Log(MW) peak representing the HMW polyethylene component and the Log(MW) peak representing the LMW polyethylene component, measured according to Bimodality Test Method; (b) a density from 0.950 to 0.960 g/cm 3 , measured according to ASTM D792-13 Method B; (c) a melt index (12) of from 0.5 to 1.5 g/10 min., measured according to ASTM D1238-13 (190° C., 2.16 kg); (d) a melt flow ratio (I 21 /I 2 ) of from 150 to 300, wherein I 2 is measured as above and I 21 is flow index measured according to ASTM D1238-13 (190° C., 21.6 kg); (e) a flow index (Is) from 2.0 to 10.0 g/10 min., measured according to ASTM D1238-13 (190° C., 5.0 kg); and wherein the HMW polyethylene component of the bimodal polyethylene composition is characterized by limitations (f) and (g): (f) a weight-average molecular weight (Mw) of greater than 350,000 grams per mole (g/mol), as measured by Gel Permeation Chromatography Method; and (g) a molecular mass dispersity, D M , (Mw/Mn) greater than 3.50.

2. The bimodal PE composition of claim 1 further described by any one of limitations (i) to (vi): (i) a spiral flow length of from 25 to 40 centimeters (cm) measured at 68.95 megapascals (MPa), a spiral flow length from 30 to 60 cm measured at 103.4 MPa, or a spiral flow length from 40 to 70 cm measured at 137.9 MPa according to the Spiral Flow Length Test Method; (ii) an environmental stress crack resistance (ESCR) F50 measured according to ASTM D1693-15 in 10 weight percent (wt %) Igepal CO-630 in water at 50° C. of greater than 500 hours; (iii) a shrinkage from melt to solid form of from 3.0% to 5.0% in flow direction or a shrinkage from melt to solid form of from 0.2% to 1.5% in cross-flow direction, measured according to ASTM D-955 utilizing a 60 mm×60 mm×2 mm plaques; (iv) an oxidative induction time (OIT) of greater than 40 minutes at 210° C. as measured by differential scanning calorimetry (DSC) according to OIT Test Method; (v) at least two of (i) to (iv); (vi) each of (i) to (iv).

3. The bimodal PE composition of claim 1 further described by any one of limitations (i) to (vii): (i) a molecular mass dispersity (M w /M n ),D M (pronounced D-stroke M), from 15 to 30, measured according to Gel Permeation Chromatography (GPC) Test Method; (ii) a weight average molecular weight (M n ) of the LMW polyethylene component from 4,000 to 6,000 g/mol and a M n of the HMW polyethylene component from 110,000 to 130,000 g/mol, measured according to GPC Test Method, after deconvoluting the LMW and HMW polyethylene components of the bimodal PE composition according to Deconvoluting Test Method; (iii) no measurable amount of long chain branching per 1,000 carbon atoms (“LCB Index”), measured according to LCB Test Method; (iv) both (i) and (ii); (v) both (i) and (iii); (vi) both (ii) and (iii); and (vii) each of (i) to (iii).

4. The bimodal PE composition of claim 1 further described by any one of limitations (i) to (iv): (i) the (C 3 -C 20 )alpha-olefin-derived comonomeric units are derived from 1-butene; (ii) the (C 3 -C 20 )alpha-olefin-derived comonomeric units are derived from 1-hexene; (iii) the (C 3 -C 20 )alpha-olefin-derived comonomeric units are derived from 1-octene; and (iv) the (C 3 -C 20 )alpha-olefin-derived comonomeric units are derived from a combination of any two, alternatively each of 1-butene, 1-hexene, and 1-octene.

5. A method of making the bimodal polyethylene composition of claim 1 , the method comprising contacting ethylene (monomer) and at least one (C 3 -C 20 )alpha-olefin (comonomer) with a mixture of a bimodal catalyst system and a trim solution in the presence of molecular hydrogen gas (H 2 ) and, optionally, an induced condensing agent (ICA) in one, two or more polymerization reactors under (co)polymerizing conditions, thereby making the bimodal polyethylene composition; wherein prior to being mixed together the trim solution consists essentially of a (tetramethylcyclopentadienyl)(n-propylcyclopentadienyl)zirconium complex and an inert liquid solvent and the bimodal catalyst system consists essentially of an activator species, a non-metallocene ligand-Group 4 metal complex and a metallocene ligand-Group 4 metal complex, all disposed on a solid support; and wherein the (co)polymerizing conditions comprise a reaction temperature from 80 degrees (°) to 110° Celsius (C.); a molar ratio of the molecular hydrogen gas to the ethylene (H2/C2 molar ratio) from 0.001 to 0.050; and a molar ratio of the comonomer (Comer) to the ethylene (Comer/C2 molar ratio) from 0.005 to 0.10.

6. A manufactured article comprising a shaped form of the bimodal polyethylene composition of claim 1 .

7. The manufactured article of claim 6 selected from: coatings, films, sheets, extruded articles, and injection molded articles.

8. A bottle cap or closure comprising a base member and a skirt member, the base member defining a perimeter edge therearound, and the skirt member being in operative connection to the perimeter edge of the base member and extending axially from the perimeter of the base member; wherein the skirt member defines an inner surface; wherein the base member being for sealing a bottle opening of a bottle and the skirt member being for operatively attaching the bottle cap or closure to an exterior cap-or-closure-receiving portion of the bottle proximate the bottle opening, wherein at least one of the base member and skirt member of the bottle cap or closure is composed of the bimodal polyethylene composition of claim 1 .

Assignees

• Univation Tech Llc

Inventors

• Borse Nitin
• Chandak Swapnil B
• Zhang Yi
• Lynn Timothy R
• Kuhlman Roger L
• Szul John F

Classifications

• C08F210/02 Primary

  Ethene · CPC title

• B29C45/0001

  characterised by the choice of material · CPC title

• C08F2/34

  Polymerisation in gaseous state · CPC title

• C08F4/64148

  NN(R)N · CPC title

• C08F4/65904

  in combination with another component of C08F4/64 · CPC title