Modified Polyethylene Compositions for Blown Film

{
  "publication_number": "US2013224463A1",
  "country": "US",
  "kind": "A1",
  "title": "Modified Polyethylene Compositions for Blown Film",
  "abstract": "The present invention relates to a blown film comprising more than 25 wt % (based on the weight of the composition) of one or more linear ethylene polymers having a g′vis of 0.97 or more and an Mw of 20,000 g/mol or more and at least 0.1 wt % of a branched modifier where the modifier has a) a g′vis of 0.90 or less; b) an Mw of 100,000 g/mol or more; c) an Mw/Mn of 3.0 or more; d) an Mz/Mn of 7.0 or more; e) optionally, an Mz of 2,000,000 g/mol or less; and f) a shear thinning ratio of 40 or more.",
  "claims": [
    "1. A film comprising polyethylene and a branched polyethylene modifier comprising at least 50 mol % ethylene, one or more C 4 to C 40 comonomers, and a polyene having at least two polymerizable bonds, wherein said branched polyethylene modifier has: a) a g′vis of 0.90 or less; b) an Mw of 100,000 g/mol or more; c) an Mw/Mn of 3.0 or more; d) an Mz/Mn of 7.0 or more; and e) a shear thinning ratio of 40 or more; where the film has an improvement in dart drop or no greater than a 25% reduction in dart drop (as measured in g/mil) as compared to the polyethylene formed into a film under the same conditions, except that the branched modifier is absent, and the film has an improvement in MD Elmendorf tear or no greater than a 35% reduction in Elmendorf tear (as measured in g/mil) as compared to the polyethylene formed into a film under the same conditions, except that the branched modifier is absent, and the film has an improvement in maximum extrusion rate of at least 20% as compared to the polyethylene formed into a film under the same conditions, except that the branched modifier is absent. 2. The film of claim 1, wherein the comonomer in the branched modifier is present at from 0.5 mol % to 30 mol % and the polyene in the branched modifier is present at from 0.001 mol % to 10 mol %. 3. The film of claim 1, wherein the branched modifier has an Mz of 2,000,000 g/mol or less and an 121 of 20 dg/min or less. 4. The film of claim 1, wherein the modifier has a g′ (Zave) of 0.70 or less. 5. The film of claim 1, wherein the modifier has a strain-hardening ratio of 0.5 or greater. 6. The film of claim 1, wherein the C 4 to C 40 comonomers in the branched modifier are one or more C 6 to C 40 alpha olefin comonomers. 7. The film of claim 1, wherein the modifier has a phase angle at complex shear modulus G*=100,000 Pa of 40° or less. 8. The film of claim 1, wherein the C 4 to C 40 comonomers in the branched modifier are one or more of butene, hexene, or octene. 9. The film of claim 1, wherein the polyene in the branched modifier is selected from the group consisting of: 1,4-pentadiene, 1,5-hexadiene, 1,6-heptadiene, 1,7-octadiene, 1,8-nonadiene, 1,9-decadiene, 1,10-undecadiene, 1,11-dodecadiene, 1,12-tridecadiene, 1,13-tetradecadiene, tetrahydroindene, norbornadiene also known as bicyclo-(2.2.1)-hepta-2,5-diene, dicyclopentadiene, 5-vinyl-2-norbornene, 1,4-cyclohexadiene, 1,5-cyclooctadiene, and 1,7-cyclododecadiene. 10. A film comprising a blend comprising: 1) branched polyethylene modifier comprising at least 50 mol % ethylene, one or more C 4 to C 40 comonomers, and a polyene having at least two polymerizable bonds, wherein said branched polyethylene modifier has: a) a g′vis of 0.90 or less; b) an Mw of 100,000 g/mol or more; c) an Mw/Mn of 3.0 or more; d) an Mz/Mn of 7.0 or more; and e) a shear thinning ratio of 40 or more; and 2) polyethylene having a density of 0.910 g/cc or more, a g′vis of 0.97 or more, and an Mw of 20,000 g/mol or more, where the film has an improvement in dart drop or no greater than a 25% reduction in dart drop (as measured in g/mil) as compared to the polyethylene formed into a film under the same conditions, except that the branched modifier is absent, and the film has an improvement in MD Elmendorf tear or no greater than a 35% reduction in Elmendorf tear (as measured in g/mil) as compared to the polyethylene formed into a film under the same conditions, except that the branched modifier is absent, and the film has an improvement in maximum extrusion rate of at least 20% as compared to the polyethylene formed into a film under the same conditions, except that the branched modifier is absent. 11. The film of claim 10, wherein the modifier has an Mz of 2,000,000 g/mol or less and an 121 of 20 dg/min or less. 12. The film of claim 10, wherein the branched polyethylene modifier is present at 0.5 wt % to 10 wt %, based upon the weight of the blend. 13. The film of claim 10, wherein the polyethylene comprises a copolymer of ethylene and one or more C 3 to C 20 alphaolefins and has an Mw of 20,000 to 1,000,000 g/mol. 14. The film of claim 10, wherein the polyethylene has a density of 0.92 to 0.94 g/cm 3. 15. The film of claim 10, wherein the branched polyethylene modifier is present at from 0.1 wt % to 99.5 wt %, (based upon the weight of the blend); and the polyethylene has a composition distribution breadth index of 60% or more and a density of 0.90 g/cm 3 or more. 16. The film of claim 10, wherein the modifier has a strain-hardening ratio of 0.5 or greater. 17. The film of claim 1, wherein the modifier is an ethylene, octene, 1,9-decadiene copolymer. 18. The film of claim 10, wherein where the polyethylene has a g′vis of 0.975 or more. 19. The film of claim 1 wherein the film is a blown film. 20. The film of claim 10 wherein the film is a blown film. 21. The film of claim 10, wherein the branched polyethylene modifier has an Mw of 150,000 g/mol or more. 22. The film of claim 10, wherein the blend has a melt strength at least 60% higher than the melt strength of the polyethylene having a density of 0.88 g/cc or more and an Mw of 20,000 g/mol or more used in the blend. 23. The film of claim 10, wherein the blend has a melt strength at least 100% higher than the melt strength of the polyethylene prior to combination with the branched polyethylene modifier. 24. The film of claim 10, where in the film is a blown film at least 75 μm thick. 25. The film of claim 10, wherein the film has an improvement in maximum extrusion rate of at least 20% as compared to the polyethylene formed into a film under the same conditions, except that the branched modifier is absent. 26. The film of claim 10, said film having a haze of 20% or less."
  ],
  "description_excerpt": "The present invention relates to branched modifiers, and polyethylene compositions useful in blown films comprising an ethylene based polymer and a branched modifier. More particularly, the present invention relates to polyethylene compositions having significantly improved processability, without substantial loss in mechanical properties and/or optical properties.\n\nFor many polyolefin applications, including films and fibers, increased melt strength and good optical properties are desirable attributes. Higher melt strength allows fabricators to run their blown film lines at a faster rate. It also allows them to handle thicker films in applications such as geomembranes.\n\nTypical metallocene catalyzed polyethylenes (mPE) are somewhat more difficult to process than low-density polyethylenes (LDPE) made in a high-pressure polymerization process. Generally, mPEs (which tend to have narrow molecular weight distributions and low levels of branching) require more motor power and produce higher extruder pressures to match the extrusion rate of LDPEs. Typical mPEs also have lower melt strength which, for example, adversely affects bubble stability during blown film extrusion, and are prone to melt fracture at commercial shear rates. On the other hand, mPEs exhibit superior physical properties as compared to LDPEs. In the past, various levels of LDPE have been blended with the mPE to increase melt strength, to increase shear sensitivity, i.e. to increase flow at commercial shear rates in extruders; and to reduce the tendency to melt fracture. However, these blends generally have poor mechanical properties as compared with neat mPE.",
  "cpc": [
    "C08L 23/06",
    "B32B 5/00",
    "C08F 210/14",
    "C08F 210/16",
    "C08F 210/18",
    "C08J 2323/08",
    "C08J 5/18",
    "C08L 2203/16",
    "C08L 2205/025",
    "C08L 2207/07",
    "C08L 23/08",
    "C08L 23/0815"
  ],
  "ipc": [
    "B32B 5/00",
    "C08L 23/06",
    "C08F 210/18",
    "C08J 5/18",
    "C08L 23/08"
  ],
  "assignees": [
    "ExxonMobil Chemical Patents Inc"
  ],
  "inventors": [
    "Pradeep P. Shirodkar",
    "Jianya Cheng",
    "Peijun Jiang"
  ],
  "filing_date": "2013-03-27",
  "publication_date": "2013-08-29",
  "priority_date": "2011-09-23",
  "application_number": "US-201313851769-A",
  "family_id": "49003172",
  "cited_by_count": 17,
  "citations": [
    "US20020150757A1",
    "US20040118592A1",
    "US20060178478A1",
    "US20130090433A1"
  ]
}