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EP1003813A1 - Polyethylenes aux proprietes de thermosoudage ameliorees - Google Patents

Polyethylenes aux proprietes de thermosoudage ameliorees

Info

Publication number
EP1003813A1
EP1003813A1 EP98938296A EP98938296A EP1003813A1 EP 1003813 A1 EP1003813 A1 EP 1003813A1 EP 98938296 A EP98938296 A EP 98938296A EP 98938296 A EP98938296 A EP 98938296A EP 1003813 A1 EP1003813 A1 EP 1003813A1
Authority
EP
European Patent Office
Prior art keywords
low density
component
polyethylene
extrusion
density polyethylene
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP98938296A
Other languages
German (de)
English (en)
Inventor
Ray Edwards
Bruce Alexander Gillespie
Diane Hines Farnham
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Eastman Chemical Co
Original Assignee
Eastman Chemical Co
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from US09/088,904 external-priority patent/US6174612B1/en
Application filed by Eastman Chemical Co filed Critical Eastman Chemical Co
Publication of EP1003813A1 publication Critical patent/EP1003813A1/fr
Withdrawn legal-status Critical Current

Links

Classifications

    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L23/00—Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers
    • C08L23/02—Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers not modified by chemical after-treatment
    • C08L23/04—Homopolymers or copolymers of ethene
    • C08L23/06—Polyethene
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L2205/00—Polymer mixtures characterised by other features
    • C08L2205/02—Polymer mixtures characterised by other features containing two or more polymers of the same C08L -group
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L2205/00—Polymer mixtures characterised by other features
    • C08L2205/02—Polymer mixtures characterised by other features containing two or more polymers of the same C08L -group
    • C08L2205/025—Polymer mixtures characterised by other features containing two or more polymers of the same C08L -group containing two or more polymers of the same hierarchy C08L, and differing only in parameters such as density, comonomer content, molecular weight, structure
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L2207/00—Properties characterising the ingredient of the composition
    • C08L2207/06—Properties of polyethylene
    • C08L2207/066—LDPE (radical process)
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L2666/00—Composition of polymers characterized by a further compound in the blend, being organic macromolecular compounds, natural resins, waxes or and bituminous materials, non-macromolecular organic substances, inorganic substances or characterized by their function in the composition
    • C08L2666/02—Organic macromolecular compounds, natural resins, waxes or and bituminous materials
    • C08L2666/04—Macromolecular compounds according to groups C08L7/00 - C08L49/00, or C08L55/00 - C08L57/00; Derivatives thereof
    • C08L2666/06—Homopolymers or copolymers of unsaturated hydrocarbons; Derivatives thereof

Definitions

  • the present invention relates to a composition of matter obtained by the blending of two polyethylenes to provide strong heat seals for extrusion coated structures.
  • Prior art blends of polyethylenes are discussed, for instance, in U.S. Patent No. 4,339,507.
  • One component of this blend is a linear low density copolymer of ethylene and octene and a second component is a low density polyethylene homopolymer.
  • An example of such a linear low density polyethylene blend is Dow Chemical Company's Linear Low Density Polyethylene 3010.
  • Such blends are typically useful as extrusion coatings onto various structures, such as flexible polymeric film/paper packages for foods, and metallized polymeric film balloons. The coatings serve as heat seal media and as barriers to protect the contents of a package from outside contamination, or to retain the contents, such as a gas such as helium, within a coated and sealed balloon.
  • the ethylene-octene copolymer component of the prior art two-component blends is used to provide strong heat seal strengths required in certain extrusion coated structures.
  • these prior art blends create many problems in an extrusion coating operation.
  • the blends require excessively high extruder amps to extrude; some extruders are not rated for these high amps.
  • the high amps requirement is the reason that low density polyethylenes are combined with the copolymers, usually at about 20 weight percent of the low density polyethylene, to enhance processability.
  • these prior art blends exhibit high viscosities at the high shear rates associated with extrusion coating, they tend to generate excessive melt temperatures in the feed sections of extruder screws.
  • Ethylene vinyl acetate (EVA) copolymers permit lower heat seal initiation temperatures in those heat sealing operations requiring such low sealing temperatures.
  • Ethylene methyl acrylate (EMA) copolymers display strong heat-seal characteristics for both film and extrusion coating applications.”
  • Copolymers of ethylene and methyl acrylate containing about 2 weight percent to about 5 weight percent methyl acrylate, are thermally stable.
  • the prior art blends containing linear low density copolymers of ethylene and octene (or any other ⁇ -olefin), and the low density copolymers of ethylene and vinyl acetate, containing about 2 weight percent to about 18 weight percent vinyl acetate are thermally unstable. Either copolymer will degrade if it remains for too long in a heated extruder barrel, such as during a temporary operational shutdown. Such degradation, or molecular breakdown, generates massive defects in subsequent extrusion coatings. In most cases, the extrusion operator must clean his equipment before he can continue with production.
  • the purge material is usually an inert polymer such as a low density polyethylene homopolymer.
  • an inert polyethylene homopolymer can remain in an extruder until that extruder's next operational startup, and it can remain in an extruder through the heat-up cycle necessary to reach the extruder temperatures required to extrusion coat a copolymer.
  • This need for purging the thermally unstable copolymers from extruders is materially costly, with the purge material having to be purchased and inventoried at the site of the extrusion coating operation.
  • Such a polymer would be an inert homopolymer of ethylene, extrusion coatings of which would be capable of equaling or exceeding the heat seal strengths of linear low density copolymers of ethylene and octene (or any other ⁇ -olefin), or the low density copolymer of ethylene and vinyl acetate.
  • Such an ideal homopolymer would exhibit none of those problems of a linear low density polyethylene blend; that is, the ideal homopolymer would not require high extruder drive amps.
  • the present inventors have unexpectedly discovered an improved extrusion coating ethylene homopolymer composition of matter comprising a two-component blend of polyethylene homopolymers.
  • the first component is a low melt index medium density polyethylene to provide strong heat seals.
  • the second component is a high melt index low density polyethylene to provide a good wetting of substrates, such good wetting being essential to good coating-to-substrate adhesion, with a good adhesion being essential to strong heat seals.
  • the present invention unexpectedly permits heat seal strengths exceeding those of linear low density polyethylene compositions.
  • the present invention presents none of the aforementioned extrusion coating problems, such as thermal instability, associated with linear low density copolymers of ethylene and octene (or any other ⁇ -olefin) or low density copolymers of ethylene and vinyl acetate.
  • 60/055,768, filed August 14, 1997; Eastman Chemical Company Docket No. 70732 discloses improved 3-component blends of a linear low density polyethylene and two polyethylene homopolymers.
  • One polyethylene involved in each of the above five documents is a medium density polyethylene of narrow molecular weight distribution having a melt index of 0.5-dg/min to 4-dg/min at 190°C, a swell ratio of 1.2 to 1.35, an annealed density of about 0.926-g/cc, and a polydispersity index at or below 9.
  • This same medium density polyethylene is the first component of the two component polyethylene blend according to the present invention.
  • the blend according to the present invention also contains a second component, a low density polyethylene of broad molecular weight distribution having a melt index range of 18-dg/min to 22-dg/min, measured at 190°C, a swell ratio greater than 1.60, an annealed density of about 0.91- g/cc to about 0.92-g/cc, and a polydispersity above 9.
  • a second component a low density polyethylene of broad molecular weight distribution having a melt index range of 18-dg/min to 22-dg/min, measured at 190°C, a swell ratio greater than 1.60, an annealed density of about 0.91- g/cc to about 0.92-g/cc, and a polydispersity above 9.
  • the blends are prepared by mixing at least the above two components by methods known in the art. Additional polyethylene components may also be added, as well as other known additives such as fillers, pigments, etc. It is preferred that the first component above be present in a major amount, i.e., greater than 50 weight percent. An even more preferred blend is one wherein the first component above is present in the amount of about 80 weight percent and the second component above is present in the amount of about 20 weight percent.
  • extrusion coating methods are known in the art, such as extruding against glossy chill rolls or matte chill rolls.
  • the composition according to the present invention can be used in any known extrusion process.
  • Swell ratio is defined as the ratio of the diameter of the extrudate over that of the orifice diameter of the extrusion plastometer in ASTM D1238-62T.
  • the diameter of the specimen is measured in the area between 0.159-cm and 0.952-cm of the initial portion of the specimen as it emerges from the extrusion plastometer.
  • M w and M n were obtained by size- exclusion chromotography on a Waters 150C gel permeation chromatograph equipped with the standard refractometer detector and a Viscotek 150R differential viscometer system.
  • the 3-column set consisted of Waters' 10 3 , 10 4 , and linear- mixed bed (10 3 , 10 4 , and 10 5) ) Micro-Styragel HT columns.
  • the samples were run as 0.125% (weight volume) solutions in ortho-dichlorobenzene at 140°C.
  • the data were interpreted using Viscotek Unical software (V4.02), by universal calibration using NBS 1475 (linear polyethylene) and NBS 1476 (branched polyethylene) for any polyethylene sample.
  • Heat seal strength is determined by thermally welding opposing polymer coating specimens, each 1.00-inch (2.54-cm) wide, using a Sentinel Bar Sealer, Model 12AF.
  • the top sealing bar only is heated to 400°F (205°C), with the non-heated bottom sealing bar protected with a teflon tape.
  • the opposing coatings are clamped between the sealing bars at a force of 40-psi (2.82-Kg/cm 2 ) for 2.0-seconds.
  • Sealed specimens are then tested for seal strength in a Thwing-Albert Tensile Tester, Model 1450- 24-8, equipped with a 9.8-lb (4.4-Kg) load cell, pulled at a separation rate of 5.0-in/min (12.6-cm/min). Seal strength, in grams, is noted.
  • a 2-component polymeric blend according to the present invention was made by blending the following components as previously described in the Description of the Preferred Embodiments, above:
  • the resultant melt index of this blend was 2.8-dg/min.
  • This formulation was extrusion coated to a foil/polyethylene/ paperboard structure having aluminum foil as an outer surface; namely, 0.000285-inch (0.00725-mm) foil/Low Density Polyethylene/Bleached Machine-Glazed paper.
  • the foil surface had first been primed with MICA Corporation's MICA A-291-C, a water based polymeric chromium complex compound, designed for aluminum foil.
  • the polymer was applied to the primed foil at a melt temperature of 580°F (305°C) at a sufficient extrusion rate to achieve a coating thickness of 0.002-inch (0.0508-mm) at 132-fpm (14-m/min).
  • the extruder feed zones, Zones 1 , 2, and 3, equilibrated to 290°F (143°C), 250°F (121°C), and 548°F (287°C), respectively.
  • Heat seal strength was 9.0-lb/inch (1.65 kg/cm).
  • Dow Chemical Company's linear low density polyethylene formula 3010 is a blend of about 20% by weight of a low density homopolymer polyethylene and about 80% by weight of a copolymer of ethylene and octene, containing about 7% to 10% by weight of octene.
  • This formulation was extrusion coated to a foil/polyethylene/ paperboard structure having aluminum foil as an outer surface; namely, 0.000285 foil/Low Density Polyethylene/Bleached Machine-Glazed paper.
  • the foil surface had first been primed with MICA Corporation's MICA A-291-C, a water based polymeric chromium complex compound, designed for aluminum foil.
  • the polymer was applied to the primed foil at a melt temperature of 597°F (314°C) at a sufficient extrusion rate to achieve a coating thickness of 0.002-inch (0.0508-mm) at 132-fpm (14-m/min).
  • Heat seal strength was 6.6-lb/inch (1.84 kg/cm).
  • DSM's linear low density polyethylene formula STAMYLEX 1066F is a blend of about 20% by weight of a low density homopolymer polyethylene and about 80% by weight of a copolymer of ethylene and octene, containing about 7% to 10% by weight of octene.
  • This formulation was extrusion coated to a foil/polyethylene/ paperboard structure having aluminum foil as an outer surface; namely, 0.000285 foil/Low Density Polyethylene/Bleached Machine-Glazed paper.
  • the foil surface had first been primed with MICA Corporation's MICA A-291-C, a water based polymeric chromium complex compound, designed for aluminum foil.
  • the polymer was applied to the primed foil at a melt temperature of 600°F (316°C) at a sufficient extrusion rate to achieve a coating thickness of 0.002-inch (0.0508-mm) at 132-fpm (14-m/min).
  • Rexene's linear low density polyethylene formula 2503-10 is a blend of about 20% by weight of a low density homopolymer polyethylene and about 80% by weight of a copolymer of ethylene and octene, containing about 7% to 10% by weight of octene.
  • This formulation was extrusion coated to a foil/polyethylene/ paperboard structure having aluminum foil as an outer surface; namely, 0.000285 foil/Low Density Polyethylene/Bleached Machine-Glazed paper.
  • the foil surface had first been primed with MICA Corporation's MICA A-291-C, a water based polymeric chromium complex compound, designed for aluminum foil.
  • the polymer was applied to the primed foil at a melt temperature of 597°F (314°C) at a sufficient extrusion rate to achieve a coating thickness of 0.002-inch (0.0508-mm) at 132-fpm (14-m/min).
  • Heat seal strength was 7.0-lb/inch (1.34 kg/cm).
  • Example 5 - comparative Millennium's formula GA615050 is a an octene-ethylene copolymer containing 7 weight percent to 10 weight percent octene.
  • Rexene's low density polyethylene formula 5050 is a polyethylene homopolymer.
  • the two polymers were tumble blended at a ratio of 80 weight percent of the Millennium GA615050 copolymer to 20 weight percent of the Rexene low density formula 5050.
  • Such dilution of the Millennium copolymer was necessary to permit its being extrusion coatable.
  • This tumbled blend was extrusion coated to a foil/polyethylene/ paperboard structure having aluminum foil as an outer surface; namely, 0.000285 foil/Low Density Polyethylene/Bleached Machine-Glazed paper.
  • the foil surface had first been primed with MICA Corporation's MICA A-291-C, a water based polymeric chromium complex compound, designed for aluminum foil.
  • the polymer was applied to the primed foil at a melt temperature of 601 °F (316°C) at a sufficient extrusion rate to achieve a coating thickness of 0.002-inch (0.0508-mm) at 132-fpm (14-m/min).
  • the extruder feed zones, Zones 1 , 2, and 3, equilibrated to 401°F (205°C), 498°F (258°C), and 563°F (295°C), respectively.
  • Heat seal strength was 5.1-lb/inch (0.90 kg/cm).
  • Example 1 provides stronger heat seals than the linear low density polyethylene formulations (Examples 2 through 5), even as a pure homopolymer of ethylene, without the presence of an ⁇ -olefin-ethylene copolymer.
  • the absence of a copolymer in the present invention means that it is thermally stable, unlike those examples containing copolymers, and requires no purging of an extruder following an operational shutdown.
  • the present invention unlike the linear low density polyethylenes, does not build up excessive heat in the feed sections of the extruder.
  • the present invention solves the problems of surging, melt fracture, and gel formation.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Health & Medical Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Medicinal Chemistry (AREA)
  • Polymers & Plastics (AREA)
  • Organic Chemistry (AREA)
  • Extrusion Moulding Of Plastics Or The Like (AREA)
  • Compositions Of Macromolecular Compounds (AREA)
  • Laminated Bodies (AREA)

Abstract

L'invention concerne un revêtement par extrusion amélioré comprenant au moins deux homopolymères de polyéthylène, un constituant étant un homopolymère de polyéthylène de densité moyenne à indice de fusion faible, et l'autre constituant étant un homopolymère de polyéthylène de faible densité à indice de fusion élevé. Avec ce mélange, on atteint des résistances de thermosoudage supérieures.
EP98938296A 1997-08-14 1998-08-03 Polyethylenes aux proprietes de thermosoudage ameliorees Withdrawn EP1003813A1 (fr)

Applications Claiming Priority (5)

Application Number Priority Date Filing Date Title
US5577097P 1997-08-14 1997-08-14
US55770P 1997-08-14
US09/088,904 US6174612B1 (en) 1998-06-02 1998-06-02 Polyethylenes with enhanced heat seal properties
US88904 1998-06-02
PCT/US1998/016122 WO1999009097A1 (fr) 1997-08-14 1998-08-03 Polyethylenes aux proprietes de thermosoudage ameliorees

Publications (1)

Publication Number Publication Date
EP1003813A1 true EP1003813A1 (fr) 2000-05-31

Family

ID=26734609

Family Applications (1)

Application Number Title Priority Date Filing Date
EP98938296A Withdrawn EP1003813A1 (fr) 1997-08-14 1998-08-03 Polyethylenes aux proprietes de thermosoudage ameliorees

Country Status (5)

Country Link
EP (1) EP1003813A1 (fr)
JP (1) JP2001515115A (fr)
KR (1) KR20010022793A (fr)
CA (1) CA2297827A1 (fr)
WO (1) WO1999009097A1 (fr)

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
AU4457200A (en) * 1999-04-16 2000-11-02 E.I. Du Pont De Nemours And Company Coating composition containing a low mfi ethylene acrylic acid copolymer
WO2019018023A1 (fr) 2017-07-21 2019-01-24 Exxonmobil Chemical Patents Inc. Matériau stratifié et son procédé de fabrication

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1983000490A1 (fr) * 1981-07-28 1983-02-17 Eastman Kodak Co Melanges de revetement par extrusion de polyethylene a deux composants
CA1218181A (fr) * 1983-04-21 1987-02-17 Asahi Kasei Kogyo Kabushiki Kaisha Composition de polyethylene
JP3307395B2 (ja) * 1992-09-16 2002-07-24 エクソンモービル・ケミカル・パテンツ・インク 強化された物理的特性を有する軟質フィルム
US5536542A (en) * 1995-07-20 1996-07-16 Eastman Chemical Company Process for low temperature heat sealing of polyethylene

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See references of WO9909097A1 *

Also Published As

Publication number Publication date
JP2001515115A (ja) 2001-09-18
KR20010022793A (ko) 2001-03-26
CA2297827A1 (fr) 1999-02-25
WO1999009097A1 (fr) 1999-02-25

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