Classifications

• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J5/00—Manufacture of articles or shaped materials containing macromolecular substances
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J5/00—Manufacture of articles or shaped materials containing macromolecular substances
  • C08J5/18—Manufacture of films or sheets
• • 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
  • C08L23/08—Copolymers of ethene
  • C08L23/0807—Copolymers of ethene with unsaturated hydrocarbons only containing more than three carbon atoms
  • C08L23/0815—Copolymers of ethene with aliphatic 1-olefins
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J2323/00—Characterised by the use of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Derivatives of such polymers
  • C08J2323/02—Characterised by the use of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Derivatives of such polymers not modified by chemical after treatment
  • C08J2323/16—Ethene-propene or ethene-propene-diene copolymers
• • 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
  • 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
  • C08L2314/00—Polymer mixtures characterised by way of preparation
  • C08L2314/06—Metallocene or single site catalysts

Definitions

• This invention is directed to the area of liquid packaging, namely to the manufacture of liquid containing pouches.
• this invention relates to pouches for flowable materials made from films formed principally from ethylene-alpha-olefm interpolymers that demonstrate superior performance in pouches for foods, such as milk.
• the fluid containing disposable pouches may be manufactured on form, fill and seal equipment, preferably employing impulse sealing techniques.
• the interpolymers are selected so that the film exhibits melt strengths in the range of from about 10 to about 15 centiNewtons. Packages made from such films exhibit superior leaker frequency performance in use.
• U.S. Patent No. 4 521 437 discloses film for making pouches for containing liquids, which comprise a linear polymer of ethylene and an ⁇ -olefin with at least one other polymer selected from linear low density copolymers of ethylene and a C4-C10 ⁇ - olefin and high pressure low density polyethylene.
• the film is selected based on its performance in the M-Test, which results are superior to a known film standard. For many years, this test has been a good indicator of film performance in a pouch package.
• Hybrid film is obtained from resin that is produced using a combination catalyst that includes metallocene catalysts and Zeigler-Natta catalysts. Processes for producing such films are described in U.S. Patent No.
• SCLAIRFILMTM SM3 is a blend of linear low density ethylene-octene copolymer resin and high pressure low density polyethylene resin and its use in pouches is described in U.S. Patent No. 4,521,437 to Storms.
• U.S. Patent No. 5,879,768 issued March 9, 1999 to Falla et al describes an environmentally friendly polymer film pouch made from a polyethylene film structure for the packaging of flowable materials, for example milk, including, for example, a pouch made from a monolayer or multilayer film structure such as a two-layer or a three-layer coextruded film containing at least one layer of a blend of a substantially linear ethylene polymer or a homogeneously branched ethylene polymer and a high pressure low density polyethylene as a seal layer. Also described is a process for making the pouch for packaging flowable materials using a film structure described hereinabove.
• the pouch is formed from a film structure that has one seal layer that includes a high pressure low density polyethylene that has a melt strength greater than 10 cN as determined using a Gottfert Rheotens unit at 190°C.
• the melt strength of the polymeric composition is described as being greater than 5 cN, ranging from 5 to 70 cN, 10 to 70 cN, preferably from about 15 to 70 cN and most preferably from 15 to 50 cN.
• Falla et al disclose an environmentally friendly polymer film pouch made from a polyethylene film structure for the packaging of flowable materials, for example, a pouch made from a monolayer or multilayer film structure such as a two-layer or a three-layer coextruded film containing at least one layer of a blend of a substantially linear ethylene polymer and a high pressure low density polyethylene as a seal layer. Also disclosed is a process for making the pouch for packaging flowable materials using the film structure described.
• Falla et al disclose an environmentally friendly polymer film pouch made from a polyethylene film structure for the packaging of flowable materials, for example, milk.
• the film may be a monolayer or multilayer structure, such as a two-layer or a three-layer coextruded film containing at least one layer of a blend of an ultra low density polyethylene and a high pressure low density polyethylene as a seal layer having high melt strength.
• Also disclosed is a process of making the pouch for packaging flowable materials using a film structure as described.
• an environmentally friendly polymer film pouch made from a polyethylene film structure for the packaging of flowable materials, for example milk, including, for example, a pouch made from a monolayer or multilayer film structure such as a two-layer or a three-layer coextruded film containing at least one layer of a blend of a linear ethylene interpolymer and a high pressure low density polyethylene as a seal layer. Also disclosed is a process for making a pouch for packaging flowable materials using a film structure of a blend of a linear ethylene interpolymer and a high pressure low density polyethylene.
• melt strength of the polymeric composition is preferably greater than 5 cN and most preferably above 15 cN.
• Falla et al were concerned with reducing the high incidence of "leakers” , that is seal defects such as pinholes which develop at or near the seal through which flowable material, for example milk, escapes from the pouch, they place emphasis on higher hot tack strength and lower hot tack and heat seal initiation temperatures in order to improve the processability of the film and to improve pouches made from the films.
• Falla et al, in the aforementioned references have indicated that their film structures have improved melt strength and heat seal strength, particularly the end-seal strength.
• melt strength of the final film structure is in the range of about 10 to about 15 centiNewtons, pouches may be obtained for containing flowable materials, i.e. liquids, that exhibit significantly improved leaker frequency rates in actual use.
• Melt Strength or Melt Tension is defined as the stress or force (as applied by a wind-up drum equipped with a strain cell) required to draw a molten extrudate at some specified rate above its melting point as it passes through the die of a standard plastometer such as that described in ASTM D1238-E. Melt strength values are determined using a Gottfert Rheotens at 190°C. In general, for ethylene ⁇ -olefin interpolymers and high pressure ethylene polymers, melt strength tends to increase with increased molecular weight, or with broadening of the molecular weight distribution and/or with increased melt flow ratios. Long chain branching also contributes to increasing melt strength.
• the present invention provides in one aspect a pouch for containing a flowable material, said pouch being made from a film in tubular form and having transversely heat-sealed ends, said film comprising at least one layer made from a material comprising from about 30 to about 100 parts of at least one linear or substantially linear interpolymer of ethylene and a C 3 - o alpha-olefin having a density of from about 0.840 to about 0.940 g/ cm 3 and a melt index of about 0.01 to about 2.0 dg/min, and from 0 to 70 parts by weight of at least one high-pressure polyethylene having a density of at least about 0.916 g/cm 3 and a melt index of from about 0.01 to about 2 dg/min, said film having an overall melt strength of from about 10 to about 15 cN as determined using a Goettfert Rheotens unit at 190°C, so that the horizontal or transverse seal integrity of the pouch exhibits a leaker frequency rate, as measured in terms
• the interpolymer comprises from about 75 to about 90 parts by weight, most preferably 85 parts by weight with the high pressure low density polyethylene comprising about 10 to about 25 parts by weight, most preferably 15 parts by weight.
• the melt strength of each polymer layer be greater than about 7 cN in order to produce a pouch film of the required melt strength and to achieve the field results set out herein.
• the individual layers must have a melt strength of greater than 10 cN.
• the film preferably has an overall density that ranges from about .900 to about
• the melt index of the high-pressure, low-density polyethylene ranges preferably from about 0.1 to about 2 dg/min.
• the interpolymer may be selected from single-site catalyst, multi-site catalyst or mixed catalyst polymers. There are many examples of such polymers known in the art and it is expected that any of these would be suitable as long as the melt strength values set out herein are met.
• the interpolymer is selected from the following:
• the interpolymer is selected from the following: (a) from about 40 to about 100% by weight of the total parts by weight of the linear interpolymer of an ethylene C 3 -C 2 o ⁇ -olefin having a density of from about 0.915 to about 0.925 g/cc and a melt index of from about 0.1 to about 1.0 dg/min, and (b) from about 0 to about 60% by weight of the total parts by weight of the linear interpolymer of an ethylene C3-Q0 ⁇ -olefin having a density of from about 0.900 to about 0.910 g/cc and a melt index of from about 0.1 to about 1.0 dg/min.
• melt strength of a film can be increased by increasing molecular weight of either the linear interpolymer component or the high pressure polyethylene component, by broadening the molecular weight distribution of the linear interpolymer component, or by selecting a polymer with a greater frequency of long chain branching.
• Typical polymers with long chain branching are high pressure low density polyethylenes, but substantially linear ethylene interpolymers are also available which have a limited amount of long chain branching.
• Increasing the molecular weight of linear or high pressure polyethylenes will reduce the melt index.
• Molecular weight of a polymer is generally indicated by its melt index.
• the invention provides a process for making a pouch for containing a flowable material using a vertical form, fill and seal machine, in which process each pouch is made from a flat web of film by forming a tubular film therefrom with a longitudinal seal and subsequently flattening the tubular film at a first position and transversely heat sealing said tubular film at the flattened position, flattening the tubular film above the predetermined quantity of flowable material at a second position, the improvement comprising using the film of the present description.
• the preferred type of form, fill and seal equipment is that which produces a melt through seal and this seal is provided preferably by impulse sealing means.
• the invention provides a process for making a pouch for containing a flowable material using a vertical form, fill and seal machine, in which process each pouch is made from a flat web of film by forming a tubular film therefrom with a longitudinal seal and subsequently flattening the tubular film at a first position and transversely heat sealing said tubular film at the flattened position, flattening the tubular film above the predetermined quantity of flowable material at a second position, the improvement comprising using the film as defined previously and operating the process at machine speeds above 100 pouches per minute.
• Figure 1 illustrates graphically hot tack strength vs. heat seal temperature curves for typical films of the present invention used to manufacture liquid packages
• Figure 2 is a plot of melt strength vs. horizontal seal leaker frequency for films and pouches made therefrom in accordance with the present invention.
• LLDPE linear low density polyethylene interpolymers
• VLDPE very low density polyethylene interpolymers
• metallocene single site catalyst interpolymers
• multi-site catalyst interpolymers multi-site catalyst interpolymers
• hybrid single site catalyst metalocene
• Metallocene ethylene-octene, ethylene-hexene, ethylene-butene-hexene and ethylene-butene interpolymers are available commercially in the density range from 0.80 to .915 gm/cc. Films of these densities generally are too low in modulus to be used alone to make pouches for flowable materials.
• the metallocene interpolymers must be either blended with Zeigler-Natta interpolymers or used in co-extrusions to form liquid pouches.
• SSC single site catalyst
• metallocene metallocene
• ethylene interpolymers ranging from crystalline to elastomeric materials.
• These ethylene interpolymers have features such as improved impact strength and toughness, better melt characteristics, because of the control over molecular structure, and better clarity.
• Exxon and Dow have developed SSC or metallocene ethylene interpolymers and each has the benefit of a number of patents relating to these polymers. Exxon is said to use mono- and bis-cyclopentadienyl metallocenes, while Dow's focus is on titanium cyclopentadienyl metallocenes, which it calls "constrained geometry catalysts" .
• the structure comprises an interposed layer of polyethylene having a thickness in the range of 5 to 20 microns and a density of at least 0.93 gm/cc and a melt index of from about 1 to 10 dg/minute, with the outer layer being a SSC or metallocene polyethylene/alpha-olefin film which may have a density in the range of 0.88 to 0.93 gm/cc.
• the only requirements placed on the stiffening interposed layer are that it be of a particular thickness and density.
• stiffening layer is included in order for the fluid containing pouch to stand up properly so that fluid may be poured from it when the pouch is placed in a supporting container.
• 4,521,437(Storms) disclose a polyethylene film for use in a form, fill and seal process for the manufacture of a disposable pouch for liquids such as milk.
• U.S. Patent No. 4,503,102 discloses pouches made from a blend of a linear ethylene copolymer of ethylene and a C 4 -Go ⁇ -olefin and an ethylene-vinyl acetate polymer copolymerized from ethylene and vinyl acetate.
• the linear polyethylene copolymer has a density of from 0.916 to 0.930 g/cm 3 and a melt index of from 0.3 to 2.0 dg/min.
• the ethylene-vinyl acetate polymer has a weight ratio of ethylene to vinyl acetate from 2.2: 1 to 24: 1 and a melt index of from 0.2 to 10 dg/min.
• the blend disclosed in Mollison U.S. Patent No. 4,503,102 has a weight ratio of linear low density polyethylene to ethylene-vinyl acetate polymer of from 1.2: 1 to 24: 1.
• U.S. Patent No. 4,503,102 also discloses multi-layer films having as a sealant film the aforementioned blend.
• U.S. Patent No. 4,521,437 (Storms) describes pouches made from a sealant film which is from 50 to 100 parts of a linear copolymer of ethylene and octene-1 having a density of from 0.916 to 0.930 g/cm 3 and a melt index of 0.3 to 2.0 dg/min and from 0 to 50 parts by weight of at least one polymer selected from the group consisting of a linear copolymer of ethylene and a G-Go-alpha-olefin having a density of from 0.916 to 0.930 g/cm 3 and a melt index of from 0.3 to 2.0 dg/min, a high-pressure polyethylene having a density of from 0.916 to 0.924 g/cm 3 and a melt index of from 1 to 10 g/ 10 minutes and blends thereof.
• the sealant film disclosed in U.S. Patent No. 4,521,437 is selected on the basis of providing (a) pouches with an M-test value substantially smaller, at the same film thickness, than that obtained for pouches made with film of a blend of 85 parts of a linear ethylene/butene-1 copolymer having a density of about 0.919 g/cm 3 and a melt index of about 0.75 dg/min and 15 parts of a high pressure polyethylene having a density of about 0.918 g/cm 3 and a melt index of 8.5 dg/min, or (b) an M(2)-test value of less than about 12% , for pouches having a volume of from greater than 1.3 to 5 litres, or (c) an M(1.3)-test value of less than about 5% for pouches having a volume of from 0.1 to 1.3 litres.
• the M, M(2) and M(1.3)-tests are defined pouch drop tests for U.S. Patent No. 4,521,
• the ULDPE may be selected from ethylene- 1-propylene, ethylene- 1-butene, ethylene- 1-pentene, ethylene-4-methyl-l-pentene, ethylene- 1-hexene, ethylene- 1- heptene, ethylene- 1-octene and ethylene- 1-decene interpolymers, preferably ethylene- 1-octene copolymer.
• metallocene polymers useful for making sealed articles comprising ethylene interpolymers having a CDBI of at least 50% and a narrow molecular weight distribution or a polymer blend comprising a plurality of said ethylene interpolymers as blend components.
• the hybrid interpolymer may be obtained from a multiple catalyst polymerization process.
• the process may comprise at least two reactors in series or in parallel or both, with each reactor having at least one catalyst selected from metallocene catalysts or at least one catalyst selected from Zeigler-Natta catalysts, and the process utilizes both types of catalysts. Alternatively, both types of catalysts may be used in a single reactor.
• the process may be set up to produce desired weight fractions of polymers in accordance with known methods in the art.
• the polymer resins produced may comprise preferably from about 20 to about 80 wt. % of metallocene catalyst derived polymer and from about 80 to about 20 wt. % Zeigler-Natta catalyst derived polymer. More preferably the mixture of weight fractions may comprise from about 40 to about 60 wt. % of metallocene catalyst derived polymer with from about 60 to about 40 wt. % Zeigler- Natta catalyst derived polymer. Most preferably, the proportion is about 50:50 wt. % .
• An example of a commercially available resin which may be modified to produce film for pouches in accordance with this invention is the Dow series of ELITETM Brand resins.
• the film used to make the pouch of this invention may be a monolayer or a multi-layer film.
• the individual polymers preferably have melt strengths in the required range.
• the previously referenced patents provide many examples of suitable multi-layer structures, which may be used to make the pouches of the present invention.
• a pouch formed from a film material which comprises from about 70 to about 100, preferably 80 to about 100, more preferably 85 or 90 parts by weight of the hybrid interpolymer and from about 0 to about 30, preferably from 0 to about 20, more preferably, 10 or 15 parts by weight of the high pressure polyethylene.
• the ⁇ -olefin for the interpolymer is selected from the group consisting of 1-propylene, 1-butene, 1-isobutylene, 1- hexene, 4-methyl-l-pentene, 1-pentene, 1-heptene and 1-octene.
• Typical structures for the films of this invention are those known in the art and which will suit the packaging application.
• vertical form, fill and seal apparatus is used to make the pouches envisaged herein.
• a flat web of film is unwound from a roll and formed into a continuous tube in a tube forming section by sealing the longitudinal edges together by either a lap seal or a fin seal.
• This tube is pulled vertically towards a filling station and is then collapsed across a transverse cross section of the tube, the position of which section coincides with a sealing device below a filling station.
• a horizontal or transverse heat seal is made at the section providing an air and liquid tight seal across the tube.
• the material to be packaged enters the tube above the horizontal seal, the tube drops a predetermined distance under the influence of gravity on its load.
• the sealing device is operated again, and a second horizontal seal is made together with a cut through the tube and then through the liquid or fluid being packaged in the pouch.
• the pouch which has an elongate pillow shape is formed, filled and sealed in a rapid sequence of steps.
• typical liquid packaging apparatus used for this type of manufacture are made by Hayssen, Thimonnier and Prepac.
• the term "flowable materials" as used herein encompasses materials which flow under gravity or which may be pumped. Gaseous materials are not included in this definition.
• the flowable materials include liquids, for example, milk, water, fruit juice and oil; emulsions, for example, ice cream mix and soft margarine; pastes, for example, meat pastes and peanut butter; preserves, for example, jams, pie fillings, marmalade, jellies and doughs; ground meat, for example, sausage meat; powders, for example, gelatine powders and detergents; granular solids, for example, nuts, sugar and like materials.
• the pouch of the present invention is particularly useful for liquids, for example, milk.
• the resins used to make the film of this invention are preferably extruded in known ways, although other suitable methods may be used, such as those involving laminates, coatings and the like. When blends are used, these may be made by blending the components prior to or at the time of extrusion just prior to remelting in the extruder.
• a film extruder may be used and the film made using known techniques. An example of a blown film process is found in Canadian Patent No. 460,963 issued November 8, 1949 to Fuller. Canadian Patent No. 893,216 issued February 15, 1972 to Bunga et al describes a preferred method using an external or internal cooling mandrel in the blown film process.
• Additives known to those skilled in the art, such as anti-block agents, slip additives, antioxidants, UV stabilisers, pigments and processing aids may be added to the polymers from which the pouches of the present invention are made.
• these may comprise up to about 5% by weight of total resin components.
• the film of this invention may be used in packaging applications where sealing properties, particularly hot tack strength is important.
• Melt strength determinations are made at 190°C using a Goettfert Rheotens and an Instron capillary rheometer.
• the capillary rheometer is aligned and situated above the Rheotens unit and delivers, at a constant plunger speed of 25.4 mm/min, a filament of molten polymer to the Rheotens unit.
• the Instron is equipped with a standard capillary die of 2.1 mm diameter and 42 mm length (20: 1 L/D). The Instron delivers the filament to the toothed take-up wheels of the Rheotens unit rotating at 10 mm/s.
• the distance between the exit of the Instron capillary die and the nip point on the Rheotens take-up wheels is 100 mm.
• the experiment to determine melt strength begins by accelerating the take-up wheels on the Rheotens unit at 2.4 mm/s 2 , the Rheotens unit is capable of acceleration rates from 0.12 to 120 mm/s 2 .
• the draw down force is recorded in centiNewtons (cN) using the Linear Variable Displacement Transducer (LVDT) on the Rheotens unit.
• the computerized data acquisition system of the Rheotens unit records the draw down force as a function of take-up wheel velocity.
• the actual melt strength value is taken from the plateau of the recorded draw down force.
• the velocity at filament break is also recorded in mm/s as the melt strength break speed.
• the code dates on the milk packaging were colour coded to allow identification of the line from which a returned package was produced and on what date.
• the dairy distributed much of its milk through its own dairy store outlets along with some regular supermarkets. Any leaking or damaged packages were returned from the outlet stores or supermarkets to the dairy for credits. For this reason, a very high proportion of leaking packages was returned to the dairy.
• the cause and frequency of leakers could be determined for each of the test films to be evaluated.
• the cause and location of each leaker was identified and classified into three categories; horizontal seal leakers, vertical seal leakers and physical damage caused by a puncture or tear.
• the leaker frequency was calculated for each category per 10,000 pouches produced during the test period.
• Physical damage may be caused by abuse during distribution (transportation, loading and unloading, etc.) or packaging machinery used to put milk pouches in bags and then in dairy cases.
• this field trial was designed to evaluate films under the actual conditions of use, looking at the three main modes of failure.
• melt strength versus horizontal seal leaker failure rates were plotted.
• the surprisingly strong correlation between Rheotens melt strength and horizontal seal failure rate had never been observed and measured before.
• the correlation confirmed that melt strength is a critical and previously unknown parameter in formulation of films for liquid pouch application in which seals and cutoff are made through a liquid column.
• melt strength can be increased by increasing molecular weight of the interpolymer, by broadening the molecular weight distribution of the interpolymer or by selecting a fractional melt index high pressure polyethylene in the film blend. Molecular weight of a polymer is generally indicated by its melt index.
• the base resin used at about 85% in Film A had a melt index of 0.85 dg/min.
• Test film B contained a similar ethylene octene hybrid copolymer at the 85 % level in which the melt index was reduced to 0.5.
• the same high-pressure low density polyethylene (5.0 melt) was blended at 10% in Film A and Film B.
• melt index is independent of polymer used and must be carefully controlled whether using a conventional linear low density polyethylene or the metallocene-hybrid linear copolymer of ethylene.

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• Chemical & Material Sciences (AREA)
• Organic Chemistry (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Engineering & Computer Science (AREA)
• Health & Medical Sciences (AREA)
• Manufacturing & Machinery (AREA)
• Medicinal Chemistry (AREA)
• Polymers & Plastics (AREA)
• Materials Engineering (AREA)
• Compositions Of Macromolecular Compounds (AREA)
• Wrappers (AREA)
• Bag Frames (AREA)
• Manufacture Of Macromolecular Shaped Articles (AREA)
• Making Paper Articles (AREA)
• Laminated Bodies (AREA)
• Separation Using Semi-Permeable Membranes (AREA)
• Lining Or Joining Of Plastics Or The Like (AREA)
• Containers And Plastic Fillers For Packaging (AREA)

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• 1999
  • 1999-08-20 JP JP2000566339A patent/JP2002523310A/ja active Pending
  • 1999-08-20 EP EP99939289A patent/EP1112321A1/de not_active Withdrawn
  • 1999-08-20 WO PCT/CA1999/000775 patent/WO2000011074A1/en not_active Application Discontinuation
  • 1999-08-20 CA CA002341390A patent/CA2341390A1/en not_active Abandoned
  • 1999-08-20 AU AU53668/99A patent/AU5366899A/en not_active Abandoned
  • 1999-08-20 BR BR9913434-9A patent/BR9913434A/pt not_active IP Right Cessation
  • 1999-08-20 KR KR1020017002236A patent/KR20010079676A/ko not_active Application Discontinuation
  • 1999-08-20 PA PA19998480501A patent/PA8480501A1/es unknown
  • 1999-08-23 AR ARP990104221A patent/AR022070A1/es unknown

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