CA2151589C - Pouches of ethylene copolymer film containing a flowable material - Google Patents
Pouches of ethylene copolymer film containing a flowable material Download PDFInfo
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- CA2151589C CA2151589C CA002151589A CA2151589A CA2151589C CA 2151589 C CA2151589 C CA 2151589C CA 002151589 A CA002151589 A CA 002151589A CA 2151589 A CA2151589 A CA 2151589A CA 2151589 C CA2151589 C CA 2151589C
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- 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
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- 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
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- 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
- C08J2323/04—Homopolymers or copolymers of ethene
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- 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
- C08L2205/03—Polymer mixtures characterised by other features containing three or more polymers in a blend
-
- 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
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
- Y10T428/00—Stock material or miscellaneous articles
- Y10T428/13—Hollow or container type article [e.g., tube, vase, etc.]
- Y10T428/1334—Nonself-supporting tubular film or bag [e.g., pouch, envelope, packet, etc.]
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
- Y10T428/00—Stock material or miscellaneous articles
- Y10T428/13—Hollow or container type article [e.g., tube, vase, etc.]
- Y10T428/1334—Nonself-supporting tubular film or bag [e.g., pouch, envelope, packet, etc.]
- Y10T428/1345—Single layer [continuous layer]
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
- Y10T428/00—Stock material or miscellaneous articles
- Y10T428/13—Hollow or container type article [e.g., tube, vase, etc.]
- Y10T428/1352—Polymer or resin containing [i.e., natural or synthetic]
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
- Y10T428/00—Stock material or miscellaneous articles
- Y10T428/13—Hollow or container type article [e.g., tube, vase, etc.]
- Y10T428/1352—Polymer or resin containing [i.e., natural or synthetic]
- Y10T428/139—Open-ended, self-supporting conduit, cylinder, or tube-type article
- Y10T428/1393—Multilayer [continuous layer]
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
- Y10T428/00—Stock material or miscellaneous articles
- Y10T428/13—Hollow or container type article [e.g., tube, vase, etc.]
- Y10T428/1352—Polymer or resin containing [i.e., natural or synthetic]
- Y10T428/1397—Single layer [continuous layer]
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
- Y10T428/00—Stock material or miscellaneous articles
- Y10T428/27—Web or sheet containing structurally defined element or component, the element or component having a specified weight per unit area [e.g., gms/sq cm, lbs/sq ft, etc.]
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
- Y10T428/00—Stock material or miscellaneous articles
- Y10T428/31504—Composite [nonstructural laminate]
- Y10T428/31855—Of addition polymer from unsaturated monomers
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
- Y10T428/00—Stock material or miscellaneous articles
- Y10T428/31504—Composite [nonstructural laminate]
- Y10T428/31855—Of addition polymer from unsaturated monomers
- Y10T428/31909—Next to second addition polymer from unsaturated monomers
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- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Manufacturing & Machinery (AREA)
- Engineering & Computer Science (AREA)
- Health & Medical Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Medicinal Chemistry (AREA)
- Polymers & Plastics (AREA)
- Materials Engineering (AREA)
- Manufacture Of Macromolecular Shaped Articles (AREA)
- Compositions Of Macromolecular Compounds (AREA)
- Addition Polymer Or Copolymer, Post-Treatments, Or Chemical Modifications (AREA)
- Bag Frames (AREA)
Abstract
A pouch containing a flowable material and films and processes for making the pouch are disclosed. The pouch is made from a sealant film having at least two heat-sealed edges and made from a material comprising a copolymer of ethylene and at least one C4-C10 alpha-olefin manufactured in a polymerization process using a single-site polymerization catalyst.
Description
POUCHES OF ETHYLENE COPOLYMER FILM CONTAINING A
FLOWABLE MATERIAL
The invention relates to films used to make pouches filled with flowable materials, e.g. liquids.
As used herein, the term "flowable material" does not include gaseous materials, but encompasses materials which are flowable under gravity or may be pumped. Such materials include liquids, e.g. milk, water, fruit juice, oil;
emulsions, e.g. ice cream mix, soft margarine; pastes, e.g. meat pastes, peanut butter; preserves, e.g. jams, pie fillings, marmalade; jellies; doughs; ground meat, e.g. sausage meat; powders, e.g. gelatin powders, detergents; granular solids, e.g.
nuts, sugar; and like materials. The invention described herein is particularly useful for flowable foods, e.g. milk.
It is well known to package flowable materials, for example, milk, on a pouch-forming apparatus such as a so-called vertical form, fill and seal apparatus.
Typically, using such an apparatus, a flat web of synthetic thermoplastic film is unwound from a roll and formed into a continuous tube in a tube-forming section, by sealing the longitudinal edges on the film together to form a so-called lap seal or a so-called fin seal. The tube thus formed is pulled vertically downwards to a filling station. The tube is then collapsed across a transverse cross-section of the tube, the position of such cross-section being at a sealing device below the filling station. A
transverse heat seal is made, by the sealing device, at the collapsed portion of the tube, thus making an air-tight seal across the tube. The material being packaged enters the tube above the transverse heat seal in a continuous or intermittent manner, thereby filling the tube upwardly from the transverse heat seal. The tube is then allowed to drop a predetermined distance usually under the influence of the weight of the material in the tube. The jaws of the sealing device are closed again, thus collapsing the tube at a second transverse section, which may be at, above or below the air/material interface in the tube, depending on the nature of the material being packaged and the mode of operation of the process. The sealing device seals and severs the tube transversely at the second transverse section. The material-filled portion of the tube is now in the form of a pillow shaped pouch. Thus, the sealing device has sealed the top of the filled pouch, sealed the bottom of the next-to-formed pouch and separated the filled pouch from the next-to-be-formed pouch, all in one operation. Variations on pouch-forming machines and in particular on this type of vertical form, fill and seal apparatus are either known or conceivable. For example, the forming and sealing functions may be performed separately from severing function on separate machines. Also, the jaws of the sealing device could move to the next sealing position rather than have the film drop to the next position or there could be two sets of sealing jaws that seal both transverse ends simultaneously.
Further, instead of forming a tube, two pieces of film could be fed into the machine and the pouch could be made by four seals, two longitudinal and two transverse.
Examples of the vertical, form, fill and seal apparatus of the type described above are the Prepac~ IS-6 or IS-7 liquid packaging machine.
A sealing device commonly used is a so-called impulse sealer which has a sealing element mounted in sealing jaws and electrically insulated therefrom.
In operation, the sealing jaws are closed and an electrical current is caused to flow through a sealing element, e.g. a wire, for a fraction of the time that the jaws are closed. The jaws remain closed during a cooling or equilibration period, during which the seal forms, before the sealing jaws are opened. The synthetic thermoplastic film must be able to provide a transverse seal that supports the weight of the flowable material, e.g. liquid, in the next-to-be-formed pouch. It is important that the cooling of the seal takes effect before the weight of the liquid can weaken or rupture the bottom seal. Sealing may also be carried out using any other suitable heat-sealing apparatus.
In the operation of pouch-forming machines, it is known to use film made from a blend containing 70-90% linear ethylene/butene-1 copolymer having a density of about 0.919 g/cm3 and a melt index of about 0.75 dg/min and 10-30 high pressure polyethylene, i.e. a homopolymer, having a melt index of about 2 to 10 dg/min and a density of from 0.916 to 0.924 g/cm3. Density is determined by ASTM Procedure D1505-85 and melt index by ASTM Procedure D1238-90B
MHY-l~-1010 ld-b9 tKUM=SWHtJt;Y UliILVY htt:IHHUL'1' lU- YHlit 110/11 (Condition )~. Such fllxus having a thiclmess of about 76 micarometers, have been used commercially on vertical form, fill and seal apparatuses for m,aIdng pouches containing about i .3 litres of mxll~. Pouches made from such film tend to suffer frarn defective seals, i.e_ a tendencir to have wtak transverse cndla~ud longitudinal scats even thoagh the operating conditions of the iiupulse sealer have been optimized. Defective seals roay lead to the phenomenon known as "Ieakers", in wluich tb~e ~owable matexxal, e_g. m~i~, may escape from the pouch through piaholes that develop at ar close to the seal. It has been estimated that leakcrs accQUUt ;fox about 1-23~ of tha 1.3 litre milk pouch produrxiotz~
x0 US-A-4,521,437 discloses the use of pouches of ethyleneloctcnc-1 copolymer fi~J~m in the packaging of flowable materials. That patent discloses that pouches made from the ethylene/octene-i copolymer provide superior lcaker performance, i_e_ a lower percentage of leake;rss, compared ~uvith related films descn'bed above that arc formed from linear ethylene/bntene-I copolyzxlexs_ W~93102859 describes heat sealed plastic film pouches from a film comprising: (i) 10-100wt. 9~ of a linear ethylene copolymer with a Cs-C~a alpha-olefin; and (ii) 0-90wt. °r~ of at least one polymer selected from a lvateax copolymer of ethylene and a Ca-C~a alpha-olefin, a high pressure lore density polyethylene, and ethylene vinyl acetate copolymer. The use of polymers fortxled by a single-site caratyst polymeri2atioa process is not disclosed iua this reference.
W093/03493 describes the use of an ethylene alpha-olefin copolymer farmed by a single-site catalyst polymerization process, or a blend of such polymers, for the preparation of improved boat sealed articl~s_ h has now been surprisingly found that further improvements in leakcr performance may be achieved using resin blends comprising ethylene copolymers manufactured using a singlo-sitc polymerization catalyst_ The presem invernlo~n provides a process for malting pouches ~Iled with a flowable material, made acing a vertical form, fill and seal apparatus, in wlticb~ process each pouch is made from a flat web of film by forming a tubular film 3~ therefrom with a longitudinal seal and subsequently flattGaing the tubular film at a MHY-1~J-1010 'lb_Sy YIsUM:SWHtIttY UlsILVY htt;NNUL'1' lU- NHliir 11/11 first posx4otA atzd tramgversely heat sealing sand tubular film at the flattened position, continuously' filling the tubular film with a predetermined quantity of flowable material above said first position, flattening the tubular film at a second position above the first position and transversely heat sealing said tubular flea at the second position, the improvement comprising malsa~ag tb~e pouch, fxoxxt a film comprising a polymer of ethyleme with at least one C<-Coo alpha-olefin marntfadx~l in a single-site catalyst pol~aaerixatio~n process, and at Toast one of the following a) a linear polymer of ethylene and at least one C+-Coo alpha-olefin made by a mmld-site catalyst polymerization process;
b) a high pressure Iow density polyethylene; and c) additives;
wherein the transverse heat seals are tirade tluough flowable material using impulse scaling.
In another aspect, the inveintion provides a pouch for containing a flowable material > said pouch leaving at least two heat sealed edges and being formed by a vertical form, fi'tl and seal process using impulse sealing through the flowabIe material on the at least two heat sealed edges. said pouch being zttade brom a film comprising a polymer of ethylene with at bast one C4-Coo alpha-olefin manufactured in a single-site catalyst pOlymerixauon process, and at last one of tht followiuxg a) a lizzear polymGC of ethylene and at Ieast one GrClo alpha-olefin made by a mufti-site catalyst polyunexization process;
b) a high pressure low densiCy polyethylene; and c) additives;
wbexein the transverse heat seals are nxade through flowable material using impulse sealing.
The film of the present invetttiort pxefexably has a density in the range of 0.86 to 0-94 glem3 and a melt index of 0.2 to 10 dglmin and most preferably has a density in the range of 0.88 to 0.93 glom' and a melt index of 0_3 to 5 dglmin.
MPIY-1~J-i010 ld-S9 r'h'UM-SWNt3JrY UliILVY l2t;NI~IUL'1' lU= YNlst ld!'s'1 Ethylene copolymers made with single-site catalyst may be obtained using a variety of lmown polymerisation processes for the manufacture of Iitteax polyethylene including proccSSCS that optratc in solution, in the gas phase or as a slurry process. Ethylene copolymers made with the singlo-site catalysts are 3 commercially available and may be manufactured is accordance with processes diSClosed in Modern Plastics, p_ 15, May 1993, Plastics Foc2tS Vol_ 2S, No_ l2 lone 21, 1993 and in Ex~con Chemical Exact Facts, vol_ l, Febxuaxy x993. 13y the tcrFn "sit~,gl~site catalyst" is meant a metallocene or constrained geometry catalyst.
Metalloceae catalysts are organametallic coordiazation compounds obtained as a cyclopentadienyl (Cp) derivative of a transition metal or metal halide. The metal is b0~ to the Cp ring by electrons moving in orbitals eatendin~ above and below the plant of the rung (pi bo~ad)_ Metallocene catalyst syscelrls are e~c~~ely sensitive to the geometry of the catalytic site at the transition metal (the "singlo-site").
Examples of sicogle-site catalysts include CpzTiClz, CpaZrClx, CpzHfClz, (Cs(CH3)s~TiClz, PrizMe(1nd)zZrClz, and (MeaCpSi(MenN(t-Bu)]TiCHx[o-Fbl~1(Me~)]-The polyethylene obtained ~uvith the single-site catalyst preferably has a density in the range of 0.8 to 0.93 g/cm3, and especially in the range of 0.88 to 0.915 glaoa~'. laa, addition, the polymer preiierably has a melt index of less than 3 dg/min, pazticularly in tlae z~ange of 0.3 to 2 dglm~ sad especially iu~ the ravage of 0.5 to 1.5 dglmin. preferred polymers include cthylene/butcne-1, ethylenelhexeno-1, ethyle~o~e-ootene-1 and etb~yle~eJl~e~xene-l.ibutene-i. terpolyu~rs_ The resin blend suitable to make the pouches further comprises at least one polymer selected from the group comprising a linear copolymer of ethylene and at least one Ca-Coo alpha-olefin, a high pressure polyethylene and blends thereof.
Preferably the composition comprises 10 to 100 parts by weight of a copolymer of ethylene and at least one Ca-Coo alpha-olefin manufactured in a polymerization process using a single-site polymerization catalyst and up to 90 parts by weight of at least one polymer selected from the group comprising a linear copolymer of ethylene and at least one Ca-Coo alpha-olefin, a high pressure polyethylene and blends thereof. In particularly preferred embodiments, the composition comprises 20 to 100 and especially 50 to 100 parts of the copolymer obtained using the single-site catalyst, and conversely 0 to 80 and 0 to 50 parts of the other polymers specified above. The composition comprises a total of 100 parts by weight.
Processes for the manufacture of so-called high pressure polyethylene from ethylene monomer have been operated commercially for decades. A variety of such polymers are available. The high pressure polyethylene preferably has a density of 0.916 to 0.93 g/cm3, especially 0.918 to 0.925 g/cm3. In addition, the high pressure polyethylene preferably has a melt index in the range of 1 to 10 dg/min and especially in the range of 1.5 to 5 dg/min.
Processes for the commercial manufacture of linear copolymers of ethylene and at least one Ca-Coo alpha-olefin have been known for more than thirty years.
Such processes may be operated in solution, in the gas phase or as a slurry process.
The catalysts used are frequently based on titanium and are referred to as coordination catalysts; such catalysts may also be described as multi-site catalysts or heterogeneous catalysts. The polymer obtained is linear in nature, as opposed to the branched nature of high pressure polyethylene. The Ca-Coo alpha-olefin hydrocarbon comonomer is preferably at least one of butene-1, hexene-1 or octene-1. The linear polyethylene preferably has a density in the range of 0.9 to 0.93 g/cm3, preferably 0.912 to 0.93 g/cm3 and especially in the range of 0.918 to 0.925 g/cm3. In addition, the polymer preferably has a melt index in the range of 0.3 to dg/min, preferably 0.3 to 2 dg/min and especially in the range of 0.5 to 1.5 dg/min.
The film may be used by itself to form the pouch or a part or a composite film. The composite film may be a coextruded film, a coated film or a laminated 5 film. The film of the present invention could be laminated with the other films such as a nylon film, a polyester film, a metallized polyester film, an EVA
copolymer film, or with a PVDC coating. It could also be coextruded with, for example, an ethylene vinyl acetate copolymer.
In all of the pouches of the present invention, the film is at least on the inside 10 of the pouch. The end use for the pouch tends to dictate, in a large degree, the selection of the other material or materials used in combination with the film. For example, nylon may be used in combination with the film of the present invention, for packaging oleagenous substances, e.g. cooking oil, motor oil;
polyvinylidene chloride (PVDC) or ethylene vinyl alcohol copolymers may be used in combination with the film of the present invention where a flavour or aroma barrier is desirable.
It will be appreciated by those skilled in the art that a composite film having a film only on the inside of the pouch would be sufficient for pouches made with a longitudinal fin seal, whereas a composite film having films on the two outer layers of the composite film would be necessary for pouches made with a longitudinal lap seal.
When composite films in which the two outer layers are the film of the present invention, the two outer films may be made from the same or different polymers or blends. Preferably, however, they are the same polymers or blends.
It is to be understood that the composite film may consist of two layers of the film of the present invention. This latter composite film is useful when one or both layers are, for example coloured with dyes or pigments, e.g. a layer having carbon black, iron oxide, aluminum, bronze powder or some other dark pigment and an outer layer which contains a light pigment, e.g. titanium dioxide, zinc oxide.
The blends useful in the present invention may be made by blending the constituents prior to feeding to the hopper of a film extruder, or may be made by blending the constituents at the time of extrusion just prior to remelting in the extruder, or alternatively the constituents may be melt blended in the extruder.
The ethylene/alpha-olefin copolymer or blend of ethylene/alpha-olefin copolymer, e.g. in pellet form, may be fed into a film extruder and extruded into film form using known techniques. One preferred method of manufacturing film is the so-called blown film process disclosed in Canadian Patent No. 460,963 issued November 8, 1949 to E.D. Fuller. Another preferred method of manufacturing film uses an internal or external cooling mandrel in the blown film process, as disclosed, for example, in Canadian Patent No. 893,216 issued February 15, 1972 to M.
Bunga and D.V. Thomas.
The film, after manufacture, is slit longitudinally into appropriate widths.
Where a vertical form, fill and seal apparatus is used, the width is selected on the basis of the diameter of the tube to be formed.
It will be understood by those skilled in the art that additives, e.g. UV
stabilizers, anti-block agents, slip additives, may be added to the polymers from which the pouches of the present invention are made.
The pouches of the present invention may be used in the packaging of flowable materials, e.g. liquids, as defined above. In particular, the pouches may be used in the packaging of milk. The pouches may be made using any liquid pouch-forming apparatus, including vertical form, fill and seal machines such as the Prepac~ IS-6 or IS-7.
The films of the present invention may be used to make pouches of improved integrity as compared to prior art pouches, thereby substantially reducing the leaker rate of the pouches. The leaker rate may be measured using a drop test. In a drop test, pouches of the same dimensions containing the same type and amount of liquid are made using the same type of pouch-forming equipment and are all dropped from the same height and position. The number of leakers expressed as a percentage of the total number of pouches dropped is used as the basis of comparison between pouches made from different films. The particular drop test used in the Examples herein is referred to as the Mu-test. The Mn-test is carried out as follows:
In general terms, the M~ ~-test is a drop test carried out on 1.3 litre water-filled pouches. In the test, pouches containing 1.3 litres of water, at a temperature of 10~5 °C, are made from a 32 cm. wide film web, on a Prepac~ IS-6 vertical form, fill and seal machine. The water-filled pouches containing cold water, are dropped onto a concrete floor from a height of 335 cm. The pouches are positioned with the longitudinal axis of the tube, i.e. pouch, parallel to an imaginary vertical line.
Any pouch from which water flows or weeps after the pouch has been dropped onto the floor, is termed a "leaker" . The number of leakers, expressed as a percentage of the total number of pouches dropped is the Mu-test value for the particular film being tested. It will be noted that the Mu-test value will be affected by the thickness of the film as well as the material from which the film is made.
The process for forming the pouch with the Prepac~ IS-6 machine for the purpose of carrying out the Mu-test in the Examples is as follows. The web of film is formed into a continuous tube with a lap seal, said tube having an inside diameter of approximately 9.8 cm. A typical vertical sealing jaw of the Prepac~ IS-6 apparatus has an approximately 3.5 by 0.3 mm rectangular sealing wire made of Nichrome~ alloy, and a transverse sealing jaw with an approximately 1.8 by 0.7 mm sealing wire made of Nichrome~ alloy. The operation of the vertical and transverse sealing element should be optimized for the particular film type and thickness used. Typically, during vertical sealing of the tube, a 35-50 amp current at 14-24 volts is passed through the sealing wire for about 0.2-0.5 seconds.
The force applied by the vertical sealing jaws to the film is about 8 Newtons applied for a dwell time of about 0.9 seconds. The vertical sealing jaw is cooled by water at 13~6°C. During transverse sealing of the tube, a 35-55 amp current at 10-15 volts is passed through the sealing wire for about 0.2-0.5 seconds. The force applied by the transverse sealing jaws to the film is about 19 N applied for a dwell time of about 0.9 second. The transverse sealing jaw is cooled by water at 13~6°C. Both sealing jaws are covered with 150 ~m thick glass fibre tape impregnated with Teflon~ polytetrafluoroethylene resin. With respect to optimizing the sealing operations, it will be recognized that the sealing conditions (e.g. amperage, voltage, dwell time) depend on the thickness and melting characteristics of the film.
For example, a 50 ~,m film would require lower amperage and voltage, as controlled by the rheostat on the apparatus, than would a 75 ~m film. Typically such a change in film thickness requires an adjustment of approximately 10% of the rheostat range.
5 It is the film of the present invention that is selected upon the basis of a drop test such as the Mu-test, not the composite film, where the film is coextruded or laminated with other film, and not the pouch.
The present invention is illustrated by the following examples.
EXAMPLE I
10 The following monolayer films were manufactured using a conventional blown film process and slit to a width of 324 mm, Film A being a comparative film:
A 85 % of a (mufti-site catalyst) linear low density ethylene/octene-1 copolymer, with a density of 0.920 g/cm3 and a melt index of 0.75 dg/min;
% of a high pressure low density polyethylene, having a density of 0.921 15 g/cm3, and a melt index of 5.0 dg/min;
B 85 % of a linear low density ethylene/butene-1 copolymer, manufactured with a single-site catalyst, having a density of 0.900 g/cm3 and a melt index of 1.2 dg/min commercially available from Exxon, sold under the trade name Exxon Exact 3028~; 15 % of the low density polyethylene of A;
C 45% of the linear ethylene/octene-1 copolymer of A; 40% of a linear low density ethylene/butene-1 copolymer manufactured with a single-site catalyst commercially available from Exxon, sold under the trade name Exxon Exact 4011~, having a density of 0.887 g/cm3, a melt index of 2.2 dg/min and a stress exponent of 1.08; and 15 % of the low density polyethylene of A.
Each of the films has a thickness of 3 mil.
Each of the films were fed to a Prepac~ IS-6 vertical form, fill and seal pouch forming apparatus. Pouches having a vertical lap seal and two horizontal end seals were made, each being about 28 cm in length and containing 1.3 litres of water. The pouches obtained were dropped end-wise from a height of 335.3 cm onto a concrete floor in accordance with the Mn-test. After dropping, each pouch was examined for leakers.
The results obtained were as follows:
FILM NO. DROPPED NO. LEAKERS LEAKER %
A 177 36 20.3 B 204 29 14.2 C 204 36 17.6 This example shows that the pouches formed from the polyethylene manufactured using a single-site catalyst (Films B and C) performed significantly better than the multi-site catalyst ethylene/octene-1 copolymer (Film A).
EXAMPLE II
The procedure of Example I was repeated using the following films which were made using an internal cooling mandrel in the blown film process; Film D
being a comparative film:
D 85 % of a mufti-site catalyst linear low density ethylene/octene-1 copolymer, with a density of 0.920 g/cm3, a melt index of 0.75 dg/min and a stress exponent of 1.31; 15 % of a high pressure low density polyethylene, having a density of 0.921 g/cm3;
E 45 % of a linear low density ethylene/octene-1 copolymer manufactured using a mufti-site catalyst, as described in D; 40% of a single-site catalyst linear ethylene/butene-1 copolymer having a density of 0.887 g/cm3, a melt index of 2.2 dg/min commercially available from Exxon sold under the trade name Exxon Exact 4011~; 15% of the low density polyethylene of D;
F 65 % of the linear low density ethylene/octene-1 copolymer of D; 20% of the single-site catalyst linear ethylene/butene-1 copolymer of E and 15 % of the low density polyethylene of D.
The pouches were manufactured and dropped using the procedure of Example I. The results obtained were as follows:
FILM NO. DROPPED NO. LEAKERS LEAKER %
D 204 39 19.1 E 203 29 14. 3 %
F 204 32 15 .7 The results again showed the superior performance of the pouches of the present invention.
EXAMPLE III
The procedure of Example I was repeated using the following films, Film G
being a comparative film:
G 85 % of a mufti-site catalyst linear low density ethylene/octene-1 copolymer, with a density of 0.920 g/cm3, a melt index of 0.75 dg/min and a stress exponent of 1.31; 15 % of a high pressure low density polyethylene, having a density of 0.921 g/cm3, and a melt index of 5.0 dg/min;
H 85% of a single-site catalyst-produced ethylene/hexene-1/butene-1 terpolymer commercially available from Exxon sold under the trade name Exxon Exact 3006~ having a density of 0.910 g/cm3, a melt index of 1.7 dg/min and a stress exponent of 1.07; 15 % of a low density polyethylene of G;
I 45 % of a mufti-site catalyst linear low density ethylene/octene-1 copolymer;
40% of a single-site catalyst ethylene/butene-1 copolymer commercially available from Exxon, sold under the trade name Exxon Exact 4011~ having a density of 0.87 g/cm3, a melt index of 2.2 dg/min; 15 % of a low density polyethylene of G.
The pouches were manufactured and tested using the procedure of Example I. The results obtained were as follows:
FILM NO. DROPPED NO. LEAKERS LEAKER %
G 204 82 40. 2 H 204 57 27.9 I 204 51 25.0%
The films of the invention showed significantly superior performance.
EXAMPLE IV
The procedure of Example I was repeated using the following comparative films:
L 85 % of mufti-site catalyst octene copolymer LLDPE, density 0.920 g/cm3, melt index 0.75 g/10 min; 15% of a high pressure polyethylene, density 0.921 g/cm3, melt index 5.0 g/10 min.
M 94% of a single-site catalyst octene copolymer LLDP, density 0.915 g/cm3, melt index 1.02 g/10 min, commercially available from Dow under the trade name Dow Affinity FM 1570~, 6% additive concentrates.
N 94 % single-site catalyst octene copolymer LLDPE, density 0.908 g/cm3, melt index 1.08 g/10 min, stress exponent 1.51 commercially available from Dow under the trade name Dow Affinity PL 1840, 6 % additive concentrates.
FILM NO. DROPPED NO. LEAKERS LEAKER %
L 204 67 32.8 M 203 34 16.7 N 204 46 22.5 EXAMPLE V
The following films were made using an internal cooling mandrel in the blown film process (otherwise the process of Example I was as follows):
O 85 % of a mufti-site catalyst octene copolymer LLDPE, density 0.920 g/cm3, melt index 0.75 g/10 min; 15% of a high pressure polyethylene, density 0.921 g/cm3, melt index 5.0 g/10 min.
P 30% of a single-site catalyst octene copolymer LLDPE, density 0.915 g/cm3, melt index 1.02 g/ 10 min, commercially available from Dow under the trade name Dow Affinity FM 1570~; 58 % of a mufti-site catalyst octene copolymer LLDPE, density 0.920 g/cm3, melt index 0.75 g/ 10 min; 10 % of a high pressure polyethylene, density 0.921 g/cm3, melt index 5:0 g/10 min;
and 2 % of additive concentrates.
Q 94 % of a single-site catalyst octene copolymer LLDPE, density 0.915 g/cm3, melt index 1.02 g/ 10 min, commercially available from Dow under the trade name Dow Affinity PL 1570~; and 6 % of additive concentrates.
FILM NO. DROPPED NO. LEAKERS LEAKER %
O 204 80 39.2 P 204 67 32. 8 Q 204 51 25 . 0 EXAMPLE VI
The following films were made using the process of Example V and the procedure of Example I was followed:
R 85 % of a mufti-site catalyst octene copolymer LLDPE, density 0.920 g/cm3, melt index 0.75 g/10 min; and 15 % of a high pressure polyethylene, density 0.921 g/cm3, melt index 5.0 g/10 min.
S 95 % single-site catalyst octene copolymer LLDPE, density 0.903 g/cm3, melt index 1.22 g/10 min, commercially available from Dow and sold under the trade name Dow Affinity PL 1880~; and 6% of additive concentrates.
T 94% of a single-site catalyst octene copolymer LLDPE, density 0.908 g/cm3, melt index 1.08 g/ 10 min, commercially available from Dow and sold under the trade name Dow Affinity PL 1840~; and 6 % of additive concentrates.
FILM NO. DROPPED NO. LEAKERS LEAKER %
R 203 85 41.9 S 215 52 24.2%
T 202 55 27.2 The results show the improvement obtained using single-site octene copolymer LLDPE over mufti-site octene copolymer LLDPE.
EXAMPLE VII
The films made in Examples I-VI were measured to determine their density and melt index. The results are tabulated below:
EXAMPLE , FILM DENSITY (G/CUBICMELT INDEX (G/lO
CENTIMETRE) MIN) I A 0.919 0.7 B 0.907 1.3 C 0.908 1.3 II D 0.918 0.7 E 0.909 1.3 F 0.914 0.9 III G 0.923 0.7 H 0.916 1.4 I 0.911 1.3 IV L 0.921 0.9 M 0.916 1.1 N 0.911 1.2 V O 0.918 0.7 P 0.917 0.8 Q 0.913 1.1 VI R 0.918 0.7 S 0.905 1.3 T 0.910 1.1
FLOWABLE MATERIAL
The invention relates to films used to make pouches filled with flowable materials, e.g. liquids.
As used herein, the term "flowable material" does not include gaseous materials, but encompasses materials which are flowable under gravity or may be pumped. Such materials include liquids, e.g. milk, water, fruit juice, oil;
emulsions, e.g. ice cream mix, soft margarine; pastes, e.g. meat pastes, peanut butter; preserves, e.g. jams, pie fillings, marmalade; jellies; doughs; ground meat, e.g. sausage meat; powders, e.g. gelatin powders, detergents; granular solids, e.g.
nuts, sugar; and like materials. The invention described herein is particularly useful for flowable foods, e.g. milk.
It is well known to package flowable materials, for example, milk, on a pouch-forming apparatus such as a so-called vertical form, fill and seal apparatus.
Typically, using such an apparatus, a flat web of synthetic thermoplastic film is unwound from a roll and formed into a continuous tube in a tube-forming section, by sealing the longitudinal edges on the film together to form a so-called lap seal or a so-called fin seal. The tube thus formed is pulled vertically downwards to a filling station. The tube is then collapsed across a transverse cross-section of the tube, the position of such cross-section being at a sealing device below the filling station. A
transverse heat seal is made, by the sealing device, at the collapsed portion of the tube, thus making an air-tight seal across the tube. The material being packaged enters the tube above the transverse heat seal in a continuous or intermittent manner, thereby filling the tube upwardly from the transverse heat seal. The tube is then allowed to drop a predetermined distance usually under the influence of the weight of the material in the tube. The jaws of the sealing device are closed again, thus collapsing the tube at a second transverse section, which may be at, above or below the air/material interface in the tube, depending on the nature of the material being packaged and the mode of operation of the process. The sealing device seals and severs the tube transversely at the second transverse section. The material-filled portion of the tube is now in the form of a pillow shaped pouch. Thus, the sealing device has sealed the top of the filled pouch, sealed the bottom of the next-to-formed pouch and separated the filled pouch from the next-to-be-formed pouch, all in one operation. Variations on pouch-forming machines and in particular on this type of vertical form, fill and seal apparatus are either known or conceivable. For example, the forming and sealing functions may be performed separately from severing function on separate machines. Also, the jaws of the sealing device could move to the next sealing position rather than have the film drop to the next position or there could be two sets of sealing jaws that seal both transverse ends simultaneously.
Further, instead of forming a tube, two pieces of film could be fed into the machine and the pouch could be made by four seals, two longitudinal and two transverse.
Examples of the vertical, form, fill and seal apparatus of the type described above are the Prepac~ IS-6 or IS-7 liquid packaging machine.
A sealing device commonly used is a so-called impulse sealer which has a sealing element mounted in sealing jaws and electrically insulated therefrom.
In operation, the sealing jaws are closed and an electrical current is caused to flow through a sealing element, e.g. a wire, for a fraction of the time that the jaws are closed. The jaws remain closed during a cooling or equilibration period, during which the seal forms, before the sealing jaws are opened. The synthetic thermoplastic film must be able to provide a transverse seal that supports the weight of the flowable material, e.g. liquid, in the next-to-be-formed pouch. It is important that the cooling of the seal takes effect before the weight of the liquid can weaken or rupture the bottom seal. Sealing may also be carried out using any other suitable heat-sealing apparatus.
In the operation of pouch-forming machines, it is known to use film made from a blend containing 70-90% linear ethylene/butene-1 copolymer having a density of about 0.919 g/cm3 and a melt index of about 0.75 dg/min and 10-30 high pressure polyethylene, i.e. a homopolymer, having a melt index of about 2 to 10 dg/min and a density of from 0.916 to 0.924 g/cm3. Density is determined by ASTM Procedure D1505-85 and melt index by ASTM Procedure D1238-90B
MHY-l~-1010 ld-b9 tKUM=SWHtJt;Y UliILVY htt:IHHUL'1' lU- YHlit 110/11 (Condition )~. Such fllxus having a thiclmess of about 76 micarometers, have been used commercially on vertical form, fill and seal apparatuses for m,aIdng pouches containing about i .3 litres of mxll~. Pouches made from such film tend to suffer frarn defective seals, i.e_ a tendencir to have wtak transverse cndla~ud longitudinal scats even thoagh the operating conditions of the iiupulse sealer have been optimized. Defective seals roay lead to the phenomenon known as "Ieakers", in wluich tb~e ~owable matexxal, e_g. m~i~, may escape from the pouch through piaholes that develop at ar close to the seal. It has been estimated that leakcrs accQUUt ;fox about 1-23~ of tha 1.3 litre milk pouch produrxiotz~
x0 US-A-4,521,437 discloses the use of pouches of ethyleneloctcnc-1 copolymer fi~J~m in the packaging of flowable materials. That patent discloses that pouches made from the ethylene/octene-i copolymer provide superior lcaker performance, i_e_ a lower percentage of leake;rss, compared ~uvith related films descn'bed above that arc formed from linear ethylene/bntene-I copolyzxlexs_ W~93102859 describes heat sealed plastic film pouches from a film comprising: (i) 10-100wt. 9~ of a linear ethylene copolymer with a Cs-C~a alpha-olefin; and (ii) 0-90wt. °r~ of at least one polymer selected from a lvateax copolymer of ethylene and a Ca-C~a alpha-olefin, a high pressure lore density polyethylene, and ethylene vinyl acetate copolymer. The use of polymers fortxled by a single-site caratyst polymeri2atioa process is not disclosed iua this reference.
W093/03493 describes the use of an ethylene alpha-olefin copolymer farmed by a single-site catalyst polymerization process, or a blend of such polymers, for the preparation of improved boat sealed articl~s_ h has now been surprisingly found that further improvements in leakcr performance may be achieved using resin blends comprising ethylene copolymers manufactured using a singlo-sitc polymerization catalyst_ The presem invernlo~n provides a process for malting pouches ~Iled with a flowable material, made acing a vertical form, fill and seal apparatus, in wlticb~ process each pouch is made from a flat web of film by forming a tubular film 3~ therefrom with a longitudinal seal and subsequently flattGaing the tubular film at a MHY-1~J-1010 'lb_Sy YIsUM:SWHtIttY UlsILVY htt;NNUL'1' lU- NHliir 11/11 first posx4otA atzd tramgversely heat sealing sand tubular film at the flattened position, continuously' filling the tubular film with a predetermined quantity of flowable material above said first position, flattening the tubular film at a second position above the first position and transversely heat sealing said tubular flea at the second position, the improvement comprising malsa~ag tb~e pouch, fxoxxt a film comprising a polymer of ethyleme with at least one C<-Coo alpha-olefin marntfadx~l in a single-site catalyst pol~aaerixatio~n process, and at Toast one of the following a) a linear polymer of ethylene and at least one C+-Coo alpha-olefin made by a mmld-site catalyst polymerization process;
b) a high pressure Iow density polyethylene; and c) additives;
wherein the transverse heat seals are tirade tluough flowable material using impulse scaling.
In another aspect, the inveintion provides a pouch for containing a flowable material > said pouch leaving at least two heat sealed edges and being formed by a vertical form, fi'tl and seal process using impulse sealing through the flowabIe material on the at least two heat sealed edges. said pouch being zttade brom a film comprising a polymer of ethylene with at bast one C4-Coo alpha-olefin manufactured in a single-site catalyst pOlymerixauon process, and at last one of tht followiuxg a) a lizzear polymGC of ethylene and at Ieast one GrClo alpha-olefin made by a mufti-site catalyst polyunexization process;
b) a high pressure low densiCy polyethylene; and c) additives;
wbexein the transverse heat seals are nxade through flowable material using impulse sealing.
The film of the present invetttiort pxefexably has a density in the range of 0.86 to 0-94 glem3 and a melt index of 0.2 to 10 dglmin and most preferably has a density in the range of 0.88 to 0.93 glom' and a melt index of 0_3 to 5 dglmin.
MPIY-1~J-i010 ld-S9 r'h'UM-SWNt3JrY UliILVY l2t;NI~IUL'1' lU= YNlst ld!'s'1 Ethylene copolymers made with single-site catalyst may be obtained using a variety of lmown polymerisation processes for the manufacture of Iitteax polyethylene including proccSSCS that optratc in solution, in the gas phase or as a slurry process. Ethylene copolymers made with the singlo-site catalysts are 3 commercially available and may be manufactured is accordance with processes diSClosed in Modern Plastics, p_ 15, May 1993, Plastics Foc2tS Vol_ 2S, No_ l2 lone 21, 1993 and in Ex~con Chemical Exact Facts, vol_ l, Febxuaxy x993. 13y the tcrFn "sit~,gl~site catalyst" is meant a metallocene or constrained geometry catalyst.
Metalloceae catalysts are organametallic coordiazation compounds obtained as a cyclopentadienyl (Cp) derivative of a transition metal or metal halide. The metal is b0~ to the Cp ring by electrons moving in orbitals eatendin~ above and below the plant of the rung (pi bo~ad)_ Metallocene catalyst syscelrls are e~c~~ely sensitive to the geometry of the catalytic site at the transition metal (the "singlo-site").
Examples of sicogle-site catalysts include CpzTiClz, CpaZrClx, CpzHfClz, (Cs(CH3)s~TiClz, PrizMe(1nd)zZrClz, and (MeaCpSi(MenN(t-Bu)]TiCHx[o-Fbl~1(Me~)]-The polyethylene obtained ~uvith the single-site catalyst preferably has a density in the range of 0.8 to 0.93 g/cm3, and especially in the range of 0.88 to 0.915 glaoa~'. laa, addition, the polymer preiierably has a melt index of less than 3 dg/min, pazticularly in tlae z~ange of 0.3 to 2 dglm~ sad especially iu~ the ravage of 0.5 to 1.5 dglmin. preferred polymers include cthylene/butcne-1, ethylenelhexeno-1, ethyle~o~e-ootene-1 and etb~yle~eJl~e~xene-l.ibutene-i. terpolyu~rs_ The resin blend suitable to make the pouches further comprises at least one polymer selected from the group comprising a linear copolymer of ethylene and at least one Ca-Coo alpha-olefin, a high pressure polyethylene and blends thereof.
Preferably the composition comprises 10 to 100 parts by weight of a copolymer of ethylene and at least one Ca-Coo alpha-olefin manufactured in a polymerization process using a single-site polymerization catalyst and up to 90 parts by weight of at least one polymer selected from the group comprising a linear copolymer of ethylene and at least one Ca-Coo alpha-olefin, a high pressure polyethylene and blends thereof. In particularly preferred embodiments, the composition comprises 20 to 100 and especially 50 to 100 parts of the copolymer obtained using the single-site catalyst, and conversely 0 to 80 and 0 to 50 parts of the other polymers specified above. The composition comprises a total of 100 parts by weight.
Processes for the manufacture of so-called high pressure polyethylene from ethylene monomer have been operated commercially for decades. A variety of such polymers are available. The high pressure polyethylene preferably has a density of 0.916 to 0.93 g/cm3, especially 0.918 to 0.925 g/cm3. In addition, the high pressure polyethylene preferably has a melt index in the range of 1 to 10 dg/min and especially in the range of 1.5 to 5 dg/min.
Processes for the commercial manufacture of linear copolymers of ethylene and at least one Ca-Coo alpha-olefin have been known for more than thirty years.
Such processes may be operated in solution, in the gas phase or as a slurry process.
The catalysts used are frequently based on titanium and are referred to as coordination catalysts; such catalysts may also be described as multi-site catalysts or heterogeneous catalysts. The polymer obtained is linear in nature, as opposed to the branched nature of high pressure polyethylene. The Ca-Coo alpha-olefin hydrocarbon comonomer is preferably at least one of butene-1, hexene-1 or octene-1. The linear polyethylene preferably has a density in the range of 0.9 to 0.93 g/cm3, preferably 0.912 to 0.93 g/cm3 and especially in the range of 0.918 to 0.925 g/cm3. In addition, the polymer preferably has a melt index in the range of 0.3 to dg/min, preferably 0.3 to 2 dg/min and especially in the range of 0.5 to 1.5 dg/min.
The film may be used by itself to form the pouch or a part or a composite film. The composite film may be a coextruded film, a coated film or a laminated 5 film. The film of the present invention could be laminated with the other films such as a nylon film, a polyester film, a metallized polyester film, an EVA
copolymer film, or with a PVDC coating. It could also be coextruded with, for example, an ethylene vinyl acetate copolymer.
In all of the pouches of the present invention, the film is at least on the inside 10 of the pouch. The end use for the pouch tends to dictate, in a large degree, the selection of the other material or materials used in combination with the film. For example, nylon may be used in combination with the film of the present invention, for packaging oleagenous substances, e.g. cooking oil, motor oil;
polyvinylidene chloride (PVDC) or ethylene vinyl alcohol copolymers may be used in combination with the film of the present invention where a flavour or aroma barrier is desirable.
It will be appreciated by those skilled in the art that a composite film having a film only on the inside of the pouch would be sufficient for pouches made with a longitudinal fin seal, whereas a composite film having films on the two outer layers of the composite film would be necessary for pouches made with a longitudinal lap seal.
When composite films in which the two outer layers are the film of the present invention, the two outer films may be made from the same or different polymers or blends. Preferably, however, they are the same polymers or blends.
It is to be understood that the composite film may consist of two layers of the film of the present invention. This latter composite film is useful when one or both layers are, for example coloured with dyes or pigments, e.g. a layer having carbon black, iron oxide, aluminum, bronze powder or some other dark pigment and an outer layer which contains a light pigment, e.g. titanium dioxide, zinc oxide.
The blends useful in the present invention may be made by blending the constituents prior to feeding to the hopper of a film extruder, or may be made by blending the constituents at the time of extrusion just prior to remelting in the extruder, or alternatively the constituents may be melt blended in the extruder.
The ethylene/alpha-olefin copolymer or blend of ethylene/alpha-olefin copolymer, e.g. in pellet form, may be fed into a film extruder and extruded into film form using known techniques. One preferred method of manufacturing film is the so-called blown film process disclosed in Canadian Patent No. 460,963 issued November 8, 1949 to E.D. Fuller. Another preferred method of manufacturing film uses an internal or external cooling mandrel in the blown film process, as disclosed, for example, in Canadian Patent No. 893,216 issued February 15, 1972 to M.
Bunga and D.V. Thomas.
The film, after manufacture, is slit longitudinally into appropriate widths.
Where a vertical form, fill and seal apparatus is used, the width is selected on the basis of the diameter of the tube to be formed.
It will be understood by those skilled in the art that additives, e.g. UV
stabilizers, anti-block agents, slip additives, may be added to the polymers from which the pouches of the present invention are made.
The pouches of the present invention may be used in the packaging of flowable materials, e.g. liquids, as defined above. In particular, the pouches may be used in the packaging of milk. The pouches may be made using any liquid pouch-forming apparatus, including vertical form, fill and seal machines such as the Prepac~ IS-6 or IS-7.
The films of the present invention may be used to make pouches of improved integrity as compared to prior art pouches, thereby substantially reducing the leaker rate of the pouches. The leaker rate may be measured using a drop test. In a drop test, pouches of the same dimensions containing the same type and amount of liquid are made using the same type of pouch-forming equipment and are all dropped from the same height and position. The number of leakers expressed as a percentage of the total number of pouches dropped is used as the basis of comparison between pouches made from different films. The particular drop test used in the Examples herein is referred to as the Mu-test. The Mn-test is carried out as follows:
In general terms, the M~ ~-test is a drop test carried out on 1.3 litre water-filled pouches. In the test, pouches containing 1.3 litres of water, at a temperature of 10~5 °C, are made from a 32 cm. wide film web, on a Prepac~ IS-6 vertical form, fill and seal machine. The water-filled pouches containing cold water, are dropped onto a concrete floor from a height of 335 cm. The pouches are positioned with the longitudinal axis of the tube, i.e. pouch, parallel to an imaginary vertical line.
Any pouch from which water flows or weeps after the pouch has been dropped onto the floor, is termed a "leaker" . The number of leakers, expressed as a percentage of the total number of pouches dropped is the Mu-test value for the particular film being tested. It will be noted that the Mu-test value will be affected by the thickness of the film as well as the material from which the film is made.
The process for forming the pouch with the Prepac~ IS-6 machine for the purpose of carrying out the Mu-test in the Examples is as follows. The web of film is formed into a continuous tube with a lap seal, said tube having an inside diameter of approximately 9.8 cm. A typical vertical sealing jaw of the Prepac~ IS-6 apparatus has an approximately 3.5 by 0.3 mm rectangular sealing wire made of Nichrome~ alloy, and a transverse sealing jaw with an approximately 1.8 by 0.7 mm sealing wire made of Nichrome~ alloy. The operation of the vertical and transverse sealing element should be optimized for the particular film type and thickness used. Typically, during vertical sealing of the tube, a 35-50 amp current at 14-24 volts is passed through the sealing wire for about 0.2-0.5 seconds.
The force applied by the vertical sealing jaws to the film is about 8 Newtons applied for a dwell time of about 0.9 seconds. The vertical sealing jaw is cooled by water at 13~6°C. During transverse sealing of the tube, a 35-55 amp current at 10-15 volts is passed through the sealing wire for about 0.2-0.5 seconds. The force applied by the transverse sealing jaws to the film is about 19 N applied for a dwell time of about 0.9 second. The transverse sealing jaw is cooled by water at 13~6°C. Both sealing jaws are covered with 150 ~m thick glass fibre tape impregnated with Teflon~ polytetrafluoroethylene resin. With respect to optimizing the sealing operations, it will be recognized that the sealing conditions (e.g. amperage, voltage, dwell time) depend on the thickness and melting characteristics of the film.
For example, a 50 ~,m film would require lower amperage and voltage, as controlled by the rheostat on the apparatus, than would a 75 ~m film. Typically such a change in film thickness requires an adjustment of approximately 10% of the rheostat range.
5 It is the film of the present invention that is selected upon the basis of a drop test such as the Mu-test, not the composite film, where the film is coextruded or laminated with other film, and not the pouch.
The present invention is illustrated by the following examples.
EXAMPLE I
10 The following monolayer films were manufactured using a conventional blown film process and slit to a width of 324 mm, Film A being a comparative film:
A 85 % of a (mufti-site catalyst) linear low density ethylene/octene-1 copolymer, with a density of 0.920 g/cm3 and a melt index of 0.75 dg/min;
% of a high pressure low density polyethylene, having a density of 0.921 15 g/cm3, and a melt index of 5.0 dg/min;
B 85 % of a linear low density ethylene/butene-1 copolymer, manufactured with a single-site catalyst, having a density of 0.900 g/cm3 and a melt index of 1.2 dg/min commercially available from Exxon, sold under the trade name Exxon Exact 3028~; 15 % of the low density polyethylene of A;
C 45% of the linear ethylene/octene-1 copolymer of A; 40% of a linear low density ethylene/butene-1 copolymer manufactured with a single-site catalyst commercially available from Exxon, sold under the trade name Exxon Exact 4011~, having a density of 0.887 g/cm3, a melt index of 2.2 dg/min and a stress exponent of 1.08; and 15 % of the low density polyethylene of A.
Each of the films has a thickness of 3 mil.
Each of the films were fed to a Prepac~ IS-6 vertical form, fill and seal pouch forming apparatus. Pouches having a vertical lap seal and two horizontal end seals were made, each being about 28 cm in length and containing 1.3 litres of water. The pouches obtained were dropped end-wise from a height of 335.3 cm onto a concrete floor in accordance with the Mn-test. After dropping, each pouch was examined for leakers.
The results obtained were as follows:
FILM NO. DROPPED NO. LEAKERS LEAKER %
A 177 36 20.3 B 204 29 14.2 C 204 36 17.6 This example shows that the pouches formed from the polyethylene manufactured using a single-site catalyst (Films B and C) performed significantly better than the multi-site catalyst ethylene/octene-1 copolymer (Film A).
EXAMPLE II
The procedure of Example I was repeated using the following films which were made using an internal cooling mandrel in the blown film process; Film D
being a comparative film:
D 85 % of a mufti-site catalyst linear low density ethylene/octene-1 copolymer, with a density of 0.920 g/cm3, a melt index of 0.75 dg/min and a stress exponent of 1.31; 15 % of a high pressure low density polyethylene, having a density of 0.921 g/cm3;
E 45 % of a linear low density ethylene/octene-1 copolymer manufactured using a mufti-site catalyst, as described in D; 40% of a single-site catalyst linear ethylene/butene-1 copolymer having a density of 0.887 g/cm3, a melt index of 2.2 dg/min commercially available from Exxon sold under the trade name Exxon Exact 4011~; 15% of the low density polyethylene of D;
F 65 % of the linear low density ethylene/octene-1 copolymer of D; 20% of the single-site catalyst linear ethylene/butene-1 copolymer of E and 15 % of the low density polyethylene of D.
The pouches were manufactured and dropped using the procedure of Example I. The results obtained were as follows:
FILM NO. DROPPED NO. LEAKERS LEAKER %
D 204 39 19.1 E 203 29 14. 3 %
F 204 32 15 .7 The results again showed the superior performance of the pouches of the present invention.
EXAMPLE III
The procedure of Example I was repeated using the following films, Film G
being a comparative film:
G 85 % of a mufti-site catalyst linear low density ethylene/octene-1 copolymer, with a density of 0.920 g/cm3, a melt index of 0.75 dg/min and a stress exponent of 1.31; 15 % of a high pressure low density polyethylene, having a density of 0.921 g/cm3, and a melt index of 5.0 dg/min;
H 85% of a single-site catalyst-produced ethylene/hexene-1/butene-1 terpolymer commercially available from Exxon sold under the trade name Exxon Exact 3006~ having a density of 0.910 g/cm3, a melt index of 1.7 dg/min and a stress exponent of 1.07; 15 % of a low density polyethylene of G;
I 45 % of a mufti-site catalyst linear low density ethylene/octene-1 copolymer;
40% of a single-site catalyst ethylene/butene-1 copolymer commercially available from Exxon, sold under the trade name Exxon Exact 4011~ having a density of 0.87 g/cm3, a melt index of 2.2 dg/min; 15 % of a low density polyethylene of G.
The pouches were manufactured and tested using the procedure of Example I. The results obtained were as follows:
FILM NO. DROPPED NO. LEAKERS LEAKER %
G 204 82 40. 2 H 204 57 27.9 I 204 51 25.0%
The films of the invention showed significantly superior performance.
EXAMPLE IV
The procedure of Example I was repeated using the following comparative films:
L 85 % of mufti-site catalyst octene copolymer LLDPE, density 0.920 g/cm3, melt index 0.75 g/10 min; 15% of a high pressure polyethylene, density 0.921 g/cm3, melt index 5.0 g/10 min.
M 94% of a single-site catalyst octene copolymer LLDP, density 0.915 g/cm3, melt index 1.02 g/10 min, commercially available from Dow under the trade name Dow Affinity FM 1570~, 6% additive concentrates.
N 94 % single-site catalyst octene copolymer LLDPE, density 0.908 g/cm3, melt index 1.08 g/10 min, stress exponent 1.51 commercially available from Dow under the trade name Dow Affinity PL 1840, 6 % additive concentrates.
FILM NO. DROPPED NO. LEAKERS LEAKER %
L 204 67 32.8 M 203 34 16.7 N 204 46 22.5 EXAMPLE V
The following films were made using an internal cooling mandrel in the blown film process (otherwise the process of Example I was as follows):
O 85 % of a mufti-site catalyst octene copolymer LLDPE, density 0.920 g/cm3, melt index 0.75 g/10 min; 15% of a high pressure polyethylene, density 0.921 g/cm3, melt index 5.0 g/10 min.
P 30% of a single-site catalyst octene copolymer LLDPE, density 0.915 g/cm3, melt index 1.02 g/ 10 min, commercially available from Dow under the trade name Dow Affinity FM 1570~; 58 % of a mufti-site catalyst octene copolymer LLDPE, density 0.920 g/cm3, melt index 0.75 g/ 10 min; 10 % of a high pressure polyethylene, density 0.921 g/cm3, melt index 5:0 g/10 min;
and 2 % of additive concentrates.
Q 94 % of a single-site catalyst octene copolymer LLDPE, density 0.915 g/cm3, melt index 1.02 g/ 10 min, commercially available from Dow under the trade name Dow Affinity PL 1570~; and 6 % of additive concentrates.
FILM NO. DROPPED NO. LEAKERS LEAKER %
O 204 80 39.2 P 204 67 32. 8 Q 204 51 25 . 0 EXAMPLE VI
The following films were made using the process of Example V and the procedure of Example I was followed:
R 85 % of a mufti-site catalyst octene copolymer LLDPE, density 0.920 g/cm3, melt index 0.75 g/10 min; and 15 % of a high pressure polyethylene, density 0.921 g/cm3, melt index 5.0 g/10 min.
S 95 % single-site catalyst octene copolymer LLDPE, density 0.903 g/cm3, melt index 1.22 g/10 min, commercially available from Dow and sold under the trade name Dow Affinity PL 1880~; and 6% of additive concentrates.
T 94% of a single-site catalyst octene copolymer LLDPE, density 0.908 g/cm3, melt index 1.08 g/ 10 min, commercially available from Dow and sold under the trade name Dow Affinity PL 1840~; and 6 % of additive concentrates.
FILM NO. DROPPED NO. LEAKERS LEAKER %
R 203 85 41.9 S 215 52 24.2%
T 202 55 27.2 The results show the improvement obtained using single-site octene copolymer LLDPE over mufti-site octene copolymer LLDPE.
EXAMPLE VII
The films made in Examples I-VI were measured to determine their density and melt index. The results are tabulated below:
EXAMPLE , FILM DENSITY (G/CUBICMELT INDEX (G/lO
CENTIMETRE) MIN) I A 0.919 0.7 B 0.907 1.3 C 0.908 1.3 II D 0.918 0.7 E 0.909 1.3 F 0.914 0.9 III G 0.923 0.7 H 0.916 1.4 I 0.911 1.3 IV L 0.921 0.9 M 0.916 1.1 N 0.911 1.2 V O 0.918 0.7 P 0.917 0.8 Q 0.913 1.1 VI R 0.918 0.7 S 0.905 1.3 T 0.910 1.1
Claims (34)
1. A process for making pouches filled with a flowable material, made using a vertical form, fill and seal apparatus, 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, continuously filling the tubular film with a predetermined quantity of flowable material above said first position, flattening the tubular film at a second position above the first position and transversely heat sealing said tubular film at the second position, the improvement comprising making the pouch from a film comprising a polymer of ethylene with at least one C4-C10 alpha-olefin manufactured in a single-site catalyst polymerization process, and at least one of the following.
a) a linear polymer of ethylene and at least one C4-10 alpha-olefin made by a multi-site catalyst polymerization process;
b) a high pressure low density polyethylene; and c) additives;
wherein the transverse heat seals are made through flowable material using impulse sealing.
a) a linear polymer of ethylene and at least one C4-10 alpha-olefin made by a multi-site catalyst polymerization process;
b) a high pressure low density polyethylene; and c) additives;
wherein the transverse heat seals are made through flowable material using impulse sealing.
2. A process for making pouches filled with a flowable material, made using a vertical form, fill and seal apparatus, 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, continuously filling the tubular film with a predetermined quantity of flowable material above said first position, flattening the tubular film at a second position above the first position and transversely heat sealing said tubular film at the second position, the improvement comprising making the pouch from a film comprising a linear polymer of ethylene with at least one C4-C10 alpha-olefin manufactured in a single-site catalyst polymerization process, and at least one of the following a) a linear polymer of ethylene and at least one C4-Coo alpha-olefin made by a multl-site catalyst polymerization process;
b) a high pres,,sure low density polyethylene; and c) additives;
when~in the transverse heat seals are made through flowable material using impulse sealing.
b) a high pres,,sure low density polyethylene; and c) additives;
when~in the transverse heat seals are made through flowable material using impulse sealing.
3. The process as claimed in claim 2, wherein the film comprises from 14 to $5 parts by weight of a linear polymer of ethylene and at feast one C4-Coo alpha-olefin manufactured in a single-site catalyst process, and from 15 to 90 parts by weight of at least cane of the following a) a linear polymer of ethylene and at feast one Ca-C1o alpha-olefin made by a mufti-site catalyst polymerization process, b) a high pressure taw density polyethylene, and d) additives.
4. The process as claimed in any of claims 1 to 3, wherein the film comprises a) from 10 to 85 parts by weight of a linear polymer of ethylene and at least one G4-Cib alpha-olefin manufactured in a single~ite catalyst polymerization process, said polymer having a density in the range of from 0.8 fio 0.93 glcm~ and a melt index of less than 5 dg.lmin.;
b) from 0 to 75 part$ 4y weight of a linear polymer of ethylene and at least one C~-C,a alpha-olefin manufactured by a muHi-site catalyst polymerization process, said polymer having a density in the range of from 0.9 to 0.83 g/~n3 and a melt index of from 0.3to 10 dg./min.; and c) 15 parts by weight of a high pressure low density polyethylene having a den$ity ef from g.g16 to 0.8~ g/cm~ and a melt index of from 1 to 10 dg.lmin.
b) from 0 to 75 part$ 4y weight of a linear polymer of ethylene and at least one C~-C,a alpha-olefin manufactured by a muHi-site catalyst polymerization process, said polymer having a density in the range of from 0.9 to 0.83 g/~n3 and a melt index of from 0.3to 10 dg./min.; and c) 15 parts by weight of a high pressure low density polyethylene having a den$ity ef from g.g16 to 0.8~ g/cm~ and a melt index of from 1 to 10 dg.lmin.
5. The pmcess as claimed in claim 2 or 3, wherein the film comprises a) from 10 to 85 parts by weight of a linear polymer of ethylene and at least one C4-Coo alpha-olefin manufactured in a single-site catalyst polymerization process, said polymer having a density in the range of from 0.8 to 0.915 g/cm3 and a melt index of from 0.3 to 2 dg./min.;
b) from 0 to 75 parts by weight of a linear polymer of ethylene and at least one C4-C10 alpha-olefin manufactured by a multi-site catalyst polymerization process, said polymer having a density in the range of from 0.912 to 0.93 g/cm3 and a melt index of from 0.3 to 2 dg./min.; and c) 15 parts by weight of a high pressure low density polyethylene having a density of from 0.918 to 0.925 g/cm3 and a melt index of from 1.5 to 5 dg./min.
b) from 0 to 75 parts by weight of a linear polymer of ethylene and at least one C4-C10 alpha-olefin manufactured by a multi-site catalyst polymerization process, said polymer having a density in the range of from 0.912 to 0.93 g/cm3 and a melt index of from 0.3 to 2 dg./min.; and c) 15 parts by weight of a high pressure low density polyethylene having a density of from 0.918 to 0.925 g/cm3 and a melt index of from 1.5 to 5 dg./min.
6. The process as claimed in any of claims 2 to 5, wherein the pouch is made from a film wherein the linear polymer of ethylene and at least one C4-C10 alpha-olefin manufactured in a single-site catalyst polymerization process is selected from the group consisting of ethylene/butene-1, ethylene/hexene-1, and ethylene/hexene-1/butene-1 polymers.
7. The process as claimed in any of claims 2 to 6, wherein the linear polymer manufactured in a single-site catalyst polymerization process is an ethylene/hexene-1 polymer.
8. The process as claimed in claim 1, wherein the single-site catalyst polymer comprises a long chain branched linear polymer of ethylene and at least one C4-C10 alpha-olefin manufactured in a single-site catalyst polymerization process.
9. The process as claimed in claim 8, wherein the polymer of ethylene and at least one C4-C10 alpha-olefin manufactured in a single-site catalyst polymerization process is a substantially linear polymer.
10. The process as claimed in claim 8 or 9, wherein the single-site catalyst linear polymer is ethylene/octene-1.
11. The process as claimed in any of claims 8 to 10, wherein the single/site catalyst linear polymer has a density in the range of 0.9 to 0.93 g/cm3 and a melt index in the range of less than 5 dg/min., and the high pressure low density polyethylene has a density in the range of 0.916 to 0.93 g/cm3 and a melt index in the range of 1 to 10 dg/min.
12. The process as claimed in any of claims 1 to 11, wherein the film has a density in the range of from 0.86 to 0.94 g/cm3 and a melt index of from 0.2 to 10 dg/min.
13. The process as claimed in any of claims 1 to 11, wherein the film has a density in the range of from 0.88 to 0.93 g/cm3 and a melt index of 0.3 to 5 dg/min.
14. The process as claimed in any of claims 8 to 11, wherein the single-site catalyst polymer has a density of 0.8 to 0.93 g/cm3 and a melt index of less than 5 dg/min; the multi-site catalyst polymer has a density of 0.9 to 0.93 g/cm3 and a melt index of 0.3 to 10 dg/min; and the high pressure polymer has a density of 0.916 to 0.93 g/cm3 and a melt index of 1 to 10 dg/min.
15. The process as claimed in any of claims 8 to 10, wherein the single-site catalyst polymer has a density of 0.88 to 0.915 g/cm3 and a melt index of 0.3 to 2 dg/min; and the multi-site catalyst polymer has a density of .912 to .93 g/cm3 and a melt index of 0.3 to 2 dg/min; and the high pressure polymer has a density of .918 to .925 g/cm3 and a melt index of 1.5 to 5 dg/min.
16. The process as claimed in claim 8, wherein the film comprises 94 parts by weight of a single-site catalyst long chain branched linear polymer of ethylene-octene selected from the group consisting of polymers of density 0.915 g/cm3 and melt index 1.02 g/10 min.;
density 0.908 g/cm3 and melt index 1.08 g/10 min.; and density 0.903 g/cm3 and melt index 1.22 g/10 min.;
and 6 parts by weight of additive concentrates.
density 0.908 g/cm3 and melt index 1.08 g/10 min.; and density 0.903 g/cm3 and melt index 1.22 g/10 min.;
and 6 parts by weight of additive concentrates.
17. The process as claimed in claim 8, wherein the film comprises 30 parts by weight of a single-site catalyst long chain branched linear polymer of ethylene-octene selected from the group having density 0.915 g/cm3 and melt index 1.02 g/10 min.; 58 parts by weight of a linear copolymer of ethylene-octene manufactured by a multi-site catalyst process of density 0.920 g/cm3 and melt index 0.75 g/10 min.; 10 parts by weight of a high pressure polyethylene of density 0.921 g/cm3 and melt index 5.0 g/10 min.;
and 2 parts by weight of additive concentrates.
and 2 parts by weight of additive concentrates.
18. A pouch for containing a flowable material, said pouch having at least two heat sealed edges and being formed by a vertical form, fill and seal process using impulse sealing through the flowable material on the at least two heat sealed edges, said pouch being made from a film comprising a polymer of ethylene with at least one C4-C10 alpha-olefin manufactured in a single-site catalyst polymerization process, and at least one of the following a) a linear polymer of ethylene and at least one C4-C10 alpha-olefin made by a multi-site catalyst polymerization process;
b) a high pressure low density polyethylene; and c) additives;
wherein the transverse heat seats are made through flowable material using impulse sealing.
b) a high pressure low density polyethylene; and c) additives;
wherein the transverse heat seats are made through flowable material using impulse sealing.
19. A pouch for containing a flowable material, said pouch having at least two heat seated edges and being formed by a vertical form, fill and seal process using impulse sealing through the flowable material on the at least two heat seated edges, said pouch being made from a film comprising a linear polymer of ethylene with at least one C4-C10 alpha-olefin manufactured in a single-site catalyst polymerization process, and at least one of the following a) a linear polymer of ethylene and at least one C4-C10 alpha-olefin made by a multi-site catalyst polymerization process;
b) a high pressure low density polyethylene; and c) additives;
wherein the transverse heat seals are made through flowable material using impulse sealing.
b) a high pressure low density polyethylene; and c) additives;
wherein the transverse heat seals are made through flowable material using impulse sealing.
20. The pouch as claimed in claim 18 or 19, wherein the film comprises from 10 to 85 parts by weight of a linear polymer of ethylene and at least one C4-C10 alpha-olefin manufactured in a single-site catalyst process, and from 15 to 90 parts by weight of at least one of the following a) a linear polymer of ethylene and at least one C4-C10 alpha-olefin made by a multi-site catalyst polymerization process.
b) a high pressure low density polyethylene, and c) additives.
b) a high pressure low density polyethylene, and c) additives.
21. The pouch as claimed in claim 18, 19 or 20 wherein the pouch is made from a film wherein a linear polymer of ethylene and at least one C4-C10 alpha-olefin manufactured in a single-site catalyst polymerization process is present and is selected from the group consisting of ethylene/butene-1, ethylenelhexene-1 and ethylene/hexane-1/butene-1 polymers.
22. The pouch as claimed in claim 18, 19 or 20, wherein the film comprises a) from 10 to 85 parts by weight of a linear polymer of ethylene and at least one C4-C10 alpha-olefin manufactured in a single-site catalyst polymerization process, said polymer having a density in the range of from 0.8 to 0.93 g/cm3 and a melt index of less than 5 dg./min.;
b) from 0 to 75 parts by weight of a linear polymer of ethylene and at least one C4-C10 alpha-olefin manufactured by a multi-site catalyst polymerization process, said polymer having a density in the range of from 0.9 to 0.93 g/cm3 and a melt index of from 1 to 14dg./min.; and c) 15 parts by weight of a high pressure low density polyethylene having a density of from 0.916 to 0.93 g/cm3 and a melt index of from 1 to 10 dg./min.
b) from 0 to 75 parts by weight of a linear polymer of ethylene and at least one C4-C10 alpha-olefin manufactured by a multi-site catalyst polymerization process, said polymer having a density in the range of from 0.9 to 0.93 g/cm3 and a melt index of from 1 to 14dg./min.; and c) 15 parts by weight of a high pressure low density polyethylene having a density of from 0.916 to 0.93 g/cm3 and a melt index of from 1 to 10 dg./min.
23. The pouch as claimed in claim 18, 19 or 20, wherein the film comprises a) from 10 to 85 parts by weight of a linear polymer of ethylene and at least one C4-C10 alpha-olefin manufactured in a single-site catalyst polymerization process, said polymer having a density to the range of from 0.8 to 0.915 g/cm3 and a melt index of from 0.3 to 2 dg./min.;
b) from 0 to 75 parts by weight of a linear polymer of ethylene and at least one C4-C10 alpha-olefin manufactured by a multi-site catalyst polymerization process, said polymer having a density in the range of from 0.912 to 0.93g/cm3 and a melt index of from 0.3 to 2 dg./min.; and C) 15 parts by weight of a high pressure low density polyethylene having a density of from 0.918 to 0.925 g/cm3 and a melt index of from 1.5 to 5 dg./min.
b) from 0 to 75 parts by weight of a linear polymer of ethylene and at least one C4-C10 alpha-olefin manufactured by a multi-site catalyst polymerization process, said polymer having a density in the range of from 0.912 to 0.93g/cm3 and a melt index of from 0.3 to 2 dg./min.; and C) 15 parts by weight of a high pressure low density polyethylene having a density of from 0.918 to 0.925 g/cm3 and a melt index of from 1.5 to 5 dg./min.
24. The pouch as claimed in any of claims 18 to 23, wherein the film comprises a linear polymer of ethylene and at least one C4-C10 alpha-olefin manufactured in a single-site catalyst polymerization process which is an ethylenelhexene-1 polymer.
25. The pouch as claimed in claim 18, wherein the single-site catalyst linear polymer comprises a long chain branched linear polymer of ethylene and at least one C4-C10 alpha-olefin manufactured in a single-site catalyst polymerization process.
26. The pouch as claimed in claim 25, wherein the polymer of ethylene and at least one C4-C10 alpha-olefin manufactured in a single-site catalyst polymerization process is a substantially linear polymer.
27. The pouch as claimed in claim 25, wherein the linear polymer is single-site catalyst ethylenelhexene-1.
28. The pouch as claimed in any of claims 25 to 27, wherein the single-site catalyst linear polymer has a density in the range of 0.9 to 0.93 g/cm3 and a melt index of less than 5 dg/min., and the high pressure low density polyethylene has a density in the range of 0.916 to 0.93 g/cm3 and a melt index in the range of 1 to 10 dg/min.
29. The pouch as claimed in any of claims 25 to 28, wherein the film has a density in the range of from 0.86 to 0.94 g/cm3 arid a melt index of from 0.2 to 10 dg/min.
30. The pouch as claimed in any of claims 25 to 28, wherein the film has a density in the range of from 0.88 to 0.93 g/cm3 and a melt index of 0.3 to 5 dg/min.
31. The pouch as claimed in any of claims 25 to 27, wherein the single-site catalyst polymer has a density of 0.8 to 0.93 g/cm3 and a melt index of less than 5 dg/min; the multi-site catalyst polymer has a density of 0.9 to 0.93 g/cm3 and a melt index of 0.3 to 10 dg/min; and the high pressure polymer has a density of 0.916 to 0.93 g/cm3 and a melt index of 1 to 10 dg/min.
32. The pouch as claimed in any of claims 25 to 27, wherein the single-site catalyst polymer has a density of 0.88 to 0.915 g/cm3 and a melt index of 0.3 to 2 dg/min; and the multi-site catalyst polymer has a density of 912 to .93 g/cm3 and a melt index of 0.3 to 2 dg/min; and the high pressure polymer has a density of .918 to .925 g/cm3 and a melt index of 1.5 to 5 dg/min.
33. The pouch as claimed in claim 25, wherein the film comprises 94 parts by weight of a single-site catalyst long chain branched linear polymer of ethylene-octane selected from the gmup consisting of polymers of density 0.915 g/cm3 and melt index 1.02 g/10 min.;
density 0.908 g/cm3 and melt index 1.08 g/10 min.; and density 0.903 g/cm3 and melt index 1.22 g/10 min.;
end 6 parts by weight of additive concentrates.
density 0.908 g/cm3 and melt index 1.08 g/10 min.; and density 0.903 g/cm3 and melt index 1.22 g/10 min.;
end 6 parts by weight of additive concentrates.
34. The pouch as claimed in claim 25, wherein the film comprises 30 parts by weight of a single-site catalyst long chain branched linear polymer of ethylene-octane selected from the group having density 0.915 g/cm3 and melt index .02 g/10 min.; 58 parts by weight of a linear copolymer of ethylene-octane manufactured by a multi-site catalyst process of density 0.920 g/cm3 and melt index 0.75 g/10 min.; 10 parts by weight of a high pressure polyethylene of density 0.921 g/cm3 and melt index 5.0 g/10 min.;
and 2 parts by weight of additive concentrates.
and 2 parts by weight of additive concentrates.
Applications Claiming Priority (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GB939321254A GB9321254D0 (en) | 1993-10-14 | 1993-10-14 | Pouches of ethylene copolymer film containing a flowable material |
GB9321254.6 | 1993-10-14 | ||
PCT/CA1994/000571 WO1995010566A1 (en) | 1993-10-14 | 1994-10-13 | Pouches of ethylene copolymer film containing a flowable material |
Publications (2)
Publication Number | Publication Date |
---|---|
CA2151589A1 CA2151589A1 (en) | 1995-04-20 |
CA2151589C true CA2151589C (en) | 2001-04-17 |
Family
ID=10743575
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
CA002151589A Expired - Fee Related CA2151589C (en) | 1993-10-14 | 1994-10-13 | Pouches of ethylene copolymer film containing a flowable material |
Country Status (10)
Country | Link |
---|---|
US (3) | US6406765B1 (en) |
EP (1) | EP0673397B1 (en) |
JP (1) | JPH08504884A (en) |
BR (1) | BR9406308A (en) |
CA (1) | CA2151589C (en) |
DE (1) | DE69422383T2 (en) |
ES (1) | ES2141844T3 (en) |
GB (1) | GB9321254D0 (en) |
IN (1) | IN183372B (en) |
WO (1) | WO1995010566A1 (en) |
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GB9321254D0 (en) * | 1993-10-14 | 1993-12-01 | Du Pont Canada | Pouches of ethylene copolymer film containing a flowable material |
-
1993
- 1993-10-14 GB GB939321254A patent/GB9321254D0/en active Pending
-
1994
- 1994-10-13 CA CA002151589A patent/CA2151589C/en not_active Expired - Fee Related
- 1994-10-13 DE DE69422383T patent/DE69422383T2/en not_active Revoked
- 1994-10-13 BR BR9406308A patent/BR9406308A/en not_active IP Right Cessation
- 1994-10-13 JP JP7511130A patent/JPH08504884A/en active Pending
- 1994-10-13 ES ES94929438T patent/ES2141844T3/en not_active Expired - Lifetime
- 1994-10-13 EP EP94929438A patent/EP0673397B1/en not_active Revoked
- 1994-10-13 WO PCT/CA1994/000571 patent/WO1995010566A1/en not_active Application Discontinuation
- 1994-10-17 IN IN844CA1994 patent/IN183372B/en unknown
-
1996
- 1996-10-15 US US08/732,533 patent/US6406765B1/en not_active Expired - Lifetime
-
1998
- 1998-03-10 US US09/037,528 patent/US6256966B1/en not_active Expired - Fee Related
-
2002
- 2002-05-24 US US10/155,382 patent/US6767599B2/en not_active Expired - Lifetime
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US10960649B2 (en) | 2017-11-14 | 2021-03-30 | Liqui-Box Corporation | Flex-crack resistant and thermally resistant aseptic bulk bags for flexible packaging |
Also Published As
Publication number | Publication date |
---|---|
EP0673397B1 (en) | 1999-12-29 |
JPH08504884A (en) | 1996-05-28 |
US20020166626A1 (en) | 2002-11-14 |
GB9321254D0 (en) | 1993-12-01 |
DE69422383T2 (en) | 2000-06-08 |
US6406765B1 (en) | 2002-06-18 |
CA2151589A1 (en) | 1995-04-20 |
US6767599B2 (en) | 2004-07-27 |
WO1995010566A1 (en) | 1995-04-20 |
DE69422383D1 (en) | 2000-02-03 |
ES2141844T3 (en) | 2000-04-01 |
US6256966B1 (en) | 2001-07-10 |
IN183372B (en) | 1999-12-11 |
EP0673397A1 (en) | 1995-09-27 |
BR9406308A (en) | 1996-01-02 |
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