GB2245572A - A stretch wrap film - Google Patents

A stretch wrap film Download PDF

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Publication number
GB2245572A
GB2245572A GB9014181A GB9014181A GB2245572A GB 2245572 A GB2245572 A GB 2245572A GB 9014181 A GB9014181 A GB 9014181A GB 9014181 A GB9014181 A GB 9014181A GB 2245572 A GB2245572 A GB 2245572A
Authority
GB
United Kingdom
Prior art keywords
film
polymer
ethylene
copolymer
polyethylene
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
GB9014181A
Other versions
GB9014181D0 (en
Inventor
David Charles Climenhage
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
DuPont Canada Inc
Original Assignee
DuPont Canada Inc
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by DuPont Canada Inc filed Critical DuPont Canada Inc
Priority to GB9014181A priority Critical patent/GB2245572A/en
Publication of GB9014181D0 publication Critical patent/GB9014181D0/en
Priority to EP91911377A priority patent/EP0502132A1/en
Priority to AU80052/91A priority patent/AU641253B2/en
Priority to HU9202208A priority patent/HUT65769A/en
Priority to PL29716591A priority patent/PL297165A1/en
Priority to CA002072599A priority patent/CA2072599C/en
Priority to PCT/CA1991/000226 priority patent/WO1992000344A1/en
Priority to NZ238679A priority patent/NZ238679A/en
Priority to TW080104932A priority patent/TW205016B/zh
Publication of GB2245572A publication Critical patent/GB2245572A/en
Priority to NO922758A priority patent/NO922758D0/en
Withdrawn legal-status Critical Current

Links

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
    • C08J5/18—Manufacture of films or sheets
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
    • B29C48/03—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor characterised by the shape of the extruded material at extrusion
    • B29C48/09—Articles with cross-sections having partially or fully enclosed cavities, e.g. pipes or channels
    • B29C48/10—Articles with cross-sections having partially or fully enclosed cavities, e.g. pipes or channels flexible, e.g. blown foils
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
    • B29C48/25—Component parts, details or accessories; Auxiliary operations
    • B29C48/88—Thermal treatment of the stream of extruded material, e.g. cooling
    • B29C48/90—Thermal treatment of the stream of extruded material, e.g. cooling with calibration or sizing, i.e. combined with fixing or setting of the final dimensions of the extruded article
    • B29C48/901—Thermal treatment of the stream of extruded material, e.g. cooling with calibration or sizing, i.e. combined with fixing or setting of the final dimensions of the extruded article of hollow bodies
    • B29C48/902—Thermal treatment of the stream of extruded material, e.g. cooling with calibration or sizing, i.e. combined with fixing or setting of the final dimensions of the extruded article of hollow bodies internally
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
    • B65B—MACHINES, APPARATUS OR DEVICES FOR, OR METHODS OF, PACKAGING ARTICLES OR MATERIALS; UNPACKING
    • B65B53/00—Shrinking wrappers, containers, or container covers during or after packaging
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
    • B65D—CONTAINERS FOR STORAGE OR TRANSPORT OF ARTICLES OR MATERIALS, e.g. BAGS, BARRELS, BOTTLES, BOXES, CANS, CARTONS, CRATES, DRUMS, JARS, TANKS, HOPPERS, FORWARDING CONTAINERS; ACCESSORIES, CLOSURES, OR FITTINGS THEREFOR; PACKAGING ELEMENTS; PACKAGES
    • B65D65/00—Wrappers or flexible covers; Packaging materials of special type or form
    • B65D65/38—Packaging materials of special type or form
    • 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
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
    • B29C48/001—Combinations of extrusion moulding with other shaping operations
    • B29C48/0018—Combinations of extrusion moulding with other shaping operations combined with shaping by orienting, stretching or shrinking, e.g. film blowing
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
    • B29C48/03—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor characterised by the shape of the extruded material at extrusion
    • B29C48/07—Flat, e.g. panels
    • B29C48/08—Flat, e.g. panels flexible, e.g. films
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
    • B29K2995/00—Properties of moulding materials, reinforcements, fillers, preformed parts or moulds
    • B29K2995/0037—Other properties
    • B29K2995/0041—Crystalline
    • 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
    • C08J2323/08—Copolymers of ethene

Abstract

A process for wrapping articles, particularly large or heavy articles, with a stretch wrap film is disclosed. The film is at least 45 mu m thick and is made from a polymer blend, such blend comprising (i) from 1 to 20 wt.-% of at least one polybutene having a number average molecular weight of from 500 to 10,000 and (ii) a polyethylene selected from the group consisting of at least one linear ethylene/C4-C10 alpha -olefin copolymer having a density of from 0.915 to 0.940 g/cm<3> and blends of such copolymer with a second polymer, selected from a homopolymer of ethylene and a copolymer of ethylene and vinyl acetate, said second polymer having a density of from 0.910 to 0.940 g/cm<3>, said polyethylene having up to 70 wt.-% of said second polymer, and wherein said film has a low crystallinity.

Description

STRETCH WRAPPING OF A HORIZONTAL BEAM The present invention relates to the wrapping of an article with a stretch wrap film. In particular it relates to wrapping of a horizontal beam, e.g. of paper, with a stretch wrap film.
Stretch wrap films are known. For example, U.S. Patent 4 657 982 to Breck and Mollison, which issued 1987 April 14, discloses stretch wrap films made from 80-90 percent by weight of a polyethylene, 0.5 to 10.0 percent by weight of a polybutene having a number average molecular weight of from 500 to 1500 and 0.5 to 10.0 percent by weight of a polybutene having a number average molecular weight of from 1700 to 10 000. West German Patent 2 821 733 A49, to British Cellophane Limited, published 1978 November 30, discloses a method of manufacturing a wrapping film suitable for use in spin wrapping applications, comprising extruding a blend of polyethylene and 0.5 to 10 percent by weight of polyisobutylene to form a film, and treating one surface of the film with corona discharge. Low density polyethylenes are exemplified.
It is also known to wrap articles in a spin wrap operation whereby the articles are rotated about a vertical axis. The film used to wrap such articles is usually made from low density polyethylene or linear low density polyethylene blended with at least one polybutene in a conventional blown film process.
Film thicknesses are generally from 20 pm to 30 pm. Unsuccessful attempts have been made to wrap large roll stock, e.g. paper, carpets and the like, on a horizontal beam, or heavy articles, e.g.
bricks on a pallet, with linear low density polyethylene film, where such film has been made using a conventional blown film process and has a thickness of about 51 pm. Such attempts showed non-uniform stretching of the film, especially if it is prestretched to at least about 100%. Prestretching at higher ratios tends to cause a higher frequency of breaks in the film. Such processes are wasteful. The present invention is intended to alleviate the aforementioned difficulties.
Accordingly the present invention provides in a process for wrapping a large or heavy article with a stretch wrap film, an improvement wherein the film is at least 45 pm thick and is made from a polymer blend, such blend comprising i) from 1 to 20 wt.% of at least one polybutene having a number average molecular weight of from 500 to 10 000 and ii) a polyethylene selected from the grrlp consisting of at least one linear ethylene/C4 -C10 a-olefin copolymer having a density of from 0.905 to 0.940 g/cm3 and blends of such copolymer with a second polymer, selected from a homopolymer of ethylene and a copolymer of ethylene and vinyl acetate, said second polymer having a density of from 0.910 to 0.940 g/cm3, said polyethylene having up to 70 wt.% of said second polymer, and wherein said film has a low crystallinity.
Preferably the article is cylindrical, and circular in cross-section.
In one embodiment the article has a ratio of length to height of at least about 1.5.
In another embodiment of the process the film is prestretched at least 400% immediately prior to wrapping the article.
In yet another embodiment the ethylene/C4-C10 a-olefincopolymer is an ethylene/octene-l copolymer having a density of from 0.910 to 0.930 g/cm3.
In a further embodiment the polyisobutene has a number average molecular weight of from 700 to 5000, especially from 900 to 3000.
In yet another embodiment the polymer blend has from 2 to 12 wt.% of polybutene, especially from 3 to 10 wt.%.
In a further embodiment the film is from 50 pm to 110 pm in thickness.
In yet another embodiment the article is a beam of paper, fabric or carpet.
Molecular weights of the polybutenes referred to herein, unless otherwise specified, are number average molecular weights determined using ASTM Procedure D-2503-67.
The term "polybutene" as used herein in lation to the present invention, refers to polymers .having a backbone predominantly based on n-butene or isobutylene. Polybutenes known in the trade as polyisobutylenes may be made by catalytically polymerizing an isobutylene-rich mixtures, with more 1- and 2-butenes being incorporated in the lower weight polyisobutylenes than in the higher molecular weight polyisobutylenes. Polybutenes may also be synthesized, by a low temperature catalytic process, from a refinery gas stream containing polymerizable olefins, particularly isobutylene.
The constituents of the composition of the film may be blended by methods known in the art, e.g.
the constituents may be preblended, the polybutene may be incorporated in a masterbatch concentrate and then "let down" by admixing with polyethylene, or the polybutene may be directly injected into the film extruder. The blend may be directly extruded into film form in a flat film or blown film process which causes the film to have low crystallinity, as described more fully hereinafter.
Crystallinity is not easily measured in films of the present invention but an indication of crystallinity may be given by the clarity of the film.
The blown film process is the preferred process for forming the film useful in the present invention. In the blown film process the polymer blend is extruded through a circular die. The resulting film is pulled from the die by cooperating nip rollers which collapse the tubular film at the nip. The tubular film, between the circular die and the nip is sometimes referred to as a bubble. While in the molten or plastic formative state the tubular film is expanded by air or inert gas admitted into the bubble trough an orifice in the centre of the circular die. The film may be cooled by directing air onto the exterior of the film while in the plastic formative state. The film is cooled until it is in the solid state. Cooling to the solid state is often referred to as quenching. The faster the film is cooled the lower the level of crystallinity.Fast quenching, in the blown film process, may be accomplished by passing the expanding film about a cooled mandrel which is situated within the bubble.
One such process, using a cooled mandrel, is disclosed in Canadian 893 216 which issued 1972 February 15 to M. Bunga and C.V. Thomas. Conventional blown film processes do not have rapid quenching.
It is to be understood that the films u#sed in the present invention may contain ultra-violet light stabilizers, pigments, antioxidants and other modifiers known in the art.
The invention may also be better understood by reference to the following examples: Example I: On a horizontal stretch wrapping apparatus, a large roll of non-woven fabric was attempted to be stretch wrapped with a 51 pm thick stretch wrap film (Control). Such film was made from a blend of polybutene and linear low density polyethylene, which had been made into film using a conventional blown film process. The apparatus was capable of prestretching film at ratios from 50 to 650%. The film yielded in a non-uniform manner, tend to lack high prestretch capability and have insufficient cling, at prestretch ratios of 50 to 100%. The film tended to stretch and then fail to stretch, forming transverse lanes 25 to 50 mm wide, 51 pm thick, followed by a length 1 Hm thick.The unstretched portions were hazy and the stretched portions were clear. Above stretch ratios of 100% the film tended to break more frequently, which caused a loss of productivity.
A similar film composition was blown int film form, using a blown film process in which there has a cooled metal mandrel inside the film bubble.
The film (Film A) was substantially more crystalline than the Control film, as evidenced by the clarity of the films. Film A was used to wrap large rolls of paper at prestretch ratios of 50, 100, 150, 200, 250, 300, 350, 400, 50, 500, 550, 600 and 650%. No film breaks were experienced over the entire prestretch ratio range. Additionally the film stretched evenly at all prestretch rations and cling properties were retained. Furthermore the film was crystal clear after stretching. This example clearly demonstrates the surprising improvement in performance of films having low crystallinity.

Claims (3)

CLAIMS:
1. A process for wrapping a large or heavy article with a stretch wrap film wherein the film is at least 45 pm thick and is made from a polymer blend, such blend comprising i) from 1 to 20 wt.% of at least one polybutene having a number average molecular weight of from 500 to 10 000 and ii) a polyethylene selected from the group consisting of at least one linear ethylene/C4-C10 a-olefin copolymer having a density of from 0.915 to 0.940 g/cm3 and blends of such copolymer with a second polymer, selected from a homopolymer of ethylene and a copolymer of ethylene and vinyl acetate, said second polymer having a density of from 0.910 to 0.940 g/cm3, said polyethylene having up to 70 wt.% of said second polymer, and wherein said film has a low crystallinity.
2. A process substantially as herein described and exemplified.
3. An article wrapped by a process according to claim 1 or claim 2.
GB9014181A 1990-06-26 1990-06-26 A stretch wrap film Withdrawn GB2245572A (en)

Priority Applications (10)

Application Number Priority Date Filing Date Title
GB9014181A GB2245572A (en) 1990-06-26 1990-06-26 A stretch wrap film
PCT/CA1991/000226 WO1992000344A1 (en) 1990-06-26 1991-06-21 Stretch wrapping of a horizontal beam
PL29716591A PL297165A1 (en) 1990-06-26 1991-06-21 Method of wrapping with shrinkable packaging foil
AU80052/91A AU641253B2 (en) 1990-06-26 1991-06-21 Stretch wrapping of a horizontal beam
HU9202208A HUT65769A (en) 1990-06-26 1991-06-21 Process for wrapping articles with stretch wrap films
EP91911377A EP0502132A1 (en) 1990-06-26 1991-06-21 Stretch wrapping of a horizontal beam
CA002072599A CA2072599C (en) 1990-06-26 1991-06-21 Stretch wrapping of a horizontal beam
NZ238679A NZ238679A (en) 1990-06-26 1991-06-24 Process of wrapping articles with stretch wrap film comprising a blend of
TW080104932A TW205016B (en) 1990-06-26 1991-06-25
NO922758A NO922758D0 (en) 1990-06-26 1992-07-13 TENSIONING OF A HORIZONTAL ROLL

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB9014181A GB2245572A (en) 1990-06-26 1990-06-26 A stretch wrap film

Publications (2)

Publication Number Publication Date
GB9014181D0 GB9014181D0 (en) 1990-08-15
GB2245572A true GB2245572A (en) 1992-01-08

Family

ID=10678208

Family Applications (1)

Application Number Title Priority Date Filing Date
GB9014181A Withdrawn GB2245572A (en) 1990-06-26 1990-06-26 A stretch wrap film

Country Status (9)

Country Link
EP (1) EP0502132A1 (en)
AU (1) AU641253B2 (en)
CA (1) CA2072599C (en)
GB (1) GB2245572A (en)
HU (1) HUT65769A (en)
NZ (1) NZ238679A (en)
PL (1) PL297165A1 (en)
TW (1) TW205016B (en)
WO (1) WO1992000344A1 (en)

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB0716457D0 (en) 2007-08-23 2007-10-03 Innovia Films Ltd Naked collation package

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3972964A (en) * 1973-12-26 1976-08-03 W. R. Grace & Co. Coating composition for polyethylene films comprising EPR and polybutene
GB2060658A (en) * 1979-05-10 1981-05-07 Asahi Dow Ltd Composition for production of cold drawn film
GB2063278A (en) * 1978-10-04 1981-06-03 Asahi Dow Ltd Composition for Production of Cold Drawn Film

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB8300074D0 (en) * 1983-01-04 1983-02-09 Du Pont Canada Blends of polyethylene and polybutenes
FR2580224A1 (en) * 1985-04-12 1986-10-17 Deome Plastiques Process and device for manufacturing, by extrusion, stretchable (drawable) films for bonding by surface adhesion, and multi-layer films obtained which are intended especially for the strapping of palletised products
EP0208634B1 (en) * 1985-07-01 1989-09-06 Rhone-Poulenc Chimie Maleimides and thermohardening compositions containing them
US4833017A (en) * 1987-04-17 1989-05-23 Mobil Oil Corporation Particle-impregnated one-sided cling stretch wrap film
ES2051307T5 (en) * 1987-11-19 1999-04-16 Exxon Chemical Patents Inc THERMOPLASTIC FILMS SUITABLE FOR USE IN STRETCH / ADHESION APPLICATIONS.

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3972964A (en) * 1973-12-26 1976-08-03 W. R. Grace & Co. Coating composition for polyethylene films comprising EPR and polybutene
GB2063278A (en) * 1978-10-04 1981-06-03 Asahi Dow Ltd Composition for Production of Cold Drawn Film
GB2060658A (en) * 1979-05-10 1981-05-07 Asahi Dow Ltd Composition for production of cold drawn film

Also Published As

Publication number Publication date
AU8005291A (en) 1992-01-23
NZ238679A (en) 1994-02-25
GB9014181D0 (en) 1990-08-15
EP0502132A1 (en) 1992-09-09
WO1992000344A1 (en) 1992-01-09
CA2072599A1 (en) 1991-12-27
PL297165A1 (en) 1993-09-06
AU641253B2 (en) 1993-09-16
HUT65769A (en) 1994-07-28
CA2072599C (en) 2003-10-07
TW205016B (en) 1993-05-01

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WAP Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1)