Classifications

• • 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
  • B29C71/00—After-treatment of articles without altering their shape; Apparatus therefor
• • 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
  • B29C43/00—Compression moulding, i.e. applying external pressure to flow the moulding material; Apparatus therefor
  • B29C43/02—Compression moulding, i.e. applying external pressure to flow the moulding material; Apparatus therefor of articles of definite length, i.e. discrete articles
  • B29C43/10—Isostatic pressing, i.e. using non-rigid pressure-exerting members against rigid parts or dies
• • 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
  • B29K2067/00—Use of polyesters or derivatives thereof, as moulding material
• • 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
  • B29K2995/0065—Permeability to gases
  • B29K2995/0067—Permeability to gases non-permeable
• • 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
• • 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
  • Y10T428/31938—Polymer of monoethylenically unsaturated hydrocarbon

Definitions

• the present invention relates to a material which has a high degree of impermeability to gases, especially to atmospheric oxygen, and which is particularly suitable for the manufacture of containers for easily oxidizable foods or beverages, such as, for example, beer, milk, "soft drinks", and fruit juices.
• oxidizable beverages are beer, diary products and "soft drinks".
• the latter term is intended to define, in particular, tea and isotonic beverages or beverages supplemented with vitamins or other organic ingredients such as to render them difficult to preserve.
• the problem underlying the present invention is therefore to provide a low-cost material having a high degree of impermeability to oxygen.
• polymeric material is intended preferably to define a thermoplastic material and, more preferably, a single- layer or multi-layer, flexible or semi-rigid material composed of polymers, preferably selected from low- density and high-density polyethylene, polypropylene, PEN, EVOH, polyethylene terephthalate, copolymers and blends thereof, possibly additionally including nylon and/or scavangers.
• the layers are not generally of the same material, but are selected from materials of different types .
• thermoplastic material is a single layer of polyethylene terephthalate.
• the method for the production of a polymeric material with high degree of impermeability to oxygen is not limited to materials for containers but extends generally to materials of various types for different uses.
• Other polymeric materials which fall within the scope of the present invention are in fact materials having a substantially fibrous structure such as, for example, textile fibres.
• Other examples of suitable polymeric materials are so-called "non-woven fabrics”.
• containers is intended to define containers of all types (including closure) which are made of a material, preferably a non-rigid material, that comprises at least one layer formed of polymeric material as defined above. Examples of these containers are beverage bottles of any shape and size, containers for preserving foods, packages of the Tetrapack® type, and containers of any type for holding liquids.
• the containers may be made purely of the polymeric material of the present invention or of a multi-layer material comprising, for example, in addition to the polymeric material according to the present invention, a card layer and/or an aluminium layer and/or a layer of plastics material which is not treated in accordance with the present invention.
• the "original" thermoplastic material (that is, the material produced by the polymerization process or resulting from the immediately subsequent extrusion process, for example, for the production of parisons) has preferably undergone a deformation outside its elastic range such as, for example, a blowing, stretching, pressing or injection-moulding process.
• This deformation outside the elastic range preferably follows a step for heating/softening the material .
• the pressures applied to the thermoplastic material according to the present invention are pressures greater than 500 bar, preferably between 4000 and 9000 bar, even more preferably between 5000 and 7000 bar.
• the high-pressure treatment according to the present invention is carried out by applying to the material temperatures generally of between -10°C and 60°C, preferably between 10°C and 30°C.
• the polymeric material will generally be subject to actual temperatures of between 0°C and 80°C during the process.
• the high-pressure treatment may be carried out in known apparatus such as hyperbaric chambers which are filled with a fluid (for example, water or oil) and in which the pressure is raised to the desired pressure progressively over a predetermined period of time.
• a fluid for example, water or oil
• the material is then subjected to the high pressure for a period of time which may vary from a few seconds to an hour or more.
• the material may be subjected to a cycle of compressions-decompressions having an overall duration no greater than a few minutes, typically from 1 second to 2 minutes.
• Apparatus suitable for implementing the high-pressure process according to the present invention is that described in European patent application No. 99830254.1 of 29.04.1999 in the name of the same applicant, of which the description relating to this apparatus is incorporated herein by reference.
• This patent application describes a hydrostatic device which can impart a pressure of up to 10,000 bar inside a pressurization chamber in which an individual container can be inserted.
• the pressurization chamber on which a piston acts, is filled with water or other incompressible fluid.
• the pressure imparted by the piston is transmitted isostatically to the surface of the container and to the liquid held in the container.
• the piston is connected to a pressure-multiplying system which acts upstream.
• the piston is in communication with a chamber filled with an incompressible fluid which is acted on by a second piston the acting area of which is smaller than that of the first piston.
• the application of a small pressure to the second piston thus brings about a multiplication of the pressure up to a few thousand bar, by Pascal's principle, and this pressure can also be reached within an infinitesimal period of time.
• the polymeric material may be treated at high pressures in any form, for example, in sheet form or already moulded in the form of bottles or other containers .
• the container may be subjected to the high-pressure treatment when it has already been filled with the beverage and sealed.
• the permeability to oxygen (the oxygen transmission rate) of the material treated at high pressures in accordance with the present invention has been determined in accordance with the ASTM F1307-90 standard which provides for the isostatic method and for the use of MoCon OX-TRAN 2/20 instrumentation operating, in this case, at 20°C and 0% RH.
• the test was performed on 333 ml PET bottles weighing 25 g.
• the bottles were glued to a metal support to which two 1/8" copper tubes with 1/8" SWAGELOK connectors were welded.
• the sample thus assembled was connected to the inner half-cell of the apparatus.
• the carrier nitrogen + 2% hydrogen
• the carrier was caused to flow inside the sample and the oxygen of the air which penetrated the system from the environment was carried to the coulometric sensor by the carrier.
• the amount of oxygen which reached the detector through the bottle was assessed.
• the permeability of the bottle to oxygen was given by the difference in the signal produced by the detector, in stationary conditions, in the two stages:
• the permeability to carbon dioxide (the C0 2 transmission rate) of the material treated at high pressures in accordance with the present invention has been determined by MoCon Permatran-C 4/40 instrumentation operating, in this case, at 20°C and at ambient RH. The test was performed on 330 ml PET bottles weighing 25 g.
• Each bottle was introduced in a metallic chamber and glued to a metal support to which two 1/8" copper tubes with 1/8" S AGELOK connectors were welded.
• the sample thus assembled was connected to the inner half- cell of the apparatus.
• the carrier nitrogen
• the carrier was caused to flow inside the sample and the dry C0 2 in the metallic chamber (100% C0 2 ) .
• the carbon dioxide penetrated through the bottle wall was carried to the IR sensor by the carrier.
• Figure 1 shows an electron-microscope image of the structure of blown PET from a 333 ml bottle weighing 25 g-
• Figure 2 is an enlarged electron-microscope image of the blown PET structure of the bottle of Figure 1
• Figure 3 is an electron-microscope image, with the same enlargement as Figure 1, of the blown PET structure of the bottle of Figure 1 after treatment at 6000 bar.
• PET which has undergone deformation outside its elastic range, for example, by blowing, has a fibrous/laminar structure.
• Figure 2 there is a separation of a few microns between one fibre or lamina and another, to which the high degree of permeability of the material can substantially be attributed.
• FIG. 3 The electron-microscope photograph shows a structure which is substantially compact or in any case with a compacted or reduced space between the fibres, so as to create a greater barrier to atmospheric oxygen for a given thickness and degree of stretch of the material .
• PET to oxygen varies in dependence both on the thickness of the sheet and on the degree of deformation outside the elastic range which it has undergone. These parameters in turn depend on parison weight and on bottle size; for a given parison weight, the material will be thinner and more deformed the larger is the volume of the bottle blown; conversely, for a given bottle size, the degree of deformation of the material will be greater for parisons of small weight and length.

Landscapes

• Wrappers (AREA)
• Packages (AREA)
• Laminated Bodies (AREA)
• Processing And Handling Of Plastics And Other Materials For Molding In General (AREA)

Priority Applications (1)

Applications Claiming Priority (4)

Publications (1)

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Family Cites Families (5)

• 2001
  • 2001-06-05 US US10/297,726 patent/US20040091728A1/en not_active Abandoned
  • 2001-06-05 AR ARP010102673A patent/AR030290A1/es unknown
  • 2001-06-05 EP EP01945256A patent/EP1289737A1/de not_active Withdrawn
  • 2001-06-05 AU AU2001267525A patent/AU2001267525A1/en not_active Abandoned
  • 2001-06-05 WO PCT/EP2001/006387 patent/WO2001094102A1/en not_active Application Discontinuation

Non-Patent Citations (1)

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