Search

EP-4735349-A1 - COMPOSTABLE HIGH BARRIER FILM AND METHODS OF CONSTRUCTING THE SAME

EP4735349A1EP 4735349 A1EP4735349 A1EP 4735349A1EP-4735349-A1

Abstract

A compostable high barrier film having a thickness comparable to traditional non-compostable films for use in packaging and a method of manufacture. The compostable high barrier film includes a compostable outer film defining a first exterior surface, a sealing layer defining a second exterior surface and having a thickness in a range of about 2 micron to 15 micron, a barrier layer positioned between the sealing layer and the compostable outer film, and an adhesive layer positioned between the barrier layer and the compostable outer film with the compostable high barrier film having a thickness in the range of about 20 micron to 50 micron. The compostable high barrier film is manufactured from a pair of separate film structures that are laminated together and subsequently deconstructed to form a compostable high barrier film having a thickness that is considered comparable to traditional non-compostable films.

Inventors

  • ELIAS, Marcelo B.
  • GRUETZMACHER, Ross K.
  • BERBERT, OTACILIO T.

Assignees

  • Amcor Flexibles North America, Inc.

Dates

Publication Date
20260506
Application Date
20230627

Claims (20)

  1. 1 . A compostable packaging film displaying high barrier properties, the compostable packaging film comprising: a compostable outer film defining a first exterior surface of the compostable packaging film; a sealing layer defining a second exterior surface of the compostable packaging film, the sealing layer having a sealing layer thickness in a range from about 2 micron to 15 micron; a vacuum deposited barrier layer, the vacuum deposited barrier layer positioned between the compostable outer film and the sealing layer; and an adhesive layer, the adhesive layer positioned between the vacuum deposited barrier layer and the compostable outer film; wherein the compostable packaging film comprises a thickness in the range of from 20 micron to 50 micron.
  2. 2. The compostable packaging film of claim 1 , wherein the compostable outer film has a thickness in a range from about 10 micron to 40 micron or from about 15 micron to 30 micron.
  3. 3. The compostable packaging film of claim 1 , wherein the compostable packaging film has a water vapor transmission rate (WVTR) according to ASTM F1249 of less than 0.5g/m 2 /24 hours at 38°C and 90% relative humidity and an oxygen transmission rate (OTR) according to ASTM F1927 of about less than 0.5 cc/m 2 /24 hours at 23°C and 0% relative humidity.
  4. 4. The compostable packaging film of claim 1 , wherein the sealing layer comprises a compostable polymer.
  5. 5. The compostable packaging film of claim 1 , wherein the sealing layer comprises one or more of an amorphous polylactic acid polymer (aPLA), a polyhydroxyalkanoate polymer (PHA), a vinyl alcohol copolymer, a cyclic olefin copolymer, a polyethylene (metallocene) or blends thereof.
  6. 6. The compostable packaging film of claim 1 , further comprising a printed indicia layer located on a non-exposed surface of the compostable outer film.
  7. 7. The compostable packaging film of claim 1 , wherein the compostable outer film is oriented.
  8. 8. The compostable packaging film of claim 1 , wherein the compostable outer film comprises at least one of a polylactic acid polymer (PLA), a polyhydroxyalkanoate polymer (PHA), a polybutylene adipate terephthalate polymer (PBAT), polybutylene succinate (PBS), polyhydroxybutyrate (PHB), a cellophane, a compostable paper or a cellulose acetate.
  9. 9. A thin compostable packaging film displaying high barrier properties, the thin compostable packaging film comprising: a compostable outer film having an exposed side and a non-exposed side, the exposed side located at a first exterior surface of the compostable packaging film; a sealing layer, the sealing layer comprising a compostable polymer and located at a second exterior surface of the compostable packaging film; a barrier layer, the barrier layer located on the sealing layer opposite the second exterior surface at a non-exposed surface of the sealing layer; a printed indicia layer, the printed indicia layer on the non-exposed side of the compostable outer film; and an adhesive layer, the adhesive layer bonding the barrier layer to the printed indicia layer; wherein the compostable packaging film comprises a thickness in the range of from about 20 micron to 50 micron.
  10. 10. The compostable packaging film of claim 9, wherein the sealing layer has a sealing layer thickness in a range of about from 2 micron to 10 micron.
  11. 1 1 . The compostable packaging film of claim 10, wherein the barrier layer is a vacuum deposited metal layer.
  12. 12. The compostable packaging film of claim 10, wherein the compostable polymer of the sealing layer is an amorphous polylactic acid polymer (aPLA), a poly(vinyl alcohol) (PVOH), a butanediol vinyl alcohol copolymer (BVOH), or combinations thereof.
  13. 13. A method of producing a compostable high barrier packaging film comprising the steps of: providing a multilayer film comprising one or more base layers and a sealing layer, the sealing layer having an exposed surface; coating the exposed surface of the sealing layer of the multilayer film with a vacuum deposited barrier layer by a vacuum deposition process to produce a multilayer barrier film; attaching a compostable outer film to the vacuum deposited barrier layer of the multilayer barrier film by adhesive lamination process to produce an intermediate structure; and removing the one or more base layers from the intermediate structure to yield the compostable packaging film comprising the compostable outer film, the vacuum deposited barrier layer, and the sealing layer; wherein the compostable outer film is located at a first exterior surface of the compostable packaging film and the sealing layer is located at a second exterior surface of the compostable packaging film.
  14. 14. The method of claim 13, wherein the sealing layer comprises a sealing layer thickness in a range of from about 2 micron to 10 micron.
  15. 15. The method of claim 13, wherein the compostable high barrier packaging film comprises a thickness of from about 25 micron to 40 micron.
  16. 16. The method of claim 13 further comprising a single transfer operation comprising attaching the compostable outer film to the vacuum deposited barrier layer of the multilayer barrier film and removing the one or more base layers from the intermediate structure.
  17. 17. The method of claim 13, wherein the one or more base layers comprises a delamination layer in direct contact with the sealing layer and the step of removing the one or more base layers from the intermediate structure comprises separation of the delamination layer from the sealing layer.
  18. 18. The method of claim 17, wherein the delamination layer comprises an incompatible polyolefin chemically modified to promote slight adhesion to avoid premature delamination during conversion.
  19. 19. The method of claim 18, wherein the delamination layer comprises an ethylene vinyl acetate polymer.
  20. 20. The method of claim 13, wherein the coating step comprises application of aluminum in a vacuum metallizer resulting in a multilayer barrier film having an optical density in the range of from 4.5 to 6.0, a water vapor transmission rate (WVTR) according to ASTM F1249 of less than 0.5g/m 2 /24 hours at 38°C and 90% relative humidity, an optical density greater then about 3.0, and metal adhesion higher than about 400gf/in.

Description

COMPOSTABLE HIGH BARRIER FILM AND METHODS OF CONSTRUCTING THE SAME TECHNICAL FIELD [001 ] This disclosure is related to compostable multilayer films that are suitable for packaging food products that require high barrier properties and are capable of being produced in a thickness comparable to traditional non- compostable films. More particularly, the disclosure is related to a thin and compostable film structure for use in packaging snacks and confections and a method of constructing the same. BACKGROUND [002] It has become increasingly desirable to design flexible packaging structures that are more sustainable. One sustainable solution is the use of a film or film laminate having a compostable structure comprising compostable polymers. A compostable structure is generally defined as comprising biodegradable polymeric materials which can be digested by micro-organisms within a given environment to degrade over time at a consistent rate into water, CO2, biomass, and inorganic compounds without leaving any visible residue or toxic residue. More particularly, if compostable, the packaging should be able to fulfill well established compostable standards, such as the standard established by ASTM D6400, that require disintegration and biodegradation at industrial and home composting conditions (12 weeks at 58°C or 26 weeks at 21 °C, respectively) to conform to chemical characterization and ecotoxicity requirements. [003] Despite the obvious sustainable value, these compostable structures and compostable polymers, in general, are disfavored in certain applications requiring a barrier. Further, typical compostable structures, due to manufacturing limitations requiring tenter frame assets, are generally produced in a thickness that is considered much thicker than a traditional non- compostable structure, such as the thickness of an oriented polypropylene (OPP) film. [004] The typical non-compostable film structure used within the snack and confection industries is a biaxially oriented polypropylene (BOPP) laminate produced from a blown, cast, or machine direction orientation (MDO) film machine and includes a metallized layer with an overall final thickness of about 30 micron (1 .2 mil). These typical films are considered thin and high barrier wherein it is desired to have water vapor transmission rates (WVTR) of about below 0.3 g/m2/day (38°C, 90% R.H.) when tested according to ASTM F1249 for Water Vapor Transmission Rate Through Plastic Film and Sheeting Material Using a Modulated Infrared Sensor. SUMMARY [005] The developments described herein include multilayer structures that can expand the applicability of compostable materials by providing high barrier and thin packages for particular use in packaging snacks and confections. The compostable high barrier film comprises a compostable outer film defining a first exterior surface of the compostable high barrier film. A sealing layer defines a second exterior surface of the compostable high barrier film, with this sealing layer having a sealing layer thickness in a range from about 2 micron to 15 micron. A barrier layer is positioned between the compostable outer film and the sealing layer. An adhesive layer is positioned between the barrier layer and the compostable outer film with the compostable high barrier film having an overall thickness in a range of from 20 micron to 50 micron. This compostable high barrier film structure provides a compostable film having high barrier properties and a thickness comparable to more traditional and non-compostable structures for use in packaging. [006] The compostable resins for the compostable high barrier film are selected from the group comprising at least one of a polylactic acid (PLA) polymer, amorphous polylactic acid (aPLA), polybutylene adipate terephthalate (PBAT) polymer, polybutylene succinate (PBS) polymer, polyhydroxyalkanoates (PHAs), polyhydoxybutyrate (PHB), 4- hydroxybenzoate hydroxylase (PHBH), cellulose acetate (CA), poly(vinyl alcohol) (PVOH), a cellophane, a compostable paper, or combinations thereof. [007] The sealing layer defining the second exterior surface of the compostable high barrier film is generally provided from a sealant structure that is produced from a coextruded polyolefinic based film comprising a layered structure having distinct compostable and polyolefinic layers to promote controlled delamination resulting in the final compostable high barrier film for packaging. Accordingly, the compostable layers of the coextruded film are coated with the barrier layer being of the type of barrier that could be considered high barrier, such as, but not limited to, a metal or an inorganic deposition that is liquid coated or deposited for forming the barrier layer. This barrier layer may be a vacuum deposited barrier layer. Alternately, this barrier layer may be deposited by way of an atmospheric atomic layer deposition. The sealant structure including the barrier layer is laminated via the adh