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EP-4741160-A1 - PACKAGING FILM, PACKAGING CONTAINER, AND PACKAGING PRODUCT

EP4741160A1EP 4741160 A1EP4741160 A1EP 4741160A1EP-4741160-A1

Abstract

A packaging film includes a gas barrier film, an adhesive layer, and a sealant layer in this order. The gas barrier film includes a substrate layer, a vapor deposition layer, and a coating layer provided between the vapor deposition layer and the adhesive layer to cover the vapor deposition layer. The substrate layer includes a polyolefin substrate layer containing a polyolefin-based resin, and the coating layer has a hardness of 1.15 GPa or less measured in a cross section thereof using a nanoindentation method. The adhesive layer is obtained by bonding an adhesive resin composition containing a polyolefin adhesive resin to the gas barrier film by melt extrusion, and the sealant layer contains a polyolefin-based resin.

Inventors

  • OTSUKA HIROYUKI
  • ITO YUTAKA
  • NISHIHARA TSUGUKI
  • OCHIAI SHINYA
  • TOMATSURI TAKEO

Assignees

  • Toppan Holdings Inc.

Dates

Publication Date
20260513
Application Date
20240401

Claims (8)

  1. A packaging film comprising a gas barrier film, an adhesive layer, and a sealant layer in this order, wherein the gas barrier film includes a substrate layer, a vapor deposition layer, and a coating layer provided between the vapor deposition layer and the adhesive layer to cover the vapor deposition layer; the substrate layer includes a polyolefin substrate layer containing a polyolefin-based resin; the coating layer has a hardness of 1.15 GPa or less measured in a cross section thereof using a nanoindentation method; the adhesive layer is obtained by bonding an adhesive resin composition containing a polyolefin adhesive resin to the gas barrier film by melt extrusion; and the sealant layer contains a polyolefin-based resin.
  2. The packaging film according to claim 1, wherein the coating layer is a gas barrier coating layer.
  3. The packaging film according to claim 1, wherein the polyolefin substrate layer is a stretched film.
  4. The packaging film according to claim 1, wherein the gas barrier film further includes an anchor coat layer containing a polyurethane resin between the vapor deposition layer and the substrate layer.
  5. The packaging film according to claim 1, wherein the coating layer has a hardness of 0.8 Gpa or less measured in a cross section thereof using a nanoindentation method.
  6. The packaging film according to claim 1, wherein the coating layer has a hardness of 0.15 Gpa or more measured in a cross section thereof using a nanoindentation method.
  7. A packaging container comprising the packaging film according to any one of claims 1 to 6.
  8. A packaged product comprising the packaging container according to claim 7, and contents filled in the packaging container.

Description

[Technical Field] The present disclosure relates to packaging films, packaging containers, and packaged products. [Background Art] In recent years, packaging films are increasingly being made from mono-materials to facilitate material recycling. On the other hand, packaging materials are also required to maintain functions such as gas barrier properties. In contrast, packaging films are under consideration which include a gas barrier film, which is formed by providing a gas barrier layer by vapor deposition on a polyolefin substrate layer containing a polyolefin-based resin and a polyolefin sealant layer containing a polyolefin-based resin, with these layers bonded together by dry lamination using an adhesive forming a non-polyolefin-based resin. However, such packaging films, which use adhesives forming non-polyolefin-based resins, may deteriorate the quality of the recycled resins obtained from material recycling of the packaging films. Therefore, in order to suppress deterioration of the quality of recycled resins, laminates are known which use, as an adhesive layer, an adhesive resin composition containing a polyolefin adhesive resin such as maleic anhydride graft-polymerized polypropylene, in place of an adhesive forming a non-polyolefin-based resin (see PTL 1 below). [Citation List] [Patent Literatures] PTL 1: JP2020049679A [Summary of the Invention] [Technical Problem] However, although the laminate described in PTL 1 can increase the ratio of polyolefin-based resins in the entire laminate, there is still room for improvement in terms of gas barrier properties. The present disclosure has been made in light of the issues mentioned above and aims to provide a packaging film which can suppress decrease in the ratio of polyolefin-based resins in the entire packaging film, while exhibiting excellent gas barrier properties, and to provide a packaging container and a packaged product. [Solution to Problems] In order to solve the above issues, an aspect of the present disclosure provides a packaging film including a gas barrier film, an adhesive layer, and a sealant layer in this order, wherein the gas barrier film includes a substrate layer, a vapor deposition layer, and a coating layer provided between the vapor deposition layer and the adhesive layer to cover the vapor deposition layer; the substrate layer includes a polyolefin substrate layer containing a polyolefin-based resin; the coating layer has a hardness of 1.15 GPa or less measured in a cross section thereof using a nanoindentation method; the adhesive layer is obtained by bonding an adhesive resin composition containing a polyolefin adhesive resin to the gas barrier film by melt extrusion; and the sealant layer contains a polyolefin-based resin. According to the above packaging film, decrease in the ratio of polyolefin-based resins in the entire packaging film can be suppressed, while exhibiting excellent gas barrier properties. The inventors of the present disclosure presume that the reasons for the above effect are as follows. That is, after bonding of an adhesive resin composition containing a polyolefin adhesive resin to a gas barrier film by melt extrusion, the adhesive resin composition is at a high temperature when it comes into contact with the gas barrier film, but is then cooled by a cooling roll to a low temperature and contracts. In this case, the contraction stress is not necessarily transmitted directly to the vapor deposition layer, but may be transmitted indirectly via the coating layer. The coating layer, which is sufficiently soft as having a hardness of 1.15 GPa or less, may effectively mitigate the expansion and contraction stresses. Therefore, expansion and contraction of the vapor deposition layer may be suppressed to thereby suppress expansion and contraction of the fragile vapor deposition layer. Consequently, the packaging film may be able to have excellent gas barrier properties. Furthermore, the gas barrier film, which includes a sufficiently soft coating layer, can effectively suppress expansion and contraction of the vapor deposition film, although the gas barrier film is thin. Therefore, decrease in the ratio of polyolefin-based resins in the entire packaging film can be suppressed. In the above packaging film, the coating layer is preferably a gas barrier coating layer. In this case, gas barrier properties of the packaging film are improved. Furthermore, even if damage such as cracking occurs in the vapor deposition layer, deterioration in gas barrier properties of the packaging film can be suppressed. In the packaging film, it is preferable that the polyolefin substrate layer is a stretched film. In this case, crystallinity of the polyolefin substrate layer and the heat-resistant layer included in the substrate layer is improved to raise the melting point, and therefore the difference in melting point between the sealant layer and the substrate layer can be increased, and thus melting of the substrate layer can be