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EP-4741447-A1 - FILM

EP4741447A1EP 4741447 A1EP4741447 A1EP 4741447A1EP-4741447-A1

Abstract

In an embodiment of the present invention, in a film in which polypropylene is dispersed in polyethylene, deterioration in quality due to polypropylene can be suppressed. In a film according to the embodiment of the present invention, a dispersed phase is dispersed in a matrix phase. The film includes a matrix phase containing polyethylene and a dispersed phase containing polypropylene. The dispersed phase includes at least a flat phase oriented in an MD direction and the flat phase has an average aspect ratio of 15 or more.

Inventors

  • FUKUDA, YUKI
  • NIITSU, TAICHI

Assignees

  • Kao Corporation

Dates

Publication Date
20260513
Application Date
20230705

Claims (20)

  1. A film in which a dispersed phase is dispersed in a matrix phase, comprising: a matrix phase containing polyethylene; and a dispersed phase containing polypropylene, the dispersed phase including at least a flat phase oriented in an MD direction, the flat phase having an average aspect ratio of 15 or more.
  2. The film according to claim 1, wherein a ratio of a total cross-sectional area of the flat phase to a total cross-sectional area of the dispersed phase in an image of the film taken with a transmission electron microscope is 60% or more.
  3. The film according to claim 1 or 2, wherein the dispersed phase further includes a spherical phase that includes a resin and has an aspect ratio of 3 or less.
  4. The film according to claim 3, wherein the spherical phase further contains at least one of polyethylene terephthalate or polyurethane.
  5. The film according to any one of claims 1 to 4, wherein the dispersed phase further includes an inorganic material phase.
  6. The film according to any one of claims 1 to 5, wherein a ratio of a total cross-sectional area of polyethylene to a total cross-sectional area of the film in an image of the film taken with a transmission electron microscope is 50% or more and 99% or less.
  7. The film according to any one of claims 1 to 6, wherein a ratio of a total cross-sectional area of polypropylene to a total cross-sectional area of the film in an image of the film taken with a transmission electron microscope is 1% or more and 50% or less.
  8. The film according to any one of claims 1 to 7, which has a tensile elongation of 700% or more.
  9. The film according to any one of claims 1 to 8, which has tensile strength of 0.23 N/(µm · cm) or more.
  10. The film according to any one of claims 1 to 9, which has tear strength of 0.015 N/ µm or more.
  11. The film according to any one of claims 1 to 10, which has MMD by a KES surface test of 0.05 or less.
  12. The film according to any one of claims 1 to 11, which has SMD by a KES surface test of 3.0 or less.
  13. The film according to any one of claims 1 to 12, wherein glossiness of a surface of the film is 80 or less.
  14. The film according to any one of claims 1 to 13, wherein wettability of a surface of the film is 40 mN/m or more.
  15. The film according to any one of claims 1 to 14, wherein waste derived from an absorbent article is used as part of a raw material.
  16. A method of producing a film in which a dispersed phase is dispersed in a matrix phase, comprising: molding a kneaded product into a film, the kneaded product being obtained by kneading a first raw material that contains polyethylene and constitutes the matrix phase and a second raw material containing polypropylene as a component constituting the dispersed phase, a ratio ηB/ηA of viscosity ηB of polypropylene contained in the second raw material at a molding temperature during the molding of the film to viscosity ηA of the first raw material at the molding temperature being 0.015 or more and less than 1.
  17. The method of producing a film according to claim 16, wherein the second raw material includes waste derived from an absorbent article.
  18. The method of producing a film according to claim 16 or 17, wherein a single-screw extruder is used to knead the first raw material and the second raw material.
  19. The method of producing a film according to any one of claims 16 to 18, wherein the kneaded product is molded into a film using an inflation molding method.
  20. The method of producing a film according to any one of claims 16 to 19, wherein the second raw material further includes, as a component constituting the dispersed phase, at least one of a thermoplastic resin or a thermosetting resin having a melting point 100°C or more higher than that of the first raw material.

Description

Technical Field The present invention relates to a film containing polyethylene. Background Art A technology has been known that recycles polyethylene films (see, for example, Patent Literature 1). The technology described in Patent Literature 1 allows used polyethylene films to be regenerated into new polyethylene films by providing a special cleaning process for sufficiently cleaning mud and the like adhered to the polyethylene films used in fields or the like. There is also known a technology that recycles waste resin films whose main component is a resin other than polyethylene as one component of polyethylene films (see, for example, Patent Literature 2). This technology allows the amount of virgin materials of polyethylene used to be reduced by the amount of waste resin films in the production of polyethylene films. Citation List Patent Literature Patent Literature 1: Japanese Patent Application Laid-open No. 2002-052532Patent Literature 2: Japanese Patent Application Laid-open No. 2004-182957 Disclosure of Invention In a film according to an embodiment of the present invention, a dispersed phase is dispersed in a matrix phase. The film includes a matrix phase containing polyethylene and a dispersed phase containing polypropylene. The dispersed phase includes at least a flat phase oriented in an MD direction and the flat phase has an average aspect ratio of 15 or more. In a method of producing a film in which a dispersed phase is dispersed in a matrix phase according to an embodiment of the present invention, a kneaded product is molded into a film, the kneaded product being obtained by kneading a first raw material that contains polyethylene and constitutes the matrix phase and a second raw material containing polypropylene as a component constituting the dispersed phase. A ratio ηB/ηA of viscosity ηB of polypropylene contained in the second raw material at a molding temperature during the molding of the film to viscosity ηA of the first raw material at the molding temperature is 0.015 or more and less than 1. Brief Description of Drawings [Fig. 1] Fig. 1 is a diagram schematically showing a partial cross section of a film according to an embodiment of the present invention.[Fig. 2] Fig. 2 is a flowchart showing a method of producing the film.[Fig. 3] Fig. 3 is a TEM image of the cross section of a kneaded product obtained in a kneading step.[Fig. 4] Fig. 4 is a TEM image of the MD cross section of a film obtained in a film molding step.[Fig. 5] Fig. 5 is a TEM image of the TD cross section of the film obtained in the film molding step.[Fig. 6] Fig. 6 is a TEM image of the MD cross section of a film according to Comparative Example.[Fig. 7] Fig. 7 is a TEM image of the MD cross section of a film according to Example 4.[Fig. 8] Fig. 8 is a TEM image of the MD cross section of a film according to Example 24. Detailed Description of the Invention Absorbent articles such as diapers and sanitary napkins contain many resin-based components, and thus, recycling waste absorbent articles is highly significant. However, when polypropylene, which is abundant in absorbent articles, is used as a component of a polyethylene film, it tends to impair the quality of the polyethylene film in terms of strength, elongation, a smooth feel, and the like. The present invention relates to suppressing deterioration in quality due to polypropylene in a film in which polypropylene is dispersed in polyethylene. A film according to an embodiment of the present invention and a method of producing the same will be described. [Configuration of film] The film according to this embodiment includes a matrix phase and a dispersed phase, and has a configuration in which the dispersed phase is dispersed in the matrix phase. The matrix phase contains polyethylene. The dispersed phase includes a flat phase containing polypropylene. In Fig. 1, the right-and-left direction of the page corresponds to an MD direction (Machine Direction: flow direction of resin molding) of the film, the depth direction of the paper corresponds to a TD direction (Transverse Direction: direction orthogonal to MD) of the film, and the up-and-down direction of the paper corresponds to the thickness direction of the film. Each flat phase of the film according to this embodiment has a flat shape with an aspect ratio of 5 or more, is oriented in at least the MD direction of the in-plane direction, and is preferably oriented also in the TD direction. Further, the average aspect ratio of the flat phase of the film according to this embodiment, which is defined as the average value of the aspect ratios of the flat phase, is 15 or more, preferably 20 or more. Further, the average aspect ratio of the flat phase of the film according to this embodiment is preferably 100 or less, more preferably 50 or less, from the viewpoint of maintaining preferable low-temperature heat sealability. Each flat phase preferably extends omnidirectionally in the in-plane direction, but may ext