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JP-7855609-B2 - Biaxially oriented film

JP7855609B2JP 7855609 B2JP7855609 B2JP 7855609B2JP-7855609-B2

Inventors

  • オービー、ノーマン
  • ギロン、ブロンウィン
  • キャレロ、クリスチャン
  • テイラー、ジャレッド
  • フェレイドゥーン、マリアム
  • ゴヤール、シヴェンドラ
  • ライトボディー、オーウェン

Assignees

  • ノバ ケミカルズ（インターナショナル）ソシエテ アノニム

Dates

Publication Date
20260508
Application Date
20220414
Priority Date
20210419

Claims (20)

  1. A biaxially oriented polyethylene film structure comprising at least three layers, The three adjacent layers are, i) A first polyethylene comprising 50 to 99.5% by weight, wherein the first polyethylene is an ethylene copolymer having a density greater than 0.940 g/ cm³ , ii) A second polyethylene comprising 0.5 to 50% by weight, wherein the second polyethylene is a polyethylene homopolymer composition having a density of at least 0.950 g/ cm³ , A polyethylene homopolymer composition contains a nucleating agent or a mixture of nucleating agents. Biaxially oriented polyethylene film structure.
  2. The biaxially oriented polyethylene film structure according to claim 1, wherein the polyethylene homopolymer composition has a density of 0.952 to 0.975 g/ cm³ .
  3. The biaxially oriented polyethylene film structure according to claim 1, wherein the polyethylene homopolymer composition has a melt index of 0.5 to 5 g/10 min.
  4. A polyethylene homopolymer composition i) 5 to 70% by weight of a first ethylene homopolymer having a density of 0.950 to 0.975 g/ cm³ , ii) comprising 95 to 30% by weight of a second ethylene homopolymer having a density of 0.950 to 0.975 g/ cm³ , The ratio of the melt index I² of the second ethylene homopolymer to the melt index I² of the first ethylene homopolymer is at least 10. The biaxially oriented polyethylene film structure according to claim 1.
  5. The biaxially oriented polyethylene film structure according to claim 1, wherein the first polyethylene has a density of 0.941 to 0.962 g/ cm³ .
  6. The biaxially oriented polyethylene film structure according to claim 1, wherein the first polyethylene has a melt index of 0.5 to 5.0 g/10 min.
  7. The biaxially oriented polyethylene film structure according to claim 1, wherein the first polyethylene has a molecular weight distribution of 3.0 to 20.0.
  8. The biaxially oriented polyethylene film structure according to claim 1, wherein the first polyethylene has a molecular weight distribution of 8.5 to 20.0.
  9. The biaxially oriented polyethylene film structure according to claim 1, wherein the first polyethylene has a Z-average molecular weight Mz of at least 500,000 g/mol.
  10. The biaxially oriented polyethylene film structure according to claim 1, wherein the polyethylene homopolymer composition comprises 100 to 3,000 ppm (based on the weight of the polyethylene homopolymer composition) of a nucleating agent or a mixture of nucleating agents.
  11. The biaxially oriented polyethylene film structure according to claim 1, wherein the nucleating agent or mixture of nucleating agents comprises a salt of a dicarboxylic acid.
  12. Each of the three adjacent layers, i) 70-99.5% by weight of a first polyethylene, ii) The biaxially oriented polyethylene film structure according to claim 1, comprising 0.5 to 30% by weight of a second polyethylene.
  13. Each of the three adjacent layers, i) 90-99.5% by weight of a first polyethylene, ii) The biaxially oriented polyethylene film structure according to claim 1, comprising 0.5 to 10% by weight of a second polyethylene.
  14. A biaxially oriented polyethylene film structure according to claim 1, having a haze value of less than 15%.
  15. A biaxially oriented polyethylene film structure according to claim 1, having a transparency value exceeding 80%.
  16. A biaxially oriented polyethylene film structure, The core layer, The first skin layer adjacent to the first side of the core layer, Including a second skin layer adjacent to the second side of the core layer, Each of the layers, the core layer, the first skin layer, and the second skin layer, i) A first polyethylene comprising 50 to 99.5% by weight, wherein the first polyethylene is an ethylene copolymer having a density greater than 0.940 g/ cm³ , ii) A second polyethylene comprising 0.5 to 50% by weight, wherein the second polyethylene is a polyethylene homopolymer composition having a density of at least 0.950 g/ cm³ , A polyethylene homopolymer composition is a biaxially oriented polyethylene film structure comprising a nucleating agent or a mixture of nucleating agents.
  17. The biaxially oriented polyethylene film structure according to claim 16, wherein the polyethylene homopolymer composition has a density of 0.952 to 0.975 g/ cm³ .
  18. The biaxially oriented polyethylene film structure according to claim 16, wherein the polyethylene homopolymer composition has a melt index of 0.5 to 5 g/10 min.
  19. A polyethylene homopolymer composition i) 5 to 70% by weight of a first ethylene homopolymer having a density of 0.950 to 0.975 g/ cm³ , ii) comprising 95 to 30% by weight of a second ethylene homopolymer having a density of 0.950 to 0.975 g/ cm³ , The ratio of the melt index I² of the second ethylene homopolymer to the melt index I² of the first ethylene homopolymer is at least 10. The biaxially oriented polyethylene film structure according to claim 16.
  20. The biaxially oriented polyethylene film structure according to claim 16, wherein the first polyethylene has a density of 0.941 to 0.962 g/ cm³ .

Description

This disclosure relates to a BOPE film or film structure comprising at least three layers and having good optical properties. Biaxially oriented polyethylene (BOPE) films are prepared by stretching a thick precursor (or base) film, typically known as a cast sheet, in two directions: machine direction (MD) and transverse direction (TD). Stretching may be performed in a single procedure (simultaneous biaxial stretching) or in two consecutive procedures (sequential biaxial stretching). The equipment commonly used in the stretching process is generally called a "tenter frame" line. Compared to conventional inflation films, BOPE films can achieve up to twice the stiffness (tensile modulus), resulting in improved tensile strength, impact strength, puncture resistance, and flexural crack resistance, as well as improved optical properties (e.g., reduced haze and increased transparency). BOPE film has the potential to be suitable for a wide variety of packaging applications. The improved properties observed in biaxially oriented films or film structures may enable the design of "all-polyethylene" packaging (as opposed to packaging made with different types of polymers). Such "all-polyethylene" packaging would inherently be highly recyclable. The tenter-frame process is widely used for the preparation of biaxially oriented polypropylene (BOPP) and biaxially oriented polyethylene terephthalate (BOPET) films. However, polyethylene is relatively difficult to stretch/biaxially oriented, which limits the commercial use of BOPET. Prior to this study, it was observed that high-density polyethylene (e.g., high-density polyethylene with a density greater than approximately 0.950 g/ cm³ ) behaves poorly when subjected to biaxial orientation. In fact, producing BOPET films from high-density polyethylene required specific or precise process conditions (i.e., a very narrow process window). Alternatively, high-density polyethylene has been co-extruded using adhesion promoter layers ("casting promoters") such as layers containing low-density polyethylene materials and their blends, or layers containing ethylene/propylene copolymers and terpolymers, as adjacent co-extruded layers. Alternatively, high-density polyethylene has been co-extruded using adhesion promoter layers ("casting promoters"), such as layers containing low-density polyethylene materials and their blends, or ethylene/propylene copolymers and terpolymers, as adjacent co-extruded layers. There is still a need for new polyethylene compositions, particularly high-density polyethylene compositions that offer improved "stretchability" in BOPE processes, such as the Tenterframe BOPE process. One embodiment of this disclosure provides an "all-polyethylene" biaxially oriented film structure that has good optical properties and can be improved in recyclability compared to BOPE films made from mixed polymer materials. One embodiment of the present disclosure is a biaxially oriented polyethylene film structure comprising at least three layers, The three adjacent layers are, i) A first polyethylene comprising 50 to 99.5% by weight, wherein the first polyethylene is an ethylene copolymer having a density greater than 0.940 g/ cm³ , ii) A second polyethylene comprising 0.5 to 50% by weight, wherein the second polyethylene is a polyethylene homopolymer composition having a density of at least 0.950 g/ cm³ , The polyethylene homopolymer composition is a biaxially oriented polyethylene film structure containing a nucleating agent or a mixture of nucleating agents. One embodiment of the present disclosure is a biaxially oriented polyethylene film structure, The core layer, The first skin layer adjacent to the first side of the core layer, Including a second skin layer adjacent to the second side of the core layer, Each of the layers, the core layer, the first skin layer, and the second skin layer, i) A first polyethylene comprising 50 to 99.5% by weight, wherein the first polyethylene is an ethylene copolymer having a density greater than 0.940 g/ cm³ , ii) A second polyethylene comprising 0.5 to 50% by weight, wherein the second polyethylene is a polyethylene homopolymer composition having a density of at least 0.950 g/ cm³ , The polyethylene homopolymer composition is a biaxially oriented polyethylene film structure containing a nucleating agent or a mixture of nucleating agents. One embodiment of the present disclosure is a biaxially oriented polyethylene film structure comprising at least three layers, The three adjacent layers are, i) A first polyethylene comprising 50 to 99.5% by weight, wherein the first polyethylene is an ethylene copolymer having a density greater than 0.940 g/ cm³ , ii) comprising 0.5 to 50% by weight of a second polyethylene, wherein the second polyethylene is high-density polyethylene having a density of at least 0.950 g/ cm³ , High-density polyethylene contains a nucleating agent or a mixture of nucleating agents. The biaxially oriented polyethylene film