Search

JP-2026075243-A - Laminates and packaging

JP2026075243AJP 2026075243 AJP2026075243 AJP 2026075243AJP-2026075243-A

Abstract

[Problem] To provide a laminate and packaging with good barrier properties, comprising a metal layer and/or an inorganic compound layer and a coating layer laminated on a polyolefin resin film. [Solution] A laminate having a metal layer and/or an inorganic compound layer and a coating layer in that order on a polyolefin resin film, wherein the coating layer contains a polyvinyl alcohol resin backbone and a siloxane compound. A laminate that satisfies requirements 1 and 2 below. Requirement 1: A1/(A1+A2) is 0.50 or more and 0.85 or less. Requirement 2: [B1/(B1+B2)-A1/(A1+A2)] is 0.10 or less. A1: Area of Raman bands showing the network structure derived from siloxane compounds obtained by measuring the coating layer by laser Raman spectroscopy. A2: Area of Raman bands showing linear polysiloxane structures and cyclic siloxanes with 4 or fewer members obtained by measuring the coating layer by laser Raman spectroscopy. B1: Area of Raman bands showing the network structure obtained by measuring the coating layer by laser Raman spectroscopy after heat treatment at 121°C for 30 minutes. B2: Area of Raman bands showing linear polysiloxane structures and cyclic siloxanes with 4 or fewer members obtained by measuring the coating layer by laser Raman spectroscopy after heat treatment at 121°C for 30 minutes. [Selected Figure] None

Inventors

  • 甲斐 倫子
  • 山田 絵美
  • 佐藤 誠

Assignees

  • 東レ株式会社

Dates

Publication Date
20260508
Application Date
20241022

Claims (10)

  1. A laminate having a metal layer and/or an inorganic compound layer and a coating layer in this order on at least one surface of a polyolefin resin film, The coating layer contains a polyvinyl alcohol-based resin backbone and a siloxane compound. A laminate that satisfies requirements 1 and 2 below. Requirement 1: A1/(A1+A2) is 0.50 or more and 0.85 or less. Requirement 2: [B1/(B1+B2)-A1/(A1+A2)] is 0.10 or less. A1: Area of Raman bands showing the network structure derived from siloxane compounds obtained by measuring the coating layer by laser Raman spectroscopy. A2: Area of Raman bands showing linear polysiloxane structures and cyclic siloxanes with 4 or fewer members obtained by measuring the coating layer by laser Raman spectroscopy. B1: Area of Raman bands showing the network structure obtained by measuring the coating layer by laser Raman spectroscopy after heat treatment at 121°C for 30 minutes. B2: Area of Raman bands showing linear polysiloxane structures and cyclic siloxanes with 4 or fewer members obtained by measuring the coating layer by laser Raman spectroscopy after heat treatment at 121°C for 30 minutes.
  2. The laminate according to claim 1 , wherein when the stress at 121°C in the direction of the principal orientation axis, measured by thermomechanical analysis (TMA), is denoted as SF 121°C and the stress at 145°C in the direction of the principal orientation axis, is denoted as SF 145°C , then SF 145°C - SF 121°C ≤ 2.50 MPa.
  3. The laminate according to claim 1 or 2, wherein the loss tangent tanδ at 145°C in the direction of the principal orientation axis is 0.25 or less.
  4. The laminate according to claim 1 or 2 , wherein when the elongation at the break point in the direction of the principal orientation axis is defined as T0, and the elongation at the break point in the direction of the principal orientation axis measured after heat treatment of the laminate at 130°C for 10 minutes is defined as T130, the value of T0 / T130 is 1.20 or less.
  5. The laminate according to claim 1 or 2, wherein the ratio P1/P2 of the following peak intensities P1 and P2 detected by measuring the coating layer using the FT-IR-ATR method (total reflection Fourier transform infrared spectroscopy) is 3.5 or more and 8.0 or less. P1: Intensity of the maximum peak located at 1,050–1,080 cm⁻¹ P2: Intensity of the maximum peak located at 920–970 cm⁻¹
  6. The laminate according to claim 1 or 2, wherein [B1/(B1+B2) - A1/(A1+A2)] is 0.08 or less.
  7. The laminate according to claim 1 or 2, wherein the water vapor permeability of the laminate is 1.0 g/ m² /24hr or less, and the oxygen permeability is 1.0 cc/ m² /24hr or less.
  8. The laminate according to claim 1 or 2, wherein the thickness of the coating layer is 200 nm or more and 600 nm or less.
  9. The laminate according to claim 1 or 2, wherein the metal layer or inorganic compound layer contains aluminum.
  10. A packaging body having the laminate described in claim 1 or 2.

Description

This invention relates to laminates and packaging materials with good barrier properties using polyolefin resin substrates. Packaging materials for food, pharmaceuticals, and daily necessities require oxygen barrier and water vapor barrier properties to prevent deterioration of the contents. Barrier films, which consist of a resin film such as polyester laminated with a metal layer such as aluminum, a metal oxide layer, or a protective layer, have been used as such barrier packaging materials. In particular, when a metal oxide layer is laminated, the resulting film is transparent, offering good visibility, and in food packaging, it allows for microwave heating, among other conveniences, making it widely used. On the other hand, plastic packaging materials are a cause for concern because they do not decompose in soil even when landfilled after use, and they generate a large amount of heat when incinerated. Furthermore, in recent years, marine pollution caused by leaked plastic waste has become a major problem, and there is a growing global movement to reduce the use of plastic materials and promote reuse. Therefore, from an environmental protection perspective, the collection and recycling of packaging materials is being advocated. Conventional barrier films used in packaging materials have traditionally utilized polyester resins, such as polyethylene terephthalate, which offers high heat resistance and transparency, or polyamide resins, which boast excellent mechanical strength. These films lack the heat-sealing properties necessary for bag manufacturing and other packaging processes. Therefore, they are laminated with heat-sealable polypropylene resins to create packaging materials. However, lamination of dissimilar materials is difficult to separate during recycling. To improve recyclability, attempts have been made to create monomaterials—that is, to use olefin-based materials similar to heat-sealable polypropylene resins—as the base material for barrier films. However, olefin-based materials have a drawback: their oxygen barrier properties are inferior to those of polyester and polyamide resins. Therefore, methods have been investigated to improve barrier properties by forming a coating layer to enhance oxygen barrier properties and improve the preservation of contents in packaging materials (Patent Documents 1 and 2). Patent No. 4784039Patent No. 4972951 This is a schematic cross-sectional view showing an example of the structure of the laminate of the present invention. A preferred embodiment of the laminate, packaging, and method for manufacturing the laminate of the present invention will be described in more detail below. The polyolefin resin film in this invention is a film mainly composed of a resin whose main constituent unit is an olefin hydrocarbon. The main constituent unit refers to the monomer unit with the highest content (number of units) among the monomer units contained in the resin, and the main component refers to the component with the highest content (mass%) among all the constituent components. Examples of polyolefin resins include polymers and copolymers of α-olefins having alkyl groups in their side chains, such as ethylene, propylene, and 4-methyl-1-pentene; copolymers obtained by copolymerizing α-olefins with acrylic acid, C=C bond-containing carboxylic acids, C=C bond-containing carboxylate salts, or C=C bond-containing alkyl carboxylate esters; polymers of norbornene and cyclodiene; and polymers of these. The film may be a single layer or multiple layers. Among these, polyethylene or polypropylene is preferred due to its relatively low cost, polypropylene is more preferred in terms of heat resistance, and polypropylene is even more preferred as the main component from a similar viewpoint. The film may be unstretched or stretched, but biaxial stretching is preferred from the viewpoint of thermal dimensional stability. That is, a biaxially stretched polyolefin resin film is preferred. The polyolefin resin film preferably has a melting point of 150°C or higher. A melting point of 150°C or higher prevents thermal damage during processes such as metal oxide formation and packaging material construction, and also improves heat resistance after processing, thereby suppressing deterioration of barrier properties. The melting point of the film shall be determined by the method described in the examples. The glass transition temperature (Tg) of the polyolefin resin film is preferably 50°C or lower. This embodiment increases the flexibility of the film even at low temperatures, preventing it from hardening easily when used in packaging, and enabling stable use over a wide temperature range. The thickness of the polyolefin resin film is preferably 3 μm to 100 μm, more preferably 5 μm to 50 μm, and even more preferably 8 μm to 30 μm. A film thickness of 3 μm or more maintains rigidity as a support, while a thickness of 100 μm or less maintains flexibility as a packaging material and impro