Gas Barrier Layer Composition for Retort Packaging

The patent uses a composite structure combining a vinyl alcohol polymer layer with a metal compound layer (such as aluminum oxide or silicon oxide). This composite approach allows the vinyl alcohol polymer to provide transparency while the metal compound layer maintains gas barrier properties under high humidity conditions by forming a stable, non-hygroscopic barrier that prevents oxygen permeation even when the polymer absorbs moisture.

The patent applies a thin metal compound layer (such as aluminum oxide or silicon oxide) specifically as the gas barrier layer, rather than using thick metal foil. This thin layer provides sufficient oxygen barrier properties while maintaining transparency, allowing consumers to see the contents through the packaging. The metal compound is deposited in a controlled manner to achieve the optimal thickness for both barrier performance and visibility.

The patent changes the physical and chemical parameters of the metal compound layer by using amorphous metal compounds (such as aluminum oxide or silicon oxide) deposited in a controlled manner. This creates a more flexible, crack-resistant layer compared to crystalline structures. The amorphous structure can better accommodate deformation without forming cracks, maintaining both flexibility and gas barrier properties under impact and bending conditions.

The patent applies a preliminary heat treatment or cross-linking process to the vinyl alcohol polymer layer before final packaging use. This preliminary action pre-densifies the polymer structure and strengthens the metal compound layer adhesion, so that when the packaging undergoes retort sterilization, the layer maintains its integrity and gas barrier properties without breaking or delaminating during the high-temperature steam sterilization process.