EVOH Resin Composition with Polyamide Network for Retort Packaging

The patent introduces polyamide resin as an intermediary substance between EVOH resin and inorganic drying agents. The polyamide resin forms a network structure that encapsulates the inorganic salt, allowing the drying agent to function while preventing direct contact between inorganic salt and EVOH resin, thus suppressing elution. This mediator approach resolves the contradiction by enabling the drying agent effect without the harmful elution side effect.

The patent creates a composite resin composition combining EVOH resin, polyamide resin, and inorganic salt in specific ratios (polyamide resin 1-25 parts, inorganic salt 2-50 parts based on 100 parts EVOH resin). This composite structure leverages the gas barrier properties of EVOH, the network-forming capability of polyamide resin, and the drying agent function of inorganic salt, achieving both improved gas barrier property and suppressed elution through material composition.

The patent optimizes the content parameters of polyamide resin (1-25 parts by mass per 100 parts EVOH resin) and inorganic salt (2-50 parts by mass per 100 parts EVOH resin) to achieve the desired balance. By controlling these parameters within specific ranges, the patent achieves sufficient elution suppression while maintaining acceptable processability, resolving the contradiction through parameter optimization.

The patent applies polyamide resin locally as a network-forming component rather than uniformly throughout the entire composition. The polyamide resin forms a localized network structure that encapsulates inorganic salt and prevents elution, while the bulk EVOH resin maintains its processing characteristics. This localized application of polyamide resin's function resolves the contradiction between elution suppression and processability.