EVOH Resin Composition with Hydrate-Forming Salt for Moisture Resistance
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Solution Overview
Problem
Multilayered structures with EVOH resin layers as gas-barriers face deterioration in gas-barrier performance and blister formation under high-temperature and high-humidity conditions, particularly after hot water treatments, due to moisture absorption and release, which affects the packaging's integrity and appearance.
Innovation Solution
A saponified ethylene-vinyl ester-based copolymer (EVOH) resin composition incorporating a hydrate-formable alkaline earth metal salt, specifically completely or partially dehydrated trimagnesium dicitrate, with controlled water absorption properties to prevent blistering and maintain gas-barrier performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If EVOH resin is used as a gas-barrier layer in multilayered film, then excellent oxygen barrier performance is achieved, but gas-barrier performance deteriorates after hot water treatment due to moisture absorption breaking hydrogen bonds
Solution Approach 1:
The patent introduces a hydrophobic resin layer as an intermediary between the EVOH gas-barrier layer and the external environment. This hydrophobic layer acts as a mediator that prevents moisture from reaching the EVOH layer during hot water treatment, thereby protecting the hydrogen bonding structure and maintaining gas-barrier performance without altering the EVOH layer itself
Solution Approach 2:
The patent creates a composite multilayered film structure combining EVOH resin layer with hydrophobic resin layers. This composite structure leverages the excellent gas-barrier properties of EVOH while using the hydrophobic resin to provide moisture resistance, achieving synergistic protection of the hydrogen bonding structure and gas-barrier performance
2Reliability
If drying agent is added to EVOH resin composition to retain gas-barrier performance after hot water treatment, then gas-barrier performance is improved, but blister formation occurs under high-temperature and high-humidity conditions
Solution Approach 1:
The hydrophobic resin layer serves as an intermediary barrier that prevents moisture from reaching the drying agent in the EVOH layer during high-temperature and high-humidity storage. This mediation stops the drying agent from absorbing excess moisture and expanding, thereby preventing blister formation while preserving the gas-barrier performance enhancement
Solution Approach 2:
The patent applies beforehand cushioning by pre-positioning a hydrophobic resin layer that anticipates and prevents moisture intrusion during subsequent high-temperature and high-humidity storage. This protective layer cushions the drying agent against moisture exposure, preventing the harmful expansion and blister formation before they can occur
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The EVOH resin composition effectively retains gas-barrier performance and prevents blister formation even under prolonged high-temperature and high-humidity conditions, ensuring the packaging's integrity and appearance are maintained.
Implementation Method 1
addition of hydrate-formable alkaline earth metal salt as a drying agent to an EVOH resin
Implementation Method 2
the moisture entering into an EVOH resin layer would be absorbed as crystallization water
Implementation Method 3
EVOH resin has a crystal part by firmly hydrogen bonding between hydroxyl groups of the molecular chains thereof
Implementation Method 4
EVOH resin has a crystal part by firmly hydrogen bonding between hydroxyl groups of the molecular chains
Implementation Method 5
Oxygen in atmosphere is prohibited to intrude into the crystal part and therefore EVOH resin can exhibit excellent oxygen barrier performance and other gas-barrier performance
Data Source
AI summary
Provided are: an EVOH resin composition which can exhibit excellent gas-barrier performance after being subjected to a hot water treatment and rarely generates blisters even when being placed under a high-temperature and high-humidity condition; and a multilayered structure including a layer of the resin composition as a gas-barrier layer. A hydrate-formable alkaline earth metal salt having a specific water absorption property, particularly completely or partially dehydrated alkaline earth metal salt of acid, or a mixture thereof. The acid is selected from the group consisting of lactic acid, silicic acid, phosphoric acid, and citric acid. The partially dehydrated alkaline earth metal salt of the salt has a water content of 50 wt% or less.