Multilayer Packaging Barrier Layer Separation via Water-Soluble Interlayer
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Multilayer structures composed of ethylene-vinyl alcohol copolymer (EVOH) or polyamide-based packaging materials face issues with recyclability due to crosslinking or degradation when repeatedly heated, leading to impaired adhesiveness and separability during recycling processes.
Innovation Solution
A multilayer structure is designed with a barrier layer, a water-soluble layer, and an adhesive layer, where the water-soluble layer contains alkali metal ions and a vinyl alcohol polymer, and the adhesive layer is laminated via the water-soluble layer on the barrier layer, enabling superior adhesiveness under high humidity and separability in water, along with viscosity stability during recycling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If EVOH or polyamide is used as barrier layer in multilayer packaging, then oxygen barrier properties and strength are improved, but recyclability deteriorates due to crosslinking and degradation when repeatedly heated
Solution Approach 1:
The multilayer packaging structure is divided into functionally distinct layers: a barrier layer (A) containing EVOH or polyamide for oxygen barrier properties, a water-soluble layer (B) containing alkali metal ions for separability, and an adhesive layer (C) for interlayer bonding. This segmentation allows the barrier layer to maintain its performance while the water-soluble layer enables easy separation and recycling of the barrier layer through water treatment, resolving the contradiction between reliability and recyclability.
2Ease of manufacture
If water-soluble layer containing alkali metal ions is introduced to improve separability, then recyclability is improved, but adhesiveness under high humidity may deteriorate
Solution Approach 1:
The adhesive layer (C) acts as an intermediary between the barrier layer (A) and water-soluble layer (B). This intermediate layer provides strong adhesion under high humidity conditions while allowing the water-soluble layer to dissolve in water for separation. The adhesive layer mediates between the conflicting requirements of maintaining adhesiveness and enabling separability, resolving the contradiction by providing different functions in different conditions.
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 proposed multilayer structure enhances recyclability by maintaining adhesiveness and separability, even when exposed to water, and allows for independent melt molding of separated components, improving the recycling suitability of packaging materials while preventing performance and quality deterioration.
Implementation Method 1
the water-soluble layer (B) contains an alkali metal ion (b1) at a content of 10 ppm or more and 2,000 ppm or less
Implementation Method 2
the adhesive layer (C) is laminated via the water-soluble layer (B) on one or both faces of the barrier layer (A)
Implementation Method 3
a multilayer structure that is superior in adhesiveness of the interlayer under high humidity and separability of the barrier layer in water, and is also superior in viscosity stability, even in a case in which the barrier layer is exposed to water in a separating and collecting step
Data Source
AI summary
Provided are a multilayer structure and the like being superior in adhesiveness of an interlayer under high humidity and separability of a barrier layer in water, and even in a case in which the barrier layer is exposed to water in a separating and collecting step, being superior in viscosity stability after separating and collecting a resin that constitutes the barrier layer. The multilayer structure of the present invention is a multilayer structure including a barrier layer (A), a water-soluble layer (B), and an adhesive layer (C), in which: the adhesive layer (C) is laminated via the water-soluble layer (B) on one or both faces of the barrier layer (A); the barrier layer (A) contains a polyamide or an ethylene-vinyl alcohol copolymer (a1) as a principal component; and the water-soluble layer (B) contains an alkali metal ion (b1) at a content of 100 ppm or more and 2,000 ppm or less.