Multilayer Packaging Structure for Recyclable EVOH Barrier Films

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Solution Overview

Problem

Existing laminated films face issues with recyclability due to crosslinking of polyamide resin and EVOH, and uneven thickness and layer disorder during film formation, leading to poor appearance and mechanical strength.

Innovation Solution

A multilayer structure comprising a polyolefin layer, an adhesive resin layer, and a resin composition layer with specific ethylene-vinyl alcohol copolymer and polyvalent metal ions, which prevents crosslinking and maintains layer integrity, ensuring mechanical strength, recyclability, and stable moldability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If polyamide resin and EVOH are used in laminated film, then mechanical strength is improved, but recyclability deteriorates due to crosslinking reaction

Engineering Contradiction:

Improvemechanical strengthVSAvoidrecyclability

Core Design Contradiction:

StrengthVSEase of manufacture

Solution Approach 1:

The patent removes the polyamide resin layer from the laminated structure, extracting the source of crosslinking reactions. The multilayer film uses only EVOH and polyolefin layers that do not undergo crosslinking, thereby maintaining mechanical strength while enabling recyclability through repeated melt processing without aggregate formation.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent changes the material composition parameters by selecting specific EVOH resin types and polyolefin combinations that prevent crosslinking. By controlling the resin selection and layer configuration, the patent achieves both mechanical strength and recyclability without the harmful crosslinking reactions that occur with polyamide-EVOH combinations.

Inventive Principle:

Principle #35Parameter changes

2Stability of the object's composition

If adhesive resin layer is used to laminate polyolefin layer on EVOH layer, then layer bonding is improved, but film appearance deteriorates due to thickness unevenness and layer disorder

Engineering Contradiction:

Improvelayer bondingVSAvoidfilm appearance

Core Design Contradiction:

Stability of the object's compositionVSManufacturing precision

Solution Approach 1:

The patent uses a composite multilayer structure with specifically designed EVOH and polyolefin layers that achieve both bonding and appearance. The composite structure leverages the complementary properties of EVOH (gas barrier) and polyolefin (mechanical strength and processability) while controlling layer thickness and composition to prevent appearance defects.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The patent applies different material properties to different layers: the EVOH layer provides gas barrier function with controlled thickness, while the polyolefin layer provides mechanical strength and surface quality. By optimizing the local properties of each layer and their interface, the patent achieves both bonding stability and uniform film appearance without thickness unevenness.

Inventive Principle:

Principle #3Local quality

Data Source

PatentUS12583208B2Multilayer structure, packaging material in which same is utilized, regrind composition, and method for producing regrind composition

Publication Date: 2026.03.24 KURARAY CO LTD

AI summary

The present disclosure provides a multilayer structure having: a polyolefin layer (A); an adhesive resin layer (B); and a resin composition layer (C), wherein the polyolefin layer (A) is laminated on at least one face of the resin composition layer (C) via the adhesive resin layer (B).