Recyclable Resealable Container Using Resin-Compatible Adhesive

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Solution Overview

Problem

Flexible films used in rigid reclosable packaging are not recyclable through standard single-stream recycling due to machinery limitations, leading consumers to dispose of them with regular trash despite the recyclability of the rigid container.

Innovation Solution

A resealable and recyclable container structure where a flexible film is permanently or resealably sealed to a rigid tray using a combination of adhesives and sealants, allowing the entire package to be recycled together by being sorted into the correct resin stream, such as PET, by maintaining the film's adherence during the recycling process.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Duration of action of stationary object

If flexible film is used to close the rigid container, then the package becomes resealable and extends shelf-life, but the flexible film cannot be recycled through standard single-stream recycling

Engineering Contradiction:
Improveshelf-lifeVSAvoidrecyclability
Core Design Contradiction:
Duration of action of stationary objectVSReliability

Solution Approach 1:

The patent merges the flexible film and rigid container into a single recyclable unit by using a resin-compatible adhesive that bonds the film to the container rim. This combination allows both components to be recycled together through standard single-stream recycling processes, eliminating the need for consumer separation while maintaining the resealable functionality that extends shelf-life.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The patent introduces a resin-compatible adhesive as an intermediary substance between the flexible film and rigid container. This adhesive acts as a mediator that enables both components to be processed together in recycling streams, resolving the incompatibility between flexible film and standard recycling machinery while preserving the beneficial resealable properties of the flexible closure.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Strength

If flexible film is sealed to the rigid tray, then the package structure is stable and protective, but the film separates during recycling processing

Engineering Contradiction:
Improveseal strengthVSAvoidadherence during recycling
Core Design Contradiction:
StrengthVSReliability

Solution Approach 1:

The patent changes the chemical parameters of the adhesive by selecting a resin-compatible formulation that maintains strong bonding strength for package stability while simultaneously being compatible with recycling stream processing conditions. This parameter adjustment allows the seal to remain intact during recycling, preventing film separation while preserving protective package structure.

Inventive Principle:
Principle #35Parameter changes

3Reliability

If consumers separate the flexible film from the rigid container for disposal, then the rigid container can be recycled, but the flexible film is disposed of with regular trash

Engineering Contradiction:
Improverecycling complianceVSAvoiddisposal convenience
Core Design Contradiction:
ReliabilityVSEase of operation

Solution Approach 1:

The patent combines the flexible film and rigid container into a single recyclable assembly using a durable, resin-compatible adhesive bond. This merging eliminates the need for consumer separation actions, making the recycling process as convenient as placing the entire package in the recycling bin, thereby improving both recycling compliance and ease of operation simultaneously.

Inventive Principle:
Principle #5Merging (Combining)

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

Enables the recycling of both the rigid tray and flexible film together, increasing the package's environmental sustainability and consumer compliance with recycling protocols.

Implementation Method 1

an adhesive which provides a releasable and resealable bond between the closure and the lip

Methodology Applied
Scientific EffectAdhesive bonding: Adhesive

Implementation Method 2

a flexible film is permanently or resealably sealed to a rigid tray using a combination of adhesives and sealants

Methodology Applied
Scientific EffectSealing:

Data Source

PatentEP4059867B1Recyclable container and lidding construction
Publication Date: 2024.01.24 SONOCO DEVELOPMENT INC
  • EP4059867B1 patent drawingFigure 1
  • EP4059867B1 patent drawingFigure 2
  • EP4059867B1 patent drawingFigure 3

AI summary

A resealable, recyclable container structure comprises: a polymeric rigid tray comprising a bottom wall and at least one upwardly extending sidewall, wherein the at least one sidewall terminates in a flange and wherein the flange comprises at least one resealable zone and at least one permanently affixed zone; a flexible polymeric film lidding, wherein the lidding is permanently affixed to the flange in the permanently affixed zone and resealably affixed to the flange in the resealable zone; a permanent adhesive disposed between the lidding and the flange in the permanently affixed zone; and wherein the polymeric rigid tray and the polymeric film comprise the same polymer.