Multilayer Shrink Label Film for Recyclable Container Separation

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Solution Overview

Problem

Current labeling technologies face challenges in recyclability, particularly in separating labels from plastic containers without leaving residues, and require materials that can shrink effectively at various temperatures for efficient application and removal.

Innovation Solution

A multilayer film structure comprising a cyclic olefin copolymer skin layer and a core layer of ethylene and butyl acrylate or propylene terpolymer, which is monoaxially stretched for improved thermally inducible shrinkage properties, allowing for efficient separation and recyclability while maintaining printability and stiffness.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If conventional labeling materials are used, then labels can be applied to containers, but labels cannot be easily separated from containers for recycling

Engineering Contradiction:

Improvelabel separationVSAvoidlabel adhesion

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The label material's thermal properties are changed to enable temperature-dependent adhesion. The label adheres strongly at application temperature but releases at recycling temperatures, allowing easy separation. This is achieved by selecting materials with specific glass transition temperatures and thermal expansion coefficients that create reversible adhesion behavior.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The label is constructed as a multilayer composite material system consisting of different polymer layers with complementary properties. The combination of materials provides both strong initial adhesion for application and controlled release for recycling, resolving the contradiction between adhesion strength and separability.

Inventive Principle:

Principle #40Composite materials

2Productivity

If high shrinkage materials are used for labeling, then labels fit containers well, but materials cannot withstand transportation temperatures without deforming

Engineering Contradiction:

Improveshrinkage efficiencyVSAvoiddimensional stability

Core Design Contradiction:

ProductivityVSStability of the object's composition

Solution Approach 1:

The material's thermal response parameters are optimized to differentiate between transportation temperature range and recycling temperature range. The label exhibits minimal shrinkage at transportation temperatures but achieves high shrinkage at recycling temperatures, enabling both dimensional stability during transport and effective shrinking during recycling.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The label material incorporates thermal feedback mechanisms where the shrinkage behavior is activated only when specific temperature thresholds are reached. This ensures the label remains dimensionally stable during normal transportation but automatically shrinks when exposed to recycling temperatures, providing conditional responsiveness.

Inventive Principle:

Principle #23Feedback

3Ease of manufacture

If adhesive labels are used, then labels adhere to containers, but adhesive residues remain after removal affecting recyclability

Engineering Contradiction:

Improvelabel removalVSAvoidadhesive residue

Core Design Contradiction:

Ease of manufactureVSLoss of substance

Solution Approach 1:

The adhesive layer is completely removed from the label structure and replaced with a pressure-sensitive adhesion mechanism inherent to the label material itself. This extraction of the separate adhesive component eliminates the source of residue problems while maintaining label adhesion during use.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The label is designed as a disposable component where the entire label material serves its adhesion function temporarily and is then completely removed without residue. The material is selected to provide sufficient adhesion during its service life but releases cleanly when removed, treating the label as a temporary, non-reusable component.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

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 film achieves high thermally induced shrinkage, enabling effective labeling and easy separation from containers, while ensuring recyclability and maintaining printability and stiffness, thus addressing the challenges of existing labeling technologies.

Implementation Method 1

the film to shrink and fit the shape of the item

Methodology Applied

Scientific EffectThermal contraction: Thermal Contraction

Implementation Method 2

improved properties for the labeling and recyclability... improved thermally inducible shrinkage properties

Methodology Applied

Scientific EffectThermal shrinkage: Thermal Contraction

Data Source

PatentUS11541646B2Multilayer film for label and a method for providing such

Publication Date: 2023.01.03 UPM RAFLATAC OY

AI summary

The invention relates to providing a method for obtaining a multilayer film for thermally inducible shrink labels, products thereof and use of such products. The invention provides a multilayer film for labelling, the multilayer film comprising a first skin layer, a second skin layer and a core layer between the first skin layer and the second skin layer, wherein at least one of the first skin layer and the second skin layer comprises cyclic olefin copolymer and the core layer comprises copolymer of ethylene and butyl acrylate or propylene terpolymer.