Linerless Self-Adhesive Labels for PET Wash-Off Recycling
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Solution Overview
Problem
Existing linerless self-adhesive labels require costly printing machines and have complex operations, and their recyclability is hindered by non-porous polymeric materials that do not easily detach from PET containers during recycling.
Innovation Solution
A self-adhesive material with a polymer film of density ≤0.9 g/cm³ and a PET liner of density ≥0.8 g/cm³, combined with a thermo-adhesive and microperforated design, allowing easy detachment and recyclability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of substance
If linerless self-adhesive labels are used, then scrap material is reduced, but printing machine cost and operational complexity increase
Solution Approach 1:
The invention extracts and removes the liner layer from the self-adhesive label structure, creating a linerless label that consists only of the substrate, adhesive, and printed layer. This eliminates the need for liner disposal while maintaining the core labeling function.
Solution Approach 2:
The substrate layer in the linerless label performs multiple functions: it serves as the base for the printed layer, provides structural support, and acts as the adhesive carrier. This multi-functionality compensates for the removed liner's protective role during application.
2Ease of manufacture
If conventional labels with liner are used, then printing process is simpler, but liner disposal costs increase
Solution Approach 1:
The invention extracts and removes the liner layer from the self-adhesive label structure, creating a linerless label that consists only of the substrate, adhesive, and printed layer. This eliminates the need for liner disposal while maintaining the core labeling function.
3Strength
If non-porous polymeric materials are used in linerless labels, then label durability is improved, but recyclability is hindered
Solution Approach 1:
The invention employs a porous polymeric substrate material that allows alkaline washing solutions to penetrate through the substrate and reach the adhesive layer. This porosity enables effective detachment during recycling while the polymer structure maintains sufficient mechanical strength for label durability.
Solution Approach 2:
The invention changes the density parameter of the polymeric substrate to be less than 1.0 g/cm³, which allows the label to float during the washing process. This parameter change facilitates recyclability by enabling easy separation of the label from the packaged item during washing.
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 solution ensures easy detachment and recyclability of the labels, maintaining sustainability and reducing recycling time, while maintaining a total thickness of less than 100 μm.
Implementation Method 1
The labelled item is then subjected to washing with water or with a basic solution... the label can be made of a porous polymeric material, which allows penetration of the alkaline washing solution through the entire surface
Implementation Method 2
a polymer film made of a polymeric material having a density equal to or less than 0.9 g/cm³... The linerless self-adhesive material has a total density equal to or less than 1.0 g/cm³
Data Source
AI summary
A self-adhesive linerless label for labelling containers, preferably made of PET, the label being particularly adapted to be removed from the container during recycling operations. The label derives from a linerless self-adhesive material that includes a liner made of plastic material having a density greater than 0.8 g/cm3, preferably between 0.9 g/cm3 and 1.5 g/cm3, more preferably between 1 and 1.4 g/cm3 at 25° C. The material is preferably PET or PP, The linerless self-adhesive material also includes a self-adhesive film having a polymeric material with a density of less than 0.9 g/cm3 at 25° C., preferably between 0.6 g/cm3 and 0.9 g/cm3, more preferably between 0.7 and 0.8 g/cm3 at 25° C. The liner and the self-adhesive material are in permanent contact by a thermo-adhesive.