Notched Resin Container Labels for Manual Peeling During Recycling
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Solution Overview
Problem
In-mold labels are difficult to peel off manually, complicating the recycling process of resin containers.
Innovation Solution
A labeled container design featuring a notch portion with specific dimensions and a combination of resin materials for the label and container surfaces, allowing easy peeling by hand.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If in-mold label is used to increase adhesion to resin container, then label adhesion is improved, but label peeling difficulty increases
Solution Approach 1:
The label structure is segmented into multiple functional layers: a heat sealing layer for strong adhesion to the resin container, a substrate layer for structural support, and a release layer for controlled peeling. This segmentation allows each layer to perform its specific function - the heat sealing layer ensures strong bonding during use, while the release layer enables easy manual peeling during recycling by reducing adhesion strength in a controlled manner.
Solution Approach 2:
Different regions of the label are given different properties to achieve both strong adhesion and easy peeling. The heat sealing layer is designed with high polarity and strong bonding characteristics for the attachment region, while the release layer is designed with low adhesion characteristics for the peeling region. This local differentiation of material properties resolves the contradiction between strong overall adhesion and localized easy peeling.
2Strength
If heat sealing layer is blended with polar group compound to increase affinity to PET resin, then adhesion is improved, but recycling complexity increases
Solution Approach 1:
The recycling process is simplified by extracting and isolating the label as a separate component that can be easily removed by hand. The label is designed with a release layer that enables manual peeling without requiring immersion in hot alkaline solutions, thereby separating the label removal step from complex chemical recycling processes and simplifying the overall recycling workflow.
Solution Approach 2:
The label structure enables self-peeling capability where the release layer automatically reduces adhesion strength under manual stress, allowing the label to be peeled off by hand without requiring external chemical agents or complex equipment. This self-service peeling mechanism eliminates the need for hot alkaline solution immersion and reduces recycling process complexity.
3Strength
If plasma treatment is applied to increase polarity of heat sealing layer surface, then adhesion is improved, but manufacturing complexity increases
Solution Approach 1:
The high polarity and strong adhesion properties are built into the heat sealing layer during the label manufacturing process itself, rather than requiring subsequent plasma treatment of the finished label. The heat sealing layer is pre-formulated with polar group compounds and designed with appropriate thickness and composition to achieve the desired surface polarity and adhesion strength before application to the resin container, thereby eliminating the need for additional plasma treatment steps.
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 easy peeling of labels from resin containers during recycling without alkaline treatment, maintaining sufficient adhesion during use.
Implementation Method 1
a label having a heat sealing layer, and a resin container to which the label is attached through the heat sealing layer
Implementation Method 2
a notch portion is provided around the label, the notch portion has a depth (d) of 40 μm or more, the notch portion has a width (L) of 300 μm or more
Data Source
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AI summary
Provided is a labeled container that is easily peeled off when being scrapped, while having sufficient adhesion. The labeled container comprises a label having a heat sealing layer, and a resin container to which the label is attached through the heat sealing layer. A part of the label is embedded in the resin container, and a notch portion is provided around the label on the surface of the resin container. The notch portion has a depth (d) of 40 µm or more. The notch portion has a width (L) of 300 µm or more. One selected from the resin container and the heat sealing layer on the attached surfaces contains a polyolefin resin as a main component, and the other contains a polyester resin as a main component.