Heat-shrinkable Polyester Label Solvent Bonding Barrier
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Solution Overview
Problem
Heat-shrinkable polyester-based labels face issues with solvent permeation-through and insufficient peel strength, especially when using thin films with high amorphous content or PET-bottle-recycled materials, which affect their functionality and environmental sustainability.
Innovation Solution
A solvent composition combining 1,3-dioxolane and/or tetrahydrofuran with a polyester containing monomer components that can turn amorphous, along with optional organic solvents, is used to bond the film ends, preventing solvent permeation and enhancing peel strength, even at high speeds and with high crystallinity PET materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the applied amount of 1,3-dioxolane is increased to gain stable solvent-bonded portion with high peel strength in high-speed tubing step, then the peel strength is improved, but the solvent permeates through the film from the solvent-applied surface to the rear surface side, causing the tubular label to be squashed into flat form and unable to function as a tube
Solution Approach 1:
A barrier layer is introduced as an intermediary between the solvent-bonded portion and the rear surface of the film. This barrier layer prevents the solvent from permeating through to the rear surface, thereby maintaining the tubular shape and functionality of the label while still allowing the solvent to effectively bond the end portions with high peel strength.
Solution Approach 2:
The film is segmented into distinct functional layers: a solvent-bonded portion for joining end portions, a barrier layer to prevent solvent permeation-through, and the remaining film structure. This segmentation allows each layer to perform its specific function independently, resolving the contradiction between bonding strength and solvent permeation prevention.
2Loss of substance
If the thickness of the film is reduced to decrease waste amount and improve environmental sustainability, then the environmental sustainability is improved, but the solvent easily permeates through the thin film, causing bonding failures and functional issues
Solution Approach 1:
The barrier layer acts as a mediator that compensates for the reduced thickness of the film. Even though the overall film is thin to reduce waste, the barrier layer within the film structure prevents solvent permeation-through, ensuring reliable bonding while maintaining the thin-profile advantage for environmental sustainability.
Solution Approach 2:
The invention utilizes a thin film structure with integrated barrier properties, allowing the film to be sufficiently thin for environmental sustainability while the barrier layer within the film prevents solvent permeation, maintaining bonding reliability despite the reduced thickness.
3Temperature
If a polyethylene terephthalate high in crystallinity is used as film raw material to improve heat resistance and solvent resistance, then the heat resistance and solvent resistance are improved, but the solvent bonding becomes difficult and the peel strength of solvent-bonded portion decreases
Solution Approach 1:
The film is designed with local quality variations: the barrier layer has high crystallinity for heat and solvent resistance, while the solvent-bonded portion has modified properties (lower crystallinity or different composition) that facilitate solvent penetration and bonding. This local differentiation allows the film to exhibit both heat resistance and good solvent bonding performance.
Solution Approach 2:
The film is constructed as a composite material combining polyester resin with other components in specific layers. The barrier layer uses high-crystallinity PET for heat and solvent resistance, while the solvent-bonded portion incorporates materials or structures that enhance solvent wettability and bonding, achieving both heat resistance and high peel strength through composite construction.
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 prevents solvent permeation-through and achieves high peel strength in the solvent-bonded portions, ensuring the labels function effectively and reducing waste, while being suitable for use with PET-bottle-recycled materials, thus enhancing environmental sustainability.
Implementation Method 1
bonding both end portions of the film to each other with a solvent composition containing 1,3-dioxolane and/or tetrahydrofuran
Implementation Method 2
a polyester containing monomer components that can turn amorphous
Data Source
AI summary
Provided are a heat-shrinkable polyester-based label, and a package which each have a solvent-bonded portion where no solvent permeation-through is caused even when a film of the label is small in thickness. Provided are, in particular, a heat-shrinkable polyester-based label and a package which each have a solvent-bonded portion giving a high peel strength stably even through a high-speed tubing step, or even when the film is a heat-shrinkable polyester-based film in which a PET-bottle-recycled material is used in a large proportion. The label is a heat-shrinkable polyester-based label that is a tubular label in which both end portions of a heat-shrinkable polyester-based film are bonded to each other with a solvent composition. In this label, the solvent composition is a solvent composition containing at least 1,3-dioxolane and/or tetrahydrofuran (THF), and a polyester, and the end portion bonded has a peel strength of 2 N/15mm or more.