Removable Polymeric Labels via Thermal Expansion
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Solution Overview
Problem
Polymeric film labels used on reusable beverage bottles are difficult to completely remove during washing processes due to their lack of water permeability, which contrasts with the ease of removal of paper labels in hot washing liquids.
Innovation Solution
A label structure comprising a first polymeric layer with a lower coefficient of thermal expansion and a second polymeric layer with a higher coefficient of thermal expansion, along with an adhesive layer, that reversibly curls towards the first layer at temperatures above 50°C, allowing for gradual detachment from the bottle during hot washing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If polymeric film labels are used on beverage bottles, then aesthetic appearance and mechanical properties are improved, but label removal during washing process becomes difficult
Solution Approach 1:
The label is divided into multiple polymeric layers with different coefficients of thermal expansion. The top layer has a lower coefficient while the bottom layer has a higher coefficient, creating internal stress that causes the label to curl and detach during washing. This segmentation allows the label to maintain structural integrity during use while enabling easy removal during cleaning.
Solution Approach 2:
The invention changes the physical parameters of the label by using polymeric materials with different coefficients of thermal expansion. This parameter difference causes the label to respond differently to temperature changes during washing, with the bottom layer expanding more than the top layer, generating curling force that facilitates label removal while maintaining aesthetic and mechanical properties during normal use.
2Reliability
If polymeric film labels are used instead of paper labels, then water permeability is reduced improving durability, but label detachment during hot washing is hindered
Solution Approach 1:
The invention exploits thermal expansion differences between layers to solve the contradiction. The bottom polymeric layer has a higher coefficient of thermal expansion than the top layer. During hot washing, this differential expansion creates internal stress that causes the label to curl toward the top layer, facilitating detachment. The low water permeability of the polymeric materials is maintained, preserving durability during normal use while enabling detachment during thermal washing cycles.
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 complete removal of the polymeric film label from bottles while maintaining superior aesthetic and mechanical properties, ensuring effective cleaning and reuse of the containers.
Implementation Method 1
a first polymeric layer having a first coefficient of thermal expansion; (b) a second polymeric layer having a second coefficient of thermal expansion underlying the first polymeric layer, wherein the first coefficient of thermal expansion is less than the second coefficient of thermal expansion
Data Source
AI summary
This invention relates to labels, particularly removable polymeric labels for use on reusable containers. The labels contain at least two polymeric layers having different coefficients of linear thermal expansion, such that, upon exposure to elevated temperatures, the label is reversibly curled.