LED-Curable Adhesive Shrink Film Labeling
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Solution Overview
Problem
Traditional shrink film label processes using hot-melt adhesives face issues with premature shrinkage and defects such as irregular shape and multidirectional wrinkles due to high application temperatures, which are hard to manage and result in undesirable label appearance.
Innovation Solution
The use of LED-curable adhesives applied at lower temperatures, which can be cured rapidly with LED light, providing better appearance and bonding strength in the shrink tunnel environment, and allowing for efficient labeling of irregularly shaped articles at high speeds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If hot-melt adhesives are used at high temperatures, then bonding strength is improved, but premature shrinkage and wrinkles occur causing poor label appearance
Solution Approach 1:
The patent changes the temperature parameter from high (hot-melt) to low (LED-curable adhesive applied at lower temperatures), eliminating premature shrinkage and wrinkles while maintaining bonding strength through UV/LED curing
Solution Approach 2:
The patent replaces the thermal bonding mechanism (hot-melt adhesive) with a photochemical bonding mechanism (LED-curable adhesive), eliminating the need for high heat and associated defects while achieving strong bonding through light-induced curing
2Productivity
If high labeling speed is achieved, then productivity is improved, but label integrity and bonding quality may deteriorate
Solution Approach 1:
The patent applies the adhesive in an uncured state that maintains tackiness, allowing the label to be applied and positioned correctly at high speeds before final curing sets the bond, ensuring both speed and integrity
Solution Approach 2:
The patent uses a two-stage process: initial application at low temperature with uncured adhesive for quick positioning, followed by rapid LED curing to lock in the bond, enabling high-speed operation without sacrificing label integrity
3Strength
If hot-melt adhesive is used, then bonding is achieved, but wrinkles and irregular shapes are caused reducing label quality
Solution Approach 1:
The patent changes the temperature parameter from high to low, preventing the thermal shrinkage and distortion that cause wrinkles and irregular shapes while maintaining bonding effectiveness through photochemical curing
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
LED-curable adhesives improve the appearance of shrink film labels by eliminating wrinkles and providing higher bonding strength, enabling efficient labeling of articles with irregular shapes at speeds up to 720 articles per minute while maintaining label integrity during shipping and storage.
Implementation Method 1
curing the LED-curable adhesive disposed in the overlap between the leading and trailing edges with LED
Data Source
Figure 1A~1B
Figure 2A~2B
Figure 2C~2D
AI summary
Provided herewith are methods of preparing a labeled article comprising curing an LED-curable adhesive on a film label such as a shrink film label, wherein at least portions of the LED-curable adhesive are disposed in the overlap formed between a leading edge and trailing edge of the film label. The curing can be conducted at a temperature below 70 °C and is suitable for labeling 500-720 articles per minute in a sequential manner. Also provided herewith are apparatus for labeling articles with film labels, such as shrink film labels comprising an LED station. Further, a method of retrofitting an existing hot-melt labeling system for use in labeling articles with film labels such as shrink film labels is also provided.