Switchable Adhesive Composition Visible Light Tack Reduction
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Solution Overview
Problem
Conventional adhesives cause localized trauma and pain upon removal from fragile skin surfaces, especially in patients with long-term conditions or elderly individuals, and existing switchable adhesives are either unsuitable for wet environments or require hazardous UV radiation.
Innovation Solution
A pressure-sensitive switchable adhesive composition comprising a mixture of curable molecules and a photoinitiator, which undergoes transformation from a tacky to a non-tacky state upon exposure to visible light without requiring UV radiation, allowing for controlled reduction in peel strength and easy removal without causing skin trauma.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional pressure sensitive adhesives are used to ensure strong adhesion to fragile surfaces, then adhesion strength is improved, but skin trauma and pain occur upon removal
Solution Approach 1:
The adhesive transitions from a static high-tack state to a dynamic low-tack state through light exposure. The adhesive layer contains photoinitiators and curable molecules that, when exposed to visible light, initiate polymerization crosslinking that reduces tackiness. This dynamic state change allows the adhesive to provide strong initial adhesion for secure application while enabling gentle removal after switching, eliminating skin trauma.
Solution Approach 2:
The adhesive's key parameter (tackiness/peel strength) is changed by exposing it to visible light. The photoinitiators absorb light energy and trigger chemical reactions that modify the adhesive's molecular structure, reducing its tackiness. This parameter change allows the same adhesive material to provide both strong initial adhesion and gentle removal properties at different time points.
2Speed
If UV switchable adhesives are used to achieve rapid tack reduction, then switching speed is improved, but hazardous UV radiation and photoinitiators are required
Solution Approach 1:
The invention uses visible light (a more abundant and safer form of radiation) instead of UV light to trigger the switching mechanism. The photoinitiators are designed to absorb visible light wavelengths, making the system safer for medical applications while maintaining rapid switching capability. This substitution of radiation type eliminates the hazards associated with UV exposure.
Solution Approach 2:
Visible light acts as an intermediary energy source that triggers the same chemical switching mechanism as UV light would, but without the harmful effects. The photoinitiators serve as intermediaries that convert visible light energy into the chemical reactions needed for tack reduction, bridging the gap between safe radiation and effective switching.
3Ease of operation
If water-based switchable adhesives are used to enable easy removal, then removal ease is improved, but they are unsuitable for wound dressings requiring dry environments
Solution Approach 1:
The invention replaces the mechanical/chemical water-based switching mechanism with an optical-based mechanism. Instead of using water to trigger adhesive removal, visible light initiates photopolymerization crosslinking that reduces tackiness. This substitution allows the adhesive to function in dry wound environments while still providing easy removal capability through light exposure.
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 adhesive composition reduces peel strength by up to 90% within seconds to minutes, enabling gentle removal from fragile surfaces without leaving residues, using commercially available ingredients and minimizing production hazards and costs.
Implementation Method 1
comprising a mixture, in proportions by weight, of 2% to 80% of curable molecules and 0.05% to 10% of photoinitiator... undergoes transformation from a tacky to a non-tacky state upon exposure to visible light
Data Source
AI summary
The present invention provides switchable adhesives comprising a mixture, in proportions by weight, of 20% to 98% of an adhesive, 2% to 80% of curable molecules and 0.05% to 10% of photoinitiator. Preferably, the adhesive and curable molecules are mutually soluble when dry, or the curable molecules and adhesive may be uniformly dispersed in each other. Preferably the amount of adhesive in the mixture is in the range 40% to 98% by weight, more preferably 60% to 95% by weight, even more preferably 70% to 85% by weight. Preferably the proportion of curable molecules in the mixture ranges from 2% to 60% by weight, more preferably 5% to 40% by weight, even more preferably 15% to 30% by weight. Preferably, the photoinitiator is present in the mixture in the proportions 0.5% to 5% by weight, more preferably 1% to 3% by weight. Such switchable adhesives are useful in medical dressings and other removable sheet products, and may be simply prepared by stirring the adhesive, the curable molecules and the photoinitiator together at room temperature.