Latent Adhesive Layers with Redox Initiation for Repositioning
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
High-strength bonding tapes require precise initial placement due to aggressive adhesion, lacking the ability for removal and repositioning without damaging the substrate.
Innovation Solution
Adhesive articles with tacky latent adhesive layers containing a redox initiator system, including a transition metal complex, oxidizing agent, and blocked reducing agent, which exhibit extended open time for initial low adhesion, allowing for removal and repositioning before achieving high adhesion upon exposure to actinic radiation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If aggressive adhesive layers are used to achieve high-strength bonding, then bonding strength is improved, but placement flexibility deteriorates (cannot be removed and repositioned)
Solution Approach 1:
The adhesive layer transitions from a static aggressive adhesive to a dynamic system where adhesion strength changes over time. Initially, the adhesive exhibits low adhesion allowing placement flexibility, then progressively increases to high adhesion for strong bonding. This temporal dynamic resolves the contradiction between initial placement ease and final bond strength.
Solution Approach 2:
The adhesive composition parameters change over time through controlled polymerization. The system starts with monomers and initiators that provide low initial adhesion, then undergoes gradual curing to achieve high final adhesion. This parameter evolution allows the adhesive to provide both placement flexibility and bonding strength at different stages.
2Reliability
If immediate high adhesion is achieved, then bonding reliability is improved, but handling capability deteriorates (cannot be repositioned)
Solution Approach 1:
The adhesive bonding process occurs in periodic stages: first a placement period with low adhesion allowing handling and repositioning, then a progressive curing period where adhesion increases to achieve reliable bonding. This periodic action separates the handling phase from the bonding phase, resolving the contradiction between reliability and handling capability.
Solution Approach 2:
The adhesive is formulated with preliminary low adhesion properties to enable easy handling and precise placement before final bonding occurs. The polymerization process is initiated in a controlled manner after placement, ensuring the adhesive provides handling capability first, then develops reliable bonding subsequently.
3Manufacturing precision
If precise initial placement is required, then bonding accuracy is improved, but operational complexity increases (cannot be adjusted after placement)
Solution Approach 1:
The adhesive system provides dynamic adhesion properties that evolve from low to high over time. During the initial low-adhesion phase, the tape can be easily repositioned and adjusted to achieve precise placement. Once placement is finalized, the adhesive progressively cures to lock in the precise position, eliminating the need for complex adjustment mechanisms.
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 the secure bonding of adherends with improved handling and placement capabilities, ensuring strong and reliable adhesion over time.
Implementation Method 1
exposing the first and second tacky latent adhesive layers to actinic electromagnetic radiation to provide exposed first and second tacky latent adhesive layers
Implementation Method 2
a redox initiator system comprising: a transition metal complex that participates in a redox cycle; an oxidizing agent; and a blocked reducing agent
Data Source
AI summary
An adhesive article comprising first and second tacky latent adhesive layers disposed on respective first and second opposed major surfaces of a substrate. Each of the first and second tacky latent adhesive layers independently comprises at least one polymerizable component, and a redox initiator system comprising a transition metal complex that participates in a redox cycle, an oxidizing agent, and a blocked reducing agent represented by the formula ((I). Each of R1 and R2 are independently H, an alkyl, an aryl, or RPhoto5 with the proviso that at least one of R1 and R2 is RPhoto. RPhoto represents a photoremovable group. Each of R3 and R4 independently represents H, an alkyl group, or an aryl group comprising a monovalent ester, ether, urethane, or carbonate group. Methods of making and using the adhesive articles are also disclosed.