Energy-Ray-Crosslinkable Adhesive Composition Against Adherend Staining
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Solution Overview
Problem
Existing pressure-sensitive adhesives using hydrogen-withdrawing photoinitiators with low molecular weight leave low-molecular-weight substances that cause staining on adherends during crosslinking, leading to issues like cloudiness and ghost marks.
Innovation Solution
A pressure-sensitive adhesive composition comprising a (meth)acrylic resin with no energy ray crosslinkability and an acrylic resin with energy ray crosslinkability, specifically with a benzophenone structure in the side chain, is used to form a crosslinked adhesive that minimizes adherend staining.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a hydrogen-withdrawing photoinitiator with low molecular weight is used for crosslinking, then crosslinking reaction efficiency is improved, but low-molecular-weight substances remain that cause staining on adherends
Solution Approach 1:
The patent extracts and removes the harmful low-molecular-weight photoinitiator substances from the crosslinking system by replacing them with a photopolymerizable monomer that forms high-molecular-weight crosslinked structures, thereby eliminating the staining problem while maintaining crosslinking efficiency
Solution Approach 2:
The patent changes the molecular weight parameter of the crosslinking agent from low (photoinitiator) to high (photopolymerizable monomer), which fundamentally alters the crosslinking mechanism from photoinitiator-mediated radical reaction to direct photopolymerization, resolving the staining issue
2Strength
If crosslinking is performed to improve cohesive strength, then adhesive strength is improved, but adherend staining occurs due to remaining low-molecular-weight substances
Solution Approach 1:
The patent creates a composite adhesive system combining the base adhesive resin with photopolymerizable monomers that have specific functional groups, forming a crosslinked composite structure that achieves high cohesive strength without the harmful byproducts of traditional photoinitiator systems
Solution Approach 2:
The photopolymerizable monomer acts as an intermediary that enables crosslinking without leaving residual low-molecular-weight substances, serving as a bridge between the base adhesive and the crosslinked network structure
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 composition achieves good adhesive strength with minimal adherend staining, forming a crosslinked adhesive that is suitable for various applications without leaving marks.
Implementation Method 1
an acrylic resin (B) having energy ray crosslinkability, specifically with a benzophenone structure in the side chain
Implementation Method 2
a radical is generated in the acrylic resin, and a crosslinking reaction is proceeded by a coupling reaction of the generated radical
Data Source
AI summary
An energy-ray-crosslinkable pressure-sensitive adhesive composition may contain a (meth)acrylic resin (A) having no energy ray crosslinkability and an acrylic resin (B) having energy ray crosslinkability. A pressure-sensitive adhesive sheet may use such a energy-ray-crosslinkable pressure-sensitive adhesive composition. A crosslinked pressure-sensitive adhesive may be obtained by subjecting the energy-ray-crosslinkable pressure-sensitive adhesive composition to energy ray crosslinking. A pressure-sensitive adhesive sheet may use the crosslinked pressure-sensitive adhesive.