Tackifier-Free UV-Crosslinked Acrylate Adhesive for Rough Surfaces
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Solution Overview
Problem
Existing pressure-sensitive adhesive tapes face challenges in achieving effective adhesion to rough surfaces and low surface energy surfaces, and they often leave residue upon removal, due to the difficulty in incorporating tackifiers into crosslinked networks and the adverse effects of tackifiers absorbing actinic radiation.
Innovation Solution
A crosslinkable composition comprising two different (meth)acrylate polymers, each with a weight average molecular weight of 50,000 to 500,000 Daltons, where at least one polymer contains pendant aromatic ketone groups that crosslink upon ultraviolet radiation exposure, forming a crosslinked composition free of tackifiers, which can be used as pressure-sensitive adhesives for rough and low surface energy surfaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If tackifiers are added to improve adhesion to rough and low surface energy surfaces, then adhesion performance is improved, but the adhesive leaves residue upon removal and absorbs actinic radiation adversely affecting crosslinking
Solution Approach 1:
The invention extracts and eliminates tackifiers from the adhesive composition entirely. Instead of using tackifiers to achieve adhesion to rough and low surface energy surfaces, the patent employs a tackifier-free (meth)acrylate polymer formulation that crosslinks upon UV exposure, achieving strong adhesion without the harmful residue-forming and radiation-absorbing properties of traditional tackifiers.
Solution Approach 2:
The invention changes the chemical composition parameters by using specific (meth)acrylate polymers with controlled molecular weights (50,000 to 500,000 Daltons) and incorporating UV-crosslinkable functional groups. This parameter change enables the adhesive to achieve strong initial tack and maintained adhesion without requiring tackifiers, thereby eliminating residue formation and UV radiation absorption issues.
2Strength
If crosslinking is implemented to improve cohesive strength and adhesion, then structural integrity is improved, but incorporating tackifiers into crosslinked networks is difficult
Solution Approach 1:
The invention removes tackifiers from the formulation entirely, eliminating the compatibility and incorporation difficulties associated with integrating tackifiers into crosslinked networks. The crosslinking is achieved through UV-curable functional groups inherent to the (meth)acrylate polymer structure.
Solution Approach 2:
The invention uses composite (meth)acrylate polymer formulations containing multiple polymer components with different molecular weights and UV-crosslinkable functional groups. This composite approach achieves both strong cohesive strength through crosslinking and ease of manufacture by avoiding the complex integration of tackifiers into the crosslinked network.
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 crosslinked composition demonstrates enhanced adhesion to various surfaces, including rough surfaces and low surface energy surfaces, and can be cleanly removed without leaving residue, as it forms a robust network without the limitations of tackifiers.
Implementation Method 1
At least one of the (meth)acrylate polymers contains pendant aromatic ketone groups that upon exposure to ultraviolet radiation, result in the formation of crosslinks within the polymeric material
Data Source
AI summary
Crosslinkable compositions, crosslinked compositions, articles containing these compositions, and methods of making the articles are provided. The crosslinkable compositions, which include two (meth)acrylate polymers, are used to form the crosslinked compositions upon exposure to ultraviolet radiation. The crosslinkable and crosslinked compositions are free or substantially free of tackifiers. The crosslinked compositions can function as pressure-sensitive adhesives. The crosslinkable compositions are well suited for use with hot melt processing methods.