Dual-Curable Pressure-Sensitive Adhesive for Uniform Thick-Layer Curing
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Solution Overview
Problem
Existing UV-curable pressure sensitive adhesives face limitations in curing uniformity and effectiveness with thicker layers and pigmented compositions, leading to non-uniformity and poor adhesion.
Innovation Solution
A dual-curable pressure sensitive adhesive composition that can be cured using both UV and thermal methods, comprising an acrylic copolymer, polymeric chain extender, and photoinitiator, allowing for uniform curing of thicker layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If UV radiation is used to cure thicker adhesive layers, then more radiation energy is required, but this leads to non-uniform curing within the layer
Solution Approach 1:
The patent combines UV curing and thermal curing into a single dual-curing system. The adhesive composition includes both photoinitiators for UV curing and thermal curing agents that activate at elevated temperatures. This merging allows the process to benefit from both methods: UV provides initial crosslinking and the thermal cure completes the reaction uniformly throughout thicker layers, eliminating the non-uniformity problem of UV-only curing.
Solution Approach 2:
The patent utilizes parameter changes by transitioning from UV irradiation to thermal heating as the primary curing mechanism for thicker layers. The adhesive formulation is designed with components that respond differently to UV and thermal energy, allowing the curing process to adapt to layer thickness by using thermal energy to penetrate and cure the entire layer uniformly, while UV provides surface-level crosslinking.
2Quantity of substance
If UV radiation is used to cure pigmented adhesive compositions, then the pigment limits radiation penetration, but this results in poor curing
Solution Approach 1:
The patent merges UV curing and thermal curing mechanisms to overcome the penetration limitation imposed by pigments. While UV radiation can be blocked by pigments in thicker or highly pigmented layers, the thermal curing component remains effective regardless of pigment concentration. The dual-curing system ensures that even when UV penetration is compromised, the thermal cure can still effectively crosslink the adhesive throughout the entire layer.
Solution Approach 2:
The patent introduces thermal energy as an intermediary curing mechanism that bypasses the penetration barrier created by pigments. Instead of relying solely on UV photons to penetrate and cure the adhesive, the thermal curing agents act as intermediaries that activate through heat transfer, which can penetrate pigmented materials effectively and initiate crosslinking reactions throughout the layer uniformly.
3Reliability
If extensive UV radiation is applied to cure adhesive layers, then curing is achieved, but this causes non-uniformities within the layer
Solution Approach 1:
The patent combines UV curing and thermal curing into a complementary dual-system. UV radiation provides initial and surface-level crosslinking, while thermal curing completes the reaction uniformly throughout the entire layer. This merging ensures complete curing (reliability) while maintaining uniformity across the entire adhesive layer, as the thermal component eliminates the gradients and non-uniformities that would otherwise result from UV-only curing of thick layers.
Solution Approach 2:
The patent ensures continuous and uniform curing action by transitioning from UV irradiation to thermal heating. The thermal curing process continues the crosslinking reaction initiated by UV, maintaining useful action throughout the entire layer uniformly. This continuous action prevents the formation of uncured regions or gradients that would occur with UV-only curing, thereby ensuring both completion and uniformity of the curing process.
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 dual-curable adhesive achieves uniform and strong adhesion across various substrates, including polymeric membranes and rigid materials, with improved peel strength and shear adhesion, suitable for roofing, construction, and high-temperature applications.
Implementation Method 1
The dual-curable adhesive achieves uniform and strong adhesion across various substrates, including polymeric membranes and rigid materials, with improved peel strength and shear adhesion
Implementation Method 2
A dual-curable pressure sensitive adhesive composition that can be cured using both UV and thermal methods
Data Source
AI summary
The present disclosure provides a method of curing a hot melt adhesive composition including an acrylic copolymer and a polymeric chain extender by subjecting the composition to both UV and thermal curing.