Room Temperature Curing Epoxy Adhesive for Plastics
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Solution Overview
Problem
Existing epoxy adhesives are slow-curing at room temperature and have limited adhesion to plastic substrates, requiring heat for curing and often incorporating mercaptan functionality, which can be undesirable.
Innovation Solution
A two-part epoxy adhesive composition comprising a first epoxy resin, a second polyurethane- or isocyanate-modified epoxy resin, a high equivalent weight amine curing agent, a low equivalent weight amine curing agent, an acetoacetoxy-functionalized compound, a metal salt catalyst, and a multifunctional acrylate, which allows for rapid room temperature curing and strong adhesion to plastics without mercaptan functionality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If traditional epoxy adhesives are used, then adhesion to substrates is achieved, but curing is slow at room temperature and requires heat
Solution Approach 1:
The patent changes the chemical parameters of the adhesive system by incorporating specific catalysts (metal salts like calcium triflate) and co-curing agents (acetoacetoxy-functionalized compounds and multifunctional acrylates) that enable rapid room temperature curing. This modifies the reaction kinetics parameters to achieve fast curing without thermal activation
Solution Approach 2:
The invention creates a composite curing system combining multiple components: epoxy resins, amine curing agents, metal salt catalysts, acetoacetoxy-functionalized compounds, and multifunctional acrylates. This composite approach synergistically enables both rapid curing and room temperature processing
2Strength
If mercaptan functionality is incorporated to improve adhesion, then bonding strength increases, but odor and unwanted side effects occur
Solution Approach 1:
The patent extracts and removes the mercaptan functionality from the adhesive system while preserving the adhesion performance. The harmful mercaptan group is completely eliminated from the formulation, replacing it with odor-free alternative curing mechanisms that achieve the same bonding strength
Solution Approach 2:
The invention uses transient intermediates (acetoacetoxy-functionalized compounds) that facilitate adhesion during the curing process but are consumed in the reaction, leaving no persistent harmful residues or odors in the final cured product
3Loss of time
If fast curing is achieved through chemical modification, then gel time decreases, but adhesion to plastic substrates may be compromised
Solution Approach 1:
The patent applies different functional components to different aspects of the curing process: metal salt catalysts and acetoacetoxy compounds optimize early-stage gelation speed, while multifunctional acrylates and modified epoxy resins ensure long-term adhesion to plastic substrates. Each component addresses specific local requirements of the curing timeline
Solution Approach 2:
The adhesive formulation includes components that perform preliminary bonding actions during the fast gel phase, creating initial adhesion that is subsequently strengthened and stabilized as the curing process completes. The acetoacetoxy-functionalized compound initiates rapid bonding, while other components continue to reinforce adhesion
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 achieves rapid handling strength and excellent adhesion to plastics, with gel times and handling strength times of less than 30 minutes, even at low temperatures, while being low in odor and free from mercaptan functionality.
Implementation Method 1
a metal salt catalyst
Implementation Method 2
an acetoacetoxy-functionalized compound
Implementation Method 3
a first amine curing agent having an equivalent weight of at least 50 grams per mole of amine equivalents; a second amine curing agent having an equivalent weight of no greater than 45 grams per mole of amine equivalents
Data Source
AI summary
Room temperature curing epoxy adhesives that show good adhesion to plastic substrates are described. The adhesives contain an epoxy resin component comprising a first epoxy resin and a second epoxy resin; a first amine curing agent having an equivalent weight of at least 50 grams per mole of amine equivalents; a second amine curing agent having an equivalent weight of no greater than 45 grams per mole of amine equivalents; an acetoacetoxy-functionalized compound; a metal salt catalyst; and a multifunctional acrylate.