Solventless Two-Component Adhesive with Epoxy-Adduct Metal Bonding
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Solution Overview
Problem
Traditional two-component solventless polyurethane-based laminating adhesives exhibit high initial viscosity, weak initial bonds, slow bond development, poor chemical resistance, especially in acidic conditions, and poor adhesion strength to metal or metal alloy substrates, with existing additives failing to provide satisfactory performance.
Innovation Solution
A solventless polyurethane adhesive composition incorporating an epoxy-aromatic diisocyanate adduct and phosphate ester polyol, which includes an oxazolidinone ring, is used to enhance adhesion strength by forming a polyurethane main chain with the residual moiety of the adduct covalently attached, improving adhesion to metal or metal alloy substrates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If traditional two-component solventless polyurethane-based laminating adhesives are used, then the adhesive composition is environmentally friendly and free of organic solvent, but the adhesion strength to metal or metal alloy substrates is poor
Solution Approach 1:
The patent uses a composite adhesion promoter system comprising both an epoxy-aromatic diisocyanate adduct (containing oxazolidinone rings) and a phosphate ester polyol. This composite approach combines the metal-chelating ability of phosphate esters with the reactive bonding capabilities of the epoxy-adduct, creating synergistic effects that dramatically improve adhesion to metal substrates while maintaining the solventless environmentally friendly formulation.
Solution Approach 2:
The epoxy-aromatic diisocyanate adduct and phosphate ester polyol act as intermediary substances between the polyurethane adhesive and the metal substrate. These intermediaries provide chemical bridging mechanisms, where the phosphate ester forms coordinate bonds with metal surfaces and the epoxy-adduct provides covalent bonding to the adhesive matrix, thereby enhancing interfacial adhesion strength.
2Productivity
If traditional two-component solventless polyurethane-based laminating adhesives are used, then the adhesive can be applied without organic solvent removal, but the initial bond strength is weak and bond development is slow
Solution Approach 1:
The epoxy-aromatic diisocyanate adduct is prepared in advance with pre-formed oxazolidinone rings, which are highly reactive toward isocyanates. When mixed with the polyurethane adhesive components, these pre-prepared adducts rapidly react to form strong initial bonds, eliminating the slow bond development issue while maintaining the productivity benefits of solventless application.
Solution Approach 2:
The patent modifies the chemical parameters of the adhesive system by incorporating the epoxy-adduct with specific functional groups (oxazolidinone rings) that have enhanced reactivity. This parameter change in molecular structure and chemical functionality accelerates the curing reaction kinetics, resulting in faster bond development and stronger initial adhesion without requiring solvents.
3Device complexity
If traditional two-component solventless polyurethane-based laminating adhesives are used, then the adhesive formulation is simplified, but the chemical resistance especially in acidic conditions is poor
Solution Approach 1:
The patent changes the chemical composition parameters by introducing phosphate ester polyol, which contains phosphorus atoms with lone pair electrons capable of forming strong coordinate bonds with metal ions. This parameter change in chemical composition provides exceptional resistance to acidic environments and chemical degradation, enhancing reliability without significantly complicating the formulation 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 composition achieves enhanced adhesion strength and improved chemical resistance, with cohesion failure mode indicating strong bonding to both substrates, surpassing the limitations of traditional adhesives.
Implementation Method 1
the adhesive layer comprises a polyurethane main chain to which residual moiety of the epoxy-aromatic diisocyanate adduct is covalently attached
Implementation Method 2
the two-component adhesive composition produces an adhesive layer with excellent adhesion strength to various metal or metal alloy substrates
Data Source
Figure 1
AI summary
A two-component adhesive composition is provided. The two-component adhesive composition comprises an isocyanate component, an isocyanate-reactive component and an epoxy-aromatic diisocyanate adduct, and can achieve superior adhesion strength between the adhesive and a substrate like metal alloy substrate. A laminated article prepared with said composition, a method for preparing the article and the use of the epoxy-aromatic diisocyanate adduct as adhesion promoter in a two-component polyurethane adhesive composition are also provided.