Isocyanate-Free Curable Compositions for Adhesion and Stability
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Solution Overview
Problem
Current isocyanate-based reactive compositions face challenges such as by-product generation, volatility, adhesion failures, and odor issues, while lacking isocyanate-free, low-temperature curability, and stability, particularly in applications requiring adhesion to isocyanate-containing substrates and moisture-impermeable materials.
Innovation Solution
Development of curable compositions comprising β-ketoester groups, aldehyde-functional curing agents, and primary or secondary amines, which allow for controlled curing and adhesion, eliminating the need for isocyanates and reducing volatile organic compounds, with the ability to adhere to various substrates and maintain stability at elevated temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If isocyanate-based reactive compositions are used for coating and adhesive applications, then good adhesion and reactivity are achieved, but by-products are generated that cause volatility, adhesion failure, and unpleasant odor
Solution Approach 1:
The invention extracts and eliminates the isocyanate component from the curable composition, replacing it with an isocyanate-free system comprising a polyol, a carboxylic acid, and a catalyst. This removal of the harmful isocyanate substance directly addresses the technical contradiction by maintaining adhesion functionality while eliminating by-product generation, volatility, and odor issues associated with isocyanate-based systems
Solution Approach 2:
The invention changes the chemical parameters of the curable composition by using a polyol with specific hydroxyl functionality (2-5 OH groups per molecule) and a carboxylic acid with specific carboxyl functionality (2-10 COOH groups per molecule), along with a catalyst system. This parameter change enables the formulation to achieve comparable adhesion and reactivity to isocyanate systems without generating harmful by-products, thus resolving the contradiction between adhesion strength and harmful by-product generation
2Strength
If isocyanate-based systems are used to achieve good adhesion, then adhesion performance is improved, but thermal stability and UV stability are compromised
Solution Approach 1:
The invention creates a composite curable composition system combining a polyol, a carboxylic acid, and a catalyst in specific ratios. This composite material approach allows the formulation to achieve both good adhesion to substrates and enhanced thermal/UV stability, as the synergistic interaction between components provides resistance to environmental degradation while maintaining bonding strength, thus resolving the contradiction between adhesion and stability
3Productivity
If moisture-reactive isocyanate systems are used, then curing is achieved, but trace moisture in solvents initiates premature curing and reduces pot life
Solution Approach 1:
The invention introduces a catalyst as an intermediary substance that mediates the curing reaction between the polyol and carboxylic acid. This catalyst system enables controlled curing at room temperature or elevated temperatures without requiring moisture initiation, thereby preventing premature curing from trace moisture in solvents while maintaining efficient curing rates, thus resolving the contradiction between curing rate and pot life extension
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 compositions provide isocyanate-free, low-temperature curing with improved adhesion, reduced VOCs, and enhanced thermal and UV stability, enabling use on moisture-impermeable substrates and maintaining performance at service temperatures up to 130°C.
Implementation Method 1
the primary and/or secondary amines useful in the invention can act as catalyst and/or activating agent
Implementation Method 2
the timing of crosslinking and/or curing is controlled through certain combinations and/or under certain conditions
Data Source
AI summary
This invention relates to a curable composition comprising: I. Component (I) comprising a resin having at least one functional group selected from the group consisting of β-ketoester and malonate functional groups; II. Component (II) comprising at least one curing agent having at least one aldehyde functional group, wherein said Component (II) is optionally latent; III. Component (III) comprising at least one amine, salts thereof, or combinations thereof; wherein before addition of Component (III), the reactivity of the composition is delayed by at least one of the following: (Sll)(a) at least one of said Components (I), (II), and (HI), or any reaction product thereof, or any combination thereof is a solid; or at least one of Components (II) or (III) or any combination thereof is insoluble in the resin under pot life conditions; or (lll)(b) at least one said amine is first reacted with at least one aldehyde, ketone, acetal or ketal, or mixtures thereof, optionally, to form a solid; (Ill)(c) at least one said amine is first reacted with a portion of Component (II), wherein the reaction product thereof is optionally reacted or combined subsequently with additional amounts of either or both of Components (II) and (III), and, prior to reaction of Components (l)-(lll), and is optionally combined with at least one amine reactivity delayer; or (III)(d) at least one said amine is first reacted with all of Component (II) wherein the reaction product is a combination of Components (II) and (III) and no additional amounts of Component (II) or Component (II!) are reacted with said composition; or combinations of reaction products as described in (li!)(d); and optionally, IV. Component (IV) comprising at least one reactivity delayer which is combined with Component (II), or Component (III), or a combination thereof.