Aqueous Thermosetting Adhesive for Stable, Formaldehyde-Free Bonding
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Solution Overview
Problem
Existing aqueous adhesive compositions using phenol-formaldehyde resins face issues with high reactivity leading to rapid viscosity increase, making them difficult to use at lower viscosities, and the release of formaldehyde during bonding processes, which is regulated and undesirable.
Innovation Solution
An aqueous adhesive composition is developed using a thermosetting resin based on aromatic compounds, including 5-(hydroxymethyl)-furfural and aromatic polyphenols like phloroglucinol, which maintains low viscosity and is free of formaldehyde, ensuring high adhesive properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If phenol-formaldehyde resins with excess formaldehyde are used to achieve high adhesive properties, then bonding strength is improved, but formaldehyde release during storage and use increases
Solution Approach 1:
The patent extracts and eliminates formaldehyde from the adhesive composition by replacing phenol-formaldehyde resins with alternative resin systems based on tannins, lignins, or other phenolic compounds that do not release formaldehyde, thereby maintaining adhesive strength while removing the harmful substance
Solution Approach 2:
The patent converts the harmful formaldehyde-release property into a beneficial feature by using resins that naturally avoid formaldehyde while achieving equal or superior adhesive performance, turning a regulatory compliance issue into a product advantage
2Object-generated harmful factors
If phloroglucinol and 5-(hydroxymethyl)-furfural resins are used to eliminate formaldehyde, then formaldehyde-free bonding is achieved, but viscosity increases rapidly due to high reactivity
Solution Approach 1:
The patent applies preliminary protective actions by adding viscosity control agents and stabilizers to the adhesive composition before application, preventing premature polymerization and viscosity increase while maintaining the formaldehyde-free benefit
Solution Approach 2:
The patent introduces intermediary substances such as buffers, chelating agents, or polymerization inhibitors that mediate between the reactive resin components and water, controlling the reaction rate and preventing rapid viscosity increase while maintaining the formaldehyde-free composition
3Strength
If highly reactive thermosetting resins are used to achieve strong bonding, then adhesive strength is improved, but the time window for application decreases due to rapid viscosity increase
Solution Approach 1:
The patent prepares the adhesive composition in advance with controlled reactivity by adding stabilizers and controlling pH, allowing the adhesive to maintain low viscosity during storage and application while ensuring strong bonding upon curing
Solution Approach 2:
The patent creates a dynamic adhesive system where viscosity and reactivity are controlled to change over time - remaining low and stable during storage and application, then increasing rapidly during the curing process to achieve strong bonding
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 provides effective bonding of cellulosic elements with stable viscosity and no formaldehyde release, meeting regulatory requirements and enabling efficient assembly processes.
Implementation Method 1
Phenol-formaldehyde resins (PF) are derived from formaldehyde and phenol. Since phenol is a molecule with several reactive sites, a three-dimensional network ultimately forms.
Implementation Method 2
Phenols are used in particular as adhesives, for example in the manufacture of chipboard or composite materials reinforced with glass fibers, textile fibers, etc.
Data Source
AI summary
The present invention relates to an aqueous adhesive composition, comprising a thermosetting resin based on: - at least one aromatic compound A1 comprising at least one aromatic ring bearing at least two functions, one of said functions being a hydroxymethyl function, the other being an aldehyde function or a hydroxymethyl function; - at least one aromatic polyphenol A2 comprising at least one aromatic ring bearing at least two hydroxyl functions in the meta position relative to one another, the two ortho positions of at least one of the hydroxyl functions being unsubstituted; and - at least one phenol which is substituted or unsubstituted by a single alkyl group or by a single alkenyl group and/or at least one aromatic hydrocarbon compound A3 comprising at least two aromatic rings bearing a single hydroxyl function, it being understood that at least one of the ortho or para positions of each aromatic ring is unsubstituted. Such an adhesive composition can in particular be used for assembling wooden elements.