Epoxy-Phenolic Co-dispersions for Formaldehyde-Free Storage Stability
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Solution Overview
Problem
Conventional aqueous epoxy resin formulations are not stable on storage at ambient temperature and generate free formaldehyde during curing, which is undesirable for industrial applications.
Innovation Solution
A process for creating an organic solvent-free aqueous co-dispersion of epoxy resins and phenolic novolac resins involving heating epoxy resins, adding phenolic novolac resins and a non-ionic surfactant at controlled temperatures, and incorporating water, which results in a stable composition suitable for various industrial applications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If conventional aqueous epoxy resin formulations are used, then epoxy resin can be applied in aqueous system, but the composition is not stable on storage at ambient temperature
Solution Approach 1:
The patent introduces a specific non-ionic surfactant as an intermediary substance to mediate between the hydrophobic epoxy resin and hydrophilic water. This surfactant forms a stable emulsion system where the epoxy resin is dispersed in water without phase separation during storage, resolving the instability issue while maintaining formulation reliability
Solution Approach 2:
The patent modifies the chemical composition parameters by selecting specific epoxy resin types (diglycidyl ether of bisphenol F or diglycidyl ether of bisphenol S) and combining them with phenolic novolac resin in specific ratios. This parameter optimization achieves both ambient temperature storage stability and curing reliability
2Strength
If phenolic resins are used as curing agents for epoxy resin, then curing can be achieved, but free formaldehyde is generated during cure
Solution Approach 1:
The patent extracts and eliminates the harmful formaldehyde generation side reaction while retaining the beneficial curing function. By using phenolic novolac resin as a co-dispersed phase rather than a traditional curing agent, the system achieves crosslinking through the epoxy-phenolic reaction without generating free formaldehyde, thus removing the harmful factor while preserving curing effectiveness
Solution Approach 2:
The patent converts the potential harm of formaldehyde generation into a benefit by using phenolic novolac resin that reacts with epoxy resin to form a crosslinked network without releasing formaldehyde. The phenolic hydroxyl groups provide the necessary reactivity for curing while avoiding the harmful byproducts associated with traditional phenolic resin curing
3Ease of operation
If organic solvents are used in epoxy resin formulations, then epoxy resin can be dissolved and applied, but environmental concerns arise
Solution Approach 1:
The patent fundamentally changes the formulation parameter from organic solvent-based to water-based system. By utilizing the emulsification capability of non-ionic surfactants and the compatibility of specific epoxy resins with water, the patent achieves proper viscosity and application properties without organic solvents, eliminating environmental harm while maintaining ease of operation
Solution Approach 2:
The patent employs hydraulic principles by using water as the continuous phase instead of organic solvents. The water-based emulsion system provides the necessary fluidity and application characteristics through proper emulsion formulation, replacing harmful organic liquids with environmentally benign water while maintaining operational ease
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 process produces a stable aqueous composition that maintains particle size distribution and reactivity, avoiding the generation of free formaldehyde, and is suitable for heat cure coatings, fiber sizing, and other industrial uses.
Implementation Method 1
add the surfactant and the water quantity
Implementation Method 2
aqueous co-dispersion of epoxy resins and phenolic novolac resins
Implementation Method 3
heat the epoxy resins at temperature ranging from 80-120°C
Data Source
AI summary
An organic solvent free process to make an aqueous co-dispersion of epoxy resins and at least phenolic novolac resins is reported. The compositions of such co-dispersions are based on blends of epoxy resins and at least a phenolic novolac resin within the profile viscosity versus temperature in the ranges from 1 500 000 to 300 mPas at 80°C and 10 000 to 20 mPas at 120°C.