Tannic Acid Curing Agent for Epoxy Toughening
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Solution Overview
Problem
Current epoxy resin curing agents are primarily derived from petroleum resources and lack sustainability, and existing toughening methods face challenges such as poor compatibility between resin and toughening agents, leading to issues like demulsification and high viscosity requirements.
Innovation Solution
A tannic acid curing agent is developed using bio-based materials, specifically prepared through a method involving substitution and addition reactions with 10-undecenoyl chloride, mercapto compounds, and photoinitiators under ultraviolet irradiation, which introduces a long fatty chain and improves network mobility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional petroleum-based curing agents are used, then the curing performance is reliable, but the sustainability and renewability are poor
Solution Approach 1:
The invention changes the chemical composition parameters of the curing agent by replacing petroleum-based materials with tannic acid (a natural polyphenol) as the primary curing agent and incorporating long-chain fatty acid mercapto compounds as reactive toughening agents. This substitution maintains curing performance while achieving sustainability goals with 85-93% renewable carbon content.
Solution Approach 2:
The invention creates a composite curing agent system combining tannic acid with long-chain fatty acid mercapto compounds (such as ricinoleic acid, linoleic acid, or oleic acid). This composite approach leverages the crosslinking capability of tannic acid and the toughening effect of the mercapto compounds, achieving both reliable curing performance and improved toughness while maintaining sustainability.
2Strength
If toughening agents are added to epoxy system, then the toughness is improved, but the compatibility problems arise leading to demulsification and shrinkage cavities
Solution Approach 1:
The invention merges the curing agent and toughening agent functions into a single integrated system. The long-chain fatty acid mercapto compounds serve dual purposes: they act as reactive toughening agents that incorporate into the crosslinking network and as compatibility promoters that ensure uniform mixing with epoxy resin, eliminating demulsification and shrinkage cavity issues.
Solution Approach 2:
The long-chain fatty acid mercapto compounds act as intermediaries between the polar epoxy resin and the non-polar toughening agents. Their molecular structure contains both polar groups (mercapto and carboxyl) that can interact with epoxy and non-polar long chains that provide toughness, facilitating compatibility and preventing phase separation.
3Ease of operation
If reactive toughening agents are used to introduce flexible segments, then the network mobility is increased, but the viscosity becomes excessively high
Solution Approach 1:
The invention optimizes the molecular weight and chain length parameters of the mercapto compounds used. By selecting long-chain fatty acid mercapto compounds with specific carbon chain lengths (C18-C22), the invention achieves sufficient network mobility for toughness while controlling viscosity to remain manageable for processing, avoiding the excessively high viscosity problem.
4Adaptability or versatility
If bio-based raw materials are used instead of petroleum materials, then the renewability is improved, but the performance consistency becomes challenging
Solution Approach 1:
The invention applies local quality control by selecting specific mercapto compounds from natural sources with well-defined molecular structures (ricinoleic acid, linoleic acid, oleic acid). Each component has controlled purity and composition, ensuring consistent performance while maintaining the renewable nature of the materials.
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 tannic acid curing agent significantly enhances the toughness of epoxy resins, with deformation under stress reaching 60% at 5.5 MPa, and its renewable carbon content reaches 85-93%, facilitating mass production and improved compatibility.
Implementation Method 1
mixing tannic acid, 10-undecenoyl chloride, a catalyst and a solvent for a substitution reaction to obtain undecylenyl tannic acid
Implementation Method 2
mixing the undecylenyl tannic acid, a mercapto compound, the solvent and a photoinitiator for an addition reaction under an ultraviolet irradiation to obtain the tannic acid curing agent
Implementation Method 3
mixing the undecylenyl tannic acid, a mercapto compound, the solvent and a photoinitiator for an addition reaction under an ultraviolet irradiation
Data Source
AI summary
A tannic acid curing agent and a preparation method thereof are provided. The present invention uses tannic acid as a raw material and the long fatty chain of 10-undecenoyl chloride is introduced into the tannic acid structure to obtain the tannic acid curing agent. The preparation method includes the following steps: mixing tannic acid, 10-undecenoyl chloride, a catalyst and a solvent for a substitution reaction to obtain undecylenyl tannic acid, in which the catalyst includes an acid binding agent and 4-diaminopyridine, and the solvent includes ethyl acetate and N,N-dimethylformamide; mixing the undecylenyl tannic acid, a mercapto compound, a solvent and a photoinitiator for an addition reaction under an ultraviolet irradiation to obtain the tannic acid curing agent, in which the mercapto compound is a mercapto carboxylic acid compound or a mercapto alcohol compound.