Lignin-Epoxy Hybrid Nanoparticles for Water-Resistant Adhesives
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Solution Overview
Problem
Current wood adhesives face challenges with the toxicity and non-renewable nature of petroleum-based formaldehyde, and lignin-based adhesives often require fractionation or modification, leading to limitations in water resistance and mechanical performance.
Innovation Solution
A method for forming aqueous lignin-epoxy hybrid nanoparticles using softwood Kraft lignin and bisphenol A diglycidyl ether, which eliminates the need for lignin fractionation or modification, providing a green and simple process for producing a waterborne adhesive with strong water resistance and pH-switchable surface characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If lignin-based adhesives are used to replace petroleum-based formaldehyde adhesives, then environmental friendliness and renewability are improved, but water resistance and mechanical performance deteriorate
Solution Approach 1:
The patent creates a composite adhesive system combining lignin nanoparticles with epoxy resin and crosslinking agents. This composite approach allows the adhesive to benefit from both the renewable, non-toxic properties of lignin and the superior water resistance and mechanical strength of epoxy, thereby resolving the contradiction between environmental friendliness and performance.
2Ease of manufacture
If lignin is used directly in adhesives without fractionation or modification, then process simplicity and cost are improved, but adhesive performance and water resistance deteriorate
Solution Approach 1:
The patent utilizes the inherent properties of Kraft lignin at specific pH levels (particularly pH 12 where it becomes deprotonated and more reactive) to enable direct use of unmodified lignin. By controlling pH parameters and selecting appropriate epoxy resins, the patent achieves good adhesive performance without requiring fractionation or chemical modification of lignin, thus maintaining process simplicity while improving performance.
3Strength
If BADGE is used as the epoxy resin, then adhesive strength and water resistance are improved, but safety concerns due to BADGE migration arise
Solution Approach 1:
The patent employs crosslinking agents that react with BADGE to form a crosslinked network structure before the adhesive is fully cured or before migration can occur. This preliminary chemical modification of BADGE through crosslinking prevents the migration of unreacted BADGE while maintaining the adhesive strength benefits of the epoxy resin.
4Strength
If fractionation or degradation of lignin is performed to improve adhesive performance, then adhesive strength is improved, but process complexity and production time increase
Solution Approach 1:
The patent extracts and utilizes the essential reactive components of Kraft lignin (the nanoparticulate lignin structure and hydroxyl groups) without requiring the time-consuming fractionation or degradation processes. By directly incorporating unmodified Kraft lignin into the adhesive system with epoxy and crosslinkers, the patent achieves good adhesive strength while eliminating the production time losses associated with complex lignin processing.
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 method results in a lignin-epoxy adhesive with excellent water resistance and adhesive strength, suitable for various substrates, and allows for covalent surface functionalization under harsh conditions, expanding its application potential.
Implementation Method 1
SKL and BADGE are physically mixed together in solution state and co-precipitated by reducing the solvent concentration in the mixture to give rise to SKL-BADGE hybrid nanoparticles
Implementation Method 2
the solution state epoxidation of lignin for preparing lignin-based epoxy resins
Implementation Method 3
Depending on the mass ratio of SKL to BADGE, the hy-LNPs can either be intraparticle-crosslinked for covalent surface functionalization or inter- and intraparticle cross-linked for technical adhesives
Implementation Method 4
aqueous lignin-epoxy hybrid nanoparticles with switchable surface characteristics
Data Source
AI summary
The invention describes a method of forming aqueous lignin-epoxy hybrid nanoparticles with switchable surface characteristics. The invention is applicable to production of technical adhesives and covalent surface modification of lignin nanoparticles under harsh reaction conditions. Further, in terms of the covalent functionalization of lignin nanoparticles (LNPs), this invention presents the covalent cationization of LNPs by means of attached quaternary ammonium groups.