Lignin Adhesive Preparation via Self-Cross-Linking
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Solution Overview
Problem
Existing methods for preparing lignin adhesive are costly and toxic, involving complex processes and the use of formaldehyde and other hazardous chemicals, which hinders industrialization and environmental sustainability.
Innovation Solution
A method involving the treatment of wood fiber raw materials with a mixed solution containing a hydrogen bond receptor, a polyol, and an organic polyacid, followed by solid-liquid separation, rotary evaporation, and washing to produce a lignin adhesive through cross-linking reactions, avoiding the need for chemical modification and toxic substances.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If traditional chemical modification methods (phenolization and demethylation) are used to prepare lignin adhesive, then the adhesion properties are improved, but the preparation process becomes complex, energy consumption increases, and chemical consumption increases
Solution Approach 1:
The patent extracts and utilizes the natural phenolic groups and hydroxyl groups already present in lignin structure, rather than introducing external chemical modifiers. This extraction approach allows direct cross-linking between lignin molecules through their inherent functional groups, eliminating the need for complex phenolization and demethylation processes while maintaining strong adhesion properties
Solution Approach 2:
The patent employs self-cross-linking of lignin molecules through their natural functional groups (phenolic and hydroxyl groups) without requiring external chemical modifiers. The lignin structure itself provides the reactive sites for cross-linking, making the process self-sufficient and eliminating the need for complex chemical modification steps
2Strength
If traditional chemical modification methods are used to prepare lignin adhesive, then the adhesion properties are improved, but energy consumption increases
Solution Approach 1:
The patent employs self-cross-linking of lignin molecules through their natural functional groups (phenolic and hydroxyl groups) without requiring external chemical modifiers. The lignin structure itself provides the reactive sites for cross-linking, making the process self-sufficient and eliminating the need for complex chemical modification steps
Solution Approach 2:
The patent changes the approach from chemical modification to physical cross-linking through controlled hydrolysis and condensation reactions. By adjusting reaction conditions (temperature, catalyst type, reaction time) rather than changing chemical structure, the process achieves cross-linking with lower energy consumption while maintaining adhesive performance
3Strength
If traditional chemical modification methods are used to prepare lignin adhesive, then the adhesion properties are improved, but chemical consumption increases
Solution Approach 1:
The patent extracts and utilizes the natural phenolic groups and hydroxyl groups already present in lignin structure, rather than introducing external chemical modifiers. This extraction approach allows direct cross-linking between lignin molecules through their inherent functional groups, eliminating the need for complex phenolization and demethylation processes while maintaining strong adhesion properties
Solution Approach 2:
The patent employs self-cross-linking of lignin molecules through their natural functional groups (phenolic and hydroxyl groups) without requiring external chemical modifiers. The lignin structure itself provides the reactive sites for cross-linking, making the process self-sufficient and eliminating the need for complex chemical modification steps
4Object-affected harmful factors
If soy-based adhesives are used to replace phenolic resin-based adhesives, then environmental protection is improved, but the solid content is low, viscosity is high, and overall adhesion is weak
Solution Approach 1:
The patent changes the molecular structure of lignin through controlled hydrolysis and cross-linking reactions, adjusting the degree of polymerization and creating a three-dimensional network structure. This parameter change increases the solid content and reduces viscosity while enhancing adhesion strength, making the adhesive comparable to traditional phenolic resins but with environmental benefits
Solution Approach 2:
The patent creates a composite adhesive system by combining lignin with cross-linking agents and controlling the formation of a three-dimensional network structure. This composite approach enhances the mechanical properties and adhesion strength of the lignin-based adhesive, overcoming the limitations of pure soy-based adhesives while maintaining environmental sustainability
5Object-affected harmful factors
If soy-based adhesives are used to replace phenolic resin-based adhesives, then environmental protection is improved, but hot-pressing time is long and bonding strength is unstable
Solution Approach 1:
The patent changes the molecular structure of lignin through controlled hydrolysis and cross-linking reactions, adjusting the degree of polymerization and creating a three-dimensional network structure. This parameter change increases the solid content and reduces viscosity while enhancing adhesion strength, making the adhesive comparable to traditional phenolic resins but with environmental benefits
Solution Approach 2:
The patent replaces the need for long hot-pressing mechanical compression with chemical cross-linking reactions that occur at lower temperatures. The cross-linking agents facilitate bond formation through chemical reactions rather than relying solely on thermal compression, reducing hot-pressing time while maintaining stable bonding strength
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
This method enables the efficient and cost-effective preparation of lignin adhesive with strong adhesion properties, capable of bonding various materials, while minimizing environmental impact and production costs.
Implementation Method 1
lignin is directly converted into adhesive through a series of cross-linking reactions
Implementation Method 2
subjecting an obtained liquid to a rotary evaporation to remove the organic solvent
Implementation Method 3
a homogeneous transparent liquid composed of a hydrogen bond receptor, a polyol, and an organic polyacid
Data Source
AI summary
A method for preparing a lignin adhesive and a product thereof are provided. The method includes: treating a wood fiber raw material with a mixed solution; after the treatment, adding an organic solvent to perform a solid-liquid separation while stirring, subjecting an obtained liquid to a rotary evaporation to remove the organic solvent, and washing and drying the product to obtain the lignin adhesive. The method can remove a large amount of lignin from wood fiber raw materials at a low temperature, and in the process of lignin removal, the lignin adhesive is formed by the cross-linking reaction with the solvent in the system, realizing the separation of lignin and the formation of lignin adhesive simultaneously. And the method is simple, has low cost and high yield, and can realize the large-scale preparation of lignin adhesive and the efficient removal of lignin.