Cellulose Derivatization Using Urea Swelling
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current methods for derivatizing cellulose often require thermal, mechanical, or chemical pre-treatment and excessive reagents, leading to difficulties in purification, especially when nanofibrillated cellulose is involved, and there is a lack of dry or semi-dry methods capable of effectively swelling and penetrating cellulose fibers for derivatization.
Innovation Solution
A method for derivatizing cellulose pulp at high solids content or fully dry state using a reaction medium comprising urea and derivatization reagents, which simultaneously penetrate and activate cellulose fibers, reducing the need for excessive reagents and catalysts, and allowing for benign reaction conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If thermal, mechanical or chemical pre-treatment is applied to cellulose to reduce crystallinity, then derivatization can proceed more easily, but the process complexity and cost increase
Solution Approach 1:
The patent performs preliminary swelling action by incorporating the derivatization reagent into the cellulose fiber structure before the actual derivatization reaction occurs. This preliminary penetration and swelling action prepares the cellulose for derivatization without requiring separate thermal, mechanical, or chemical pre-treatment steps, thus reducing process complexity while maintaining derivatization efficiency
Solution Approach 2:
The patent merges the swelling action and derivatization reaction into a single integrated process step. The derivatization reagent serves dual functions: it swells and penetrates the cellulose fiber structure while simultaneously performing the derivatization reaction, eliminating the need for separate pre-treatment and derivatization steps
2Productivity
If large excess of reagents and organic solvents is used to facilitate derivatization reaction, then reaction efficiency improves, but purification difficulty and cost increase
Solution Approach 1:
The patent uses water as an intermediary medium that enables the derivatization reaction to proceed efficiently without requiring large excesses of organic solvents. Water facilitates reagent penetration and reaction while being easily removable through simple washing, thus maintaining high reaction efficiency while dramatically simplifying purification compared to organic solvent-based methods
Solution Approach 2:
The patent changes the reaction medium parameter from organic solvents to water, which fundamentally alters the purification requirements. Water-based reactions allow for simple aqueous washing to remove excess reagents and byproducts, eliminating the need for complex organic solvent removal and purification steps while maintaining derivatization efficiency
3Adaptability or versatility
If cellulose nanofibrils are derivatized, then product functionality improves, but gel formation occurs making purification difficult
Solution Approach 1:
The patent converts the potentially harmful gel formation tendency into a benefit by performing derivatization in aqueous medium where gel structures, if formed, remain water-compatible and easily manageable. The water-based system allows gelated products to be processed and purified through simple filtration and washing, transforming what would be a problematic situation in organic solvents into an easily manageable process
4Loss of substance
If dry or semi-dry derivatization method is used, then reagent excess is reduced, but the ability to swell and penetrate cellulose fibers is compromised
Solution Approach 1:
The patent changes the physical state parameter of the reaction system to operate at elevated temperatures (above 100°C) where water remains in liquid or supercritical state. This parameter change allows water to maintain its swelling and penetrating capabilities in a essentially dry process, enabling reagent delivery without requiring large excesses while maintaining fiber activation
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 increases reaction efficiency, reduces costs, and simplifies purification processes, producing derivatized cellulose products with improved properties such as higher Brookfield viscosity and reduced turbidity, while maintaining the fibrous structure and avoiding gel formation.
Implementation Method 1
reagents that are capable of simultaneously penetrating/activating the cellulose fiber
Implementation Method 2
carrying out a chemical derivatisation reaction between the at least one derivatization reagent and the cellulose pulp
Data Source
AI summary
The present invention provides a method for derivatizing cellulose pulp at high solids content or even at a fully dry state without pretreating the cellulose, the method comprising preparing a reaction medium comprising urea and at least one derivatization reagent; carrying out a chemical derivatization reaction between the at least one derivatization reagent and the cellulose pulp in a reaction system comprising the cellulose pulp in contact with the reaction medium; and optionally purifying and/or recovering the derivatized cellulose product. The present description also relates to products obtainable using said method.