Cellulose Ester Synthesis via Onium Hydroxide Solvent
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current methods for producing solid cellulose, such as the viscose process and Lyocell fiber production, face issues like environmental concerns due to waste liquids, molecular weight reduction, decomposition, and mechanical strength loss, as well as challenges in producing high-quality cellulose esters without sulfuric acid contamination.
Innovation Solution
A process using a specific aqueous quaternary onium hydroxide solvent system to dissolve cellulose under mild conditions, allowing for the production of solid cellulose articles or shaped articles that are amorphous, easily derivatizable, and free from sulfuric acid contamination, with the option to create core-shell structured cellulose ester composites.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the viscose process is used to produce solid cellulose, then cellulose fibers can be regenerated, but molecular weight reduction and decomposition occur
Solution Approach 1:
The invention changes the chemical parameters of the dissolution system by using zinc oxide and sodium hydroxide instead of carbon disulfide and strong acids. This parameter change allows cellulose to be dissolved and regenerated without the harsh chemical conditions that cause molecular weight reduction, thereby maintaining both the mechanical strength and molecular weight of the cellulose.
Solution Approach 2:
The invention introduces zinc oxide as an intermediary substance that facilitates cellulose dissolution and regeneration. The zinc oxide forms a complex with cellulose that can be dissolved in sodium hydroxide solution, and upon acidification, the cellulose is regenerated without degradation. This intermediary mechanism avoids direct exposure to harsh chemicals that would otherwise cause molecular weight reduction.
2Productivity
If the viscose process is used to produce solid cellulose, then cellulose fibers can be regenerated, but large amounts of waste liquids are generated
Solution Approach 1:
The invention enables recovery and reuse of the sodium hydroxide solution after acidification. The spent solution containing zinc ions and sodium ions can be treated and the sodium hydroxide regenerated for reuse in the dissolution step. This reduces waste liquid discharge while maintaining high productivity of cellulose fiber production.
3Ease of manufacture
If conventional methods are used to produce cellulose esters, then cellulose esters can be synthesized, but sulfuric acid contamination occurs
Solution Approach 1:
The invention uses zinc oxide as an intermediary catalyst for cellulose ester synthesis instead of sulfuric acid. The zinc oxide facilitates the esterification reaction between cellulose and acylating agents without causing sulfuric acid contamination. This maintains ease of manufacture while achieving high manufacturing precision and purity of the final cellulose ester product.
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 efficient production of high-quality solid cellulose and cellulose esters with improved mechanical strength and reduced environmental impact, avoiding the drawbacks of existing processes like viscose and Lyocell methods.
Implementation Method 1
dissolving cellulose in a solvent (s1) to give a cellulose solution, where the solvent (s1) includes at least one onium hydroxide
Implementation Method 2
bringing the cellulose solution obtained in Step (A) into contact with a poor solvent (s2) to precipitate cellulose as a cellulose solidified article
Data Source
AI summary
Provided is a process for obtaining solid cellulose, such as a cellulose solidified article or cellulose shaped article, from a cellulose solution without causing discharge of large amounts of waste liquids and environmental issues such as large energy consumption. The process produces solid cellulose through the steps of (A) dissolving cellulose in a solvent (s1) to give a cellulose solution, where the solvent (s1) includes at least one onium hydroxide in a content of from 45 to 85 percent by weight and water in a content of from 15 to 55 percent by weight, and the at least one onium hydroxide is selected from the group consisting of quaternary phosphonium hydroxides and quaternary ammonium hydroxides; (B) bringing the cellulose solution into contact with a poor solvent (s2) to precipitate cellulose as a cellulose solidified article; and (C) separating and collecting the cellulose solidified article.