Cellulose Carbamate Preparation via Urea Carbamation
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Solution Overview
Problem
The viscose process for producing cellulose fibers and films using carbon disulfide is environmentally hazardous and has high environmental impact, limiting the expansion of cellulose-fiber production plants, and alternative methods like direct dissolution in N-methyl-morpholine-oxide do not match the quality of the xanthogenate process.
Innovation Solution
A process for preparing cellulose carbamate using molten dimethylsulfone or a mixture of dimethylsulfone and water, where urea reacts with cellulose at controlled temperatures to form cellulose carbamate, which is soluble in sodium hydroxide solutions, reducing environmental concerns and maintaining industrial feasibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the viscose process using carbon disulfide is used to produce cellulose fibers and films, then the quality of the final product is high and the process is industrially established, but the environmental impact is severe and the process is hazardous to human health
Solution Approach 1:
The patent extracts and removes the harmful carbon disulfide intermediate from the cellulose processing system, replacing it with a water-based carbamation process using urea. This eliminates the environmental pollution and health hazards associated with carbon disulfide while maintaining the ability to produce soluble cellulose derivatives for fiber and film production.
Solution Approach 2:
The patent introduces carbamate groups as an intermediary chemical modification on cellulose. Instead of using carbon disulfide to create xanthogenate intermediates, the process uses urea to form carbamate groups that enable solubility in alkaline solutions. This intermediary carbamation step replaces the harmful xanthogenate formation while achieving the same functional outcome of creating soluble cellulose derivatives.
2Object-affected harmful factors
If alternative methods like direct dissolution in N-methyl-morpholine-oxide are used, then the environmental impact is reduced, but the quality of the final product does not reach the standards of the xanthogenate process
Solution Approach 1:
The patent changes the chemical parameters of cellulose by introducing carbamate groups through controlled carbamation with urea. This chemical modification alters the solubility characteristics and physical properties of cellulose, enabling it to dissolve in alkaline solutions and form viscose-like products. The parameter changes in cellulose structure through carbamation allow the process to achieve both environmental sustainability and product quality comparable to traditional xanthogenate processes.
3Quantity of substance
If cellulose is carbamated using traditional methods requiring drying and high-temperature oven reactions, then cellulose carbamate can be produced, but the process complexity increases and industrial implementation becomes difficult
Solution Approach 1:
The patent merges the carbamation reaction with the dissolution step by performing the reaction in an aqueous medium without requiring separate drying and high-temperature treatment stages. The carbamation with urea occurs in water-based conditions, and the resulting cellulose carbamate remains soluble in the aqueous alkaline medium, combining multiple process steps into a more integrated and simplified workflow suitable for industrial implementation.
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 process reduces environmental impact by using non-toxic urea and eliminates the need for hazardous carbon disulfide, allowing for the reuse of existing production infrastructure and producing cellulose fibers and films with quality comparable to the xanthogenate process.
Implementation Method 1
The reaction in fact seems to pass through a reaction intermediate that arises as a result of the thermal decomposition of urea. This intermediate, which is assumed to be isocyanic acid, is formed by thermolysis of urea through the reaction
Implementation Method 2
The isocyanic acid thus produced reacts with the hydroxyls of the cellulose, giving cellulose carbamate and eliminating an ammonia molecule
Implementation Method 3
A process for preparing cellulose carbamate using molten dimethylsulfone or a mixture of dimethylsulfone and water, where urea reacts with cellulose at controlled temperatures
Implementation Method 4
cellulose carbamate, under certain conditions, can also be soluble in solvents such as sodium hydroxide solutions
Data Source
AI summary
A process is described for the preparation of cellulose derivatives and in particular a process for the production of cellulose carbamate and the cellulose carbamate that can be obtained from said process.