Cationic Starch Production via Low Shear Mixing and Parameter Control
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Solution Overview
Problem
Current methods for producing cationic starches with high degree of substitution (DS) above 0.5 face challenges in achieving adequate purity and efficiency, with existing processes resulting in low yields and purity issues due to hydrolysis and gelatinization problems.
Innovation Solution
The use of a low shear mixer, specifically a conical screw mixer, in conjunction with optimizing water content, temperature, and catalyst quantity allows for the production of cationic starch with DS ranging from 0.55 to 1.20, achieving high reaction yields and purity by controlling the cationization reaction conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional cationization methods are used to produce high DS cationic starch, then the degree of substitution increases, but the purity decreases due to hydrolysis and gelatinization problems
Solution Approach 1:
The patent changes the water content parameter to a specific range (0.5-2.0 times the stoichiometric amount) and controls temperature parameters during cationization to prevent hydrolysis and gelatinization, thereby achieving high DS while maintaining high purity and yield
Solution Approach 2:
The patent uses a phase transfer catalyst as an intermediary substance to facilitate the cationization reaction, improving reaction efficiency and selectivity, which helps achieve high DS with minimal side reactions and high purity
2Ease of manufacture
If water content is increased in the reaction mixture, then the cationization reaction proceeds more smoothly, but hydrolysis increases reducing reaction yield
Solution Approach 1:
The patent optimizes the water content parameter to a specific range (0.5-2.0 times stoichiometric amount) - enough to ensure smooth reaction progression but not excessive to cause hydrolysis, thereby balancing ease of manufacture with high reaction yield
3Device complexity
If a single polymeric retention aid is used, then the process complexity is reduced, but the balance between retention, drainage and formation is harder to achieve
Solution Approach 1:
The patent develops high DS cationic starch that performs multiple functions simultaneously - acting as both retention aid and drainage aid, and also providing formation improvement, thereby replacing the need for multiple separate polymeric additives and simplifying the retention system
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 approach enables the successful production of cationic starch with high DS and purity, improving its performance as a retention and drainage aid in papermaking by reducing anionic trash and enhancing paper quality.
Implementation Method 1
Stronger adsorption can be achieved due to electrostatic attraction forces of negative and positive charges in aqueous solution
Implementation Method 2
The use of a low shear mixer, specifically a conical screw mixer, in conjunction with optimizing water content, temperature, and catalyst quantity allows for the production of cationic starch with DS ranging from 0.55 to 1.20
Data Source
AI summary
The present invention relates to polysaccharide, preferably starch, of high purity having cationic degree of substitution over 0.50 and bound nitrogen index after cationisation reaction stage over 0.75, and to preparation thereof as well as to its use in making of paper or paperboard.