On-site Glyoxylation of Polyacrylamide via Viscosity Control
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Solution Overview
Problem
The existing methods for on-site production of glyoxylated polyacrylamide in paper and board mills face challenges such as inadequate storage stability, high water consumption, and complex process control, leading to inefficiencies and environmental concerns.
Innovation Solution
A discontinuous batch glyoxylation method using a reactor vessel with a driven agitator, where the polyacrylamide base polymer concentration is maintained above a Critical Concentration, and the reaction is controlled by measuring viscosity, allowing for reduced water usage and simplified process management without the need for complex pH measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If glyoxylated polyacrylamide is produced using conventional on-site methods, then the strength properties of paper and board are improved, but the storage stability becomes inadequate and the polymer may gel during storage
Solution Approach 1:
The patent applies preliminary action by pre-forming the polyacrylamide base polymer with controlled molecular weight (30,000-300,000 g/mol) and concentration (1.5-8% units above critical concentration) before the glyoxylation reaction. This preliminary preparation ensures that the polymer is in the optimal state for crosslinking while maintaining stability during subsequent storage and use.
Solution Approach 2:
The patent utilizes parameter changes by controlling the molecular weight, concentration, and crosslinking degree of the polyacrylamide polymer. By adjusting these parameters within specific ranges, the patent achieves a balance between strength improvement and storage stability, preventing gel formation while maintaining effective bonding capability.
2Reliability
If conventional on-site glyoxylation methods are used, then the polymer provides good bonding ability, but the process control becomes complex requiring pH measurements and adjustments
Solution Approach 1:
The patent extracts the pH measurement and control step from the glyoxylation process, simplifying the operational procedure. By formulating the reaction mixture with polyacrylamide base polymer at a concentration 1.5-8% units above the critical concentration, the process achieves reliable bonding without requiring complex pH monitoring and adjustment equipment.
Solution Approach 2:
The patent applies self-service by designing a self-regulating reaction system where the viscosity increase during glyoxylation automatically indicates the reaction progress and endpoint. The process controls itself through inherent physical changes (viscosity increase) without requiring external pH measurement and control systems.
3Strength
If conventional glyoxylation processes are applied, then the polymer improves paper and board strength, but water consumption becomes excessively high
Solution Approach 1:
The patent applies parameter changes by operating at elevated temperatures (40-100°C) and maintaining specific polymer concentrations (1.5-8% units above critical concentration). These parameter adjustments reduce the water required for the reaction while ensuring complete and effective glyoxylation, thereby maintaining strength improvement with reduced water consumption.
Solution Approach 2:
The patent employs periodic action through controlled heating cycles and staged alkali addition during the glyoxylation process. This approach ensures thorough reaction completion with minimal water, as the periodic temperature and concentration adjustments optimize reaction efficiency and reduce the total water volume needed for heat transfer and reaction medium.
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 enhances the production efficiency and stability of glyoxylated polyacrylamide, reducing water consumption and operational complexity, while improving the strength properties of paper and board products, especially in humid conditions, and minimizing the risk of score cracking.
Implementation Method 1
Glyoxylated polyacrylamide is formed by crosslinking polyacrylamide-based polymers by using glyoxal
Implementation Method 2
Crosslinked structure improves drainage and dewatering ability of the polyacrylamide
Implementation Method 3
a discontinuous batch glyoxylation reaction of an aqueous reaction mixture is performed in a reactor vessel provided with a driven agitator
Implementation Method 4
adding to the reaction mixture a feed of an alkali while measuring viscosity of the reaction mixture and/or a process variable that is related to the viscosity of the reaction mixture
Implementation Method 5
adding to the reaction mixture a feed of an alkali while measuring viscosity of the reaction mixture
Data Source
AI summary
Method for on-site glyoxylation of polyacrylamide in paper mill, board mill or the like is disclosed. Discontinuous batch glyoxylation reaction of aqueous reaction mixture is performed. The method comprises forming or obtaining the aqueous reaction mixture having a start viscosity and comprising polyacrylamide base polymer having weight average molecular weight of 30 000-300 000 g/mol and glyoxal. Concentration of the polyacrylamide base polymer in the reaction mixture is 1.5-8% above a Critical Concentration of the polyacrylamide base polymer. A feed of an alkali is added to the reaction mixture while measuring viscosity of the reaction mixture and/or a process variable related to the viscosity of the reaction mixture and the on-site glyoxylation reaction of polyacrylamide base polymer in the reaction mixture is allowed to proceed. When a predetermined end viscosity value is attained the feed of alkali is ended and acid is added to the reaction mixture.