Aldehyde Crosslinked Polyacrylamide Stabilization for Paper Strength
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Solution Overview
Problem
Current methods for producing glyoxalated polyacrylamide strengthening agents face issues with stability and gelling, leading to the need for dilute solutions and increased shipping and storage costs, which complicates the papermaking process.
Innovation Solution
A two-stage on-site production method for aldehyde crosslinked polyacrylamide compositions, where a concentrated prepolymer is stabilized and shipped, then reacted to the final product at the paper mill, allowing for higher solid content without gelling and reducing on-site reaction time and complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If glyoxal and polyacrylamide are mixed to produce concentrated GPAM composition, then the solid content and effectiveness are improved, but the composition gels rapidly and loses stability
Solution Approach 1:
The patent applies preliminary action by pre-mixing polyacrylamide with a small amount of glyoxal (0.1-10% of total glyoxal content) before use. This preliminary mixing creates a ready-to-use composition that reacts rapidly with starch upon addition to the paper machine, eliminating the need for separate mixing operations and preventing premature gelling while maintaining high effectiveness
Solution Approach 2:
The patent changes the parameter of glyoxal concentration in the pre-mixed composition, using a small controlled amount (0.1-10% of total glyoxal) rather than full concentration. This parameter change allows the composition to remain stable during storage and handling while providing sufficient crosslinking capability when activated by starch at the paper machine
2Stability of the object's composition
If dilute GPAM solutions are used to prevent gelling, then stability is improved, but shipping and storage costs increase significantly
Solution Approach 1:
The patent prepares the polyacrylamide-glyoxal pre-mix in advance at concentrated form (avoiding dilution) and ships it in this stable, concentrated state. The remaining glyoxal is added in-situ at the paper machine where starch is present, ensuring the composition remains stable during shipping while eliminating waste from premature gelling
Solution Approach 2:
The patent uses starch as an intermediary that triggers the crosslinking reaction. The pre-mixed polyacrylamide-glyoxal composition remains stable until it contacts starch at the paper machine, which then activates the crosslinking process. This intermediary mechanism allows concentrated composition to be shipped stably while preventing premature reaction
3Device complexity
If on-site mixing of glyoxal and polyacrylamide is performed, then composition complexity is reduced, but reaction time and process control become problematic
Solution Approach 1:
The patent performs preliminary mixing of polyacrylamide with a small amount of glyoxal before use, creating a pre-mixed composition that is ready for immediate application. This preliminary action eliminates the need for separate mixing operations at the paper machine, reducing both complexity and reaction time while maintaining effectiveness
Solution Approach 2:
The patent combines polyacrylamide and a portion of glyoxal into a single pre-mixed composition that is applied together with starch at the paper machine. This merging of components into one preparation step reduces the number of separate chemicals to handle and simplifies the overall process while maintaining the necessary crosslinking functionality
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 reduces shipping and storage costs, maintains product stability, and simplifies the production process while maintaining the strength-enhancing properties of the final product.
Implementation Method 1
The synthesis of GPAM was first reported in U.S. Pat. No. 3,556,932. The product was prepared by reacting glyoxal with a cationic polyacrylamide in slightly alkaline aqueous solution
Implementation Method 2
GPAM is a reactive polymer that can covalently bind with cellulose upon dehydration
Data Source
AI summary
Disclosed is a method for producing an aldehyde crosslinked polyacrylamide composition useful for strengthening paper. The method includes steps, wherein a) an aldehyde crosslinker and polyacrylamide are mixed in water to form an aqueous solution of aldehyde crosslinked polyacrylamide prepolymer; b) acid is added to the aqueous prepolymer solution to adjust the pH of the solution to a value between 1 to 5; c) storing and transporting the prepolymer solution to the location where the final glyoxalated polyacrylamide composition will be used; and d) adding a base to the stabilized prepolymer solution to adjust the pH of the solution to value between 5.5 to 12, and e) allowing the aldehyde crosslinker and polyacrylamide contained in the aldehyde crosslinked polyacrylamide prepolymer solution to react further and form aldehyde crosslinked polyacrylamide composition useful for strengthening paper.