Amphoteric Polyacrylamide Retains Hydrophobic Sizing Agents
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Solution Overview
Problem
Current paper and board manufacturing methods face challenges in effectively retaining hydrophobic internal sizing agents, leading to accumulation in process waters and surfaces, which causes quality defects and productivity issues, while also relying on cationic starch that can promote biological growth and increase costs.
Innovation Solution
A method using a combination of hydrophobic internal sizing agents like alkenyl succinic anhydride (ASA), alkyl ketene dimer (AKD), and rosin sizes with a water-soluble amphoteric polyacrylamide, which improves retention and reduces the amount of cationic starch needed, thereby enhancing sizing efficiency and reducing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If cationic starch is used as emulsifying agent to promote ASA sizing efficiency, then sizing level increases, but biological growth and deposit issues increase
Solution Approach 1:
The invention changes the chemical parameters of the emulsifying agent from cationic starch to anionic polyacrylamide, fundamentally altering the charge characteristics and chemical properties of the sizing system while maintaining emulsification and retention functions
Solution Approach 2:
The invention replaces the problematic cationic starch with an alternative polymer system that achieves the same functional goals without the harmful biological growth and deposit issues associated with starch-based emulsifiers
2Reliability
If higher dosage of cationic starch is used to achieve higher sizing level, then sizing performance improves, but cost and biological growth increase
Solution Approach 1:
The invention changes the dosage parameters and chemical nature of the emulsifying agent, using anionic polyacrylamide at optimized dosages to achieve equivalent or superior sizing levels with reduced total polymer consumption
Solution Approach 2:
The invention replaces expensive and problematic cationic starch with a more cost-effective anionic polyacrylamide system that reduces both material costs and biological growth concerns
3Reliability
If internal sizing agents are not well retained, then sizing efficiency decreases, but accumulation in process waters and surfaces increases causing quality defects and web breakages
Solution Approach 1:
The anionic polyacrylamide acts as an intermediary agent that facilitates the retention of internal sizing agents onto fibres through electrostatic and steric interactions, preventing their accumulation in process waters while maintaining effective sizing
Solution Approach 2:
The invention replaces the starch-based retention mechanism with a polymer-based electrostatic and steric retention mechanism using anionic polyacrylamide, which provides more controlled and predictable sizing agent retention
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
The method achieves improved retention of hydrophobic internal sizing agents, reducing their accumulation in process waters and surfaces, leading to better sizing performance, lower Cobb 60 values, and cost savings by minimizing the use of cationic starch, while maintaining or improving paper quality.
Implementation Method 1
improving retention of hydrophobic internal sizing agents
Implementation Method 2
hydrophobic internal sizing agents... resistance to water penetration
Data Source
AI summary
The invention relates a method for a manufacturing paper or board and to an internal sizing system for providing improved retention of hydrophobic internal sizing agents. An internal sizing system comprises a hydrophobic internal sizing agent as a first component selected from the group consisting of alkenyl5 succinic anhydride (ASA), alkyl ketene dimer (AKD), rosin sizes and any combination thereof, and a water-soluble polymer product comprising amphoteric polyacrylamide as a second component, which amphoteric polyacrylamide has neutral or cationic net charge at pH 7, a weight-average molecular weight10 of 700 000 – 18 000 000 g/mol and a total ionicity of 4 – 28 mol- %, wherein the first component and the second component are provided as separate components or as a combination of the first component and the second component.