Anionic Polymer Viscosity Stability via AMPS Copolymerization
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Solution Overview
Problem
Existing processes for producing water-soluble anionic polymers functionalized with an aldehyde result in a significant drop in viscosity, leading to poor application performance, particularly affecting the wet and dry strength of paper.
Innovation Solution
A process involving the copolymerization of at least 5 mol% of 2-acrylamido-2-methylpropane sulfonic acid and/or its salts with non-ionic monomers, followed by controlled addition of an aldehyde and acidification to maintain viscosity and enhance stability, resulting in a polymer solution with improved stability and performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If acid treatment is used to stop the reaction between aldehyde and base polymer, then the reaction is halted, but viscosity drops significantly
Solution Approach 1:
The patent changes the chemical parameter of the polymer by using 2-acrylamido-2-methylpropanesulfonic acid (AMPS) monomer which contains a sulfonic acid group. This sulfonic acid group remains ionized and stable across a wide pH range, preventing the viscosity drop that occurs when carboxylic acid groups are protonated during acidification. The parameter change from carboxylic acid to sulfonic acid functional groups resolves the contradiction between reaction control and viscosity maintenance.
2Strength
If water-soluble anionic polymers are used instead of cationic polymers, then wet strength of paper is improved, but production complexity increases
Solution Approach 1:
The patent creates a composite polymer system by copolymerizing AMPS monomer with other monomers (such as acrylamide, vinyl sulfonic acid, or carboxylic acid monomers). This composite approach combines the advantages of anionic polymers (wet strength) with controlled viscosity characteristics. The copolymerization allows tuning of the polymer properties to achieve both improved wet strength and manageable production complexity.
3Strength
If aldehyde functionalization is applied to anionic polymers, then dry strength of paper is improved, but application performance deteriorates due to viscosity loss
Solution Approach 1:
The patent changes the fundamental chemical parameter of the polymer backbone by using AMPS-containing copolymers instead of traditional carboxylic acid-containing polymers. This parameter change ensures that when aldehyde is added and subsequently acidified, the sulfonic acid groups remain ionized and maintain chain expansion, preventing the collapse and viscosity loss that would otherwise occur. This enables aldehyde functionalization while maintaining application performance.
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 process maintains viscosity and enhances the stability of the polymer solution, leading to improved dry and wet strength performance in papermaking processes.
Implementation Method 1
Aqueous polymerization of anionic monomers, including at least 5 mol% of 2-acrylamido-2-methylpropane sulfonic acid and/or one of its salts
Implementation Method 2
addition of at least one aldehyde to the solution obtained in step a)
Implementation Method 3
acidification to a pH between 3 and 4 of the solution obtained in step b)
Data Source
AI summary
The invention relates to a method for producing anionic polymers that are hydrosoluble in an aqueous solution, comprising at least the following successive steps: b) polymerisation, in an aqueous solution, of anionic monomers containing at least 5 mol % of 2-acrylamido-2-methylpropane sulfonic acid and/or one of the salts thereof and optionally non-ionic monomers up to a mass concentration of polymer A of between 5 and 40 %, b) addition of at least one aldehyde into the solution produced in step a), and c) acidification to a pH of between 3 and 4 of the solution produced in step b). The invention also relates to the use thereof in a paper-making method.