Reactive Cationic Resins for Sulfite-Resistant Paper Strength
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Solution Overview
Problem
Glyoxalated polyacrylamide resins are ineffective in sulfite-containing papermaking environments due to sulfite ions reacting with the resin, reducing its ability to impart strength to paper.
Innovation Solution
Development of reactive cationic resins comprising a copolymer of dialdehyde-reactive comonomers and cationic comonomers, with the cationic comonomer comprising greater than 10 mole % of the copolymer, which are reacted with a dialdehyde like glyoxal to produce a resin resistant to sulfite ions, enhancing wet and dry strength in papermaking systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional glyoxalated polyacrylamide resins are used in sulfite-containing papermaking systems, then the resins can provide wet and dry strength under normal conditions, but the sulfite ions react with the resin to reduce or eliminate its effectiveness
Solution Approach 1:
The patent changes the chemical parameters of the resin by incorporating cationic comonomers (such as DADMAC, vinylpyridine, or quaternary ammonium compounds) at greater than 10 mole % of the copolymer. This modification alters the resin's chemical properties to resist sulfite ion reactions while maintaining strength-enhancing capabilities in sulfite-containing environments
Solution Approach 2:
The patent creates a composite polymer structure by copolymerizing dialdehyde-reactive comonomers with cationic comonomers. This composite material combines the strength-enhancing properties of glyoxalated polyacrylamide with the sulfite resistance of cationic groups, achieving both wet/dry strength and stability in challenging papermaking conditions
2Reliability
If the cationic comonomer content is increased to greater than 10 mole % to resist sulfite ions, then the resin maintains effectiveness in sulfite environments, but the resin structure becomes more complex
Solution Approach 1:
The patent optimizes the cationic comonomer content parameter to greater than 10 mole % of the copolymer, finding the optimal balance between sulfite resistance and structural complexity. This parameter change ensures sufficient cationic charge density for sulfite resistance while maintaining practical manufacturability
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 reactive cationic resins effectively impart strength to paper even in high sulfite conditions, providing improved wet and dry strength benefits compared to conventional glyoxalated resins, with enhanced resistance to sulfite ions.
Implementation Method 1
reactive cationic resins comprising a copolymer produced from a comonomer which is dialdehyde reactive, a cationic comonomer and a dialdehyde wherein the cationic comonomer is selected from the group consisting of diallyldimethylammonium chloride (DADMAC), 2-vinylpyridine, 4-vinylpyridine, 2-vinyl-N-methylpyridinium chloride, 2-(acryloyloxyethyl)-trimethylammonium chloride, 2-(dimethylamino)ethyl acrylate, 3-acrylamidopropyl-trimethylammonium chloride, dimethylaminopropyl acrylamide, and trimethyl(p-vinylbenzyl)ammonium chloride and wherein the cationic comonomer comprises greater than 10 mole % of the copolymer before reaction with dialdehyde
Implementation Method 2
The resin reacts with sulfite and bisulfite ions present in the paper machine wet end. The anionic bisulfite adduct which forms can offset a portion or all of the cationic charge on the resin, and efficiency is lost due to reduced resin retention in the paper.
Data Source
AI summary
This invention relates to resins useful for imparting strength to paper, the process of incorporating these resins into paper and the paper produced containing the resins. In particular the invention relates to resins useful for imparting dry-strength and wet-strength to paper under conditions of high sulfite ion concentrations.