Cationic Polyacrylamide Resins Balancing Papermaking Drainage and Strength
Solution Overview
Problem
Conventional papermaking additives face challenges in achieving both excellent drainage and strength performance, with existing chemicals like DADMAC-based gPAM resins exhibiting an inverse relationship between drainage and strength, and other additives like PVAm and AmPAMs having high treatment costs or poor drainage performance.
Innovation Solution
Development of cationic polyacrylamide (cPAM) and glyoxalated polyacrylamide (gPAM) resins, prepared through radical polymerization and glyoxalation, which allow for decoupled tuning of strength and drainage performance by using cationic monomers that facilitate increased cationic monomer content without detriments to strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional DADMAC-based gPAM resins are used to improve drainage, then drainage performance is improved, but strength performance deteriorates
Solution Approach 1:
The patent changes the chemical parameters of the gPAM resin by replacing DADMAC with alternative cationic monomers (APTAC, DAMAAC, DAAA) that have different molecular structures and reactivity. This parameter change allows the resin to achieve both improved drainage and maintained strength performance, breaking the inverse relationship that existed with conventional DADMAC-based resins
Solution Approach 2:
The patent creates composite polymer structures by copolymerizing acrylamide with multiple different cationic monomers in specific ratios. This composite approach allows optimization of both drainage (through cationic charge density) and strength (through polymer chain structure and crosslinking capability), achieving properties that neither monomer could provide alone
2Productivity
If DADMAC content in gPAM is increased to improve drainage, then drainage performance is improved, but strength performance and cost effectiveness deteriorate
Solution Approach 1:
The patent replaces expensive DADMAC monomer with more cost-effective alternative cationic monomers (APTAC, DAMAAC, DAAA) that can be produced more economically. These alternative monomers provide similar or superior functionality at lower cost, improving the cost-effectiveness ratio while maintaining or enhancing drainage performance
Solution Approach 2:
The patent optimizes the cationic monomer content parameter within a broader range (1-50 mol%) compared to conventional formulations, allowing flexible adjustment of drainage performance without being constrained by the limitations of DADMAC. This parameter flexibility enables achievement of target drainage performance at lower overall monomer content, reducing cost while maintaining strength
3Productivity
If high molecular weight drainage aids are used to improve drainage and retention, then drainage and retention are improved, but strength benefits are reduced due to over-flocculation
Solution Approach 1:
The patent introduces local quality variations in the polymer structure through copolymerization of different monomers with different functions. The acrylamide units provide backbone structure for strength, while the cationic monomer units provide localized charge centers for drainage and retention. This local differentiation allows the polymer to perform multiple functions simultaneously without the over-flocculation problems of homogeneous high molecular weight drainage aids
Solution Approach 2:
The patent changes the molecular weight and charge density parameters of the drainage aid to optimize performance. By controlling the molecular weight within specific ranges and adjusting the cationic monomer content, the patent achieves effective drainage and retention without excessive molecular weight that would cause over-flocculation and strength reduction
4Strength
If polyamidoepichlorohydrins (PAE) are used to improve dry strength, then dry strength is improved, but drainage benefits are reduced and repulpability is limited
Solution Approach 1:
The patent creates a multi-functional polymer that simultaneously provides drainage aid, retention aid, and dry strength functions through copolymerization. The cationic charges provide drainage and retention benefits while the polymer structure provides dry strength, eliminating the need for separate PAE additives and enabling repulpability that PAE lacks
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 cPAM and gPAM resins provide improved drainage and strength performance in papermaking, overcoming the limitations of conventional additives by allowing independent optimization of these properties.
Implementation Method 1
cationic polyacrylamide (cPAM) and glyoxalated polyacrylamide (gPAM) resins... provide improved drainage and strength performance in papermaking
Implementation Method 2
cationic polyacrylamide (cPAM)... using cationic monomers that facilitate increased cationic monomer content
Implementation Method 3
glyoxalated polyacrylamide (gPAM) resins, prepared through radical polymerization and glyoxalation
Implementation Method 4
glyoxalated polyacrylamide (gPAM) resins... allow for decoupled tuning of strength and drainage performance
Data Source
AI summary
A cationic polyacrylamide (cPAM) and methods of making and using the same are disclosed. The cPAM comprises the radical polymerization reaction product of an acrylamide (AM) monomer, a cationic monomer, and, optionally, one or more additional ethylenically unsaturated monomer(s). A glyoxalated polyacrylamide (gPAM) resin is also disclosed, and comprises the reaction product of a glyoxalation agent and the cationic polyacrylamide (cPAM). A homopolymer of the cationic monomer is also disclosed. An additive composition for papermaking is also disclosed, along with methods of preparing and using the same. The additive composition comprises an aqueous media and the glyoxalated polyacrylamide (gPAM) resin, or the homopolymer, dispersed therein.