Cationic Copolymer Fixation for Anionic Deposit Control
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Solution Overview
Problem
The existing methods for manufacturing paper, board, and tissue are hindered by anionic particulate material and substances that form deposits, leading to web breakages and reduced quality, necessitating the development of more effective fixative agents to control these issues.
Innovation Solution
A cationic copolymer obtained by polymerizing (meth)acrylamide and cationic monomers with a standard viscosity of ≥2 mPas and a charge density at most 5 meq/g is used to effectively attach and reduce anionic substances and particulate material in the fibre stock, improving fixation and reducing chemical usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If synthetic cationic polymers with low molecular weight and high cationic charge density are used as fixative agents, then fixation effectiveness is improved, but chemical costs increase and process sustainability deteriorates due to large addition amounts required
Solution Approach 1:
The patent changes the molecular weight parameter of the cationic polymer from low (conventional) to high (invention), and adjusts the charge density parameter accordingly. This parameter change allows achieving effective fixation with smaller addition amounts, resolving the contradiction between fixation effectiveness and quantity of substance required.
Solution Approach 2:
The patent uses cationic polymers that are copolymers of multiple monomers (e.g., polyacrylamide combined with cationic monomers like DADMAC or polyethyleneimine combined with acrylamide). This composite structure combines the benefits of high molecular weight with controlled charge density, enabling effective fixation at lower addition rates compared to conventional single-component low molecular weight polymers.
2Reliability
If large amounts of synthetic polymers are added to achieve effective fixation, then anionic substance control is improved, but overall process sustainability deteriorates
Solution Approach 1:
By changing the molecular weight parameter to high values and optimizing charge density, the invention reduces the addition amount of polymer required for effective anionic substance control. This directly improves process sustainability by reducing chemical input and associated environmental impacts.
3Reliability
If conventional fixative agents are used, then anionic particulate material is controlled, but web breakages and quality issues occur due to deposit formation on process surfaces
Solution Approach 1:
The invention changes the molecular weight and charge density parameters of the cationic polymer to optimize its interaction characteristics with anionic particulate material. This results in better fixation that prevents deposit formation on process surfaces while maintaining control of anionic substances, eliminating web breakages and quality issues.
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 cationic copolymer significantly reduces anionic particulate material in the aqueous phase, enhancing the quality of the fibre web by minimizing downtime and chemical costs, while reducing the risk of overcationization and foam build-up.
Implementation Method 1
Cationic polymers react with anionic hydrophobic colloids and anionic particulate material in a manner of polyelectrolyte complexation. Cationic polymers can form agglomerates with dissolved and colloidal substances and attach them onto fibres, fillers and fines in the paper stock.
Data Source
AI summary
The invention relates to a use of a cationic copolymer obtained by polymerisation of (meth)acrylamide and cationic monomers, having a standard viscosity of ≥2 mPas and a charge density at most 5 meq/g, for reducing anionic substances and/or 5 anionic particulate material in an aqueous phase of a thick fibre stock having a consistency of ≥20 g/l in a manufacture of a fibre web, such as paper, board, tissue or the like. The invention relates also to a method in a manufacture of a fibre web, such as paper, board, tissue or the like using such cationic copolymer.