Polyelectrolyte Complexes for Paper Wet Strength
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Solution Overview
Problem
Current papermaking processes face challenges in achieving balanced paper strength, as high dosages of cationic wet strength additives like polyamidoamine epichlorohydrin (PAE) can lead to operational issues, fiber saturation, and increased waste, while seeking a cost-effective and environmentally friendly method to enhance paper strength and production efficiency.
Innovation Solution
The method involves co-mixing a cationic wet strength resin with an anionic polymer to form polyelectrolyte complexes, which are then introduced into the papermaking process, providing improved wet and dry strength without the risks of precipitation or gelling, allowing for on-site generation and flexible ratio adjustments to match pulp properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If high dosage of cationic wet strength resin (PAE) is added to improve paper wet strength, then wet strength is improved, but fiber saturation is reached and operational issues occur
Solution Approach 1:
The patent combines cationic wet strength resin with anionic polymer in a single composition, allowing the cationic polymer to bind to anionic sites on fiber surfaces while the anionic polymer provides additional binding sites and structural support. This merging enables achieving target wet strength at lower overall dosage, preventing fiber saturation and maintaining operational reliability.
Solution Approach 2:
The invention creates a composite chemical system combining two oppositely charged polymers (cationic PAE and anionic polymer) that work synergistically. The composite composition provides enhanced wet strength performance per unit dosage compared to using cationic resin alone, thereby reducing the total amount of chemical needed and avoiding the operational problems associated with high dosage application.
2Strength
If excess cationic polymer is added to achieve higher wet strength, then wet strength is improved, but zeta potential becomes cationic and excess polymer is lost to white water causing foaming and deposits
Solution Approach 1:
The anionic polymer acts as an intermediary that facilitates the binding of cationic wet strength resin to fiber surfaces. By providing additional anionic binding sites, it enables more efficient utilization of the cationic polymer, preventing excess cationic polymer from remaining unbound and causing harmful effects like foaming and deposits in the white water system.
Solution Approach 2:
The invention changes the charge parameter distribution by introducing anionic polymer alongside cationic resin. This creates a more balanced charge environment that optimizes polymer-fiber interactions, ensuring that cationic polymer is effectively utilized for strength enhancement without creating excessive cationic charge that would lead to polymer loss and operational problems.
3Strength
If cationic wet strength resin and anionic polymer are added separately to ensure proper effect, then each compound works effectively, but process complexity increases and cost increases
Solution Approach 1:
The patent merges the separate addition of cationic wet strength resin and anionic polymer into a single combined composition that is added in one step. This merging maintains the synergistic interaction between the two polymers while significantly simplifying the dosing system, reducing equipment complexity, and lowering operational costs compared to managing two separate dosing systems.
4Strength
If high dosage of strength additives is used to achieve required strength specifications, then paper strength is improved, but waste handling increases and environmental impact worsens
Solution Approach 1:
The composite composition of cationic and anionic polymers creates a synergistic effect that enhances strength performance per unit of chemical applied. This allows achieving the same or better paper strength specifications with lower total dosage, thereby reducing chemical waste and minimizing environmental impact from chemical consumption and waste handling.
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
This approach enhances paper strength, reduces additive dosage, minimizes waste, and decreases the risk of foaming and deposits, while maintaining operational efficiency and environmental sustainability.
Implementation Method 1
co-mixing a cationic wet strength resin and an anionic polymer to provide a composition comprising polyelectrolyte complexes
Data Source
AI summary
Embodiments of the present invention relate to a method of making a paper comprising the steps of: a) providing a cationic wet strength resin comprising a polyamidoamine epihalohydrin, a condensation copolymer of epihalohydrin and amine, or combination thereof; b) providing an anionic polymer; c) co-mixing the cationic wet strength resin and the anionic polymer to provide a composition comprising polyelectrolyte complexes; d) providing an aqueous pulp slurry, draining the aqueous pulp slurry on a screen to form a wet fiber web, and drying the wet fiber web to obtain the paper, wherein said co-mixed composition is introduced to the aqueous pulp slurry or on the formed wet fiber web. Embodiments of the present invention further relates to a paper wet strength composition, its use in paper making and a paper obtainable therefrom.