Cationic Fixative Composition for Hydrophobic Particle Removal
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Solution Overview
Problem
The papermaking process faces challenges with web breaks and dirt build-up due to the agglomeration of hydrophobic particles, which are not effectively addressed by existing fixative agents, particularly in systems with high concentrations of hydrophobic anionic substances, leading to decreased production speed and product quality.
Innovation Solution
A fixative composition combining a synthetic cationic polymer with a high charge density and cationic non-degraded starch is added to the paper stock, enhancing the fixation of hydrophobic and anionic substances onto fibers, thereby reducing turbidity and cationic demand, and offering economic and environmental advantages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If cationic synthetic polymers are used as fixatives to bind hydrophobic substances, then fixation efficiency is improved, but cost and environmental friendliness deteriorate
Solution Approach 1:
The invention uses a composite fixative system combining cationic starch and cationic synthetic polymer. The cationic starch (from renewable resources) and cationic polymer (high charge density) work synergistically to bind hydrophobic substances, achieving effective fixation while reducing reliance on expensive synthetic polymers alone and improving environmental sustainability.
Solution Approach 2:
The invention changes the charge density parameter of the synthetic polymer component to be in the range of 5-20 meq/g, which is higher than conventional polymers. This high charge density allows more efficient binding of anionic hydrophobic substances, reducing the total amount of fixative needed and thereby reducing cost and environmental impact while maintaining or improving fixation efficiency.
2Reliability
If cationic polysaccharides with high molecular weight are used as fixatives, then fixation capability is improved, but viscosity increases making industrial use difficult
Solution Approach 1:
The invention specifies cationic starch with charge density of 1-5 meq/g and molecular weight that balances fixation capability with acceptable viscosity. By optimizing these parameters, the fixative achieves sufficient fixation capability while remaining easy to handle and dose in industrial papermaking operations.
3Quantity of substance
If water recirculation is increased to close water systems, then water efficiency is improved, but concentration of hydrophobic substances increases leading to agglomeration and deposits
Solution Approach 1:
The cationic fixative composition acts as an intermediary that binds hydrophobic anionic substances to fibres in the paper stock. This prevents these substances from agglomerating and forming deposits in the water recirculation system, enabling effective water closing while maintaining system cleanliness and runnability.
Solution Approach 2:
The fixative removes hydrophobic anionic substances from the water phase by binding them to fibres in the paper stock. This extraction of harmful substances from the recirculating water prevents agglomeration and deposit formation, allowing effective water closing without the negative consequences of substance concentration.
4Loss of substance
If microstickies are not removed mechanically due to small particle size, then fibre loss is reduced, but agglomeration and web breaks increase
Solution Approach 1:
The cationic fixative composition acts as a chemical intermediary that binds microstickies to fibres through electrostatic attraction. This chemical binding mechanism effectively removes microstickies without requiring mechanical screening, thereby preventing web breaks while avoiding fibre loss associated with mechanical removal methods.
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 combination of synthetic cationic polymer and cationic non-degraded starch significantly improves the fixation of hydrophobic and anionic particles, reducing turbidity and cationic demand, leading to improved paper quality and reduced maintenance needs, while being more environmentally friendly and cost-effective than traditional synthetic polymers.
Implementation Method 1
Cationic polymers react with hydrophobic and anionic colloids and particles 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.
Implementation Method 2
Cationic polymers react with hydrophobic and anionic colloids and particles... An excess cationic charge in the cationic polymer is preferred to fix the hydrophobic material on the fibres
Data Source
AI summary
The present invention relates to a fixative composition and process for reducing hydrophobic and/or anionic substances in fibre-containing stock for making of paper, board or the like. The composition comprises a synthetic cationic polymer, which has a charge density of 3.0 - 24 meq/g, and a cationic non-degraded starch, which has charge density of 0.5 - 3.0 meq/g. The invention relates also to thick stock composition comprising fibres and a fixative composition according to the invention.