ASA Surface Sizing Composition Reducing Equipment Fouling
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Solution Overview
Problem
The use of alkenylsuccinic anhydride (ASA) as a surface sizing agent in paper production leads to significant fouling or deposit formation on paper-making equipment, particularly when calcium ions are present, which affects the efficiency and environmental sustainability of the process.
Innovation Solution
A surface sizing composition is prepared by separately adding an aqueous dispersion of alkenylsuccinic anhydride and a non-ionic, amphoteric, cationic, or anionic polymer to an aqueous solution with high water content, including starch, to minimize deposit formation on application equipment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If ASA is used as a surface sizing agent, then hydrophobic properties and sizing effectiveness are improved, but deposit formation on equipment increases significantly
Solution Approach 1:
A cationic polymer is introduced as an intermediary substance between ASA and the equipment surface. The polymer adsorbs onto the equipment surface first, creating a protective layer that prevents ASA from directly depositing on the equipment. This mediator approach allows ASA to perform its sizing function while the polymer protects the equipment from fouling
Solution Approach 2:
The application sequence is changed from simultaneous mixing to sequential addition. ASA is added first to the aqueous component, allowed to distribute, then the cationic polymer is added subsequently. This parameter change in addition sequence allows the polymer to modify the surface properties after ASA has been positioned, preventing deposit formation without compromising sizing effectiveness
2Reliability
If internal sizing agents are used, then sizing is achieved during paper formation, but size retention is lower than 100% and agents are lost in white water
Solution Approach 1:
ASA is applied to the paper web surface immediately after formation while the web is still wet. This preliminary action allows the sizing agent to be positioned on the formed web rather than being mixed into the pulp during formation, improving size retention and reducing loss to white water while still achieving effective sizing
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 significantly reduces deposit formation on size press equipment, allowing for effective surface sizing of paper while maintaining the hydrophobic properties of ASA, thus optimizing the paper-making process and reducing environmental impact.
Implementation Method 1
it has been found that use of ASA as a surface sizing agent under practical paper-making-conditions involves an increased problem with fouling of the paper-making equipment
Implementation Method 2
Alkenylsuccinic anhydride-based sizing agents belong to the group of cellulose-reactive sizing agent
Implementation Method 3
Aqueous dispersions of ASA have, per se, a strong tendency to form deposits on equipment surfaces, in particular on the surfaces of size press rollers
Data Source
AI summary
The invention relates to a process for the preparation of surface sizing composition comprising separately adding to an aqueous component comprising at least 80 wt% of water: (a) an aqueous dispersion comprising an alkenylsuccinic anhydride (ASA); and, (b) a non-ionic, amphoteric, cationic, or anionic polymer. The invention also relates to a composition obtainable thereby and a process for surface treatment of paper.