Cellulose-Reactive Sizing Agent Dispersion Stability
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Solution Overview
Problem
Aqueous dispersions of cellulose-reactive sizing agents, such as alkenyl succinic anhydride, face issues with poor stability and high energy consumption due to the need for high shear forces in preparation, leading to inefficient handling and short storage times, as well as equipment complexity and cost.
Innovation Solution
An aqueous dispersion of cellulose-reactive sizing agent containing an acid anhydride, an anionic polyelectrolyte, and a nitrogen-containing organic compound with a molecular weight less than 180 and/or hydroxyl groups, which can be prepared using low shear forces and energy, improving stability and sizing efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If high shear forces are used to prepare aqueous dispersions of alkenyl succinic anhydride, then adequate particle size and surface freedom are achieved, but energy consumption increases and equipment becomes complicated and expensive
Solution Approach 1:
The patent introduces a specific dispersant system comprising an anionic compound (sodium lignosulfonate) in combination with a high molecular weight amphoteric or cationic polymer as an intermediary substance that facilitates the dispersion of alkenyl succinic anhydride particles without requiring high shear forces. This dispersant system acts as a mediator between the sizing agent particles and the aqueous phase, enabling adequate particle size distribution and surface freedom with low energy input.
2Reliability
If alkenyl succinic anhydride is delivered as a liquid and dispersed prior to use, then sizing efficiency is maintained, but stability is poor and storage time is limited to 2 hours
Solution Approach 1:
The patent applies preliminary action by pre-forming stable aqueous dispersions of alkenyl succinic anhydride using the specific dispersant system before delivery to paper mills. The dispersant system is incorporated in advance to prevent particle aggregation and hydrolysis during storage, enabling the sizing agent to be delivered in a stable dispersed state rather than as a liquid requiring immediate use. This preliminary stabilization extends storage time significantly beyond 2 hours while maintaining sizing efficiency.
Solution Approach 2:
The patent creates a composite dispersion system combining alkenyl succinic anhydride particles with a specific dispersant system consisting of anionic compounds and high molecular weight amphoteric or cationic polymers. This composite structure provides both the sizing functionality of the anhydride and the stability properties of the dispersant system, enabling long-term storage while maintaining effective sizing performance.
3Reliability
If alkenyl succinic anhydride is used as a sizing agent, then paper resistance to wetting is improved, but the dispersion exhibits poor stability and hydrolyses easily
Solution Approach 1:
The dispersant system acts as an intermediary protective layer between the alkenyl succinic anhydride particles and the aqueous environment, preventing direct contact that would lead to hydrolysis. The anionic compound (sodium lignosulfonate) combined with high molecular weight amphoteric or cationic polymer creates a stable interface that maintains particle integrity and prevents aggregation, thereby preserving both dispersion stability and the sizing agent's effectiveness in providing wetting resistance.
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 solution allows for the use of simple, energy-efficient equipment and results in improved stability and sizing efficiency of paper products, enabling longer storage and reduced energy consumption.
Implementation Method 1
dispersing an acid anhydride in an aqueous phase in the presence of an anionic polyelectrolyte and a nitrogen-containing organic compound
Data Source
AI summary
The invention relates to an aqueous dispersion of cellulose-reactive sizing agent containing an acid anhydride, an anionic polyelectrolyte and a nitrogen-containing organic compound which is an amine or quaternary ammonium thereof having a molecular weight less than 180 and/or having one or more hydroxyl groups. The invention further relates to a process for the production of paper which comprises adding the aqueous dispersion of cellulose-reactive sizing agent to an aqueous cellulosic suspension.