Amphoteric Polyacrylamide for Paper Deposit Control
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Solution Overview
Problem
Modern papermaking processes face challenges with deposit formation caused by hydrophobic substances, leading to web breakages, quality degradation, and increased downtime due to the limitations of existing control methods, particularly with microstickies and pitch, which are not effectively removed by conventional fixatives.
Innovation Solution
A water-soluble amphoteric polyacrylamide polymer product with a neutral or cationic net charge is added to the fibre suspension, effectively fixing hydrophobic substances onto fibres, reducing their accumulation and deposition on process surfaces, and controlling both microstickies and pitch across various particle sizes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional fixatives are used to control deposit formation, then some hydrophobic substances are removed, but microstickies and pitch are not effectively removed leading to web breakages and quality degradation
Solution Approach 1:
The patent applies parameter changes by utilizing a polymer with specific charge characteristics (cationic or amphoteric) and optimized molecular weight (10,000-1,000,000 Daltons) to effectively bind hydrophobic substances. This parameter optimization enables the polymer to bridge between anionic hydrophobic substances and fibres, achieving effective deposit control that conventional fixatives cannot accomplish.
Solution Approach 2:
The invention employs a composite approach by using a polymer that can simultaneously interact with multiple types of hydrophobic substances (pitch, stickies, resins) and fibres. The polymer acts as a composite binder that combines the functions of fixation, dispersion, and retention enhancement in a single material system.
2Reliability
If more washing and cleaning of process surfaces is performed to prevent deposits, then deposit formation is reduced, but downtime and production loss increase
Solution Approach 1:
The patent implements preliminary action by adding the polymer to the fibre suspension before paper formation, where it proactively binds hydrophobic substances to fibres in advance. This prevents deposits from forming on process surfaces during drying and pressing operations, eliminating the need for subsequent washing and cleaning interruptions.
Solution Approach 2:
The invention converts the harmful effect of hydrophobic substances (which cause deposits) into a beneficial effect by using the polymer to redirect these substances onto the paper web where they become part of the product structure. This transforms potential contaminants into retained material that does not require removal through washing or cleaning.
3Ease of manufacture
If recycled fibre material is used as raw material to reduce costs, then production cost decreases, but hydrophobic substances accumulate leading to increased deposit formation
Solution Approach 1:
The patent introduces an intermediary substance (the cationic or amphoteric polymer) that mediates between recycled fibres containing hydrophobic substances and the paper formation process. The polymer acts as a bridge that binds the harmful hydrophobic substances to fibres, preventing their accumulation and deposition on process surfaces while allowing the use of cost-effective recycled materials.
4Reliability
If cationic polymers are used to fix hydrophobic substances, then deposit control improves, but overcationization and flocculation risks increase
Solution Approach 1:
The patent applies parameter changes by offering both cationic and amphoteric polymer options with optimized charge densities and molecular weights. The amphoteric polymer specifically provides both positive and negative charges, enabling it to bind hydrophobic substances through cationic sites while preventing overcationization through anionic sites, thus maintaining charge balance stability in the papermaking process.
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 amphoteric polyacrylamide polymer efficiently fixes hydrophobic substances of different sizes, reducing agglomeration and deposition, thereby improving paper quality, reducing downtime, and enhancing the retention of hydrophobic substances within the paper web, while minimizing the risk of overcationization and flocculation.
Implementation Method 1
A water-soluble amphoteric polyacrylamide polymer product with a neutral or cationic net charge is added to the fibre suspension, effectively fixing hydrophobic substances onto fibres
Implementation Method 2
The amphoteric polyacrylamide polymer efficiently fixes hydrophobic substances of different sizes, reducing agglomeration and deposition
Data Source
AI summary
The invention relates to a use of a water-soluble polymer product comprising amphoteric polyacrylamide, which has neutral or cationic net charge at pH 7, a weight-average molecular weight of 2 500 000 – 18 000 000 g/mol and a total ionicity of 4 – 28 mol-%. The polymer product is used for controlling deposit formation caused by hydrophobic substances in manufacture of paper or board, where a fibre web is formed from an aqueous suspension of fibres. The invention relates also to a method for controlling deposit formation caused by hydrophobic substances in manufacture of paper or board, where a fibre web is formed from an aqueous suspension of fibres, as well as to produced paper or board.