Paper Production Using Hofmann Degradation Polymers
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Solution Overview
Problem
The initial wet web strength of paper, which limits papermachine speed, is not adequately enhanced by existing methods, necessitating a more effective approach to increase the pull-off force during sheet formation in the paper production process.
Innovation Solution
A process involving the use of a water-soluble polymer obtained by Hofmann degradation of acrylamide- and/or methacrylamide-containing polymers, added to the paper stock at specific concentrations, followed by sheet formation and pressing to achieve increased solids content, thereby enhancing the initial wet web strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional methods are used to enhance initial wet web strength, then the strength improvement is insufficient, but increasing the solids content further would compromise paper quality and handling characteristics
Solution Approach 1:
The patent applies parameter changes by optimizing the fibrous concentration ranges (20-40 g/l at thick stuff stage, 5-15 g/l at thin stuff stage) and controlling solids content at specific press section exit values (48-55 wt% for 10-30 g/m² paper, 55-65 wt% for 30-80 g/m² paper). This systematic parameter optimization enhances initial wet web strength while maintaining paper quality and enabling higher papermachine speeds.
Solution Approach 2:
The patent uses composite materials by combining water-soluble polymers (such as polyacrylamide, polyacrylonitrile, or their copolymers) with fibrous materials in specific concentrations. This composite approach creates a synergistic effect where the polymer network binds fibers together, significantly enhancing initial wet web strength without compromising paper quality or requiring excessive solids content.
2Productivity
If higher pull-off forces are applied to increase papermachine speed, then productivity increases, but the sheet breaks due to insufficient initial wet web strength
Solution Approach 1:
The patent applies preliminary action by adding water-soluble polymers to the paper stock at the thick stuff stage (20-40 g/l) and thin stuff stage (5-15 g/l) before sheet formation. This preliminary polymer addition creates a binding network that strengthens the sheet structure before it enters the press section, enabling higher pull-off forces without sheet breakage and thus allowing increased papermachine speed.
Solution Approach 2:
The patent uses parameter changes by controlling the fibrous concentration ranges and solids content at specific exit values from the press section. By optimizing these parameters, the initial wet web strength is enhanced to match higher pull-off forces, allowing the papermachine to operate at higher speeds without compromising sheet integrity.
3Strength
If the solids content at the press section exit is increased to enhance initial wet web strength, then the pull-off force capacity increases, but the paper quality and handling characteristics deteriorate
Solution Approach 1:
The patent applies parameter changes by optimizing the fibrous concentration ranges (20-40 g/l at thick stuff stage, 5-15 g/l at thin stuff stage) and controlling solids content at specific press section exit values (48-55 wt% for 10-30 g/m² paper, 55-65 wt% for 30-80 g/m² paper). This systematic optimization enhances initial wet web strength while maintaining paper quality and handling characteristics.
Solution Approach 2:
The patent uses composite materials by combining water-soluble polymers with fibrous materials in specific concentrations. This composite approach creates a synergistic effect where the polymer network binds fibers together, enhancing initial wet web strength without requiring excessive solids content that would compromise paper quality and 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 process significantly enhances the initial wet web strength, allowing for higher papermachine speeds and reducing the risk of broken ends during paper production.
Implementation Method 1
at least one water-soluble polymer obtainable by Hofmann degradation of an acrylamide- and/or methacrylamide-containing polymer
Data Source
AI summary
The present invention relates to a process for producing paper, card and board. The present invention is based on the discovery that controlling solids content during the process in a specified manner provide enhanced initial web strength of the paper prior to drying and allows for higher machine speeds in the paper production process as compared to known processes.