Water-Soluble Polymer Dosing for Paper Wet Strength
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The initial wet structure strength of paper limits the maximum force that can be applied to the paper sheet during the transition from the press section to the dryer section in paper machines, restricting machine speed and efficiency.
Innovation Solution
Incorporating a water-soluble polymer obtained by Hofmann degradation of acrylamide and/or methacrylamide into the paper stock, with specific dosing and processing conditions to enhance the initial wet structure strength, allowing for higher solids content and improved paper machine operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the initial wet structure strength is increased to allow higher pull-off forces and faster machine operation, then productivity increases, but the process complexity increases due to specific polymer dosing and processing requirements
Solution Approach 1:
The water-soluble polymer is dosed into the paper stock before sheet formation in the wire section, allowing the polymer to be incorporated into the fiber network in advance. This preliminary action ensures the polymer is present when the sheet is formed and pressed, providing enhanced wet structure strength without requiring complex post-processing equipment
Solution Approach 2:
The invention specifies dosing the water-soluble polymer at concentrations of 0.1 to 5 kg per ton of dry fiber, with fiber concentrations in the range of 20 to 40 g/l. These parameter changes optimize the polymer's effectiveness in enhancing wet structure strength while maintaining processability through standard paper machine equipment
2Strength
If the solids content of the paper web after pressing is increased to improve wet structure strength, then the initial wet structure strength improves, but the energy consumption increases due to higher pressing requirements
Solution Approach 1:
The water-soluble polymer acts as an intermediary substance that enhances the bonding between fibers in the paper web. By dosing the polymer into the stock before sheet formation, it facilitates fiber-to-fiber bonding during pressing, allowing adequate wet structure strength to be achieved at lower solids content and reduced pressing energy requirements
3Productivity
If the pull-off force applied to the paper sheet is increased to improve production efficiency, then productivity increases, but the risk of sheet tearing increases if the initial wet structure strength is insufficient
Solution Approach 1:
The water-soluble polymer is incorporated into the paper stock before sheet formation and pressing, preliminarily strengthening the fiber network. This allows the sheet to withstand higher pull-off forces during transfer from the press section to the dryer section without tearing, enabling increased production efficiency while maintaining sheet integrity
Solution Approach 2:
The polymer reinforcement acts as a cushioning mechanism that pre-strengthens the paper web against the high mechanical stresses of high-speed operation. This beforehand cushioning allows the use of higher pull-off forces without risking sheet failure
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 enhanced initial wet structure strength enables higher pull-off forces and faster paper machine operation without tearing, improving production efficiency and paper quality.
Implementation Method 1
The at least one water-soluble polymer is obtainable by Hofmann degradation of a polymer containing acrylamide and/or methacrylamide
Implementation Method 2
dewatering a filler-containing paper stock which contains at least one water-soluble polymer, with sheet formation in the wire section
Implementation Method 3
pressing the paper in the press section, resulting in a paper stock with a fiber concentration of 5 to 15 g/l and a solids content of G(x) wt.% or greater
Data Source
AI summary
The invention relates to a method for producing paper, paperboard and cardboard, comprising the dehydration of a paper material comprising filler material, which contains at least one water-soluble polymer, forming sheets in the wire section and subsequent pressing of the paper in the press section, wherein the at least one water-soluble polymer is dosed to a paper material having a fiber concentration in the range of 20 to 40 g/l, the paper material is then thinned to a fiber concentration in the range of 5 to 15 g/l, the thinned paper material is dehydrated, forming a sheet, and the sheet is pressed in the press section to a solids content G(x) wt % or greater and G(x) is calculated according to G(x) = 48 + (x -15)∙0.4, where x stands for the numerical value of the filler material content of the dry paper, paperboard or cardboard (in wt %) and G(x) stands for the numerical value of the minimum solids content (in wt %) on which the sheet is pressed, wherein the water-soluble polymer is obtainable via Hofmann reduction of a polymer comprising acrylamide and/or methacrylamide and optionally subsequent post-curing.