Water-Soluble Polymer Dissolution in Papermaking
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Solution Overview
Problem
Existing papermaking processes face challenges in achieving rapid dissolution of high molecular weight water-soluble polymers, leading to prolonged preparation times and increased footprint of preparation units, which affects retention, dewatering, and mechanical properties of paper and cardboard.
Innovation Solution
A method involving the preparation of an aqueous solution with a water-soluble polymer at a concentration of 0.1 to 0.5% by weight, characterized by a factor F(C) greater than 4, which allows for rapid achievement of improved drainage, retention, and mechanical properties within two minutes or less.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high molecular weight water-soluble polymers are used as retention agents, then retention and dewatering properties are improved, but dissolution time is prolonged and preparation unit volume increases
Solution Approach 1:
The patent applies preliminary action by pre-forming the polymer in an oily suspension state before introduction to the water stream. This pre-preparation allows the polymer to be ready for rapid dissolution when contacted with water, eliminating the need for prolonged maturation time in the preparation unit while maintaining the high molecular weight necessary for effective retention and dewatering properties.
2Reliability
If high molecular weight water-soluble polymers are used as retention agents, then retention and dewatering properties are improved, but preparation unit volume and footprint increase
Solution Approach 1:
The patent applies preliminary action by pre-forming the polymer in an oily suspension state before introduction to the water stream. This pre-preparation allows the polymer to be ready for rapid dissolution when contacted with water, eliminating the need for prolonged maturation time in the preparation unit while maintaining the high molecular weight necessary for effective retention and dewatering properties.
3Reliability
If polymer concentration is increased to improve retention, then retention properties are improved, but dissolution time is further prolonged
Solution Approach 1:
The patent applies parameter changes by fundamentally altering the physical state parameter of the polymer from solid or aqueous solution to oily suspension. This state change enables the polymer to dissolve rapidly in water even at higher concentrations (50-800 g/t), because the oily suspension form allows for faster dispersion and dissolution kinetics compared to traditional solid or concentrated aqueous forms.
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 method reduces the residence time of the polymer in the preparation unit, decreases the volume of the maturation tank, and results in improved retention, dewatering, and mechanical properties of paper and cardboard, while minimizing the footprint of the paper mill.
Implementation Method 1
preparing an aqueous solution A containing at least one water-soluble polymer P at a concentration by weight C between 0.1 and 0.5% by weight... the rapid dissolution of these polymers is therefore a key factor
Implementation Method 2
the maximum viscosity of this stock solution can only be reached after several minutes, even tens of minutes... the viscosity of solution A over time being determined at 25° C. using a viscometer
Implementation Method 3
The retention agents' mode of action is based on the flocculation of these materials in suspension in water. Indeed, the flocs formed are more easily retained on the forming fabric.
Data Source
AI summary
This invention relates to a method for manufacturing a sheet of paper or cardboard, comprising the addition of a water-soluble polymer P with a weight-average molecular weight greater than 750,000 Dalton to a fibrous suspension. This method comprises the following successive steps:preparing an aqueous solution A containing at least one water-soluble polymer P at a concentration C of between 0.1 and 0.5% by weight, said polymer P having a factor F(C) strictly greater than 4, with F(C)=Δ600/C, Δ600 being the slope to reach 90% of the viscosity developed by aqueous solution A at 600 seconds at 25° C., obtained from the viscosity curve of aqueous solution A as a function of time, at the given concentration C, at 25° C.,adding aqueous solution A to the fibrous suspension, at one or more injection points,forming a sheet of paper or cardboard.