Papermaking Polymer Sequence for Drainage Without Gel Formation
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Solution Overview
Problem
Existing paper manufacturing processes face challenges in achieving improved drainage and machinability due to the fast and difficult-to-control reaction of polyvinylamine with dialdehyde, which requires costly transportation and can alter machinability, and result in polymer gel formation.
Innovation Solution
A process involving functionalization with isocyanates and addition of aldehyde-functional compounds to a water-soluble polymer before injection into a fibrous suspension, avoiding polymer gel formation and enhancing drainage and dry strength properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If polyvinylamine is reacted with dialdehyde to improve drainage and strength properties, then drainage and wet/dry strength are improved, but the reaction is very fast and difficult to control, causing polymer gel formation that alters machinability
Solution Approach 1:
The patent applies preliminary action by first functionalizing the polyvinylamine with isocyanates to create a reactive intermediate, then adding this functionalized polymer to the fibrous suspension, and finally introducing the dialdehyde. This staged approach prevents direct rapid reaction between polyvinylamine and dialdehyde, avoiding gel formation while still achieving improved strength properties.
Solution Approach 2:
The isocyanate-functionalized polyvinylamine acts as an intermediary between the original polyvinylamine and the dialdehyde. This intermediary form allows controlled reaction with dialdehyde after being added to the fibrous suspension, preventing the harmful fast reaction and gel formation while still enabling the desired crosslinking for strength improvement.
2Object-generated harmful factors
If polyvinylamine is reacted with dialdehyde in a diluted medium to control the reaction, then gel formation is reduced, but significant cost is incurred to transport the product from production to paper manufacturing site
Solution Approach 1:
The functionalization with isocyanates is performed beforehand to prepare the polymer for controlled reaction with dialdehyde at the paper manufacturing site, avoiding the need to transport pre-reacted products and reducing transportation costs while maintaining control over the reaction process.
Solution Approach 2:
The isocyanate-functionalized polymer serves as a stable intermediary that can be transported and stored without immediate reaction with dialdehyde, then introduced to the fibrous suspension where the final crosslinking occurs under controlled conditions, eliminating both gel formation issues and excessive transportation costs.
3Quantity of substance
If the reaction is carried out just upstream of polymer injection to reduce transportation cost, then transportation cost is reduced, but the fast reaction causes deposits on the paper machine that alter machinability
Solution Approach 1:
The polyvinylamine is pre-functionalized with isocyanates to create a stable intermediate that does not immediately react with dialdehyde upon contact with the fibrous suspension. This allows the functionalized polymer to be added just upstream of injection without causing rapid reaction and deposits, maintaining machinability while reducing transportation costs.
Solution Approach 2:
The isocyanate-functionalized polyvinylamine acts as a controlled intermediary that delays the crosslinking reaction until after introduction to the fibrous suspension, preventing premature reaction and deposits on the paper machine while still achieving the desired strength improvement without compromising machinability.
4Productivity
If conventional polymer treatment is used to improve drainage, then drainage is improved, but energy consumption increases due to reduced production capacity
Solution Approach 1:
The patent uses a composite approach by combining polyvinylamine functionalized with isocyanates and dialdehyde to create a crosslinked polymer structure that provides superior drainage improvement. This composite polymer treatment enhances drainage efficiency, allowing faster production cycles and increased production capacity, thereby reducing overall energy consumption per unit of paper produced.
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 process improves drainage and dry strength without affecting machinability, offering energy savings and increased production capacity by using a polymer prepared through specific Re1 and Re2 reactions within 24 hours, resulting in better performing polymers for paper or cardboard production.
Implementation Method 1
The Re1 reaction consists of adding an alkali and/or alkaline-earth hydroxide and an alkali and/or alkaline-earth hypohalide to the P1 polymer in order to obtain, after 10 seconds to 60 minutes, the P2 polymer functionalized by isocyanates
Implementation Method 2
The Re2 reaction consists of adding a compound functionalized by at least one aldehyde or capable of generating at least one aldehyde function to the P2 polymer in order to obtain the P3 polymer
Implementation Method 3
The polymer is concentrated to a concentration of 1% to 50% by weight, advantageously to a concentration of 5% to 20% by weight
Data Source
AI summary
A process for making a sheet of paper or cardboard from a fiber suspension, includes injection of a polymer P3 into a cellulosic fiber suspension, formation of a sheet of paper or cardboard, and drying of the sheet of paper or cardboard. The P3 polymer is prepared, prior to the injection, from a water-soluble P1 polymer of at least one nonionic monomer, such as acrylamide, methacrylamide, N,N-dimethylacrylamide, and acrylonitrile. The P1 polymer is subjected to a Re1 reaction to give a P2 polymer, which is then subjected to a Re2 reaction to give the P3 polymer, which is injected into the fibrous suspension within 24 hours of the start of the Re1 reaction.