Crosslinked Cationic Polymer Retention in Paper Manufacturing
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Solution Overview
Problem
Existing papermaking processes face challenges in achieving effective retention and drainage using dual retention systems, particularly when employing two cationic retention agents with crosslinked polymers, which often require high shear rates and specific viscosity conditions, leading to inefficiencies and potential system failures.
Innovation Solution
A process involving the use of a main cationic polymer and a crosslinked cationic organic polymer as dual retention agents, both with gentle agitation and specific viscosity characteristics, to enhance retention and drainage in paper production without the need for high shear rates or inorganic microparticles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If crosslinked cationic polymers are used as dual retention agents, then retention and drainage performance is improved, but high shear rates and specific viscosity conditions are required, leading to process complexity
Solution Approach 1:
The patent changes the viscosity parameter of the crosslinked cationic polymer to a specific range (1.3-2.7 cps at 20°C) to optimize its performance. This parameter modification allows the polymer to function effectively as a dual retention agent without requiring extreme shear rates or complex processing conditions, thus resolving the contradiction between improved retention/drainage performance and process complexity
Solution Approach 2:
The patent introduces a dynamic element by specifying that the crosslinked cationic polymer should have low viscosity (1.3-2.7 cps) which allows it to be easily dispersed and distributed in the fibrous suspension. This dynamic property enables the polymer to adapt to the flowing suspension without requiring high shear rates, thereby improving retention and drainage while simplifying the processing conditions
2Reliability
If conventional dual retention systems with bentonite are used, then retention is improved, but sheet quality may be compromised and costs increase
Solution Approach 1:
The patent extracts and eliminates bentonite from the conventional dual retention system, replacing it with a crosslinked cationic polymer that has been modified to have low viscosity (1.3-2.7 cps). This extraction removes the harmful effects of bentonite on sheet quality while maintaining effective retention through the optimized polymer's cationic charge and flocculation properties
Solution Approach 2:
The patent replaces expensive bentonite with a cost-effective crosslinked cationic polymer that can be used at lower concentrations. The polymer's low viscosity and high cationicity ratio (25-75%) allow it to provide equivalent or superior retention performance without the need for bentonite, thereby reducing material costs and improving sheet quality
3Reliability
If high molecular weight cationic polymers are used as main retention agents, then retention is improved, but viscosity increases, affecting drainage
Solution Approach 1:
The patent changes the viscosity parameter of the crosslinked cationic polymer to a low range (1.3-2.7 cps at 20°C), which is significantly lower than conventional high molecular weight cationic polymers. This parameter change allows the polymer to provide effective retention through its cationic charge and flocculation mechanism while maintaining low viscosity that does not impede drainage, thus resolving the contradiction between retention improvement and drainage efficiency
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 approach significantly improves retention and drainage performance while maintaining sheet quality, outperforming conventional systems and reducing the complexity and costs associated with using bentonite, enabling higher machine speeds and energy savings.
Implementation Method 1
at least one dual retention agent consisting of a crosslinked cationic (co)polymer... with a cationicity ratio apparent between 25 and 75%... to enhance retention and drainage
Implementation Method 2
Retention and drainage systems are well known in the papermaking process. Their function is to improve the retention of cellulosic fibers and mineral fillers during sheet manufacturing
Data Source
AI summary
Process for manufacturing paper, board or similar products that consists, separately or in combination, in adding, to the fibrous suspension: - at least one main retention aid composed of a cationic (co)polymer, and at least one dual retention aid composed of a crosslinked cationic (co)polymer obtained in the form of a dispersion and put into solution prior to the introduction thereof into the fibrous suspension with gentle agitation, said crosslinked cationic (co)polymer having - a UL viscosity between 1.3 and 2.7 cps, preferably 1.5 and 2.4 cps, and - an apparent cationicity ratio between 25 and 75%, and, optionally, before or after the dual retention aid or main retention aid, one, or more, tertiary retention aid(s) chosen from the group comprising mineral particles and organic polymers bearing anionic charges.