Co-mixed Cationic Polymers for Starch Retention in Recycled Fiber Systems
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Solution Overview
Problem
In paper and board production, recycled fiber materials contain low molecular weight starch that is not effectively retained on fibers, leading to poor starch retention, microbial growth, and operational issues such as web breaks and odors, due to the circulation of starch in process water, which decreases yield and affects product quality.
Innovation Solution
A method involving the co-mixing of two quick inversion cationic emulsion polymers, A and B, at optimal blend ratios, is applied to starch-containing recycled fiber stock to enhance starch trapping efficiency without over-flocculation, using a polymer coagulation system that synergistically increases starch retention and inhibits hydrophobic substance deposition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional starch trapping polymers are used, then starch retention is improved, but over-flocculation and stickies formation occur
Solution Approach 1:
The patent divides a single polymer system into two distinct quick inversion cationic emulsion polymers (A and B) with different molecular weights and charge densities. Polymer A has lower molecular weight (1-5 million Daltons) while Polymer B has higher molecular weight (5-20 million Daltons). This segmentation allows each polymer to perform specialized functions: Polymer A provides rapid starch trapping with minimal flocculation, while Polymer B provides enhanced retention without the over-flocculation problems of conventional single-polymer systems.
Solution Approach 2:
The patent changes key parameters of the polymer system by using quick inversion cationic emulsion polymers with controlled molecular weights (1-20 million Daltons) and charge densities (15-40 meq/g). The co-mixing ratio of Polymers A and B is optimized to achieve synergistic effects. These parameter changes enable effective starch trapping while preventing over-flocculation and stickies formation that occur with conventional polymers.
2Object-affected harmful factors
If starch is retained in process water circulation, then microbial growth is prevented, but yield decreases due to starch loss
Solution Approach 1:
The patent introduces quick inversion cationic emulsion polymers as intermediary substances that mediate between starch molecules and fiber surfaces. These polymers act as bridges that trap starch particles and attach them to fibers through electrostatic and hydrophobic interactions. This intermediary mechanism prevents starch from circulating in process water (thereby preventing microbial growth) while simultaneously retaining starch on the paper product (thereby maintaining yield).
3Object-generated harmful factors
If hydrophobic substances are removed during deinking, then deposit formation is reduced, but substantial amounts remain and accumulate in process waters
Solution Approach 1:
The quick inversion cationic emulsion polymers serve as intermediaries that bind to hydrophobic substances (stickies) through electrostatic and hydrophobic interactions. The polymers trap these hydrophobic contaminants and transport them to the wire section where they are removed with the paper sheet. This prevents hydrophobic substances from accumulating in process waters and forming deposits on machinery surfaces.
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 method effectively retains starch on fibers, reduces microbial growth, and prevents hydrophobic substance deposition, improving paper and board production efficiency and quality by maintaining starch retention and preventing operational disruptions.
Implementation Method 1
two quick inversion cationic emulsion polymers, A and B... co-mixed at an optimal blend ratio... to enhance starch trapping efficiency
Implementation Method 2
synergistically increases starch retention and inhibits hydrophobic substance deposition
Implementation Method 3
using a polymer coagulation system that synergistically increases starch retention
Implementation Method 4
inhibits hydrophobic substance deposition
Data Source
AI summary
The present invention provides a novel method and composition for enhancing the efficiency of starch adsorption (i.e., starch trapping) from starch-containing furnishes comprising high content of recycled fibers for use in paper making processes such as pulp, paper, or board production. A novel polymer coagulation system is disclosed in which two quick inversion cationic emulsion polymers (starch trapping polymers A and B) are co-mixed at optimal blend ratios to meet specific recycled fiber and process water requirements for different recycled fiber plants and added to furnishes prior to formation of paper or board in a paper machine. Co-mixed solutions of starch trapping polymers A and B provide synergistic enhancements in (i) starch trapping efficiency and (ii) starch retention in the produced paper or board over equivalent dosage levels of singly administered polymer A, polymer B, or conventional starch trapping products, without over-flocculation or formation of stickies.