Cationic Strength Promoter for OCC Papermaking
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Solution Overview
Problem
Existing methods for enhancing paper strength, particularly dry strength, are ineffective when dealing with furnish containing large amounts of anionic trash, such as old corrugated cardboard, as the high anionic moieties interfere with the bonding of strength aids with paper fibers, leading to impaired paper quality.
Innovation Solution
The method involves adding an acrylamide-diallyldimethyl ammonium chloride copolymer as a strength promoter to the furnish before introducing a glyoxylated acrylamide-diallyldimethyl ammonium chloride copolymer as a strength agent, which effectively blocks interactions between anionic trash and the strength agent, thereby enhancing paper strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If strength aids are added to furnish containing large amounts of anionic trash, then paper strength should be improved, but the high anionic moieties prevent the strength aid from bonding with paper fibers, resulting in impaired paper quality
Solution Approach 1:
The patent applies preliminary action by adding a cationic polymer to the furnish before adding the strength aid. This pre-treatment step neutralizes the anionic trash and creates a favorable environment for subsequent strength aid bonding, ensuring that the strength aid can effectively bond with paper fibers despite the presence of anionic contaminants
Solution Approach 2:
The cationic polymer acts as an intermediary substance that mediates between the anionic trash and the strength aid. It first binds to the anionic trash through electrostatic attraction, then facilitates the bonding of the strength aid to the paper fibers, effectively bridging the interaction between these components
2Strength
If polyacrylamides and other polymers are used to increase dry strength of paper products, then dry strength should be improved, but this approach is disappointing when furnish contains large amount of anionic trash such as old corrugated cardboard
Solution Approach 1:
The patent applies preliminary anti-action by using a cationic polymer to counteract the harmful effects of anionic trash before the strength aid is added. The cationic polymer neutralizes the anionic moieties, preventing them from interfering with the strength aid's bonding capability, thereby eliminating the harmful interference in advance
3Strength
If dry strength additives are used to increase dry strength of paper products from recycled fibers, then dry strength should be improved, but the additives should not adversely affect the drainage rate of the cellulose web
Solution Approach 1:
The patent applies parameter changes by carefully controlling the molecular weight, charge density, and concentration of the cationic polymer and strength aid. By optimizing these parameters, the formulation achieves effective fiber bonding and dry strength improvement while maintaining appropriate drainage characteristics of the cellulose web
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 increases the dry strength of paper products made from furnish with high anionic trash content, improving burst strength and folding endurance by up to 33% compared to using the strength agent alone.
Implementation Method 1
adding an acrylamide-diallyldimethyl ammonium chloride copolymer as strength promoter to the furnish before introducing a glyoxylated acrylamide-diallyldimethyl ammonium chloride copolymer as a strength agent, which effectively blocks interactions between anionic trash and the strength agent
Data Source
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AI summary
The invention is directed towards methods, compositions, and apparatus for increasing the strength of paper made out of a furnish having a large proportion of OCC. The method involves the following steps: 1) Providing a paper furnish having a large amount of OCC in it, 2) adding strength promoter to the furnish prior to adding a strength agent to the furnish, 3) adding a strength agent to the furnish, and 4) making a paper product from the furnish. This method allows cheap OCC material to be used in a papermaking process without the quality problems that the anionic trash in OCC typically causes. Thus paper products having low costs and high quality can be produced.