Filler Surface Modification for Papermaking Dewatering
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Solution Overview
Problem
High filler content in papermaking processes, particularly with PCC, reduces the efficiency of wet end chemicals like dewatering aids due to increased adsorption, leading to decreased wet web strength, wet strength, and dewatering efficiency, which affects machine runnability and production efficiency.
Innovation Solution
A method involving the preflocculation of filler particles using a first and second flocculating agent of opposite charge, combined with a dewatering aid, to reduce the adsorption of the aid on filler surfaces, thereby enhancing the effectiveness of dewatering aids and improving filler retention and wet web strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If high filler content is used in papermaking, then opacity and light reflecting properties are improved, but dewatering efficiency decreases and wet web strength is reduced
Solution Approach 1:
The patent applies preliminary action by pre-flocculating filler particles with a first flocculating agent before the dewatering stage. This pre-treatment modifies the filler surface properties in advance, reducing subsequent adsorption of dewatering aids and improving dewatering efficiency while maintaining high filler content for opacity
Solution Approach 2:
The patent uses a first flocculating agent as an intermediary substance that modifies the filler particle surfaces. This intermediary layer reduces the direct interaction between filler particles and dewatering aids, allowing high filler content to be used without proportionally reducing dewatering efficiency
2Ease of manufacture
If high filler content is used in papermaking, then cost is reduced and opacity is improved, but wet web strength is reduced due to filler interference with fiber bonds
Solution Approach 1:
The patent applies preliminary action by pre-flocculating filler particles before they are incorporated into the paper web. This pre-treatment modifies filler surface properties in advance, reducing subsequent adsorption of dewatering aids and improving both dewatering efficiency and wet web strength while maintaining high filler content
Solution Approach 2:
The patent changes the surface parameters of filler particles through chemical modification with flocculating agents. This parameter change reduces the specific surface area available for adsorption and modifies surface chemistry, allowing high filler content to be used without proportionally reducing wet web strength
3Ease of manufacture
If high filler content is used in papermaking, then cost is reduced, but adsorption of dewatering aids on filler surface increases, reducing dewatering efficiency
Solution Approach 1:
The patent applies preliminary action by pre-flocculating filler particles with a first flocculating agent before the dewatering stage. This pre-treatment modifies the filler surface properties in advance, reducing subsequent adsorption of dewatering aids and improving dewatering efficiency while maintaining high filler content for cost reduction
Solution Approach 2:
The patent uses a first flocculating agent as an intermediary substance that modifies the filler particle surfaces. This intermediary layer reduces the direct interaction between filler particles and dewatering aids, allowing high filler content to be used without proportionally reducing dewatering efficiency
4Illumination intensity
If PCC filler is used instead of GCC, then optical properties are improved due to greater specific surface area, but wet strength and wet web strength are reduced
Solution Approach 1:
The patent applies preliminary action by pre-flocculating PCC filler particles before incorporation into the paper web. This pre-treatment modifies the high-surface-area PCC particles in advance, reducing their subsequent adsorption of dewatering aids and improving wet strength while maintaining the optical properties provided by PCC's greater specific surface area
Solution Approach 2:
The patent changes the surface parameters of PCC particles through chemical modification with flocculating agents. This parameter change reduces the specific surface area available for adsorption and modifies surface chemistry, allowing high PCC content to be used without proportionally reducing wet strength
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 significantly increases dewatering efficiency, wet web strength, and wet strength, allowing for higher filler content without reducing the effectiveness of dewatering aids, leading to improved machine runnability and production efficiency, as illustrated by the synergistic effect shown in FIG. 1.
Implementation Method 1
adding a second flocculating agent to the dispersion after adding the first flocculating agent in an amount sufficient to initiate flocculation of the filler particles
Implementation Method 2
the second flocculating agent being of opposite charge to the first flocculant
Implementation Method 3
treating the combination with at least one dewatering aid, and forming a paper mat by removing some of the water from the combination
Data Source
AI summary
The invention provides a method of improving dewatering efficiency, increasing sheet wet web strength, increasing sheet wet strength and enhancing filler retention in a papermaking process. The method improves the efficiency of dewatering aid by coating at least some of the filler particles with a material that prevents the filler materials form adhering to dewatering aids. The dewatering aid holds the paper fibers together tightly and is not wasted on the filler particles.