Filler Pretreatment for Papermaking Dewatering and Strength
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Solution Overview
Problem
High filler content in papermaking decreases the efficiency of wet end chemicals, such as dewatering aids and wet strength aids, due to increased adsorption onto filler surfaces, particularly with PCC fillers, which interfere with fiber bonding and reduce paper strength and dewatering efficiency.
Innovation Solution
Pre-treating filler particles with a coagulant composition, using a rotating admixing apparatus, to reduce the adhesion of wet strength aids and drainage aids to filler particles, allowing for enhanced performance and increased filler retention, thereby improving wet web strength and dewatering efficiency.
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 end chemical efficiency is reduced
Solution Approach 1:
The patent applies preliminary action by pre-treating filler particles with a coating material before they are added to the papermaking slurry. This coating is applied in advance to modify the filler surface properties, preventing subsequent adsorption of wet end chemicals and improving dewatering efficiency without compromising opacity.
Solution Approach 2:
The patent uses a coating material as an intermediary substance between the filler particles and the wet end chemicals. This coating layer acts as a barrier that prevents direct interaction between the chemicals and filler surfaces, thereby maintaining chemical efficiency while allowing high filler content for opacity.
2Ease of manufacture
If high filler content is used in papermaking, then cost is reduced and opacity is improved, but wet web strength decreases due to interference with fiber bonding
Solution Approach 1:
The coating is applied to filler particles in advance before they are incorporated into the papermaking process. This preliminary modification of filler surface properties prevents interference with fiber bonding during sheet formation, thereby maintaining wet web strength while allowing high filler content for cost reduction.
Solution Approach 2:
The coating material serves as an intermediary that separates the filler particles from direct contact with fibers during the wet web formation process. This prevents filler interference with fiber bonding while still allowing high filler loading for cost effectiveness.
3Illumination intensity
If PCC filler is used instead of GCC, then optical properties are improved due to greater specific surface area, but paper strength decreases
Solution Approach 1:
The patent applies local quality by modifying only the surface properties of PCC filler particles with a coating, while maintaining their inherent high specific surface area and optical properties. The coating is applied locally to the filler surface to prevent chemical adsorption and improve strength without compromising optical performance.
Solution Approach 2:
The coating acts as an intermediary layer on PCC filler surfaces, preventing direct interaction between the high-surface-area filler and wet end chemicals. This allows the use of PCC for superior optical properties while the coating protects against strength degradation.
4Productivity
If wet end chemicals are added to assist dewatering, then dewatering efficiency is improved, but chemical adsorption onto filler surfaces increases, reducing chemical efficiency
Solution Approach 1:
The patent applies preliminary action by pre-coating filler particles before they encounter wet end chemicals during dewatering. This advance surface modification prevents subsequent adsorption of dewatering chemicals onto filler, ensuring that chemicals remain available to perform their dewatering function efficiently.
Solution Approach 2:
The coating material serves as an intermediary barrier between filler particles and wet end chemicals. This prevents direct adsorption interactions, allowing dewatering chemicals to remain in solution and perform their intended function without being wasted on filler surface adsorption.
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 filler pretreatment significantly increases paper strength, reduces steam demand, and enhances machine runnability by ensuring that wet strength aids and drainage aids effectively bind cellulose fibers rather than being wasted on filler particles, leading to improved production efficiency and reduced production costs.
Implementation Method 1
treating the filler particles with a coagulant composition
Data Source
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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 drainage aids or wet web strength aids or wet strength aid by coating at least some of the filler particles with a material that prevents the filler materials form adhering to a those additives. The drainage additive or wet web strength additive or wet strength aid holds the cellulose fibers together tightly and is not wasted on the filler particles.