Microfibrillated Cellulose Pre-Mix for Retention Aids

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Solution Overview

Problem

In the production of fiber-based products, it is challenging to effectively mix retention aids with microfibrillated cellulose due to uneven charge neutralization and reduced mixing efficiency, especially when high amounts of fine materials or water-soluble additives are present, leading to issues with retention and dewatering.

Innovation Solution

A pre-mix of microfibrillated cellulose, cationic or amphoteric polymers, and microparticles or nanoparticles is prepared before dosing, which improves retention and dewatering efficiency by enhancing physical-chemical interactions and facilitating higher machine speeds.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If retention aids are dosed into a multicomponent furnish containing high amounts of fine materials, then retention function is provided, but uneven charge neutralization and fluctuations in retention occur

Engineering Contradiction:
Improveretention functionVSAvoidcharge neutralization uniformity
Core Design Contradiction:
ReliabilityVSManufacturing precision

Solution Approach 1:

The patent applies preliminary action by pre-mixing the retention aid with microfibrillated cellulose (MFC) before dosing into the furnish. This pre-mixing step ensures that the retention aid is already associated with MFC particles, which prevents uneven charge neutralization and retention fluctuations when dosed into the multicomponent furnish. The pre-formed complex of MFC and retention aid is then introduced together, ensuring uniform distribution and consistent performance.

Inventive Principle:
Principle #10Preliminary action

2Adaptability or versatility

If other chemicals are added to the system, then functional requirements are met, but mixing efficiency of retention chemicals is reduced

Engineering Contradiction:
Improvefunctional chemical requirementsVSAvoidmixing efficiency
Core Design Contradiction:
Adaptability or versatilityVSEase of manufacture

Solution Approach 1:

The patent merges the retention aid with microfibrillated cellulose (MFC) to form a pre-mix complex before dosing. This combination allows the retention function to be integrated with the MFC particles, which are already present in high amounts in the furnish. By merging these components beforehand, the system maintains functional versatility while avoiding the mixing efficiency problems that would occur if retention aids were dosed separately into a complex multicomponent furnish.

Inventive Principle:
Principle #5Merging (Combining)

3Manufacturing precision

If high amounts of fine materials are present, then fiber-based product quality is improved, but retention aid mixing becomes difficult

Engineering Contradiction:
Improveproduct qualityVSAvoidretention aid mixing
Core Design Contradiction:
Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The patent uses microfibrillated cellulose (MFC) as an intermediary carrier for the retention aid. Instead of dosing the retention aid directly into the furnish containing high amounts of fine materials, the retention aid is first associated with MFC particles in a pre-mix. This intermediary approach allows the retention function to be delivered effectively even in the presence of high fine material content, as the MFC-retention aid complex can be distributed more uniformly than free retention aid would be.

Inventive Principle:
Principle #24Intermediary (Mediator)

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 pre-mix enhances retention of both organic and inorganic components, resulting in cleaner white water with reduced total organic carbon, chemical oxygen demand, and biological oxygen demand, while allowing for high-speed dewatering and improved production processes.

Implementation Method 1

a) microfibrillated cellulose, wherein the amount of the microfibrillated cellulose is 0.1 kg to 50 kg per ton dry furnish; b) cationic or amphoteric polymer, wherein the amount of the cationic or amphoteric polymer in the mixture is 0.01 kg to 10 kg per ton dry furnish

Methodology Applied
Scientific EffectElectrostatic interaction: Electrostatics

Implementation Method 2

c) microparticles or nanoparticles, wherein the amount of microparticles or nanoparticles is 0.01 kg to 10 kg per ton dry furnish

Methodology Applied
Scientific EffectAdsorption: Adsorption

Implementation Method 3

by preparing a pre-mix before dosing it to the stock in a process for manufacture of paper or board, re-flocculation of MFC and retention properties can be improved

Methodology Applied
Scientific EffectFlocculation: Flocculation

Data Source

PatentUS11198973B2Pre-mix useful in the manufacture of a fiber based product
Publication Date: 2021.12.14 STORA ENSO OYJ

AI summary

The present invention relates to a process wherein microfibrillated cellulose (MFC) is mixed with at least two retention aids, selected from a cationic or amphoteric polymer and a microparticle or nanoparticle as a pre-mix before dosing it to the stock in a process for manufacture of a fiber based product.