MFC and Precipitated Calcium Carbonate Composite Production

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Solution Overview

Problem

Existing methods for producing microfibrillated cellulose (MFC) and precipitated calcium carbonate (PCC) composites face issues such as deteriorated strength properties, uneven distribution of calcium dioxide, and opacity defects due to PCC completely covering MFC fibrils when MFC is added before carbonation, leading to quality defects in the end product.

Innovation Solution

Adding MFC to the calcium hydroxide suspension during carbonation, between 50% to 95% of the reaction, allows partial precipitation of calcium carbonate onto MFC fibers, enhancing strength and opacity, and ensuring a more homogeneous product by controlling the addition timing.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If MFC is added to milk of lime prior to carbonation, then calcium carbonate precipitates on MFC fibrils, but PCC completely covers MFC fibrils deteriorating strength properties and reducing opacity

Engineering Contradiction:

Improvefiller contentVSAvoidstrength properties

Core Design Contradiction:

Quantity of substanceVSStrength

Solution Approach 1:

The patent applies preliminary action by adding MFC to the milk of lime suspension before carbonation begins, allowing MFC to be present in the system prior to calcium carbonate precipitation. This timing control prevents complete coverage of MFC fibrils while still enabling partial precipitation, thereby maintaining strength properties while achieving filler content goals.

Inventive Principle:

Principle #10Preliminary action

2Quantity of substance

If MFC is added to milk of lime prior to carbonation, then calcium carbonate precipitates on MFC fibrils, but opacity of the composite is not satisfying

Engineering Contradiction:

Improvefiller contentVSAvoidopacity

Core Design Contradiction:

Quantity of substanceVSIllumination intensity

Solution Approach 1:

By adding MFC to the milk of lime suspension before carbonation starts, the patent ensures MFC is distributed throughout the system prior to calcium carbonate formation. This preliminary positioning allows for controlled partial precipitation that improves opacity while maintaining filler content.

Inventive Principle:

Principle #10Preliminary action

3Quantity of substance

If MFC is added to milk of lime prior to carbonation, then calcium carbonate precipitates on MFC fibrils, but uneven distribution of calcium dioxide results in uneven reaction and quality defects

Engineering Contradiction:

Improvefiller contentVSAvoideven distribution

Core Design Contradiction:

Quantity of substanceVSManufacturing precision

Solution Approach 1:

The patent uses preliminary action by incorporating MFC into the milk of lime suspension before carbonation begins, ensuring uniform distribution of MFC throughout the liquid phase. This pre-distribution prevents localized aggregation and promotes even calcium carbonate precipitation, eliminating quality defects caused by uneven reaction.

Inventive Principle:

Principle #10Preliminary action

4Quantity of substance

If MFC is added to milk of lime prior to carbonation, then calcium carbonate precipitates on MFC fibrils, but MFC forms flocs due to high viscosity

Engineering Contradiction:

Improvefiller contentVSAvoidhomogeneity

Core Design Contradiction:

Quantity of substanceVSStability of the object's composition

Solution Approach 1:

By adding MFC to the milk of lime suspension before carbonation, the patent allows MFC to disperse uniformly in the liquid phase while the system is still fluid. This preliminary dispersion prevents floc formation that would occur if MFC were added after viscosity increased during carbonation, thereby maintaining compositional homogeneity.

Inventive Principle:

Principle #10Preliminary action

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 produces a composite with improved brightness, strength, and opacity, enabling higher filler content in paper or paperboard without reducing strength or stiffness, and optimizing the bonding ability and bulk of the final product.

Implementation Method 1

The chemical reaction in which calcium hydroxide reacts with carbon dioxide and forms calcium carbonate is oftentimes referred to as carbonation, or carbonatation.

Methodology Applied

Scientific EffectCarbonation: Chemical Bonding

Implementation Method 2

performing carbonation of said calcium hydroxide to form precipitated calcium carbonate, wherein MFC is added to said suspension during said carbonation of calcium hydroxide whereby calcium carbonate is at least partly precipitated onto fibers or fibrils of the MFC

Methodology Applied

Scientific EffectPrecipitation: Precipitation

Data Source

PatentUS10683616B2Method for forming a composite comprising MFC and a composite produced by the method

Publication Date: 2020.06.16 STORA ENSO OYJ

AI summary

The invention provides a method for the production of a composite comprising microfibrillated cellulose (MFC) and precipitated calcium carbonate. The method is characterized in that MFC is added to a suspension of calcium hydroxide during carbonation, whereby calcium carbonate is precipitated onto fibers or fibrils of the MFC in a controlled manner. By adding microfibrillated cellulose to the calcium suspension during the carbonation, the brightness and the strength of the MFC/PCC-composite is enhanced. Moreover, the inventive method facilitates the distribution of calcium dioxide and MFC in the suspension and thus gives rise to a more homogenous product.