Precipitated Calcium Carbonate Morphology Control
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Solution Overview
Problem
Existing methods for precipitating calcium carbonate in-situ onto cellulose fibers lack control over morphology and particle size, leading to inconsistent properties such as opacity, brightness, and tensile strength, and there is no technical solution for preparing amorphous PCC-fiber complexes or composite materials.
Innovation Solution
A method involving the mixing of polyacrylic acid or its salt with calcium hydroxide and lignocellulosic fibers, followed by carbon dioxide precipitation and drying, to control the morphology and particle size of calcium carbonate on cellulose fibers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If calcium carbonate is precipitated in-situ onto cellulose fibers during paper manufacturing, then filler content and filler retention are improved, but control over morphology and particle size is lost
Solution Approach 1:
The patent introduces a crystallization-controlling agent as an intermediary substance that mediates between the calcium carbonate precipitation process and the cellulose fiber substrate. This agent allows control over crystal formation (morphology and particle size) while maintaining the in-situ precipitation method's advantages of high filler content and retention. The crystallization-controlling agent acts as a bridge that directs crystal growth in a controlled manner during the precipitation process.
Solution Approach 2:
The patent utilizes parameter changes by adjusting the concentration and type of crystallization-controlling agent to precisely control the morphology and particle size of precipitated calcium carbonate. By changing parameters such as agent concentration, molecular weight, and chemical structure, the patent achieves desired crystal forms (spherulitic, dendritic, or needle-like) and size distributions while maintaining high filler content in the paper product.
2Illumination intensity
If commercial precipitated calcium carbonate is used, then optical properties are improved, but distribution uniformity and strength retention are compromised
Solution Approach 1:
The patent applies preliminary action by pre-treating the cellulose fiber substrate with a crystallization-controlling agent before calcium carbonate precipitation occurs. This preliminary conditioning of the fiber surface ensures that when calcium carbonate precipitates in-situ, it does so in a controlled manner with uniform distribution. The pre-applied crystallization-controlling agent creates nucleation sites and growth templates that promote even filler distribution while maintaining optical properties.
3Ease of manufacture
If in-situ precipitation is performed without crystallization-controlling agents, then process simplicity is maintained, but property consistency becomes inconsistent
Solution Approach 1:
The patent introduces a crystallization-controlling agent as an intermediary that reconciles the conflict between process simplicity and property consistency. The agent is incorporated into the existing in-situ precipitation process with minimal additional complexity, yet it dramatically improves the consistency of physical properties such as tensile strength, opacity, and brightness. The crystallization-controlling agent enables reliable property outcomes while maintaining the simplicity of the overall manufacturing approach.
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 achieves controlled precipitation of amorphous calcium carbonate on cellulose fibers, improving filler distribution and optical properties without significant strength loss, and allows for the production of amorphous PCC-fiber complexes.
Implementation Method 1
calcium carbonate precipitated on lignocellulosic fibers
Implementation Method 2
the carbonization of calcium hydroxide, Ca(OH)2, in the presence of fibers
Implementation Method 3
the use of crystallization-controlling agents such as polymers
Implementation Method 4
Crystallization-controlling agents are reported to affect all phases of crystal formation of CaCO3, i.e. from nucleation and precursors to crystal growth and agglomeration
Implementation Method 5
drying the mixture or filtering the precipitated solids obtained in step b)
Data Source
Figure 1A~1C
Figure 2
Figure 3
AI summary
The present invention relates to crystalline and stable amorphous CaCO3 precipitated on lignocellulosic fibers.