Stabilized Spherical Amorphous Calcium Carbonate Particles
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Solution Overview
Problem
Existing amorphous calcium carbonate particles have limited stability, high basicity, and are difficult to process industrially, limiting their use as additives or modifiers in various applications due to rapid conversion into crystalline modifications.
Innovation Solution
Development of spherical, amorphous calcium carbonate particles with reduced structural water content and improved stability, achieved through specific synthesis conditions and stabilization with surface-active substances, resulting in particles with enhanced long-term stability and low basicity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If conventional amorphous calcium carbonate particles are prepared by reacting calcium chloride with carbonate sources, then spherical particles with variable water content are obtained, but their stability is limited and they transform into crystalline modifications rapidly
Solution Approach 1:
The patent applies parameter changes by controlling the water content to be less than 0.4 mol per mol of calcium carbonate through specific synthesis conditions. This parameter control prevents rapid crystallization and extends the stability of the amorphous phase, resolving the contradiction between obtaining spherical particles and maintaining their stability over time.
2Adaptability or versatility
If amorphous calcium carbonate particles are prepared with conventional methods, then particles are obtained, but their high basicity makes their use in many applications difficult or impossible
Solution Approach 1:
The patent reduces the basicity of calcium carbonate particles by controlling the synthesis parameters, specifically the water content and reaction conditions. This parameter optimization allows the particles to be used in applications where high basicity would be problematic, thereby expanding their adaptability across different industries while maintaining their functional properties.
3Stability of the object's composition
If rapid processing is used to prevent crystallization of amorphous particles, then particle stability is maintained, but industrial processing becomes difficult or impossible
Solution Approach 1:
The patent applies preliminary action by pre-controlling the water content during synthesis to be less than 0.4 mol per mol of calcium carbonate. This preliminary control of the critical parameter (water content) stabilizes the amorphous phase in advance, allowing sufficient time for industrial processing operations without requiring extremely rapid processing speeds, thus resolving the contradiction between stability and ease of manufacture.
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 resulting calcium carbonate particles exhibit improved mechanical properties, easier processing, and broader applicability, with increased stability allowing for homogeneous dispersion in polymers and extended shelf life, while maintaining a low pH value for easier handling.
Implementation Method 1
The calcium carbonate particles are obtained by reacting calcium chloride with dialkyl carbonate in the presence of an alkali metal hydroxide in aqueous solution
Implementation Method 2
The atoms in ACC do not form ordered structures, but rather an irregular pattern, thus exhibiting only short-range order and no long-range order. ACC is unstable and transforms into calcite at temperatures above 300°C. The presence of water accelerates this process, and crystallization occurs even at lower temperatures.
Data Source
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AI summary
The invention relates to stabilised, spherical, amorphous calcium carbonate particles having a mean particle diameter in the range from 0.05 μm to 2.0 μm and a water content of at most 5.0 wt %, based on the total weight thereof and measured as residual moisture at 200°C, wherein, a) the calcium carbonate particles comprise at least one substance which has a molar mass greater than 100 g/mol and satisfies the formula R-Xn, wherein the radical R represents a radical comprising at least one carbon atom, the radical X represents a group which comprises at least one oxygen atom and at least one carbon atom, sulphur atom, phosphorus atom and/or nitrogen atom and n preferably constitutes a whole number in the range from 1 to 20, b) the proportion of crystalline calcium carbonate is less than 30 wt %, based on the total weight of the calcium carbonate, and c) the specific surface area of the calcium carbonate particles is at most 20 m2/g. Preferred fields of application of the calcium carbonate particles include the use thereof as an additive or modifying agent in paper, paints, plastics, inks, adhesives and pharmaceuticals.