Surface-Reacted Calcium Carbonate Doped with Titanium for UV Absorption
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Solution Overview
Problem
Existing processes for producing surface-reacted calcium carbonate particles with titanium dioxide face challenges such as the potential carcinogenicity of submicron and nanometer-sized titanium dioxide particles and the creation of dust when mixing dry compounds, leading to health issues.
Innovation Solution
A process involving the treatment of a calcium carbonate-comprising material with calcium phosphate in an aqueous medium, followed by grinding at a pH value of at least 4.2, to produce white UV-absorbing surface-reacted calcium carbonate doped with a titanium species, where the calcium carbonate and calcium phosphate have a specific molar ratio and the titanium species is added before, during, or after the treatment and grinding steps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If titanium dioxide is used as a white pigment and UV absorber, then UV-absorbing properties and whiteness are improved, but submicron and nanometer-sized titanium dioxide particles may be carcinogenic and cause health issues
Solution Approach 1:
The patent changes the particle size parameter of titanium dioxide from submicron/nanometer range to micrometer range (0.1-10 μm, preferably 0.5-5 μm), transforming it from a harmful fine powder to a safer coarser particle that maintains UV-absorbing properties while reducing carcinogenic risk
Solution Approach 2:
The patent creates a composite material by combining titanium dioxide particles with calcium carbonate particles, where the titanium dioxide is surface-reacted with the calcium carbonate. This composite approach allows the titanium dioxide to provide UV protection while the calcium carbonate matrix reduces the harmful effects of fine titanium dioxide particles
2Productivity
If dry compounds are mixed to produce surface-reacted calcium carbonate with titanium dioxide, then production efficiency is improved, but dust is created leading to health issues
Solution Approach 1:
The patent replaces dry mechanical mixing with wet grinding in an aqueous medium. The calcium carbonate and titanium dioxide are ground together in water to form a slurry, which eliminates dust generation while maintaining effective mixing and surface reaction. The aqueous environment allows for continuous processing without the harmful effects of dry powder handling
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 process results in particles that are easy to handle, non-toxic, environmentally friendly, and free from titanium dioxide in the submicron and nanometer size range, offering excellent UV-absorbing and mechanical properties while being cost-effective and easily scalable.
Implementation Method 1
treating the calcium carbonate-comprising material with the calcium phosphate in an aqueous medium to form an aqueous suspension
Implementation Method 2
grinding the aqueous suspension at a pH value of at least 4.2 to form an aqueous suspension of a white UV-absorbing surface-reacted calcium carbonate
Implementation Method 3
the at least one titanium comprising substance is added before and/or during and/or after the treatment step and/or before and/or during the grinding step
Data Source
AI summary
The present invention refers to a process for producing white UV-absorbing surface-reacted calcium carbonate doped with a titanium species, comprising the steps of providing a calcium carbonate-comprising material, a calcium phosphate selected from monocalcium phosphate and/or dicalcium phosphate, and at least one titanium comprising substance, treating the calcium carbonate-comprising material with the calcium phosphate in an aqueous medium to form an aqueous suspension and grinding the aqueous suspension at a pH value of at least 4.2 to form an aqueous suspension of surface-reacted calcium carbonate, wherein the calcium carbonate-comprising material and the calcium phosphate in combination have a calcium ion to phosphate ion molar ratio (Ca2+:PO43−) in the range from 1.75:1 to 100:1, and wherein the at least one titanium comprising substance is added before and/or during and/or after the treatment step and/or before and/or during the grinding step.