A formulation process for CaCO3 spheres (D50 of 5.1 μm) for use as a functional filler in decorative paints was optimised. This increased the yield of CaCO3 spheres 20-fold and made the process less hazardous, with organic oils, namely rapeseed oil, being used successfully as a replacement for toluene. The CaCO3 spheres contained a multitude of < 250 nm nanovoids, with some spheres containing a core void > 800 nm. These pores formed because the crystals nucleated at the interface of emulsion droplets, resulting in CaCO3 spheres (2.42 g cm-3; 2,420 kg m-3) composed of calcite and vaterite, with a density lower than either mineral (2.71 g cm-3 (2,710 kg m-3) and 2.65 g cm-3 (2,650 kg m-3), respectively). The characterisation and performance of CaCO3 spheres in paint formulations were compared against commercially available products, namely Microdoll H600 (5 μm dolomite). There was no opacity benefit, however a 4-fold scrub resistance benefit was observed. Different oils can be used in the emulsification step in CaCO3 spheres production whilst others cannot, most likely because of the ratio of mono- to poly-unsaturated fatty acids. A technique for improving scrub resistance of other mineral extenders was developed, with AkzoNobel continuing the research into this area.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:753021 |
| Date | January 2018 |
| Creators | Ruszala, Matthew James Amor |
| Publisher | University of Birmingham |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://etheses.bham.ac.uk//id/eprint/8260/ |
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