[article]
| Titre : |
Laser diffraction measurements of pigment size distributions of coatings and mill bases: implications of dilution medium and dispersion process parameters |
| Type de document : |
texte imprimé |
| Auteurs : |
Shicong Luo, Auteur ; Claus Erik Weinell, Auteur ; Søren Kiil, Auteur |
| Année de publication : |
2023 |
| Article en page(s) : |
p. 899-917 |
| Note générale : |
Bibliogr. |
| Langues : |
Américain (ame) |
| Catégories : |
Broyeurs à billes
Dioxyde de titane
Dispersions et suspensions
Formulation (Génie chimique)
Granulométrie laser
Microscopie
Oxyde de cuivre
Pigments
Polyacryliques
Qualité -- Contrôle
|
| Index. décimale : |
667.9 Revêtements et enduits |
| Résumé : |
Coating properties, such as gloss, rheology, and exterior durability, are strongly affected by the particle size distribution (PSD) of pigment agglomerates. Consequently, moving from the industrial practice of a maximum agglomerate size evaluation after dispersion (i.e., grindometer readings) to an accurate measurement of the entire PSD, holds a promising potential for quality control, product optimization, and research. The aim of the present work was to develop an analysis procedure, based on laser diffraction, for PSD measurements of coatings. In the experiments, acrylic-based TiO2 or Cu2O predispersions (i.e., mill bases), with variations in the composition and dispersion parameters, were investigated. Results show that the laser diffraction measurements are influenced by the so-called obscuration value of the diluted sample, the equipment-input refractive index values, and the shape assumption for the pigment agglomerates. Furthermore, the unavoidable sample dilution, prior to a measurement, strongly affects the stability of primary particles and agglomerates. When using a mixture of the pertinent binder and solvent, as opposed to the pure solvent only, and taking rheology issues into consideration, solvent shock was avoided and reliable PSDs could be obtained. The new analytical procedure was used on selected dispersions with variations in coating formulations and equipment operational parameters and allowed for precise detections of the developments in PSDs and volume-moment mean diameters. In summary, the principle of laser diffraction, with proper control of the measurement conditions, was demonstrated to be a reliable technique for PSD evaluation of coatings and predispersions. |
| Note de contenu : |
- EXPERIMENTAL : Raw materials - Predispersion systems investigated - Dispersion instruments - Laser diffraction particle size analyzer - Scanning electron microscope (SEM) - Digital microscope - Fineness of grind gauge
- RESULTS AND DISCUSSION : Pigment size measurements with digital microscopy - Pigment size measurements with electron microscopy - Sensitivity analysis of the user-supplied parameters for the laser diffraction method - Particle shape - Comparison between grind gauge and laser diffraction - PSD measurements of TiO2 - Absence of reagglomeration - Effects on the PSD results of formulation and operational parameters - PSD results of Cu2O obtained using the laser diffraction method
- Table 1 : Overview of particle size measuring techniques
- Table 2 : Details of pigments used in the experiments
- Table 3 : Formulation details of predispersions
- Table 4 : Recommended parameters for the laboratory scale high-speed disk disperser
- Table 5 : Selected (present investigation) and recommended parameter values for the lab-scale, high-speed bead mill
- Table 6 : Details of beads used in the lab-scale, high-speed bead mill
- Table 7 : Equivalent spherical diameter of pigment powders, measured using STEM and subsequent image analysis supported by a python code
- Table 8 : Volume-moment mean diameter of TiO2-HS1 sample for four obscuration values |
| DOI : |
https://doi.org/10.1007/s11998-022-00742-7 |
| En ligne : |
https://link.springer.com/content/pdf/10.1007/s11998-022-00742-7.pdf?pdf=button% [...] |
| Format de la ressource électronique : |
Pdf |
| Permalink : |
https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=39436 |
in JOURNAL OF COATINGS TECHNOLOGY AND RESEARCH > Vol. 20, N° 3 (05/2023) . - p. 899-917
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Laser diffraction measurements of pigment size distributions of coatings and mill bases: implications of dilution medium and dispersion process parameters in JOURNAL OF COATINGS TECHNOLOGY AND RESEARCH, Vol. 20, N° 3 (05/2023)
