TY - JOUR
T1 - Tuning roughness and gloss of powder coating paint by encapsulating the coating particles with thin Al2O3 films
AU - Valdesueiro, David
AU - Hettinga, Hans
AU - Drijfhout, Jan Pieter
AU - Lips, Priscilla
AU - Meesters, Gabrie M.H.
AU - Kreutzer, Michiel T.
AU - van Ommen, J.R.
PY - 2017/8/1
Y1 - 2017/8/1
N2 - In this work, we report a method to change the surface finish of a standard polyester-based powder coating paint, from gloss to matt, by depositing ultrathin films of Al2O3 on the powder coating particles. The coating experiments were performed in a fluidized bed reactor at 1 bar and 27 °C, using a gas-phase coating process of alternating exposure of the particles to the two precursors (trimethylaluminium and water), similar to atomic layer deposition (ALD). We varied the number of coating cycles (1, 2, 3, 5, 7 and 9 cycles) to obtain film thicknesses of the alumina shell ranging from 1 to 30 nm. The average growth per cycle of the process is 3.5 nm, significantly larger than the one for pure self-limiting ALD. When the average alumina shell was thicker than 6 nm, the shell prevented the flow of the core particles, even though the powder particles did soften above the glass transition temperature. With the particles morphology intact, this resulted in a rough and matte surface finish of the coating after curing. The surface roughness, with a value around 9 μm determined by surface profilometry, is associated to the alumina coated particles as observed with SEM and EDX analysis. In addition, the matte finish coating showed mechanical resistance similar to that of uncoated powder particles.
AB - In this work, we report a method to change the surface finish of a standard polyester-based powder coating paint, from gloss to matt, by depositing ultrathin films of Al2O3 on the powder coating particles. The coating experiments were performed in a fluidized bed reactor at 1 bar and 27 °C, using a gas-phase coating process of alternating exposure of the particles to the two precursors (trimethylaluminium and water), similar to atomic layer deposition (ALD). We varied the number of coating cycles (1, 2, 3, 5, 7 and 9 cycles) to obtain film thicknesses of the alumina shell ranging from 1 to 30 nm. The average growth per cycle of the process is 3.5 nm, significantly larger than the one for pure self-limiting ALD. When the average alumina shell was thicker than 6 nm, the shell prevented the flow of the core particles, even though the powder particles did soften above the glass transition temperature. With the particles morphology intact, this resulted in a rough and matte surface finish of the coating after curing. The surface roughness, with a value around 9 μm determined by surface profilometry, is associated to the alumina coated particles as observed with SEM and EDX analysis. In addition, the matte finish coating showed mechanical resistance similar to that of uncoated powder particles.
KW - Alumina coating
KW - Ambient conditions
KW - Atomic layer deposition
KW - Core-shell particles
KW - Matte powder coating
KW - Surface appearance
UR - http://resolver.tudelft.nl/uuid:77ed6a3b-a5c9-4f0c-83cb-d3f0e3082a36
UR - http://www.scopus.com/inward/record.url?scp=85020854938&partnerID=8YFLogxK
U2 - 10.1016/j.powtec.2017.05.019
DO - 10.1016/j.powtec.2017.05.019
M3 - Article
AN - SCOPUS:85020854938
SN - 0032-5910
VL - 318
SP - 401
EP - 410
JO - Powder Technology
JF - Powder Technology
ER -