In-situ, simultaneous milling, coating and curing of brittle particulates pre-coated with a LED UV-curable formulation in a fluid energy mill

• Published in: Powder technology 2012-03, Vol.218, p.169-175
• Main Authors: Lu, Chunmeng, Liu, Huiju, Zhu, Linjie, Patel, Subhash H., Young, Ming-Wan, Gogos, Costas G., Bonnett, Peter
• Format: Article
• Language: English
• Subjects: Applied sciences; Chemical engineering; Coating; coatings; Curing; energy; Exact sciences and technology; Fluid energy mill; fluorescence; Grinding; microscopy; Milling; Miscellaneous; Organic polymers; particulates; Photo-polymerization; Physicochemistry of polymers; Polymerization; potassium chloride; Preparation, kinetics, thermodynamics, mechanism and catalysts; Solid-solid systems; thermal analysis; ultraviolet radiation
• ISSN: 0032-5910; 1873-328X
• DOI: 10.1016/j.powtec.2011.12.014

In conjunction with UV technology, a fluid energy mill (FEM) was demonstrated to simultaneously and in-situ achieve several functions, namely: size reduction of pre-coated coarse micron-sized particles with UV-curable chemicals into smaller (ca. 1–10 μm) particles, coating of UV chemicals onto the milled particles, and curing of the UV chemicals. Potassium chloride (KCl) was chosen as the matrix material, and acrylate was chosen as the UV-curable formulation. The hold-up mass method was utilized to estimate the average residence time of particles in the FEM, the results of which showed that the average residence time decreases with increasing grinding pressure and solid feed rate, whereas it was not significantly affected by feeding pressure. Fluorescent microscopy showed that the UV-curable chemicals were evenly transferred to almost every single particle during FEM milling without UV irradiation, whereas they were transferred extensively, but to a lesser extent during FEM milling with UV irradiation. Thermal analysis (TGA and DSC) and IR analysis were employed to characterize the conversion of the free radical polymerization. IR analysis showed that the double bond conversion was up to 71%, denoting extensive curing. [Display omitted] ► Extended FEM functions from milling to coating and coat-curing. ► Utilized the hold-up mass method to estimate the average residence time. ► IR analysis showed that the double bond conversion was almost complete.