Development of a glass with ultraviolet absorption by adding frits to flint glass

Reference Presenter Authors
11-028 Fernando Santos Ortega Sasso, D.D.(Wheaton Brasil); Ortega, F.S.(Centro Universitário da FEI); Amber glass is widely used to produce packaging for medicines, once it retains UV radiation, which can accelerate drug degradation. This property is due to the formation of the Fe3+-S2--O2--Na+ chromophore under reducing conditions into the melting furnace. In general, colored glasses are produced by adding coloring oxides to flint glass in the form of frits, directly into the feed channel (color feeder system), under conditions other than those found in the melting furnace. However, the Fe3+-S2--O2--Na+ chromophore cannot be obtained by this method and requires a furnace dedicated to its production. When the demand for amber glass is small, either the production changes from amber to flint glass or the melting furnace is switched off. Both options generate high costs. In this context, this work aimed to develop a system of coloring oxides that, once added to flint glass in the feed channel, could generate a glass with UV absorption. The tests were carried out on a small scale: frits were added to a flint glass of known composition that was melted in a crucible at 1300°C for 2h, in an environment analogous to the feed channel. Frits containing oxides in the Fe-Mn-Se system, denominated A (60% Fe), B (31.1% Mn) and C (0.88% Se) were used. The concentrations followed a 2k factorial design, having as output the integral of transmittance curves between 290 and 450nm. The 10% transmittance limit in the 290 to 450nm range, established by the American Pharmacopoeia, was taken as reference. The trichromatic coordinates of the samples, calculated according to the CIE standard, showed that samples with low transmittance in the UV region tend to have a color close to amber. The statistical analysis of data showed a pronounced influence of Fe and Mn on absorption in the UV region. The best composition, with frits contents of 5% A, 5% B and 2.5% C, produced a glass with UV retention below the established limit, for flasks with thickness above 1.6 mm.
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