Preparation of novel blue phosphate pigments in imitation of copper lazulite
- PDF / 1,019,956 Bytes
- 6 Pages / 595.276 x 790.866 pts Page_size
- 97 Downloads / 170 Views
RESEARCH
Preparation of novel blue phosphate pigments in imitation of copper lazulite Hiroaki Onoda1 · Ryota Sasaki1 Received: 4 November 2019 / Accepted: 27 October 2020 © Islamic Azad University 2020
Abstract Novel blue pigments were prepared from copper, magnesium, aluminum nitrate solutions and phosphoric acid with pH adjustments (pH 5, 7, 9). The obtained precipitates were heated at 300, 500, and 700 °C for 1 h. The precipitates and their thermal products were estimated with X-ray diffraction (XRD), infrared (IR) spectra, ultraviolet–visible (UV–Vis) reflectance spectra, and L*a*b* color space. Sample without heating is light blue powder. By heating at 300 °C, the blueness of samples decreased. The hue of samples became darker by heating. The best condition for the unheated sample was pH 7, and for the heated sample was pH 5 at 300 °C. Samples prepared at Cu/Mg = 1/1 showed a* and b* values closer to zero than samples prepared with Cu/Mg = 1/0. These materials have potential as new inorganic blue pigments for inks and paints. Keywords Phosphate pigment · Copper lazulite · Color
Introduction Recently, the use of harmful metals is restricted around world. However, because suitable substitutes have not been obtained, some materials containing harmful metals have been used in many fields [1, 2]. For example, inorganic color pigments containing metals, such as mercury, cadmium, and lead, have some merits, including high light stability, heatresistant coloring visibility, cost, etc. [3–5]. In addition, because oxide pigments have low coloring and covering, they are difficult to use for paint and plastics [6]. Sulfate and nitride pigments have lower heat resistance than oxide pigments, and require harmful and/or combustible gas to synthesize. Furthermore, it is difficult to obtain sulfide and nitride pigments with repeatability [7, 8]. Therefore, novel inorganic pigments are required with suitable properties and without difficult production methods. There are some kinds of inorganic blue pigments, for example, that are available for use, Prussian blue, mixed metal oxide, cobalt blue, cerulean, cobalt chromium blue, and so on [9–12]. Some of these pigments also include
harmful metals. Therefore, novel blue pigment without precious and harmful metals is required. We focused on the natural ore, turquoise, C uAl6(PO4)4(OH)8·4H2O, because this ore has no precious and harmful metals [13, 14]. Natural ores have high light stability and heat resistance. Because of their solidity, they are expected to have applications for plastics, paint, ceramics, and so on. Therefore, we prepared the inorganic pigments imitated with turquoise, CuAl6(PO4)4(OH)8·4H2O, in dry and wet processes [15, 16]. The obtained materials had the XRD peaks of CuAl6(PO4)4(OH)8·4H2O and CuO. However, the color of samples synthesized in dry process was dark, on the other hand, materials prepared in wet process had light blue color. In this work, we focus other natural ore, copper lazulite, CuAl2(PO4)2(OH)2·6H2O. This composition is similar with t
Data Loading...
