JOURNAL OF COLOR SCIENCE AND TECHNOLOGY
Year:2009 | Volume:3 | Issue:3|Papers Count:14

In this article optimization of water based flexography ink formulation for printing polyethylene films is investigated by the aid of Design Expert 6.06 software. Since resin, solvent and pigment are the most important components in composition of inks, which affect properties of ink, So these components are considered as factors in mixture experimental design and their effects on ink properties were studied. Measurements of some physical and mechanical properties such as viscosity, surface tension, gloss, abrasion resistance, adhesion and reversibility were carried out on ink samples. These factors and their interactions were determined and finally, the optimized area was obtained.

This study investigated the potential use of a low-cost inorganic powder (Iranian kaolin) for removal of C.I. Basic Yellow 28 (BY28) from aqueous solution. Kaolin was characterized by laser particle size analyzer (PSA), scanning electron microscopy (SEM), X-ray diffraction (XRD) and X-ray fluorescence (XRF) techniques. The effect of adsorbent dosage, dye concentration, contact time, wastewater volume, initial pH and the presence of different electrolytes were studied. Experimental results revealed that kaolin is a very strong and fast adsorbent and the presence of different electrolytes and pH changes do not have a notable effect for cationic dye removal. The experimental data were correlated reasonably well by the adsorption isotherm of the Langmuir. It was found that the adsorption of BY28 on kaolin followed the pseudo-second order equation which indicates that the adsorption process is chemisorption controlled.

In this work, a dyeable porous Aluminium oxide layer on the 6063 aluminium alloy was prepaired by a chemical or an electrochemical (anodizing) method. Different variables such as concentration oxidizing agent, temperature, pH of solution, oxygen purging in the chemical method and time and temperature in the anodizing methods were evaluated. Formed aluminium oxide layers were then dyed via direct dyestuff and sealed with thermoplastic acrylic clear coating. Physical and chemical properties of dyed and sealed prepared specimens were then studied by different techniques. Results revealed that maximum oxide layer thickness in chemical oxidizing method was achieved at pH=13, at 30°C and in the presence of oxygen gas and the best physical fastness and dyeability were achieved at pH=12. Oxide film thickness in the anodizing method was found to be much thicker as compared with those prepared via chemical solution. However, chemically oxidized specimens revealed better mechanical properties such as flexibility, enhanced uniformity and brilliant colors.

Semiconductor copper oxide pigment nanoparticles, also known as pigment black 15, is of great interest due to its numerous applications in many important fields of science and technology such as pigments, semiconductors, sensors, catalysts and solar cells. In this work, a quick and simple chemical synthesis route with a significant decrease in synthesis temperature has been developed to prepare copper oxide nanoparticles. The nanoparticles were investigated by X-ray diffraction (XRD), FTIR spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), UV-vis spectroscopy, colorimetry and diffuse reflectance spectroscopy. Their absorption spectra in water and ethanol were also studied. Our results confirmed the formation of the pure single-phase monoclinic copper oxide pigment (space group C2/c) in the mild reaction condition. The FTIR spectrum displayed typical vibrations of copper oxide pigment at 518 and 597 cm-1. TEM micrographs also showed that particle size of the synthesized nanoparticles were in the range of 18-23 nm. The band gap of nanoparticles is estimated to be 2.43 and 2.94 ev in water and ethanol, respectively which were larger than the reported value for bulk copper oxide pigment (1.85 ev).

The main purpose of this study is to investigate the possibility of using siloxane-based resin as coating for protection of brickmade monuments such as Choghazanbil temple and also the efficiency of such resin as a protective material. The initial studies were conducted on the glass substrate coated with commercial and synthetic siloxane-based resins. The synthetic siloxane-based resin was synthesized using tetraethyl orthosilicate, methyl methacrylate, and 3-(methacryloxy) propyl trimethoxy silane under the sol-gel processing conditions. According to the initial results, although the color alteration of synthetic coating after the weathering test was lower than the commercial material but its yellowing appearance was higher. Moreover, the commercial material had much higher hydrophobicity than the synthetic material. The supplementary tests such as stability analysis in the artificial weathering test, variation of the contact angle after the weathering test, transparency of coating, oxygen permeability of coating, and scanning electron microscopy were conducted on the proposed commercial material. Furthermore, the real conditions were simulated using the brick-made specimens. According to the obtained results, the efficiency of proposed commercial material for protection of brick-made monuments was considerably confirmed.

A proposal is introduced for evaluation of relative color strength of two synthesized basic dyes Yellow 28 and Blue 41 by means of the principal component analysis technique. This property is usually determined by reflectance data of dyed samples at various concentrations. However, acceptable results are only yielded whenever one constant Kubelka-Munk function (K/S) exhibited linear behavior with concentration. In the present study, principal component analysis technique was applied to K/S data to find an optimum linear concentration range. The results showed that an appropriate range of concentration can be recognized by the percent variation for the first eigenvector. In addition, the ratio of eigenvalues corresponding to the first eigenvector in both synthesized and commercial sample (standard) is described as a criterion for determination and control of relative color strength. The results are compared with those obtained by the three common methods namely visual assessment, absorptiometry of colored solution and a weighted Kubelka-Munk function.

In this study, the influence of different parameters such as atmospheric conditions, uncontrolled (wood burning) and controlled reduction (firing in H2, CO) atmospheres as well as the amount of additives (ZnO-CoO) on reduced copper glazes have been investigated. Morphology, microstructure and composition of glaze surfaces have been studied by SEM. Color properties of different parts of glaze surfaces were investigated by Spectrophotometer. Results showed that surface color changed by different amounts of copper-cobalt-zinc oxide additives, which can be related to the formation of different metallic compounds such as brass alloy, copper, zinc as well as non-stoichiometric copper oxide and zinc oxide. SEM-EDS results indicated that brass alloy rods formed on the surface of copper glazes containing 14% zinc oxide and zinc oxide. Rainbow appearance of copper glazes containing zinc oxide, specially Yellow color in the presence of 14% zinc oxide was in good agreement with SEM-EDS results. surface of this glaze and cobalt surface was compatible to While deep reduction occurred on the glaze surface during uncontrolled reduction, uniform metallic layer was detected on the glazed surfaces by controlled reduction atmosphere. This layer was formed due to continuous and long-term reducing atmosphere in the kiln.