Evaluation of Photoinitiator and Fluorescent Pigments Impact on Color Stability in Pigmented UV-Curable Coatings

The testing of thin colored coatings based on urethane acrylate composition is a technologically advanced, highly specialized and complex process. For decorative pigmented coatings color stability is crucial quality parameter. The photo chemically curable polymer films were prepared by addition of 3 different radical initiators (KTO, TPO, TPO-L) to aliphatic urethane acrylate composition with various pigments (solid and fluorescent). Coating color change were evaluated in UV chamber (with luminous intensity 130 mw spectrum λmax = 405 nm) after 1 h, 48 h and 72 h. Color measurements were performed according to the CIEL*a*b* color standard to evaluate their stability over time. It was found that pigmented coatings have higher risk of yellowness than clear coatings. Also fluorescent pigments containing red has tendency to yellow after UV light exposure. The influence of the photoinitiator on the color stability were inconsiderable.

The Effect of a Polymer-Stabilized Latex Cobinder on the Optical and Strength Properties of Pigment Coating Layers

Coated paper with a porous coating layer may have enhanced light-scattering ability and thus favorable optical properties. However, the increased porosity of such a coating layer is likely to decrease the strength of the coated paper, thereby adversely affecting the quality of the paper in the printing and converting processes. In this research, polymer-stabilized (PS) latex was prepared and used as a cobinder for the pigment coating of the paper. The PS latex particles were colloidally stabilized by a 3:1 mixture of starch and polyvinyl alcohol. The influence of the PS latex cobinder on the viscosity, sedimentation, and consolidation of coating colors was investigated. In addition, the effect of the cobinder on the properties of coating layers, namely, their porosity and surface, optical, and tensile properties, was examined. The results revealed that the PS latex cobinder formed microstructures in the coating colors and affected their viscosity. The addition of PS latex also led to enhanced interactions between coating color components, which affected the consolidation of the coating color, resulting in the formation of dried coating layers with greater porosity and improved optical properties (i.e., higher brightness and opacity) relative to coatings without the PS latex cobinder. Furthermore, the addition of PS latex improved the tensile strength of the coating layers, which was attributable to the small size and the polymeric protective shell of the cobinder particles. Thus, these results show that this PS latex cobinder has the potential to be used for the production of high-quality coated paper products.

The Influence of Drying Conditions of Clay-Based Polymer Coatings on Coated Paper Properties

Coatings based on pigment and polymer binders are applied on paper surfaces to improve their surface, optical, and printing properties. Besides the coating composition, the structure and properties of the coated papers are influenced by the coating layer consolidation upon drying. In this study, the influence of drying conditions on the structure and properties of coating layers based on natural pigments (clay) and polymer binders (butadiene acrylonitrile latex) has been analyzed. Using a laboratory rod Mayer device, the coatings were applied as thin layer (about 15–16 g/m2) on the paper surface and samples of coated paper were dried at 20 and 105 °C temperatures. The optical, structural, and water absorption properties of the coating layer were evaluated by the measurement of gloss, opacity, void fraction, light scattering, and contact angle. The obtained results highlighted that both the drying temperature and latex content in the coating color have a synergic effect on the coated paper quality.

Protective and decorative properties of titanium glass enamels

It is known that enamel coatings with enhanced protective and decorative properties can be fabricated on the basis of boron-silicate glass frits with an increased content of TiO2 in their composition. Opacity and white color of enamel coatings are due to their crystallization at firing temperatures. Titanium glass enamels are not pure white visually, and show yellow and blue shades depending on their chemical composition. The purpose of this work was to establish the influence of basic components on the water resistance and color characteristics of titanium enamel coatings. Our experimental study was focused on the glass frits with the chemical composition described by the generalized formula (76–n–m)SiO2nB2O3mNa2O24MexOy, where MexOy is the total content of TiO2, ZrO2, Al2O3, MgO, СaO, P2O5, and K2O. It was found that the glass frits with the following content of basic components (mol.%): Na2O 12–13, K2O 3, B2O3 10–11, SiO2 49–51 demonstrated the highest water-resistant properties. The color characteristics of titanium enamel coatings prepared on the basis of the mentioned glass frits differ significantly from the reference white light A; the titanium enamel coatings under consideration have a yellow-green tint. The highest deviations of the enamel coating color purity and color tone from a standard of white color were observed when increasing the Na2O content in the glass frits composition at the expense of SiO2. The color of titanium coatings with the highest water resistance has a deviation from the standard of white color within 4–6%.

CONCEPT OF HEALTH PROMOTION W.S.R. TO ORAL HYGIENE

As oral cavity is considered as the gateway to the body. The shape, coating, color and texture of oral cavity can give clues to overall health especially related to digestive system. So, oral hygiene is of prime im-portance which has significant impact on quality of life. The Global Burden of Disease Study 2016 esti-mated that oral diseases affected at least 3.58 billion people worldwide, with caries of the permanent teeth being the most prevalent of all conditions assessed. Ayurveda, the life science, mentions Dinacharya, a very unique and important aspect of lifestyle. In dinacharya, acharyas recommended dantadhavana, jiwha nirlekhana and kavala-gandusha vidhis pertaining to oral cavity. Nowadays, in this modern busy life with many unhealthy habits, incorporation of these procedures proves helpful in maintaining the heathy status of oral cavity and preventing its diseases. This paper focuses on the role of dantadhavana, jiwha nirlekhana and kavala-gandusha in promoting the health by maintaining the hygiene of the oral cavity.

Influence of Electrolyte Temperature on the Color Values of Black Plasma Electrolytic Oxidation Coatings on AZ31B Mg Alloy

A coating was prepared on an AZ31B Mg alloy substrate via black plasma electrolytic oxidation (PEO). The colorant NH4VO3 was added to Na2SiO3–(NaPO3)6 electrolyte at different temperatures (5, 15, 25, and 35 °C). The influences of electrolyte temperature on the structures, compositions, and color values of black PEO coatings were studied by UV–Visible, XRD, XPS, Raman, and SEM techniques. The results showed that the relative content of V2O3 and V2O5 was the key factor affecting the coating color value. At higher temperatures, more NH3 escaped from the electrolyte and the NH3 quantity participating in the reaction decreased, resulting in a decrease of V2O3 content, an increase in color value, and a darker coating. In the PEO process, VO3− mainly reacted to form V2O5, and then, the generated V2O5 reacted with NH3 to form V2O3.