Cholesteric liquid crystal pigments / Yash Melkeri in PAINTINDIA, Vol. LXVII, N° 6 (06/2017)  

[article]  inPAINTINDIA > Vol. LXVII, N° 6 (06/2017) . - p. 55-58 Titre : Cholesteric liquid crystal pigments Type de document : texte imprimé Auteurs : Yash Melkeri, Auteur ; Tipanna Melkeri, Auteur Année de publication : 2017 Article en page(s) : p. 55-58 Langues : Anglais (eng) Catégories : Iridescence L’iridescence (aussi connu sous le nom de goniochromisme) est la propriété de certaines surfaces qui semblent changer de couleur selon l'angle de vue ou d'illumination. Des exemples d'iridescence comprennent notamment : les bulles de savon, les ailes de certains papillons, certains coquillages et certains minéraux. L'iridescence est souvent créée par une coloration structurelle de microstructures qui interfèrent avec la lumière. Matières plastiques Opacité (optique) Pigments Polymères à cristaux liquides cholestériques Procédés de fabrication Revêtements poudre:Peinture poudre Revêtements:Peinture Silicones Les silicones, ou polysiloxanes, sont des composés inorganiques formés d'une chaine silicium-oxygène (...-Si-O-Si-O-Si-O-...) sur laquelle des groupes se fixent, sur les atomes de silicium. Certains groupes organiques peuvent être utilisés pour relier entre elles plusieurs de ces chaines (...-Si-O-...). Le type le plus courant est le poly(diméthylsiloxane) linéaire ou PDMS. Le second groupe en importance de matériaux en silicone est celui des résines de silicone, formées par des oligosiloxanes ramifiés ou en forme de cage (wiki). Index. décimale : 667.2 Colorants et pigments Résumé : Effect pigments are specialty pigments, display a wide range of properties such as colour-travel, reflect or refract light, act as a mirror (metal flakes) and multiple colour effect called Iridescence. Liquid crystals (LCs) are molecules that enter a state of malter showing characteristics of both isotropic melt and the ordered crystal when heated above their melting point. In liquid crystal polymer pigments (LCP pigment), a cholesteric phase is fixed by crosslinking therefore they also called cholesteric liquid crystal (CLC) pigments. CLC based pigment have excellent blue shifting colour travel. Most CLC pigments are based on polysiloxane. CLC Pigments are easily dispersed and compatible with most binder systems including water, solvent, and powder vehicle systems. Currently Wacker is the only commercial producer of CLC pigment under brand of Helicone HC. CLC pigments are used in both water and solvent based Paints. They also used in plastics due to their heat stability and resistance towards shear force. Note de contenu : - Application in liquid paint - Application in powder coatings paints - Application in plastics - FIGURES : 1. Structure of nematic LC phase - 2. Twisted nematic LC - 3. Opacity and liquid crystal phase - 4. Cholesteric liquid crystal structure - 5. Iridescence effect in CLC pigment - 6. Colour travelling in CLC pigments - 7. History of CLC pigments - 8. Four different coloured helicone HC pigments - 9. CLC pigment manufacturing process En ligne : https://drive.google.com/file/d/1vh2IA0WTfm_-mTYJAyWhT-hOiK2KQ0Tg/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=28978 [article]

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Effect pigments / Yash Melkeri in PAINTINDIA, Vol. LXVII, N° 3 (03/2017)  

[article]  inPAINTINDIA > Vol. LXVII, N° 3 (03/2017) . - p. 72-78 Titre : Effect pigments Type de document : texte imprimé Auteurs : Yash Melkeri, Auteur ; Tipanna Melkeri, Auteur Année de publication : 2017 Article en page(s) : p. 72-78 Langues : Anglais (eng) Catégories : Pigments à effets spéciaux Index. décimale : 667.2 Colorants et pigments Résumé : Effect pigments are those that exhibit special effects to various substrates in order to enhance its quality and to make it comparatively attractive to consumers. These pigments display a wide range of properties such as colour-travel, reflect or refract light, act as a mirror (metal flakes) and multiple colour effect called iridescence. Iridescence is an optical phenomenon of surfaces in which the hue changes with the angle of observation and the angle of illumination. It is often caused by multiple reflections from two or more semi-transparent surfaces in which the phase shift and interference of the reflections modulates the incidental light (by amplifying or attenuating some frequencies more than others). The term luster pigment is also often applied to these effect pigments because all effect pigments provide lustrous effect in practical applications. Note de contenu : - Coated substrate (pearlescent pigments) : Natural pearlescent pigments - Synthetic pearlescent pigments - Polymer stacks (iridescent film) - Helicones HC - Mirrors - Metallic flakes (silver, copper and bronze) - Basic lead carbonate - Bismuth oxy chloride crystals (BiOCl) - Titanium dioxide flakes (TiO2 flakes) - Micaceous iron oxide - Flakes type organic pigments - Metal salts stack - Market demand of effect pigments - FIGURES : 1. Ray diagram depicitng reflection, refraction and interference in various substrates - 2. Pearlescent pigments based on natural mica - 3. Polymer stacks - Iridescent films - 4. Helicones HC pigment - 5. Metallic pigment flakes - 6. Regular hexgonal crystal structure of basic lead carbonate - 7. Regular octagonal crystal structure of BiOCl - 8. TiO2 flakes - 9. Micaceous iron oxide - 10. Goethite an iron oxide, hydroxide effect pigment - 11. Effect pigment market value (2016-2021) En ligne : https://drive.google.com/file/d/1KR8VHYTjfagm_E7ddKLpqmdlq1XrMJ94/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=28448 [article]

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Effect pigments - Basic lead carbonate & bismuth oxy chloride based pearlescent pigments / Yash Melkeri in PAINTINDIA, Vol. LXVII, N° 8 (08/2017)  

[article]  inPAINTINDIA > Vol. LXVII, N° 8 (08/2017) . - P. 96-100 Titre : Effect pigments - Basic lead carbonate & bismuth oxy chloride based pearlescent pigments Type de document : texte imprimé Auteurs : Yash Melkeri, Auteur ; Tipanna Melkeri, Auteur Année de publication : 2017 Article en page(s) : P. 96-100 Langues : Anglais (eng) Catégories : Carbonate de plomb Oxychlorure de bismuth Pigments -- Synthèse Pigments à effets spéciaux Pigments nacrés Index. décimale : 667.2 Colorants et pigments Résumé : Effect pigments display a wide range of properties such as colour-travel, reflect or refract light. When substrate used are flat regular, laminar in shape then the effect pigments are mirror type. Basic lead carbonate and bismuth oxy chloride fall under this category. Basic Lead carbonate pigment is obtained by passing carbon dioxide gas in lead acetate solution having luster and brilliance that equals or excels. These pigments are used in textile, plastics, paints, artificial pearls. Lead based pearlescent pigments are having excellent pearlescent effect but considered to be toxic, so banned in most places. Bismuth Oxy chloride (BiOCI) crystals are flat, regular, octahedral in structure. These pigments look smooth microscopic compared to mica coated pearl. Despite higher refractive index (2.15) than basic Lead carbonate, bismuth oxy chloride does not show the brilliance of basic lead carbonate due to its inferior crystal forms. BiOCI is prepared reacting bismuth nitrate in presence of chloride ions with sodium hydroxide. The crystal quality can be adjusted by the chosen reaction parameters, such as bismuth salt concentration, temperature, pH-value, reactor geometry, and addition of surfactants. BiOCI is used in plastics, paints, inks, textiles artificial jewelry, and automotive coatings. The major limitation would be the higher cost and its higher density that makes it settli n application media. Note de contenu : - Basic lead carbonate based pearlescent pigments - Manufacturing of basic lead carbonate pigment - Applications of basic lead carbonate pearlescent pigments - Limitations of basic lead carbonate pearlescent pigments - Manufacturing of bismuth oxy chloride (BiOCl) - Applications of bismuth oxy chloride pearlescent pigment En ligne : https://drive.google.com/file/d/1SrrEwx6UqqTNRHuBdA6qjJrklFfKBqu9/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=29261 [article]

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Effect pigments - pearlescent pigments (Part 1) / Yash Melkeri in PAINTINDIA, Vol. LXVII, N° 4 (04/2017)  

[article]  inPAINTINDIA > Vol. LXVII, N° 4 (04/2017) . - p. 70-76 Titre : Effect pigments - pearlescent pigments (Part 1) Type de document : texte imprimé Auteurs : Yash Melkeri, Auteur ; Tipanna Melkeri, Auteur Année de publication : 2017 Article en page(s) : p. 70-76 Langues : Anglais (eng) Catégories : Matières plastiques -- Coloration Mica Oxydes métalliques Pigments à effets spéciaux Pigments inorganiques Pigments nacrés Index. décimale : 667.2 Colorants et pigments Résumé : Pearlescent pigment is a type of effect pigment. It is obtained by coating metal oxide on laminar flat surfaces such as natural mica. Different metal oxides are used to prepare pearlescent pigments, such as titanium dioxide, iron oxide, zirconium oxide, chromium oxide etc. Substrate selected can be either natural or synthetic. Between the two, natural mica is widely used substrate to prepare pearlescent pigments. But nowadays synthetic mica and borosilicateglass are also used to prepare pearlescent which provide brilliant sparkling effect. Pearlescent effect is observed as the result of multiple reflection, refraction and diffraction phenomenon. When mica is coated with titanium dioxide, a silver colour pearlescent pigment is obtained. As the thickness of TiO2 coating increases, because of the interference effect the colour changes from silver to yellow to pink to blue to green. The coating of iron oxide on mica results into bronze, copper and wine red colours as the thickness of the coating increases. When mica is coated with titanium dioxide and iron oxide together, a gold colour pearl pigment is obtained. Pearl pigments are available in the various grades depending upon the particle size. Pearlescent pigments are used in paints, plastics, papers, and automotive industry. One must follow some basic guidelines to use pearl pigment in plastics. In contrast to absorption colours, there is a trick in mixing colours to get desired colour in pearl pigment. Note de contenu : - NATURAL MICA : Calcium-aluminum borosilicate - Fluorophlogophite - Aluminum oxide (alumina) - METAL OXIDE - PEARLESCENT EFFECT - INTERFERENCE EFFECT - PEARLESCENT PIGMENTS IN PLASTICS - GUIDELINES FORF USE OF PEARLESCENT PIGMENTS IN PLASTICS - IMPORTANT TIPS FOR MOLDING AND EXTRUSION - TRICKS OF MIXING COLOURS WITH PEARLESCENT PIGMENTS En ligne : https://drive.google.com/file/d/1Uc7WWN3ZE0Mhp26i4Kgy1lpxDn0rFSOO/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=28460 [article]

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Effect pigments-pearlescent pigments (Part 2) / Yash Melkeri in PAINTINDIA, Vol. LXVII, N° 5 (05/2017)  

[article]  inPAINTINDIA > Vol. LXVII, N° 5 (05/2017) . - p. 64-68 Titre : Effect pigments-pearlescent pigments (Part 2) Type de document : texte imprimé Auteurs : Yash Melkeri, Auteur ; Tipanna Melkeri, Auteur Année de publication : 2017 Article en page(s) : p. 64-68 Langues : Anglais (eng) Catégories : Mica Nacre La nacre est le revêtement intérieur de certaines coquilles de mollusque, composé de cristaux d'aragonite et de conchyoline, aux reflets irisés. C'est un produit recherché depuis longtemps pour la décoration, la marqueterie, la confection de bijoux ou de boutons, au point que certains coquillages tels que les ormeaux ont localement disparu. Certains sont élevés pour la nacre. La nacre résiste mieux aux acides que la coquille et se reconstitue lorsqu'elle est percée ou abîmée chez le coquillage vivant. Lorsqu'un élément étranger irritant entre dans la coquille de ces mollusques, ceux-ci secrètent également de la nacre couche après couche tout autour afin de s'en protéger, formant ainsi une ou plusieurs perles. Contrairement aux autres couches de la coquille, la nacre est synthétisée par le mollusque tout au long de sa vie. La nacre fait partie des matières organique selon la HBJO. Pigments à effets spéciaux Procédés de fabrication Index. décimale : 667.2 Colorants et pigments Résumé : Pearlescent pigment, a type of effect pigment, obtained by coating metal oxide on laminar flat surfaces such as natural mica. For pearlescent pigment, muscovite grade mica is preferred. Pearlescent pigment manufacturing is a challenging job as there are many stages invo ved in manufacturing pearlescent pigments. Making pearlescent pigment is not pure chemistry oriented process rather it is physiochemical process. Depending upon the particle size and its distribution of mica powder isolated, different grades of pearlescent pigments are manufactured. Various metal oxides are used to coat mica to get various coloured pearlescent pigments. Incineration of coated mica powder is necessary to obtained good luster pigment. Note de contenu : - CHALLENGES IN MANUFACTURING PEARLESCENT PIGMENTS - MANUFACTURING PROCESS FOR MAKING PEARLESCENT PIGMENT : Manufacturing of process mica - Grinding of mica - Sizing of particles - Treatment of grounded and size separated mica - Treatment of metal oxide on mica - Filtration on metal oxide treated pigment - Drying - Blending and packing - Application in paints - FIGURES : 1a. Wet ground mica roller mill - 1b. Wet ground mica with ball mill - 1c. dry gounded mica with jet mill - 2. Sulphate process to prepare TiO2 - 3. Formation of iron oxide from iron sulphate of ferric chloride - 4. Schematic diagram representing metal oxide coating on mica powder - 6. Conversion of oxide to hydroxide during incineration En ligne : https://drive.google.com/file/d/1haF98WckW8WCDLPogGPLDwsRDduZJnpn/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=28872 [article]

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Effect pigments - Polymer stack (iridescence films) / Yash Melkeri in PAINTINDIA, Vol. LXVII, N° 7 (07/2017)  

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Specialty pigment - Fluorescent pigments / Yash Melkeri in PAINTINDIA, Vol. LXVII, N° 9 (09/2017)  

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Specialty pigment - Phosphorescent pigments / Yash Melkeri in PAINTINDIA, Vol. LXVII, N° 10 (10/2017)  

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Specialty pigment - Phosphorescent pigments / Yash Melkeri in PAINTINDIA, Vol. LXVII, N° 11 (11/2017)  

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