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Pigment/dispersant interactions in water-based coatings / J. Clayton in SURFACE COATINGS INTERNATIONAL, Vol. 80, N° 9 (09/1997)

[article]  inSURFACE COATINGS INTERNATIONAL > Vol. 80, N° 9 (09/1997) . - p. 414- 419 Titre : Pigment/dispersant interactions in water-based coatings Type de document : texte imprimé Auteurs : J. Clayton, Auteur Année de publication : 1997 Article en page(s) : p. 414- 419 Note générale : Bibliogr. Langues : Anglais (eng) Tags : 'Peinture  eau'  Adjuvant  Dispersant  'Pigment  minéral'  'Titane  Oxyde'  Interaction Index. décimale : 667.9 Revêtements et enduits Résumé : Various types of ionic and non-ionic dispersants have been classified by their ability to stabilise titanium dioxide pigment suspensions in water. It was found that some non-ionic dispersants produced suspensions that exhibited full steric stabilisation as opposed to electrosteric stabilisation that occurs with ionic dispersants. A high level of steric stabilisation was found to relate to greater flocculation resistance in both the wet and dry phases, which can result in improved paint stability and higher opacity. Note de contenu : - Dispersant demand - Zeta potential - Dispersant adsorption - Stabilisation mechanism - Flocculation and electrolyte concentration - Performance in paints - Costs Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=17218 [article]

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Pigments : myth, shape and structure / J. R. Fryer in SURFACE COATINGS INTERNATIONAL, Vol. 80, N° 9 (09/1997)

[article]  inSURFACE COATINGS INTERNATIONAL > Vol. 80, N° 9 (09/1997) . - P. 421-426 Titre : Pigments : myth, shape and structure Type de document : texte imprimé Auteurs : J. R. Fryer, Auteur Année de publication : 1997 Article en page(s) : P. 421-426 Note générale : Bibliogr. Langues : Anglais (eng) Tags : 'Article  synthèse'  'Pigment  organique'  'Interaction  intermoléculaire'  'Structure  cristalline'  'Mode  empilement'  Morphologie  'Forme  'Composé  polaire'  'Relation  fabrication  structure'  non Index. décimale : 667.9 Revêtements et enduits Résumé : The usual textbook describes pigments in terms of the chromophore, and may give a synthetic route by which this compound can be obtained as shown for an azo pigment below. However, in practice as is well known to those in the industry - the organic synthesis is only part of the process of making a pigment, and indeed may only be a minor part. The handling - eg rheology, the dispersibility, solubility, the colour strength, and even the shade of the pigment are function of the crystal properties. A molecule has colour by havinf fonctional groups whose electronic transitions absorb energy in the visible spectrum. These transitions can be affected by meighbouring groups within the molecule - particulary in conjugated systems - but also by neighbouring groups in adjacent molecules which are forced into close proximity by the crystal packing. An important aspect of any molecule, which is to be considered as a pigment, is the bonding within the crystal, and how this can affect molecular proximity, and the ultimate shape of the crystal which is formed. It is necessary to consider both molecular shape, and any polar functional groups which may dominate the packing of molecules in the crystal. Note de contenu : - TYPES OF STRUCTURE - ORGANIC CRYSTALS - NON-POLAR MOLECULES : Attractive.Dispersion forces - Repulsive forces - POLAR MOLECULES : Packing of organic molecules in a crystal - Packing coefficient K - CRYSTAL SHAPE - CRYSTAL STRUCTURE Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=17219 [article]

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The characterisation and the application of modified pigmented systems / James Thomas Guthrie in SURFACE COATINGS INTERNATIONAL, Vol. 80, N° 9 (09/1997)

[article]  inSURFACE COATINGS INTERNATIONAL > Vol. 80, N° 9 (09/1997) . - p. 427-434 Titre : The characterisation and the application of modified pigmented systems Type de document : texte imprimé Auteurs : James Thomas Guthrie, Auteur ; M. Kunaver, Auteur Année de publication : 1997 Article en page(s) : p. 427-434 Note générale : Bibliogr. Langues : Anglais (eng) Tags : Peinture  'Matériau  revêtement'  Encre  'Matière  plastique'  Pigment  Adjuvant  Caractérisation  Adsorption  Formulation  Pâte Index. décimale : 667.9 Revêtements et enduits Résumé : Studies of interactions between the components of formulations and characterisation of materials involved in pigment paste concentrates could help the formulator to find the optimum formulation. IGC provides information which allows the formulator to ascertain which wetting agent will be more efficient in wetting the pigment surface. Adsorption studies assist in the determination of the amount needed for the particular pigment. Other techniques could be used to substantiate the results. Both of the pigments used in study were used as a model and the established principles have been successfully applied to other types of pigments. Studies of the compatibility characteristics in different let-down systems could define the universal character of these pigment paste concentrates. However, all methods and formulations have their limitations. IGC cannot provide reliable results for polymers undergoing some structural changes at higher temperatures. Sometimes interactions between probes and the components under investigation could be so strong that chemisorption occurs. Adsorption studies are time consuming and depend on the exact concentration measurements. Electrophoretic mobility carried out on components dissolved in non-aqueous media are useful only when an 'appropriate' solvent is used. The results emenating from this study have been successfully applied in industrial dispensing systems, across a range of formulation options. Note de contenu : - EXPERIMENTAL : Materials - Adsorption studies - Inverse gas chromatography (IGC) - Stationary phase preparation and column assembly - Instrumentation - Measurements - SIZE EXCLUSION CHROMATOGRAPHY : Instrumentation - Preparation of samples and chromatography - Formulation procedures - Optimisation of the dispersing agent loading - Determination of the optimum milling time - Electrophoretic mobility studies - RESULTS AND DISCUSSION : Inverse gas chromatography - Adsorption studies - Formulation procedures - Dispersion process - Characterisation of the pigment paste concentrate Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=17220 [article]

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Physical characterisation of organic pigment powders / M. McGarvey in SURFACE COATINGS INTERNATIONAL, Vol. 80, N° 9 (09/1997)

[article]  inSURFACE COATINGS INTERNATIONAL > Vol. 80, N° 9 (09/1997) . - p. 435-440 Titre : Physical characterisation of organic pigment powders Type de document : texte imprimé Auteurs : M. McGarvey, Auteur ; R. B. McKay, Auteur Année de publication : 1997 Article en page(s) : p. 435-440 Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Agrégats (chimie) Caractérisation Encre Granulats lasers Microstructures Pigments organiques Porosité Poudres Index. décimale : 667.9 Revêtements et enduits Résumé : This paper describes various means of characterising organic pigment powders. The methods described are generally applicable to all organic pigment powders, although the specific examples used here feature pigments for printing inks. Organic pigments are crystalline solids, the sizes and shapes of crystals depending on chemical type and process of manufacture. The most common crystal shapes are (in approximate terms) cube/brick, rod and plate. In pigments for printings inks, the average minor crystal dimension(thick-ness of bricks, rods, plates) can vary in size from <0.02 micrométre in pigments for transparent dispersions to around 0.04 micrométre in pigments for semi-opaque dispersions Note de contenu : - CHARACTERISATION OF MICRO-STRUCTURE : Estimation of the degree of face-to-face packing in aggregates of crystals - Characterisation of porosity of aggregates of crystals - CHARACTERISATION OF BULK STRUCTURE PROPERTIES : Grain size analysis of organic pigment powders by laser diffraction - Cohesiveness and bulk handling of organic pigment powders Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=17229 [article]

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