Drying of alkyd emulsion paints / P. K. Weissenborn in JOURNAL OF COATINGS TECHNOLOGY (JCT), Vol. 72, N° 906 (07/2000)

[article]  inJOURNAL OF COATINGS TECHNOLOGY (JCT) > Vol. 72, N° 906 (07/2000) . - p. 65-74 Titre : Drying of alkyd emulsion paints Type de document : texte imprimé Auteurs : P. K. Weissenborn, Auteur ; A. Motiejauskaite, Auteur Année de publication : 2000 Article en page(s) : p. 65-74 Note générale : Bibliogr. Langues : Américain (ame) Catégories : Agents dispersants (chimie) Cobalt Dioxyde de titane Pigments inorganiques Polyalkydes Revêtements -- Additifs Revêtements en phase aqueuse:Peinture en phase aqueuse Siccatifs Un siccatif est une substance qui joue un rôle de catalyseur en accélérant le séchage ou durcissement (polymérisation) d'un matériau tel une huile ou une peinture à base d'huile (pour le bâtiment ou les artistes). Tags : 'Matériau  revêtement'  'Peinture  eau'  émulsion'  'Alkyde  résine'  'Formation  film'  Séchage  Siccatif  'Cobalt  Composé'  'Pigment  minéral'  'Titane  Oxyde'  Adjuvant  Dispersant  'Etude  expérimentale' Index. décimale : 667.9 Revêtements et enduits Résumé : The drying and film formation of long oil alkyd emulsions was investigated with emphasis on loss of dry upon storage. The main reason for loss of dry was adsorption of the cobalt (drier) on pigment surfaces as a precipitated hydroxide. Titanium dioxides with alumina surface treatment and organic pigments were most detrimental to drying. Acrylate- and phosphate-based dispersants also deactivated the cobalt, presumably due to complexation and precipitation of the cobalt. Emulsions prepared with an emulsifiable cobalt drier containing 2,2'-bipyridyl (complexing agent for cobalt) showed the best resistance to loss of dry. Atomic force microscopy of films formed from the emulsions showed that the emulsifier migrated to the film surface which, when washed with water, leaves holes or pits in the film. The pits were arranged in a hexagonal pattern characteristic of Bénard cells, which form due to surface tension and/or temperature gradients generated in the film during evaporation of water. Note de contenu : - MATERIALS: Alkyd resins - Emulsifiers - Driers - Dispersants - Pigments - Other Reagents - METHODS: Alkyd resin emulsification - Addition of dispersants to LO83 alkyd emulsions - Addition of pigments to LO83 Alkyd emulsions - Storage stability and loss of dry tests - BK drying tests - Emulsion characterization - Film formation studies - DRYING PROPERTIES OF PURE ALKYD EMULSIONS: Effect of emulsion pH - Effect of cobalt form and location - Other variables - DRYING PROPERTIES OF EMULSIONS CONTAINING PIGMENT DISPERSANTS - DRYING PROPERTIES OF EMULSIONS CONTAINING PIGMENTS - FILM FORMATION Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=17987 [article]

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Influence of drier combination on through-drying in waterborne alkyd emulsion coatings observed with magnetic resonance profiling / J. Mallégol in JOURNAL OF COATINGS TECHNOLOGY (JCT), Vol. 74, N° 933 (10/2002)

[article]  inJOURNAL OF COATINGS TECHNOLOGY (JCT) > Vol. 74, N° 933 (10/2002) . - p. 113-124 Titre : Influence of drier combination on through-drying in waterborne alkyd emulsion coatings observed with magnetic resonance profiling Type de document : texte imprimé Auteurs : J. Mallégol, Auteur ; P. K. Weissenborn, Auteur ; A. Motiejauskaite, Auteur ; M. Wallin, Auteur ; Joseph L. Keddie, Auteur ; P. J. McDonald, Auteur ; P. M. Glover, Auteur ; E. Ciampi, Auteur ; A. M. Barry, Auteur Année de publication : 2002 Article en page(s) : p. 113-124 Note générale : Bibliogr. Langues : Américain (ame) Tags : Etude  expérimentale  Mécanisme  réaction  Dureté  Feuil  Propriété  mécanique  Résonance  magnétique  Adjuvant  Siccatif  Séchage  Formation  feuille  Alkyde  résine  Peinture  émulsion  eau  Matériau  revêtement Index. décimale : 667.9 Revêtements et enduits Résumé : Achieving fast and uniform crosslinking in alkyd coatings poses a challenge to formulators that demands a fundamental understanding of drier efficiency. In recognition of this, we have examined the physical changes that accompany autooxidative crosslinking in alkyd films (cast from waterborne emulsions) in the presence of various combinations of metal carboxylate driers. A newly developed type of magnetic resonance (MR) profiling was used in conjunction with conventional techniques : Beck-Koller drying tests, pendulum hardness, and mass uptake. MR profiling noninvasively probes the molecular mobility of the alkyd as a function of depth (with a pixel resolution of about 9 µm), over drying times ranging from minutes to weeks. It thereby indicates drier efficiency via its sensitivity to viscosity build-up during drying and to subsequent film hardening. We show unequivocally that more uniform crosslinking is achieved using a combination of a primary (Co) and a secondary (Ca) drier, in support of conventional belief. Furthermore, these results yield new insight into the chemical mechanisms induced by the driers and are thus of clear benefit to coatings researchers and formulators. Notably, the secondary driers improve the efficiency of the hydroperoxide decomposition reactions, but they are only active during an initial period, after which crosslinking nonuniformity develops. Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=5618 [article]

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