[article]
Titre : |
Toward solventless liquid coatings |
Type de document : |
texte imprimé |
Auteurs : |
Frank N. Jones, Auteur |
Année de publication : |
1996 |
Article en page(s) : |
p. 25-36 |
Note générale : |
Bibliogr. |
Langues : |
Américain (ame) |
Catégories : |
Acides carboxyliques Diester Diols Formulation (Génie chimique) Haut extrait sec Liants MélamineLa mélamine, de nom chimique 1,3,5-triazine-2,4,6-triamine, est parfois dénommée cyanuramide ou cyanurotriamine. Sa formule brute est C3H6N6.
Les "résines mélamine-formaldéhyde" ou "mélamine-formol" (sigle MF) sont appelées "mélamine" dans le langage courant. Elles font partie de la famille des aminoplastes qui regroupe des résines thermodurcissables aminées, issues d'un comonomère tel l'urée ou la mélamine, parfois le thiocarbamide, le cyanamide hydrogène ou le dicyandiamide ; le second comonomère étant le formaldéhyde. Oligomères Polyesters Polyisocyanates Revêtements Rhéologie Viscosité
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Index. décimale : |
667.9 Revêtements et enduits |
Résumé : |
Results of an exploratory study of solventless (100% reactive) liquid polyester/ melamine resin and polyester/polyisocyanate coatings are described. An investigation of how the chemical structure and the molecular shape of oligomeric polyester resins affects their viscosities found that slender molecules have very low viscosities. Linear oligoester diols composed entirely of diacids and diols of the structures HOOC (CH2)nCOOH and HO(CH2)mOH with Mn of 700 or below have viscosities below 800 mPa.s at 25°C, low enough for potential use in solventless coatings. Physical properties of oligoester diols were studied, and quantitative relationships among viscosity (η), temperature (T), molar mass (Mn), glass transition temperature (Tg), and melting point (Tm) were demonstrated. The next step was to formulate solventless coatings with linear oligoester diols. An arbitrary goal was to keep viscosity below 800 mPa.s at 25°C without adding organic solvents. A two-package solventless coating made from a linear oligoester diol and a low viscosity polyisocyanate crosslinker had a viscosity of 560 mPa.s at 25°C and excellent film properties; its VOC was 8 g/L. Polyester/melamine resin coatings with similar viscosities can be formulated, but their coating films tend to be soft and to have poor adhesion to metal. Film properties can be improved by adding hardeners to the formulations, but viscosity increases. Viscosity of these solventless formulations can be further reduced by adding modest amounts of water (3 to 20 wt%). This expedient makes it possible to formulate one-package water-thinnable solventless coatings with reasonably good film properties from combinations of linear oligoester diols, hardeners, and melamine resins. Two-package coatings containing polyisocyanate crosslinkers can also be thinned with water with little effect on pot life. |
Note de contenu : |
- LOW-VISCOSITY POLYESTER RESINS : Background - Oligomers based on terephthalic acid and diols of structure HO(CH2)nOH - Linear oligomers based on dicarboxylic acids of structure HOOC(CH2)mCOOH and diols of structure HO(CH2)nOH - Synthesis of linear oligomers - Physical properties of linear and non-linear oligoester diols
- FORMULATING WITH LINEAR OLIGOESTER DIOLS : Solventless coatings - Water-thinnable solventless coatings |
Permalink : |
https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=18308 |
in JOURNAL OF COATINGS TECHNOLOGY (JCT) > Vol. 68, N° 852 (01/1996) . - p. 25-36
[article]
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