Fundamental properties of fluoropolyether‐based resins and related coatings

Abstract

New fluoropolyether polyolic resins are presented suitable to be cured with conventional hardeners as polyisocyanates or melamines. These resins are prepared by addition of fluoropolyether macrodiols (Fomblin@ ZDOLTX) of various molecular weights to isophorone diisocyanate (IPDI) to give oligomeric NCO-terminated prepolymers. The final hydroxy functionality is obtained by the reaction of those prepolymers with trimethylolpropane (TMP). The viscosity of the resins is measured at various concentrations (weight fraction 0.8 -0.4) and temperatures (T = 25 -65 "C). The results are discussed in terms of the Erickson equation (q vs. concentration) and using the WLF and Arrhenius models (q vs. T). The thermal behavior is studied by DSC for both the resins and cured films indicating the presence of two T,s, corresponding to the segregated fluorinated and hydrogenated phases, the former particularly evident with the highest molecular weights of the fluorinated macromer. Tensile curves of selfsupported films are then analyzed showing an evident tough-plastic behavior especially for the isocyanate-cured films. The application of such materials as high-durability clear coats is finally proposed. ZUSAMMENFASSUNG:Neuartige Fluoropolyether-Polyol-Harze, die mit konventionellen Hartern wie Polyisocyanaten oder Melaminen aushartbar sind, wurden hergestellt . Zunachst wurden oligomere NCO-terminierte Prepolymere durch Addition von Fluorpolyether-Makrodiolen unterschiedlicher Molekulargewichte an Isophorondiisocyanate erhalten. Durch die Reaktion dieser Prepolymeren mit Trimethylolpropan wurden endstandige Hydroxygruppen eingefuhrt. Die Viskositat von Ldsungen dieser Harze wurde bei unterschiedlichen Konzentrationen (Massenbruch 0,4 -0,8) und Temperaturen (25 "C-65 "C) gemessen. Die erhaltenen Werte wurden auf der Basis der Erickson-Gleichung (Konzentrationsabhangigkeit von q) und unter Berucksichtigung des WLFund des Arrhenius-Modells (Temperaturabhangigkeit von q) diskutiert. Das thermische Verhalten der Harze und von ausgeharteten Filmen wurde mit DSC bestimmt.

Catalyst effect on the crosslinking kinetics of a fluorine containing polyurethane network

“…This behavior is very typical of block copolymers based on PFPE [4][5][6][7] and can be explained by the extremely low solubility parameter (about 11 MPa 0.5 ) of perfluorinated polyethers. [11] It is evident that the polymer has one glassy phase at ambient temperature, and therefore during the room temperature curing the reactive functions of the polyurethane are supposed to freeze and loose progressively their molecular mobility.…”

“…[4][5][6][7] Some kinetic studies were also reported dealing with the reaction of perfluoropolyether (PFPE) macrodiols with cycloaliphatic and aromatic diisocyanates [8] to give linear prepolymers: while uncatalyzed reactions resulted very slow, PFPE alcohols are sensitive to the effect of catalyst.…”

Study of metal protective hydrophobic coatings from waterborne polyurethane ionomers

“…From an examination of Table 3 data, it appears that all the coatings are amorphous and biphasic (two different Tg indicated) due to the thermodynamic segregation of fluoroether and urethane parts; such a phenomenology is well known and already observed and reported for solventborne fluoroether polyurethane coatings [2]. The efficiency of crosslinking was investigated by MEK test.…”

“…Their surface properties like hydrophobicity and cleanability can be improved by introducing low surface tension fluorinated monomers or macromers, like in case of fluorinated polyether containing polyurethanes [2][3][4]. In these products it was observed that water permeability, barrier properties and durability are largely affected by phase segregation phenomena involving the apolar fluoroether segments and polar urethane moieties [2].…”

“…Their surface properties like hydrophobicity and cleanability can be improved by introducing low surface tension fluorinated monomers or macromers, like in case of fluorinated polyether containing polyurethanes [2][3][4]. In these products it was observed that water permeability, barrier properties and durability are largely affected by phase segregation phenomena involving the apolar fluoroether segments and polar urethane moieties [2]. More recently waterborne versions of fluoroether containing polyurethanes have been described [5,6]; they are based on the introduction within the polymer chain of ionic groups which act as internal emulsifiers allowing the formation of stable and environmentally friendly aqueous dispersions.…”