Method for synthesising a metal-oxide nanofiller, and use thereof in a fluorocarbon-resin non-stick coating

Abstract

Provided is a metal-dioxide nanofiller including at least two graft chains, at least one of the chains being a hydrophilic and the other being a hydrophobic chain compatible with fluorinated polymers. The hydrophobic chain is an oligomer, the weight-average molar mass Mw of which is between 300 and 20, 000 g/mol-1 · Also provided is a non-stick coating comprising such a filler, as well as to a culinary article provided with such a coating.

1 . A dispersion in aqueous phase of at least a fluorocarbon resin including a nanofiller of a metal-oxide comprising at least two graft chains, at least one of the chains being hydrophilic and the other being a hydrophobic chain compatible with fluorinated polymers, wherein the hydrophobic chain is an oligomer, the weight-average molar mass Mw of which is between 300 and 20,000 g/mol. 
     
     
         2 . The dispersion according to  claim 1 , wherein the fluorocarbon resin is selected among the polytetrafluoroethylene (PTFE), the copolymer of tetrafluoroethylene and perfluoro propylvinylether (PFA), and the copolymer of tetrafluoroethylene and hexafluoropropylene (FEP), the polyvinylidene fluoride (PVDF), the MVA (copolymer of TFE/PMVE) , the terpolymer TFE/PMVE/FAVE, the ETFE and their mixtures. 
     
     
         3 . The dispersion according to comprising pigments, and/or additives  claim 1 , further selected among the thickening agents, surfactants, stabilizers and cosolvents. 
     
     
         4 . A method of synthesis of a silica nanofiller comprising a hydrophilic chain consisting in a derivative of polyalkylene glycol modified by an alkoxysilane and a hydrophobic chain consisting in a hydrophobic oligomer of HFPO, and/or a VDF and/or a TFE modified by an alkoxysilane, said method comprising the following steps:
 (a) providing a polyalkylene glycol modified by an alkoxysilane;   (b) oligomerizing said hydrophobic oligomer, followed by its functionalization by an alkoxysilane; and   (c) grafting on the silica nanofiller on the one hand of said hydrophobic oligomer functionalized by an alkoxysilane, and on the other hand of polyalkylene glycol modified by analkoxysilane.   
     
     
         5 . The method according to  claim 4  wherein the grafting is a two-step grafting, in which:
 first, the functionalized hydrophobic oligomer HFPO is grafted on the silica nanofiller; then 
 second, the modified polyalkylene glycol is grafted on the silica nanofiller. 
 
     
     
         6 . The method according to  claim 4 , wherein the grafting of the functionalized hydrophobic oligomer and the modified polyalkylene glycol is achieved simultaneously on the silica nanofiller. 
     
     
         7 . A non-stick coating comprising at least a layer comprising at least a fluorocarbon resin alone or mixed with a thermally stable bonding resin and resistant to at least 200° C., this (these) resin(s) forming a continuous fritted lattice, wherein it comprises a nanofiller such as defined according to  claim 1 . 
     
     
         8 . The non-stick coating according to  claim 7  wherein the fluorocarbon resin is selected among the polytetrafluoroethylene (PTFE), the copolymer of tetrafluoroethylene and perfluoro propylvinylether (PFA), and the copolymer of tetrafluoroethylene and hexafluoropropene (FEP), the polyvinylidene fluoride (PVDF), the MVA (copolymer of TFE/PMVE), the terpolymer TFE/PMVE/FAVE, the ETFE and their mixtures. 
     
     
         9 . The non-stick coating according to  claim 7 , wherein the bonding resin is selected among polyamides imids (PAI), polyether-imids (PEI), polyamids (PA), polyimids (PI), polyetherketones (PEK), polyetheretherketones (PEEK), polythersulfones (PES), polyphenylene sulfides (PPS), polybenzimidazoles (PBI). 
     
     
         10 . The non-stick coating according to  claim 7 , wherein it comprises a bonding primer layer and at least a finishing layer. 
     
     
         11 . A culinary article comprising a support exhibiting an inner side able to receive foods and an outer side intended to be disposed towards the source of heat, wherein the inner side is coated with a non-stick coating such as defined according to  claim 7 . 
     
     
         12 . The culinary article according to  claim 11 , wherein the support is a hollow bowl having a base and a lateral wall rising from said base. 
     
     
         13 . The culinary article according to  claim 11 , wherein the support is achieved in a material selected among the metals, wood, glass, ceramics and plastic material. 
     
     
         14 . The culinary article according to  claim 13 , wherein the support is a metal support in anodized aluminum or unanodized aluminum, or in polished, brushed or microbeaded aluminum, or cast aluminum, or in beaten or polished copper. 
     
     
         15 . A method for achieving a non-stick coating such as defined accord˜ng to  claim 7 , wherein it comprises the following steps:
 (a) introducing a nanofiller in a dispersion in aqueous phase of at least a fluorinated polymer, then 
 (b) step of applying on a substrate said dispersion comprising the fluorinated polymer and said nanofiller.