Varnishing composition, a method of manufacturing the composition, a coated winding wire, and a resulting coil

Abstract

The invention relates to a varnish for winding wires, the varnish comprising a copolymer obtained from a thermoplastic or thermosetting resin and containing units derived from silane, and a mineral filler selected from compounds of B, Al, Ti, Zn, Zr, Cr, Fe, silicates, and mixtures thereof. The resin is selected from polyamide imide (PAI), polyester imide (PEI), polyimide (PI), polyester (PE), polyurethane (PU), and polyvinylacetal (PVA). The varnish makes it possible to obtain winding wires of lifetime that is increased by having improved ability to withstand partial discharges and voltage peaks, even at high temperatures. The invention is applicable to manufacturing coils, in particular for variable frequency controllers and converters.

1 / A composition comprising: 
 a) a copolymer obtained from a thermoplastic or thermosetting resin and containing at least one alkoxysilane; and    b) a mineral filler selected from compounds of B, Al, Ti, Zn, Zr, Cr, Fe, and silicates, and mixtures thereof.    
     
     
         2 / A composition according to  claim 1 , in which the thermoplastic or thermosetting resin is selected from the group comprising: polyamide imide (PAI), polyester imide (PEI), polyimide (PI), polyester (PE), polyurethane (PU), polyvinylacetal (PVA), and mixtures thereof.  
     
     
         3 / A composition according to  claim 1 , in which the copolymer is obtained by adding 10% to 50%, and preferably 20% to 40% by weight of alkoxysilane.  
     
     
         4 / A composition according to  claim 1 , in which the alkoxysilane is selected from tetraalkoxysilanes such as tetraethoxysilane (TEOS), and trialkoxysilanes such as trimethoxysilane and aminopropyl-trimethoxysilane.  
     
     
         5 / A composition according to  claim 1 , in which the mineral filler is selected from oxides and nitrides of B, Al, Ti, Zn, Zr, Cr, and Fe, and is preferably titanium dioxide.  
     
     
         6 / A composition according to  claim 1 , in which the mineral filler is selected from silicates such as clays, nanocomposite clays, and mica.  
     
     
         7 / A composition according to  claim 1 , comprising 2% to 20% by weight, and preferably 5% to 15% by weight of mineral filler.  
     
     
         8 / A composition according to  claim 1 , in which the mineral filler has a specific surface area greater than 40 m 2 /g.  
     
     
         9 / An insulation varnish for a winding wire, the varnish comprising a composition in accordance with  claim 1 .  
     
     
         10 / A method of manufacturing a composition in accordance with  claim 1 , the method comprising the following steps: 
 copolymerizing the thermoplastic or thermosetting resin with at least one alkoxysilane;    adding a mineral filler selected from compounds of B, Al, Ti, Zn, Zr, Cr, Fe, silicates, and mixtures thereof; and    homogenizing.    
     
     
         11 / A method according to  claim 10 , in which synthesis is performed in a solvent selected from ortho-cresyl, meta-cresyl, para-cresyl, cresylic acid, N-methylpyrrolidone, dimethylacetamide (DMAC), and mixtures thereof.  
     
     
         12 / A method according to  claim 10 , in which the reaction is performed in the presence of a catalyst selected from pTSA, dibutyltin, and a polysiloxane.  
     
     
         13 / A method of manufacturing a winding wire, the method comprising the following steps: 
 applying a varnish comprising a composition in accordance with  claim 1  on the wire; and    setting the varnish.    
     
     
         14 / A winding wire obtained by the method of  claim 13 .  
     
     
         15 / A coil comprising a conductor wire covered in a varnish comprising a composition in accordance with  claim 1.