Electrostatic Composition Based On A Polyamide Matrix

Abstract

The invention relates to a composition based on a polyamide matrix comprising electrically conductive charges and antistatic agents. This composition makes it possible to obtain plastic articles, for example, body parts used in the automobile industry that are well-suited for painting by means of an electrostatic paint deposition process.

1 - 19 . (canceled)  
   
   
       20 . A composition comprising a polyamide matrix, comprising: 
 at least 2% by weight of electrically conductive fillers; and    at least 1% by weight of antistatic agents;    the percentages by weight being expressed with respect to the total weight of the composition.    
   
   
       21 . The composition as claimed in  claim 20 , exhibiting a surface resistivity of between 10 5  Ω and 10 11  Ω, measured according to Standard IEC 61340-4-1.  
   
   
       22 . The composition as claimed in  claim 20 , having a discharge time of greater than or equal to 10 seconds, measured according to Standard IEC 61340-5-1.  
   
   
       23 . The composition as claimed in  claim 20 , having from 2 to 50% by weight of electrically conductive fillers, with respect to the total weight of the composition.  
   
   
       24 . The composition as claimed in  claim 20 , wherein the electrically conductive fillers are a carbon black, a metal, a graphite, a conductive polymer, a glass or an inorganic filler coated with a metal layer.  
   
   
       25 . The composition as claimed in  claim 20 , having from 2 to 10% by weight of carbon black as electrically conductive fillers, with respect to the total weight of the composition.  
   
   
       26 . The composition as claimed in  claim 20 , having from 1 to 30% by weight of antistatic agents, with respect to the total weight of the composition.  
   
   
       27 . The composition as claimed in  claim 20 , wherein the antistatic agents are a polyetheramide, a sodium alkylsulfonate, an alkylbenzenesulfonate, primary, secondary or tertiary amines, an ethoxylated amine, an ethoxylated alcohol, glyceryl monostearates, distearates or tristearates.  
   
   
       28 . The composition as claimed in  claim 20 , wherein the antistatic agent is a polyetheramide represented by the formula (I):  
     
       
         
         
             
             
         
       
       in which: 
 n is an integer between 5 and 50;  
 X represents an oxygen atom or an NH group;  
 PAO represents a poly(alkylene oxide) block;  
 PA represents a polyamide block, the repeat unit of which is represented by either of the formulae (IIa) or (IIb):  
                     
 
       in which: R 1 , R 2  and R 3  are aromatic or aliphatic radicals having 4 to 36 carbon atoms.  
     
   
   
       29 . The composition as claimed in  claim 28 , wherein the radical R 1  is a linear divalent pentyl radical.  
   
   
       30 . The composition as claimed in  claim 28 , wherein the PAO block is a poly(ethylene oxide) block.  
   
   
       31 . The composition as claimed in  claim 20 , wherein the polyamide matrix is composed of at least one (co)polyamide which is: (co)polyamide 6; 4; 11; 12; 4,6; 6,6; 6,9; 6,10; 6,12; 6,18; 6,36; 6(T); 9(T); 6(I); MXD6; their copolymers or their blends.  
   
   
       32 . The composition as claimed in  claim 20 , wherein the composition further comprises at least one modifier of the impact strength chosen from the group consisting of: ethylene-propylene (EP) optionally grafted with maleic anhydride, ethylene-propylene-diene (EPDM) terpolymer optionally grafted with maleic anhydride, styrene-maleic anhydride (SMA), ultra-low-density polyethylene (ULDPE), linear low density polyethylene (LLDPE), styrene-butadiene (SBS and SBR) compounds, styrene-ethylene-butadiene-styrene (SEBS) compounds, polypropylene (PP), acrylic elastomers, copolymers and terpolymers of ethylene with acrylic or methacrylic derivatives and/or with vinyl acetate, ionomers, acrylonitrile-butadiene-styrene (ABS) terpolymer and acrylic-styrene-acrylonitrile (ASA) terpolymer.  
   
   
       33 . A process for the preparation of a polyamide composition as claimed in  claim 20 , comprising the step of blending at least 2% by weight of electrically conductive fillers and at least 1% by weight of antistatic agents with a polyamide matrix, optionally in the molten state.  
   
   
       34 . A process for the preparation of a polyamide composition as claimed in  claim 20 , comprising the step of blending the polyamide matrix with: 
 a concentrated blend based on a thermoplastic matrix comprising at least 20% by weight of electrically conductive fillers, and    at least 1% by weight of antistatic agents.    
   
   
       35 . The process as claimed in  claim 34 , wherein the thermoplastic matrix is chosen from the group consisting of: the (co)polyamide, ethylene-vinyl acetate (EVA) copolymer, ethylene-acrylic acid (EAA), polyethylene (PE), polypropylene (PP), their copolymers and their blends.  
   
   
       36 . A process for the manufacture of an article by forming a composition as claimed in  claim 20  by an extrusion process, a molding process or an injection process.  
   
   
       37 . An article obtained by forming a composition as claimed in  claim 20 .  
   
   
       38 . The article as claimed in  claim 37 , painted by a process of applying a paint by electrostatic deposition.