Electrically conductive resin composition and production process thereof

Abstract

A resin composition comprising a polyamide, a polyphenylene ether, an impact modifier, and a carbon type filler for an electrically conductive use, the filler residing in a phase of the polyphenylene ether. The resin composition of the present invention has excellent electrical conductivity, fluidity, and an excellent balance of a coefficient of linear expansion and an impact resistance, and generation of fines caused by pelletizing thereof can be largely suppressed when processing of an extrusion thereof is conducted.

1 . A method for producing a resin composition comprising a polyamide, a polyphenylene ether, an impact modifier, and a carbon filler for an electrically conductive use, wherein the filler has been preliminarily melted and kneaded with the impact modifier.  
   
   
       2 . The method for producing a resin composition according to  claim 1 , wherein the amount of the carbon filler for an electrically conductive use is 0.5 to 5 parts by weight based on 100 parts by weight of a mixture consisting of 40 to 90 parts by weight of a polyamide, 5 to 50 parts by weight of a polyphenylene ether, and 5 to 30 parts by weight of an impact modifier.  
   
   
       3 . The method for producing a resin composition according to  claim 1 , wherein the impact modifier is at least one selected from the group consisting of a block copolymer of an aromatic vinyl compound and a conjugated diene compound, a hydrogenated block copolymer of an aromatic vinyl compound and a conjugated diene compound, and an ethylene-α-olefin copolymer, wherein the block copolymer of an aromatic vinyl compound and a conjugated diene compound comprises a polymer block segment (A) mainly composed of an aromatic vinyl compound and a polymer block segment (B) mainly composed of a conjugated diene compound, and a linking structure of the polymer block segments is at least one selected from the group consisting of an AB type, an ABA type, and an ABAB type.  
   
   
       4 . The method for producing a resin composition according to  claim 3 , wherein a content of ethylene unit in the ethylene-α-olefin copolymer is 30 to 95% by weight based on the total amount of the ethylene-α-olefin copolymer.  
   
   
       5 . The method for producing a resin composition according to  claim 3 , wherein the ethylene-α-olefin copolymer is an ethylene-α-olefin copolymer produced with a single-site catalyst.  
   
   
       6 . The method for producing a resin composition according to  claim 1 , wherein the impact modifier is a block copolymer of an aromatic vinyl compound and a conjugated diene compound of an ABAB type, which comprises a polymer block segment (A) mainly composed of an aromatic vinyl compound and a polymer block segment (B) mainly composed of a conjugated diene compound, and/or a hydrogenated product of a block copolymer of an aromatic vinyl compound and a conjugated diene compound.  
   
   
       7 . The method for producing a resin composition according to  claim 1 , wherein the impact modifier is an impact modifier preliminarily mixed with an oil containing a paraffin mainly, and the amount of the oil is not greater than 70 parts by weight based on 100 parts by weight of the impact modifier.  
   
   
       8 . The method for producing a resin composition according to  claim 1 , wherein the carbon filler for an electrically conductive use is at least one selected from the group consisting of a carbon black, a nanotube carbon, a carbon filler, and graphite, for an electrically conductive use.  
   
   
       9 . The method for producing a resin composition according to  claim 1 , wherein the carbon filler for an electrically conductive use is a carbon black for an electrically conductive use.  
   
   
       10 . The method for producing a resin composition according to  claim 1 , wherein said resin composition comprises not less than 0.001 but less than 2 parts by weight of a metallic salt as represented by the following formula, based on 100 parts by weight of the total amount of a polyamide, a polyphenylene ether, an impact modifier, and a carbon filler for an electrically conductive use,  
       M Y+   n X Z−   n·y/z    
     wherein M Y+  represents at least one metallic ion selected from the group consisting of copper, nickel, tin, cerium, and an alkaline metal, and X Z−  represents at least one negatively charged ion selected from the group consisting of a halide ion and a carboxylate ion, n is an integer of 1 to 6, y is an integer indicating electric charge of a positive ion of M, and z is an integer indicating electric charge of a negative ion of X.  
   
   
       11 . The method for producing a resin composition according to  claim 10 , wherein the metallic salt is a metallic salt comprising an alkaline metallic ion and an iodic ion.  
   
   
       12 . The method for producing a resin composition according to  claim 10 , wherein the metallic salt has been preliminarily mixed with a part or the whole of a polyamide.  
   
   
       13 . The method for producing a resin composition according to  claim 10 , wherein the metallic salt is added on polymerization of the polyamide.  
   
   
       14 . The method for producing a resin composition according to  claim 1 , wherein a part or the whole of a polyphenylene ether is a modified polyphenylene ether which has in the molecular structure thereof at least one C—C double bond or triple bond, and has at least one of a carboxylic acid group, an acid anhydride group, an amino group, a hydroxyl group, or a glycidyl group.  
   
   
       15 . The method for producing a resin composition according to  claim 1 , wherein the carbon filler for an electrically conductive use has been preliminarily melted and kneaded with the impact modifier, and then added in the form of a master batch.  
   
   
       16 . The method for producing a resin composition according to  claim 1 , wherein the ratio of a carbon filler for an electrically conductive use and an impact modifier which are preliminarily melted and kneaded, is 5 to 30 parts by weight of a carbon filler for an electrically conductive use based on 100 parts by weight of an impact modifier.  
   
   
       17 . The method for producing a resin composition according to  claim 1 , wherein the amount of a carbon filler for an electrically conductive use which is preliminarily melted and kneaded, is not less than 50% by weight based on the whole amount used of a carbon filler for an electrically conductive use.  
   
   
       18 . The method for producing a resin composition according to  claim 1 , wherein the carbon filler for an electrically conductive use is preliminarily melted and kneaded with a polyphenylene ether and an impact modifier, and then added as a form of a master batch.  
   
   
       19 . A molded article for exterior automobile parts formed from a resin composition which is produced in accordance with the method for producing a resin composition according to  claim 1 .  
   
   
       20 . A method for producing a polyamide master pellet, comprising: 
 using a twin screw extruder having a feed opening at an upstream and at least one feed opening at a downstream;    feeding a polamide and a carbon filler for an electrically conductive use from the feed opening at the upstream and at least one feed opening at the downstream, respectively; and    melt-kneading them.    
   
   
       21 . The method for producing a polyamide master pellet according to  claim 20 , wherein the carbon filler for an electrically conductive use is a carbon black having a DBP oil absorption of not less than about 350 ml/100 g.  
   
   
       22 . The method for producing a polyamide master pellet according to  claim 20 , wherein the polyamide is polyamide 66.  
   
   
       23 . The method for producing a polyamide master pellet according to  claim 20 , wherein the polyamide has a concentration ratio of (terminal amino group)/(terminal carboxyl group) of 6/4 to 1/9.  
   
   
       24 . The method for producing a polyamide master pellet according to  claim 20 , wherein the amount of the carbon filler for an electrically conductive use is about 10% by weight.  
   
   
       25 . The method for producing a polyamide master pellet according to  claim 20 , wherein vacuum suction is further carried out after the feeding of the polyamide and the carbon filler for an electrically conductive use are fed.  
   
   
       26 . The method for producing a polyamide master pellet according to  claim 20 , wherein the polyamide and the carbon filler for an electrically conductive use are fed to the extruder at a constant rate.  
   
   
       27 . A polyamide master pellet comprising a polyamide and a carbon filler for an electrically conductive use, wherein the polyamide has a concentration ratio of (terminal amino group)/(terminal carboxyl group) of 6/4 to 1/9.  
   
   
       28 . The polyamide master pellet according to  claim 27 , wherein the carbon filler for an electrically conductive use is a carbon black having a DBP oil absorpotion of not less than about 350 ml/100 g.  
   
   
       29 . The polyamide master pellet according to  claim 27 , wherein the amount of the carbon filler for an electrically conductive use is about 10% by weight.  
   
   
       30 . The polyamide master pellet according to  claim 27 , wherein the polyamide is polyamide 66.