Aqueous tetrafluoroethylene polymer dispersion,process for producing the same, tetrafluoroethylene polymer powder,and molded tetrafluoroethylene polymer

Abstract

The present invention provides a tetrafluoroethylene polymer aqueous dispersion obtained by carrying out a TFE polymerization in an aqueous medium in the presence of a fluorovinyl group-containing emulsifier, wherein the TFE polymer aqueous dispersion contains a particle comprising a TFE polymer dispersed in the aqueous medium, the fluorovinyl group-containing emulsifier comprises a fluorovinyl group-containing compound, and the TFE polymer aqueous dispersion has a fluorine-containing surfactant content of not higher than 1000 ppm by mass.

1 . A tetrafluoroethylene polymer aqueous dispersion obtained by carrying out a tetrafluoroethylene polymerization in an aqueous medium in the presence of a fluorovinyl group-containing emulsifier, 
 wherein said tetrafluoroethylene polymer aqueous dispersion contains a particle comprising a tetrafluoroethylene polymer dispersed in said aqueous medium, said fluorovinyl group-containing emulsifier comprises a fluorovinyl group-containing compound (I) represented by the general formula (I):      CF 2 ═CF—(CF 2 ) a —Y  (I)    wherein a represents an integer of 1 to 10 and Y represents —SO 3 M or —COOM in which M represents H, NH 4  or an alkali metal,    a fluorovinyl group-containing compound (II) represented by the general formula (II):      CF 2 ═CF—(CF 2 C(CF 3 )F) b —Y  (II)    wherein b represents an integer of 1 to 5 and Y represents —SO 3 M or —COOM in which M represents H, NH 4  or an alkali metal,    a fluorovinyl group-containing compound (III) represented by the general formula (III):      CF 2 ═CFO—(CFX) c —Y  (III)    wherein X represents F or —CF 3 , c represents an integer of 1 to 10 and Y represents —SO 3 M or —COOM in which M represents H, NH 4  or an alkali metal, a fluorovinyl group-containing compound (IV) represented by the general formula (IV):      CF 2 ═CFO—(CF 2 CFXO) d —(CF 2 ) e —Y  (IV)    wherein X represents F or —CF 3 , d represents an integer of 1 to 10, e represents an integer of 1 to 3 and Y represents —SO 3 M or —COOM in which M represents H, NH 4  or an alkali metal,    a fluorovinyl group-containing compound (V) represented by the general formula (V):      CH 2 ═CFCF 2 O—(CF(CF 3 )CF 2 O) f —CF(CF 3 )—Y  (V)    wherein f represents an integer of 0 to 10 and Y represents —SO 3 M or —COOM in which M represents H, NH 4  or an alkali metal, and/or    a fluorovinyl group-containing compound (VI) represented by the general formula (VI):      CF 2 ═CFCF 2 O—(CF(CF 3 )CF 2 O) g —CF(CF 3 )—Y  (VI)    wherein g represents an integer of 1 to 10 and Y represents —SO 3 M or —COOM in which M represents H, NH 4  or an alkali metal,    said tetrafluoroethylene polymer aqueous dispersion has a fluorine-containing surfactant content of not higher than 1000 ppm by mass.    
   
   
       2 . The tetrafluoroethylene polymer aqueous dispersion according to  claim 1 , wherein the tetrafluoroethylene polymer has a tetrafluoroethylene unit content exceeding 40 mole percent.  
   
   
       3 . The tetrafluoroethylene polymer aqueous dispersion according to  claim 1 , wherein the tetrafluoroethylene polymer is a perfluoro-based polymer.  
   
   
       4 . The tetrafluoroethylene polymer aqueous dispersion according to  claim 1 , wherein the tetrafluoroethylene polymerization is carried out in the absence of any non-byproduct fluorine-containing surfactant.  
   
   
       5 . The tetrafluoroethylene polymer aqueous dispersion according to  claim 1 , wherein the fluorovinyl group-containing emulsifier comprises the fluorovinyl group-containing compound (I), the fluorovinyl group-containing compound (III), the fluorovinyl group-containing compound (IV) and/or the fluorovinyl group-containing compound (V).  
   
   
       6 . The tetrafluoroethylene polymer aqueous dispersion according to  claim 5 , wherein the fluorovinyl group-containing emulsifier comprises a fluorovinyl group-containing compound (i) represented by the general formula (i):  
       CF 2 ═CF—(O) h —(CF 2 CF(CF 3 )O) i —(CF 2 ) j —Y  (i)  wherein h represents an integer of 0 or 1, i represents an integer of 0 to 2, j represents an integer of 1 to 3 and Y represents —SO 3 M or —COOM in which M represents H, NH 4  or an alkali metal, and/or a fluorovinyl group-containing compound (ii) represented by the general formula (ii):      CH 2 ═CFCF 2 O—(CF(CF 3 )CF 2 O) k —CF(CF 3 )—Y  (ii)    wherein k represents an integer of 0 to 3 and Y represents —SO 3 M or —COOM in which M represents H, NH 4  or an alkali metal.    
   
   
       7 . The tetrafluoroethylene polymer aqueous dispersion according to  claim 1 , which has a solid matter concentration of 5 to 70% by mass.  
   
   
       8 . The tetrafluoroethylene polymer aqueous dispersion according to  claim 1 , wherein the particle comprising the tetrafluoroethylene polymer has an average primary particle diameter of 50 to 500 nm.  
   
   
       9 . A tetrafluoroethylene polymer powder which is obtained by coagulating the tetrafluoroethylene polymer aqueous dispersion according to  claim 1 .  
   
   
       10 . A tetrafluoroethylene polymer molding which is obtained by molding/processing using the tetrafluoroethylene polymer aqueous dispersion according to  claim 1 .  
   
   
       11 . A method of producing a tetrafluoroethylene polymer aqueous dispersion by carrying out a tetrafluoroethylene polymerization in an aqueous medium in the presence of a fluorovinyl group-containing emulsifier, 
 wherein said tetrafluoroethylene polymer aqueous dispersion contains a particle comprising a tetrafluoroethylene polymer dispersed in said aqueous medium and has a fluorine-containing surfactant content of not higher than 1000 ppm by mass,    said fluorovinyl group-containing emulsifier is added in an amount of 0.00001 to 2% by mass relative to said aqueous medium, and    said fluorovinyl group-containing emulsifier comprises a fluorovinyl group-containing compound (I) represented by the general formula (I):      CF 2 ═CF—(CF 2 ) a —Y  (I)    wherein a represents an integer of 1 to 10 and Y represents —SO 3 M or —COOM in which M represents H, NH 4  or an alkali metal,    a fluorovinyl group-containing compound (II) represented by the general formula (II):      CF 2 ═CF—(CF 2 C(CF 3 )F) b —Y  (II)    wherein b represents an integer of 1 to 5 and Y represents —SO 3 M or —COOM in which M represents H, NH 4  or an alkali metal,    a fluorovinyl group-containing compound (III) represented by the general formula (III):      CF 2 ═CFO—(CFX) c —Y  (III)    wherein X represents F or —CF 3 , c represents an integer of 1 to 10 and Y represents —SO 3 M or —COOM in which M represents H, NH 4  or an alkali metal, a fluorovinyl group-containing compound (IV) represented by the general formula (IV):      CF 2 ═CFO—(CF 2 CFXO) d —(CF 2 ) e —Y  (IV)    wherein X represents F or —CF 3 , d represents an integer of 1 to 10, e represents an integer of 1 to 3 and Y represents —SO 3 M or —COOM in which M represents H, NH 4  or an alkali metal,    a fluorovinyl group-containing compound (V) represented by the general formula (V):      CH 2 ═CFCF 2 O—(CF(CF 3 )CF 2 O) f —CF(CF 3 )—Y  (V)    wherein f represents an integer of 0 to 10 and Y represents —SO 3 M or —COOM in which M represents H, NH 4  or an alkali metal, and/or    a fluorovinyl group-containing compound (VI) represented by the general formula (VI):      CF 2 ═CFCF 2 O—(CF(CF 3 )CF 2 O) g —CF(CF 3 )—Y  (VI)    wherein g represents an integer of 1 to 10 and Y represents —SO 3 M or —COOM in which M represents H, NH 4  or an alkali metal.    
   
   
       12 . The method of producing a tetrafluoroethylene polymer aqueous dispersion according to  claim 11 , wherein the addition of the fluorovinyl group-containing emulsifier is carried out in the manner of a supplementary addition with the progress of a tetrafluoroethylene polymerization reaction.