US2010204345A1PendingUtilityA1

Aqueous dispersion of low molecular weight polytetrafluoroethylene, low molecular weight polytetrafluoroethylene powder, and method for producing low molecular weight polytetrafluoroethylene

Assignee: DAIKIN IND LTDPriority: Aug 7, 2007Filed: Aug 7, 2008Published: Aug 12, 2010

Est. expiryAug 7, 2027(~1 yrs left)· nominal 20-yr term from priority

Inventors:Taku Yamanaka Nobuhiko Tsuda Masayuki Tsuji Yasuhiko Sawada

G03G 9/09766G03G 9/0872C08F 214/26C08F 6/22C08F 6/20C08F 6/16C08F 2/18C08F 14/26

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References

Claims

Abstract

The present invention provides an aqueous dispersion of a low-molecular-weight polytetrafluoroethylene (PTFE), which contains an easily removable surfactant, and has a good dispersion stability. Specifically, the present invention provides an aqueous dispersion of a low-molecular-weight PTFE comprising tetrafluoroethylene (TFE) units, or TFE units and modifying monomer units which are copolymerizable with the TFE units, wherein the aqueous dispersion contains from 70 to 9,000 ppm, based on the aqueous dispersion, of a fluorine-containing compound of the formula (1) below: X—(CF 2 ) m —Y (1) where X is H or F; m is an integer from 3 to 5; and Y is —SO 3 M, —SO 4 M, —SO 3 R, —SO 4 R, —COOM, —PO 3 M 2 or —PO 4 M 2 , M being H, NH 4 or an alkali metal, and R being an alkyl group having 1 to 12 carbons, and the low-molecular-weight PTFE has an average primary particle size of from 100 to 350 nm.

Claims

exact text as granted — not AI-modified

1 . An aqueous dispersion of a low-molecular-weight polytetrafluoroethylene comprising tetrafluoroethylene units, or tetrafluoroethylene units and modifying monomer units copolymerizable with the tetrafluoroethylene units,
 wherein the aqueous dispersion contains from 70 to 9,000 ppm, based on the aqueous dispersion, of a fluorine-containing compound of the formula (1) below:
   X—(CF 2 ) m —Y  (1) 
   
       where X is H or F; m is an integer from 3 to 5; and Y is —SO 3 M, —SO 4 M, SO 3 R, SO 4 R, —COOM, —PO 3 M 2  or —PO 4 M 2 , M being H, NH 4  or an alkali metal, and R being an alkyl group having 1 to 12 carbons, and
 the low-molecular-weight polytetrafluoroethylene has an average primary particle size of from 100 to 350 nm. 
 
     
     
         2 . A low-molecular-weight polytetrafluoroethylene powder comprising tetrafluoroethylene units, or tetrafluoroethylene units and modifying monomer units copolymerizable with the tetrafluoroethylene units,
 wherein the low-molecular-weight polytetrafluoroethylene powder contains not more than 100 ppm, based on the powder, of a fluorine-containing compound of the formula (1) below:
   X—(CF 2 ) m —Y  (1) 
   
       where X is H or F; m is an integer from 3 to 5; and Y is SO 3 M, SO 4 M, SO 3 R, SO 4 R, —COOM, —PO 3 M 2  or —PO 4 M 2 , M being H, NH 4  or an alkali metal, and R being an alkyl group having 1 to 12 carbons
 and is free from fluorine-containing compounds of the formula (3) below:
   X—(CF 2 ) m —Y  (3) 
 
 where X is H or F; m is an integer of 6 or more; and Y is —SO 3 M, —SO 4 M, —SO 3 R, —SO 4 R, —COOM, —PO 3 M 2  or —PO 4 M 2 , M being H, NH 4  or an alkali metal, and R being an alkyl group having 1 to 12 carbons. 
 
     
     
         3 . A method of producing a low-molecular-weight polytetrafluoroethylene, comprising: emulsion-polymerizing, in an aqueous medium, tetrafluoroethylene, or tetrafluoroethylene and a modifying monomer copolymerizable with the tetrafluoroethylene in the presence of a chain transfer agent,
 wherein the emulsion polymerization is carried out in the presence of a fluorine-containing compound of the formula (1) below:
   X—(CF 2 ) m —Y  (1) 
   where X is H or F; m is an integer from 3 to 5; and Y is —SO 3 M, —SO 4 M, —SO 3 R, —SO 4 R, —COOM, —PO 3 M 2  or —PO 4 M 2 , M being H, NH 4  or an alkali metal, and R being an alkyl group having 1 to 12 carbons.   
     
     
         4 . The method of producing a low-molecular-weight polytetrafluoroethylene according to  claim 3 ,
 wherein emulsion polymerization is further carried out in the presence of a reactive compound which has a functional group capable of reacting in radical polymerization and a hydrophilic group.   
     
     
         5 . The method of producing a low-molecular-weight polytetrafluoroethylene according to  claim 4 , wherein the reactive compound has an unsaturated bond. 
     
     
         6 . The method of producing a low-molecular-weight polytetrafluoroethylene according to  claim 4 ,
 wherein the reactive compound is a perfluorovinylalkyl compound of the formula (1a) below:
   CF 2 ═CF(CF 2 ) n1 —Y 1   (1a) 
   
       where n 1  is an integer from 1 to 10; and Y 1  is —SO 3 M 1  or —COOM 1 , M 1  being H, NH 4  or an alkali metal), 
       a perfluorovinylalkyl compound of the formula (1b) below:
   CF 2 ═CF(CF 2 C(CF 3 )F) n2 —Y 1   (1b) 
 where n 2  is an integer from 1 to 5; and Y 1  is as defined above, 
 
       a perfluorovinyl ether compound of the formula (1c) below:
   CF 2 ═CF—O—(CFX 1 ) n3 —Y 1   (1c) 
 where X 1  is F or CF 3 ; n 3  is an integer from 1 to 10; and Y 1  is as defined above, 
 
       a perfluorovinyl ether compound of the formula (1d) below:
   CF 2 ═CF—O—(CF 2 CFX 1 O) n4 —CF 2 CF 2 Y 1   (1d) 
 where n 4  is an integer from 1 to 10; and Y 1  and X 1  are as defined above, 
 
       or a fluoroallyl ether compound of the formula (1e) below:
   CX 2   2 ═CFCF 2 —O—(CF(CF 3 )CF 2 O) n5 —CF(CF 3 )Y 1   (1e) 
 where each X 2  is the same and represents F or H; n 5  is 0 or an integer from 1 to 10; and 
 
       Y 1  is as defined above. 
     
     
         7 . The method of producing a low-molecular-weight polytetrafluoroethylene according to  claim 4 ,
 wherein the reactive compound is used in an amount which corresponds to from 100 ppb to 200 ppm of the aqueous medium.   
     
     
         8 . The method of producing a low-molecular-weight polytetrafluoroethylene according to  claim 4 ,
 wherein the reactive compound is used in an amount which corresponds to from 100 ppb to 10 ppm of the aqueous medium.   
     
     
         9 . The method of producing a low-molecular-weight polytetrafluoroethylene according to  claim 3 ,
 wherein the fluorine-containing compound is used in an amount which corresponds to from 100 to 10,000 ppm of the aqueous medium.   
     
     
         10 . The method of producing a low-molecular-weight polytetrafluoroethylene according to  claim 3 ,
 wherein the modifying monomer which is copolymerizable with tetrafluoroethylene is hexafluoropropylene, perfluoropropyl vinyl ether or vinylidene fluoride.   
     
     
         11 . An aqueous dispersion of a low-molecular-weight polytetrafluoroethylene, which is obtained by the method of producing a low-molecular-weight polytetrafluoroethylene according to  claim 3 . 
     
     
         12 . A low-molecular-weight polytetrafluoroethylene, which is obtained by the method of producing a low-molecular-weight polytetrafluoroethylene according to  claim 3 . 
     
     
         13 . A coating, which comprises the aqueous dispersion of a low-molecular-weight polytetrafluoroethylene according to  claim 1 . 
     
     
         14 . An engineering plastic, which comprises the aqueous dispersion of a low-molecular-weight polytetrafluoroethylene according to  claim 1 , polytetrafluoroethylene according to  claim 12 . 
     
     
         15 . A cosmetic, which comprises the aqueous dispersion of a low-molecular-weight polytetrafluoroethylene according to  claim 1 . 
     
     
         16 . A grease, which comprises the aqueous dispersion of a low-molecular-weight polytetrafluoroethylene according to  claim 1 . 
     
     
         17 . A toner, which comprises the aqueous dispersion of a low-molecular-weight polytetrafluoroethylene according to  claim 1 .

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