Patent ID: 9346903
Filing Date: 2016-05-24
CPC Classification: C08F,C08L,Y10T

Claim Text:
1. A modified polytetrafluoroethylene fine powder constituting a particle core and a particle shell, wherein said particle core comprises a modified polytetrafluoroethylene (i) resulting from copolymerization with at least one modifier selected from the group consisting of a fluoro(alkyl vinyl ether) represented by the general formula (I): (wherein X (wherein X the modifier-derived modifier unit content in the particle core is 0.01 to 0.5% by mass based on all the primary particles constituting the modified PTFE fine powder, said particle shell comprises a modified polytetrafluoroethylene (ii), wherein the modification in the modified polytetrafluoroethylene (ii) is carried out by using a chain transfer agent and by copolymerizing a fluoro (alkyl vinyl ether) represented by the general formula (I): (wherein X or a fluoroolefin represented by the general formula (III): (wherein X the chain transfer agent comprises at least one member selected from the group consisting of water-soluble alcohols containing 1 to 4 carbon atoms, hydrocarbons containing 1 to 4 carbon atoms and fluorinated hydrocarbons containing 1 to 4 carbon atoms, wherein the content of a modifier unit derived from the modifier in the particle shell is 0.005 to 0.5% by mass based on all primary particles constituting the modified PTFE fine powder, and said modified polytetrafluoroethylene fine powder has the cylinder extrusion pressure at a reduction ratio of 1600, using an extruder according to ASTM D 4895, of not higher than 50 MPa.