公开(公告)号：JPH0420534A

公开(公告)日：1992-01-24

申请号：JP12383290

申请日：1990-05-14

Applicant: DAIKIN IND LTD

Inventor： HOSOKAWA KAZUTAKA ,  SHIMIZU TETSUO ,  ISHIWARI KAZUO ,  YAMANE NORIYASU

IPC: C08J3/12

Abstract: PURPOSE:To prepare a polytetrafluoroethylene powder in the form of a dense particle, improved in purity and being useful as a modifier for inks, coating materials, etc., by heat-treating an unfired polytetrafluoroethylene powder and grinding the resultant powder to a powder having a specified mean particle diameter and a specified specific surface area. CONSTITUTION:Tetrafluoroethylene is (co)polymerized with optionally 1wt.% or below comonomer at 10-120 deg.C under a pressure of 6-40kg/cm in an aqueous medium in the presence of a water-soluble fluorinated dispersant and an initiator to obtain an aqueous dispersion of colloidal polytetrafluoroethylene. This dispersion is coagulated and dried to obtain an unfired polytetrafluoroethylene powder of an m.p. of 313-330 deg.C, desirably 318-328 deg.C. This powder is heat-treated at a temperature lower than the m.p. by 70 deg.C to the m.p. for 1-120min and ground to obtain the title powder of a mean particle diameter of 1-30mum and a specific surface area of 2-6m /g.