Stable dispersion of high molecular weight polytetrafluoroethylene containing no additives and a process for the production thereof
AssigneeJapan Atomic Energy Research Institute
InventorsSueo Machi, Takeshi Suwa, Masaaki Takehisa, Tadao Seguchi
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Abstract
A stable aqueous dispersion of unexpectedly high molecular weight polytetrafluoroethylene, containing no additives such as dispersing and emulsifying agents, is prepared by radiation-polymerizating tetrafluoroethylene monomer in an aqueous phase in the absence of dispersing or emulsifying agent.
Claims7
A process for the production of a stable aqueous dispersion of high molecular weight polytetrafluoroethylene of molecular weight in the range of 5 .times. 10.sup.5 to 3 .times. 10.sup.7 and of average particle size of 0.05 to 0.3 microns, which comprises
- polymerizing while agitating in the substantial absence of oxygen tetrafluoroethylene monomer present in an amount of 3-50 parts by weight in 100 parts by weight of an aqueous medium by irradiation with ionizing radiation at 0-100.degree.C and a pressure of about atmospheric to 50 kg/cm.sup.2 in the absence of dispersing or emulsifying agents, the irradiation dose rate being greater than 1 .times. 10.sup.4 R/hr. and less than that dose rate leading to a violent reaction, and the total dose being in the region of 1 .times.to 10.sup.3 to 2 .times. 10.sup.5 R.
A process for the production of a stable aqueous dispersion of high molecular weight polytetrafluoroethylene of molecular weight in the range of 5 .times. 10.sup.5 to 3 .times. 10.sup.7 and of average diameter particle size of 0.05 to 0.3 microns, which comprises
- charging 3-50 parts by weight of tetrafluoroethylene monomer into 100 parts by weight of an aqueous medium containing neither a dispersing nor an emulsifying agent,
- continuously agitating the resulting mixture, and
- irradiating the mixture with ionizing radiation selected from the group consisting of alpha-rays, beta-rays, gamma-rays, X-rays, electron beams and proton beams, at a dose rate of about 1 .times. 10.sup.4 R/hr or more for a total dose of 1 .times. 10.sup.3 R to 2 .times. 10.sup.5 R, at a temperature of 0-100.degree.C and a pressure of 1 to 50 kg/cm.sup.2 and in the substantial absence of oxygen.
Dependencies are inferred from the claim text.