DE1795664C3 - Process for the preparation of aqueous polytetrafluoroethylene dispersions and their use - Google Patents

Claims (2)

1 2 Trifluorochloroethylene is particularly suitable as a comonomer for the production of such modi patent claims: fized seed dispersions. 1. Modification of the> process for the manufacture. It has now been found that in this way development of aqueous polytetrafluoroethylene dispersions S modified aqueous polytetrafluoroethylene dispersion Polymerization of tetrafluoroethylene in nen with improved properties thereby obtained Aqueous dispersion can form with the help of free radicals, if one in a further embodiment of the Verdender Catalysts and in the presence of driving the patent 17 20 738 the polymerization of submitted colloidal Polytetrafiuoräthylen so- tetrafluoroethylene in the presence of a submitted as of anticoagulants, where as an anti- ίο colloidal dispersion of a copolymer of coagulant polyoxyalkylates or their tetrafluoroethylene and 5 percent by weight trifluoro ester carries out chloroethylene in quantities of 2 to 60 parts per million. Parts of the entire mixture are used, the subject of the invention is accordingly a according to patent 17 20 738, thereby changing the process for the production of aqueous shows that in place of the submitted polytetrafluoroethylene dispersions by polyincri lytetrafluoroethylene is a submitted colloidal dis- sation of tetrafluoroethylene in an aqueous dispersion pension of a copolymer of Tetrafluoräthy- with the help of free radical catalysts and Jen and 5 weight percent trifluorochloroethylene used in the presence of initially charged colloidal polytetras will. fluoroethylene and anticoagulants, where- 2. Use of the polyoxyalkylates or polyoxyalkylenes according to claim 1 as anticoagulants made polytetrafluoroethylene dispersions for their esters in quantities of 2 to 60 parts per million Production of paste extrudates. Parts of the whole mixture are used, according to patent 17 20 738, which is characterized in that instead of submitted polytetrafluoroethylene 25 len a submitted colloidal dispersion of a copolymer of tetrafluoroethylene and 5 percent by weight of trifluorochloroethylene is used. The subject of patent 17 20 738 is a process using the method according to the invention drive for the production of aqueous polytetrafluoroethylene possible to increase the proportion of a submitted, so modified ^ dispersions by polymerization of tetra- 3 ° decorated seed dispersion up to 25%, without using fuoräthylen in aqueous dispersion with the help of free that a disruptive coagulation occurs. This avoids catalysts which form free radicals and in the presence of the complex separation of coagulate from the initially charged colloidal polytetrafluoroethylene and excellent stabilization of the obtained and anticoagulants, with dispersion being achieved. In particular, the inventively improved, colloidal polytetrafluoroethylene-containing process according to the invention has advantages for the subsequent precipitation of the dispersion, which is stable in aqueous polytetrafluoroethylene dispersions, for use in paste extrusion which is obtained as an anticoagulant: of 2 nes result in a more uniform grain of the precipitated to 60 parts per million parts of the total mixture of product with a further reduced grain diameter used. Preferably, the polyoxyalkylenates 40 ser. The excellent quality of or their esters can thus be used in quantities of 5 to 15 parts per paste extrudate from polytetra million parts of the total mixture modified in this way. Improve even further by fluoroethylene dispersions. the numerous polyalkylates and their esters
• Ind especially suitable as emulsifiers commercially available products, preferably alkyl 45 example
phenol polyglycol ethers, such as nonylphenol polyglycol Ither, Triisobutylphenolpolyglykoläther as well as In a 150-1 autoclave is an aqueous Isodecyl alcohol polyglycol ether, polypropyleneoxy liquor filled in and so much of a seed glycol ether, Fatty acid polyglycol esters and polyoxal latex, obtained by copolymerization of tetrakylates von Fettamineii, where the number of oxyalkyl- 50 fluoroethylene and 5 percent by weight trifluorochloro groups is preferably between 2 and 20. ethylene, added that the total amount of colloidal Subject of an older proposal (DT-PS dalem polytetrafluoroethylene 1%, based on the 17 95 078) is a process according to which the total amount is predominantly. Then you give another 0.5Vo Aqueous disperfluorooctanoic acid containing polytetrafluoroethylene, 0.14% ammotion, 18% be prepared by 55 niacin water and 0.5 parts of copper sulfate, 52 parts of sodium trium bisulfite and 7 parts of isodecyl alcohol polyglycol a) Initially one seed stage through dispersion polyether per million parts. After having tetrafluoromerization at least 90 percent by weight of ethylene has been pressed to 19 atmospheres, it is pumped Tetrafluoroethylene and comonomers from the still 84 parts of ammonium persulfate per million parts Gruppe deir fluoroalkenes is produced and 60 and leaves the reaction at 95 to 107 rpm and that a temperature of 32 ° C to a solid b) this seed polymer dispersion presented and content of 25% to come to an end. The coagulum formation in a second stage a further disper- can practically be neglected. The precipitated one Sion polymerization with tetrafluoroethylene under- Polymer is excellent for paste extrusion will. 65 is particularly suitable for the manufacture of pipes.