3m Innovative Properties Company

Dyneon Gmbh

Gernot L&ouml;hr

Klaus Hintzer

Werner Schwertfeger

Harald Kaspar

Werner M A Grootaert

Franz M&auml;rz

Denis Duchesne

Friedrich Kloos

Ludwig Mayer

Reinhard Albert Sulzbach

Lisa P Chen

Ralph Kaulbach

Attila A Molnar

Stephan F&uuml;hrer

Hermann Bl&auml;del

Peter Stamprech

William D Coggio

Kai Helmut Lochhaas

Robert E Kolb

Albert Killich

Bernhard Hirsch

Guy Van Gool

Georg Burkard

Rebekka Epsch

Gerd Grossmann

Fluorine-containing emulsifiers can be removed from fluoropolymer dispersions by adding to the dispersion a nonionic emulsifier, removing the fluorine-containing emulsifier by contact with an anion exchanger and separating the dispersion from the anion exchanger. The resulting dispersions can be concentrated and used for coating applications.

Aqueous dispersions of fluoropolymers

The present invention discloses a process for making a fluoropolymer having nitrile endgroups. The process comprises a free radical polymerization of one or more fluorinated monomers in the presence of a nitrile group containing salt or a nitrile group containing pseudohalogen compound.

Process for making a fluoropolymer having nitrile end groups

Process for reducing the amount of fluorinated surfactant in aqueous fluoropolymer dispersions

A fluoropolymer having a reduced amount of polar end groups. The fluoropolymer is produced by free radical polymerization of fluorinated monomers and the initiation of the polymerization is carried out in the presence of a chloride salt. Polar end groups include hydroxy groups and ionized or ionizable end groups. Examples of ionized or ionizable end groups include acid groups and salts thereof such as sulfonic acid and salts thereof, &mdash;CH &mdash;OSO H groups, sulfates and carbonyl containing end groups such as carboxylic and carboxylate groups. Due to the presence of chloride salt at the initiation of the free radical polymerization, CF Cl end groups are formed instead of the polar end groups. As a result, a fluoropolymer is obtained that has improved processibility and heat resistance.

Process for producing fluoropolymers having a reduced amount of polar end groups

The invention provides a process for removing steam-volatile fluorinated emulsifiers in their free acid form, from aqueous fluoropolymer dispersions. The process comprises adding a nonionic emulsifier, to the aqueous fluoropolymer dispersion and, at a pH-value of the aqueous fluoropolymer dispersion below 5, removing steam-volatile fluorinated emulsifier by distillation until the concentration of steam-volatile fluorinated emulsifier in the dispersion reaches the desired value.

Method of making an aqueous dispersion of fluoropolymers

A low-molecular-weight copolymer of tetrafluoroethylene with units of perfluoro alkyl vinyl ethers having a melt index of &gE;30 suitable as a mixing component with a higher-molecular-weight copolymer of the same monomers for producing moldings in injection molding or by extrusion.

Mixtures of thermoplastic fluoropolymers

Fluorinated emulsifiers can be recovered from an aqueous phase containing small amounts of fluoropolymer particles by treating the aqueous phase with a small amount of a nonionic surface-active agent, bringing the aqueous phase adjusted in this way into contact with an anionic exchanger resin, and liberating the adsorbed emulsifier from the exchanger resin. The finely divided fluoropolymer can be precipitated quantitatively in the untreated aqueous phase or the eluate using flocculating agents.

Method for recovering fluorinated emulsifiers from aqueous phases

Emulsion polymerization of liquid fluorinated monomers which have a boiling point above 50&deg; C. and low water-solubility is markedly more efficient if the monomer is pre-emulsified with a nontelogenic fluorinated emulsifier in water.

Aqueous emulsion polymerization process for the manufacturing of fluoropolymers

Fluorinated emulsifiers, in particular, perfluorooctanoic acid are bound to anionic exchange resins for the purification of aqueous effluent from the production of fluoropolymers. Said emulsifiers may be quantitatively eluted from the exchanger with a water-miscible organic solvent, containing a small amount of ammonia. It is of advantage to distil off the ammonia containing solvent, recycle the emulsifier to a further polymerization and recycle the ammoniacal solvent for elution. Addition of alkalis improves the elution efficiency.

Method for recovering fluorinated emulsifiers

A fluoropolymer composition is provided. The polymer comprises interpolymerized units derived from (i) tetrafluoroethylene, (ii) vinylidene fluoride, (iii) at least one ethylenically unsaturated monomer of the formula CF &boxH;CFR where R is a perfluoroalkyl or a perfluoroalkoxy of 1 to 8 carbon atoms, and (iv) a perfluorovinyl ether of the formula CF &boxH;CF&mdash;(OCF CF(R )) OR where R is as described in (iii), R is a perfluoroaliphatic, preferably a perfluoroalkyl or a perfluoroalkoxy, of 1 to 8, preferably 1 to 3, carbon atoms, and a has a value of 0 to 3.

Fluoropolymers with improved characteristics

Curable fluoroelastomer compositions having improved compression set after curing are provided, as well as compositions that are of relatively high purity. These compositions include a hydrogen-containing fluoroelastomer having interpolymerized units derived from a cure-site monomer, a curative (optionally with a co-agent), and an organo-onium. When the fluoroelastomer contains units derived from vinylidene fluoride, the composition is essentially free from an inorganic acid acceptor. Methods of improving the compression of cured fluoroelastomer and cured fluoroelastomers having improved compression set are also provided.

Fluoropolymers

Aqueous dispersions of fluoropolymers obtained by emulsion polymerization and containing at least one fluoropolymer A) with an average particle size (number-average) of at least 200 nm and at least one fluoropolymer B) with an average particle size (number-average) of not more than 100 nm, one of components A) and B) being a thermoplastic and the other component not being processable from the melt, and the entire dispersion having a non-monomodal number distribution of particle diameter, are suitable for saturating, impregnating surfaces, for example of fibers or sheet-like articles made from fibers or porous materials, in particular for coating glass-fiber fabrics as well as for formulating metal-coating systems.

Aqueous dispersion of fluoropolymers of varying particle size

A fluoropolymer composition is provided. The polymer comprises interpolymerized units derived from (i) tetrafluoroethylene, (ii) vinylidene fluoride, (iii) at least one ethylenically unsaturated monomer of the formula CF &boxH;CFR where R is a perfluoroalkyl or a perfluoroalkoxy of 1 to 8 carbon atoms, and (iv) a perfluorovinyl ether of the formula CF &boxH;CF&mdash;(OCF CF(R )) OR&prime; where R is as described in (iii), R&prime; is a perfluoroaliphatic, preferably a perfluoroalkyl or a perfluoroalkoxy, of 1 to 8, preferably 1 to 3, carbon atoms, and a has a value of 0 to 3.

Non-free flowable, non-dusting molding powders with a bulk density of more than 450 g/l are obtained when a suspension polymer of tetrafluoroethylene with a content of 0.01 to 1% by weight of units of at least one perfluoro(alkyl-vinyl) ether is ground to a particle diameter of 10 to 50 &mgr;m and agglomerated in water.

Growing community of inventors

Burgkirchen, Germany

Gernot Löhr

Growing community of inventors

Burgkirchen, Germany

Gernot L&ouml;hr

Gernot Löhr