Wacker Chemie Ag

Wacker-chemie Gmbh

Wacker Polymer Systems Gmbh & Co. Kg

Robert Braunsperger

Hans-Peter Weitzel

Karl Braunsperger

Reiner Figge

Rudolf Braun

Stefan Oberneder

Herbert Sollradl

Jessica Seidel

Peter Schultheiss

Michael Angerer

A polymerization reactor for producing aqueous polymer dispersions by radically initiated emulsion polymerization of one or more ethylenically unsaturated monomers in the presence of one or more protective colloids and/or emulsifiers, is cleaned by initially charging an aqueous mixture comprising one or more ethylenically unsaturated monomers, one or more protective colloids and/or emulsifiers, but no oxidation initiator, the proportion of ethylenically unsaturated monomers being 20 to 70% by weight of the aqueous mixture, heating the aqueous mixture to a temperature of 50° C. to 100° C. for 5 minutes to 3 hours, adding one or more initiators and optionally further starting materials, initiating polymerization, removing the aqueous polymer dispersion thus obtained from the polymerization reactor and post-treating the dispersion to remove wall deposits detached during the process.

Method for cleaning a polymerisation reactor

Aqueous polymer dispersions are produced by radically initiated emulsion polymerization of ethylenically unsaturated monomers in the presence of protective colloids and/or emulsifiers in a continuously operated tubular reactor, characterized in that the direction of flow of the reactor contents is reversed along the longitudinal axis of the reactor over the course of polymerization.

Method for producing aqueous polymer dispersions in a tube reactor

A method for producing aqueous polymer dispersions by means of radically initiated emulsion polymerisation, in an aqueous medium, of vinyl ester and ethylene, in series-connected polymerisation reactors, wherein in a first discontinuous polymerisation phase at least some of the reactants are introduced into the first polymerisation reactor and the remainder is added in a metered fashion. The reactor is filled up to more than 90% by volume, and at least 90 wt % of the monomers are reacted; in a second continuous polymerisation phase, the reactants are continuously supplied to the first polymerisation reactor and product is continuously withdrawn, and the product is continuously transferred into a second polymerisation reactor, and in the second polymerisation reactor the polymerisation is continued until at least 98 wt % of the monomers used have reacted.

Semi-continuous method for emulsion polymerisation

The invention provides a process for preparing polymers based on vinyl ester, ethylene and optionally further comonomers in the form of aqueous polymer dispersions thereof or of water-redispersible polymer powders by means of free-radically initiated continuous emulsion polymerization and optionally drying of the resulting polymer dispersions, characterized in that the emulsion polymerization is carried out in a cascade comprising at least one upstream heat exchanger and at least two downstream pressurized stirred tank reactors connected in series, such that the conversion on leaving the heat exchanger is at least 10% of the overall polymerization conversion.

Continuous polymerization process

A process for preparing copolymers via free-radical-initiated polymerization of one or more vinyl esters, ethylene, and also, where appropriate, other ethylenically unsaturated monomers copolymerizable therewith, at a pressure of from 5 to 100 bar abs., in an aqueous medium, by emulsion or suspension polymerization, which comprises, after termination of the polymerization, reclaiming residual unreacted ethylene by depressurizing the polymerization reaction mixture to a pressure of from 0.1 to 5 bar absolute, comprising a gas phase containing residual ethylene gas to a pressure of from 2 to 20 bar absolute, absorbing the gas phase into vinyl ester(s), and reusing the resulting solution of ethylene in vinyl esters(s) in a further polymerization.

Process for reclaiming residual ethylene in the preparation of vinyl ethylene copolymers

Process for preparing protective-colloid-stabilized polymers by continuous emulsion polymerization

The invention relates to a method of producing protective colloid free, aqueous dispersions of vinyl ester co-polymers by radical emulsion polymerization of 40 to 99.5 weight percent vinyl acetate, 0 to 40 weight percent of one or several alkenes, 0 to 40 weight percent of one or several monomers from the group consisting of vinyl esters of C,to C,alkyl carboxylic acids, and of (meth)acrylic-acid esters of alcohols with 1 to 12 C atoms and optionally, additional copolymerizable mono- or poly-ethylenically unsaturated monomers. Said method is characterized in that 0.1 to 5 weight percent of one or several emulsifiers are polymerized with a persulfate initiator in the presence of 0.5 to 20 weight percent mono- or poly-ethylenically unsaturated carboxylic acid amides or derivatives thereof. The invention also relates to a method for producing protective colloid-free dispersion powders by spray drying or freeze drying said dispersions.

Method for producing protective colloid-free dispersions and dispersion powders

Thickeners based on carboxyl-and carboxamido-containing addition polymers

Aqueous dispersions of organopolysiloxanes comprising (A) an organopolysiloxane containing groups which are capable of condensation, (B) a condensation catalyst, (C) an organopolysiloxane resin which is at least partly soluble in organopolysiloxane (A) when present in amounts of up to 50% by weight based on the weight of (A), (D) a compound containing basic nitrogen and (E) polyvinyl alcohol. The aqueous dispersions are prepared by dissolving the organopolysiloxane resin (C) in the organopolysiloxane (A) and then emulsifying the solution with polyvinyl alcohol (E) and water. The stable aqueous dispersions of the present invention cure to form transparent films.

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Emmerting, Germany

Robert Braunsperger