Abstract: A process for producing an aqueous polymer solution, including: (a) providing a hydrated polymer that has been prepared by aqueous solution polymerisation of ethylenically unsaturated monomers, which hydrated polymer contains at least 10% by weight active polymer; (b) cutting the hydrated polymer by subjecting the hydrated polymer to at least one cutting stage containing at least one stream of aqueous liquid at a pressure of at least 150 bar to reduce the size of the hydrated polymer; and (c) dissolving the hydrated polymer in an aqueous liquid so as to obtain an aqueous polymer solution. An apparatus for producing an aqueous polymer solution.

Abstract: A method for preparing an aqueous polyacrylamide solution, where the method includes: hydrating acrylonitrile in water in presence of a biocatalyst capable of converting acrylonitrile to acrylamide so as to obtain an acrylamide solution; directly polymerizing the acrylamide solution so as to obtain a polyacrylamide gel; and directly dissolving the polyacrylamide gel by addition of water so as to obtain an aqueous polyacrylamide solution, wherein the polyacrylamide gel is dissolved by water jet cutting.

Abstract: A method for preparing an aqueous polyacrylamide solution is disclosed. The method comprises:—hydrating acrylonitrile in water in presence of a biocatalyst capable of converting acrylonitrile to acrylamide so as to obtain an acrylamide solution,—directly polymerizing the acrylamide solution so as to obtain a polyacrylamide gel, and—directly dissolving the polyacrylamide gel by addition of water so as to obtain an aqueous polyacrylamide solution.

Abstract: A mixer heat exchanger insert or mixer heat exchanger insert arrangement, and a mixer heat exchanger with a corresponding mixer heat exchanger insert arrangement, which have improved mixing and temperature-control behavior, and have a reduced fouling tendency.

Abstract: A mixer/heat exchanger insert or mixer/heat exchanger having a geometry which leads to less fouling of a fluid to be temperature-controlled.

Abstract: Polyamides based on dicarboxylic acids and on diamines are produced in a batch process by 1) feeding the entire amount of monomer composed of dicarboxylic acids, of diamines, and, if appropriate, of further polyamide-forming monomers, in the desired stoichiometry, in a closed stirred-tank reactor, 2) heating the monomer mixture in the stirred-tank reactor, with stirring, and with setting of a certain pressure, to a desired reaction temperature for the production of a prepolymer, 3) if appropriate, completely or partially depressurizing the reaction mixture from stage 2), 4) if appropriate, carrying out further thermal treatment of the reaction mixture from stage 2) or 3), and 5) reacting the reaction mixture from stage 2), 3), or 4) in the melt in a vented extruder for further increase of the molecular weight, with discharge of water vapor, and without use of additional polyamide-forming monomers or of polyamides.

Abstract: The present invention provides a process for producing polyamides, which comprises a) providing a monomer composition comprising at least one lactam or at least one aminocarbonitrile and/or oligomers of these monomers, b) reacting the monomer composition provided in step a) in a hydrolytic polymerization at elevated temperature in the presence of water to obtain a reaction product comprising polyamide, water, unconverted monomers and oligomers, c) the reaction product obtained in step b) being fed into at least one kneader (3) and subjected to a postpolymerization, d) optionally forming the reaction product obtained in step c) to obtain polyamide particles, e) optionally treating the reaction product obtained in step c) or the polyamide particles obtained in step d) with at least one extractant.

Abstract: In a process for producing polyamides by polycondensation of polycondensable polyamide-forming monomers and/or oligomers in reaction mixtures comprising same, which may be water-containing but are free from organic solvents, the polycondensation is effected in an agitated reactor under agitation in a first step in the liquid phase and after a phase change taking place during the process in the same reactor is effected in a subsequent second step in the solid state, wherein the temperature in the reactor is below the melting point of the polyamide in the second step at least.

Abstract: The present invention relates to the use of polyolefin copolymers A) for reducing color changes during the heating of polymer compositions which contain at least one thermoplastic polyamide B).

Abstract: The present invention relates to a continuous process for the manufacture of highly-branched homo- or copolymers of C3-C8 ethylenically unsaturated mono- or dicarboxylic acid as well as the anhydrides and salts thereof (monomer A) by means of free-radical polymerization of monomer A and optionally water-soluble, monethylenically unsaturated comonomers (monomer B) in an aqueous medium in the presence of at least one water-soluble initiator, wherein the polymerization takes place in at least one tubular reactor segment.

Abstract: Process for producing polyamides that are stable during processing, by treating the polyamide during the solid-phase postcondensation process with a gas which comprises carrier gas (inert gas), water, and acid, or an anhydride or lactone or a mixture of these or, respectively, comprises ammonia, or amine, or a mixture of these, at a temperature from 130 to 200° C. and at a pressure of from 0.01 to 10 bar.

Abstract: The present invention relates to a process for preparing a polyamide based on dicarboxylic acids and diamines, comprising the following stages: A) providing an aqueous monomer mixture composed of dicarboxylic acids and diamines, where the molar ratio of dicarboxylic acids to diamines is adjusted such that, at the outlet of stage C), there is a molar deficiency of dicarboxylic acids or diamines of 1 to 10 mol %, based on the respective other component, B) transferring the aqueous mixture from stage A) into a continuous evaporator reactor in which diamines and dicarboxylic acids are converted at a temperature in the range from 100 to 370° C. and a pressure in the range from 1 to 50 bar, C) transferring the mixture from stage B) into a separator which is operated at a temperature in the range from 100 to 370° C.

Abstract: The present invention relates to a continuous process for the manufacture of highly-branched homo- or copolymers of C3-C8 ethylenically unsaturated mono- or dicarboxylic acid as well as the anhydrides and salts thereof (monomer A) by means of free-radical polymerization of monomer A and optionally water-soluble, monethylenically unsaturated comonomers (monomer B) in an aqueous medium in the presence of at least one water-soluble initiator, wherein the polymerization takes place in at least one tubular reactor segment.

Abstract: The invention relates to a continuous process for the preparation of amphiphilic graft polymers, wherein a vinyl ester component (B) composed of vinyl acetate and/or vinyl propionate (B1) and, if desired, a further ethylenically unsaturated monomer (B2), is polymerized in the presence of a polyalkylene oxide (A), a free radical-forming initiator (C) and, if desired, an additive (D), at a mean polymerization temperature at which the initiator (C) has a decomposition half-time of from 1 to 500 min, in at least one tubular reactor segment with a feed side and an outlet side, through which the reaction mixture comprising at least a part of component (A) to (C), and if desired (D), streams, a tubular reactor segment and the use of the inventive amphiphilic graft polymer. The invention further relates to an inventive amphiphilic graft polymer and the use thereof.

Abstract: The process for producing aromatic polyether sulfones via reaction of a dichlorodiphenyl sulfone component with a bisphenol component as monomers in the presence of alkali metal carbonate in the melt in the absence of solvents and diluents comprises carrying out the reaction in a mixing kneader which is operated with a shear rate in the range from 5 to 500 s?1.

Abstract: The process for producing aromatic polyether sulfones via reaction of a dichlorodiphenyl sulfone component with a bisphenol component as monomers in the presence of alkali metal carbonate in the melt in the absence of solvents and diluents comprises carrying out the reaction in a mixing kneader which is operated with a shear rate in the range from 5 to 500 s?1.

Abstract: The present invention relates to a process for purifying polyamide particles wherein these are contacted with a lactam-containing treatment medium with or without a gaseous treatment medium.

Abstract: The present invention relates to a detergent composition containing an amphiphilic graft polymer based on water-soluble polyalkylene oxides (A) as a graft base and side chains formed by polymerization of a vinyl ester component (B), where the polymer has a broad polarity distribution.

Abstract: The present invention relates to a process for preparing polyamides, comprising a hydrolytic polymerization and at least two extraction steps which are not in immediate succession.

Abstract: A continuous process for the multistage drying and postcondensation of polyamide pellets in the solid phase comprises 1) carrying out the predrying process in a continuous drying apparatus which is operated in countercurrent mode or in crossflow mode with inert gas or steam, or with a mixture of inert gas and steam, using a pellet temperature in the range from 70 to 200° C., and 2) Carrying out the subsequent continuous postcondensation process in a separate vertical duct with moving bed at a pellet temperature in the range from 120 to 210° C., where the duct is operated in countercurrent mode with inert gas or steam, or with a mixture of inert gas and steam, the inert gas is introduced at least two sites along the duct, and from 15 to 90% of the inert gas is introduced at the base of the vertical duct and from 10 to 85% of the inert gas is introduced in the upper half below the surface of the pellets.