摘要:
A process is described for effectively reducing the residual monomer content of an aqueous polymer dispersion by aftertreatment at atmospheric pressure or above with an initiator system comprising a) a hydroperoxide, hydrogen peroxide or a peracid, and b) an &agr;-hydroxy carboxylic acid, such as tartaric acid, or with a salt thereof.
摘要:
A process is described for reducing the residual monomer content in a liquid solution, mixture, melt, suspension or dispersion of a polymer by postpolymerization with addition of a redox initiator system at a reaction temperature appropriate to it and with an extremely short mixing time of the liquid system in the production reactor by metering—gradually, in portions or continuously—at least one of the redox initiator components required to initiate polymerization of the residual monomers over a period (metering time) which is from about 10 to 250 times the mixing time of the liquid system in said reactor.
摘要:
A process for deodorizing and subsequently cooling dispersions or liquids comprisinga) passing steam through the dispersion or liquid to be cooled and held in a vessel (1), said dispersion or liquid being caused to foam up as a result,b) discharging the foam from the top section of the vessel via a nozzle (5) into an evacuated separation vessel (4), the foam being broken in the process,c) condensing the water vapor formed from the foam in a heat exchanger (8) and removing volatile organic components at the same time, andd) returning the broken foam to the vessel (1),in which the steps a) to d) are performed until the dispersion or liquid has been deodorized to the desired extent, wherein, after completion of the deodorization (in accordance with steps a) to d)), the hot dispersion or liquid is discharged from the bottom section of the vessel (1) through the nozzle (5) into the evacuated separation vessel (4), so that the dispersion or the liquid is cooled, the nozzle (5) and the evacuated separation vessel (4) also being used beforehand for performing step b), wherein the water vapor held in the separation vessel (4) is condensed at the heat exchanger (8) which was also employed beforehand in step c), and wherein the cooled dispersion or liquid is discharged from the bottom of the separation vessel (4).
摘要:
At least one single-stage or multistage stirrer which produces not only a tangential flow component but also an axial flow field is used in a stirred-vessel reactor in connection with the preparation of polymers by liquid phase polymerization.
摘要:
A reactor for chemical reactions, especially polymerization reactions, and in particular a reactor for emulsion, suspension, solution, bulk and/or precipitation polymerizations, which has a stirring mechanism, incoming and outgoing lines and a removable lid, and where both the stirring mechanism and incoming and outgoing lines are installed on the reactor floor. The novel reactor is quick and easy to open and clean and permits simple and rapid changeover of the installed stirring elements.
摘要:
Provided is a method for performing a polymerization process in a stirred reactor, wherein a critical time window is determined by means of a monitor of at least one polymerization process parameter and an associated process window, and when a critical time window is present, an adaptation of process conditions is made in order to configure the polymerization process to conform to the process window.
摘要:
A process for preparing recyclable fiber composites, comprising bonding fibers with a polymeric bonding agent applied as an aqueous polymer dispersion to said fibers, the polymeric bonding agent comprising at least one addition polymer which, in the state of an aqueous dispersion, has a film forming capability at the temperature at which the addition polymer is combined with said fibers, and said aqueous polymer dispersion, when subjected to a change in pH, is converted into an aqueous solution of the addition polymer. The aqueous addition polymer of the addition polymer dispersion can contain protic acid groups, and the state of the dispersion can be converted to an aqueous addition polymer solution by raising the pH of the aqueous medium. Alternatively, the addition polymer may contain basic groups, in particular, amino groups, and its state as a dispersion can be converted into an aqueous addition polymer resolution by lowering the pH of the aqueous medium.
摘要:
Organic compounds containing —CH2—CHR—O— and/or —CH2—CH(OH)— groupings (R=H, C1-C4-alkyl) produce, under the action of free radicals, small amounts of C1-C2-aldehydes, the content of which can be reduced to
摘要:
Formaldehyde-free aqueous synthetic resin dispersions are obtainable by single-stage emulsion polymerization of monomer mixtures containing (A) from 50 to 99% by weight of at least one monomer selected from the group consisting of the acrylic and methacrylic esters of C.sub.1 -C.sub.14 -alkanols, the vinyl esters of monocarboxylic acids having up to 5 carbon atoms, and styrene (monomer A), (B) from 0.5 to 40% by weight of at least one of the monomers acrylonitrile and methacrylonitrile (monomer B), (C) from 0.5 to 10% by weight of at least one monomer of the general formula I ##STR1## where R.sup.1 is hydrogen or methyl and R.sup.2 and R.sup.3 are each independently of the other hydrogen or C.sub.1 -C.sub.4 -alkyl (monomer C), (D) from 0 to 5% by weight of at least one monomer selected from the group consisting of the 3 carbon to 5 carbon .alpha.,.beta.-unsaturated mono- and dicarboxylic acids and their amides and anhydrides (monomer D), and (E) from 0 to 3% by weight of at least one further bifunctional monomer (monomer E).
摘要:
The present invention relates to a method for performing a polymerization process in a stirred reactor, wherein a critical time window is determined by means of a monitor of at least one polymerization process parameter and an associated process window, and when a critical time window is present, an adaptation of process conditions is made in order to configure the polymerization process to conform to the process window.