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:
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 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:
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.
摘要:
The use of a formaldehyde-free aqueous binder comprisingA) a polymer obtained by free-radical polymerization comprising 5-100% by weight of an ethylenically unsaturated acid anhydride or of an ethylenically unsaturated dicarboxylic acid whose carboxyl groups may form an anhydride group, andB) an alkanolamine having at least two hydroxyl groupsas a coating composition for shaped articles.
摘要:
A method for forming shaped products by mixing a formaldehyde-free aqueous binder comprising A) a free-radically polymerized polymer containing from 5 to 100% by weight of units derived from an ethylenically unsaturated acid anhydride or from an ethylenically unsaturated dicarboxylic acid whose carboxyl group can form an anhydride group, and B) an alkanolamine having at least two hydroxyl groups, with fibers or chips to form a shaped article, wherein said binder has a property of drying at 50.degree. C. in 72 hours to a film from 0.3 to 1 mm in thickness and, following a subsequent 15 minute cure at 130.degree. C. in air, has a gel content of above 50% by weight, wherein the binder includes less than 0.1% by weight, based on A)+B), of a phosphorus-containing reaction accelerant with fibers or chips.
摘要:
A coating agent comprises an emulsion polymer obtained by free radical emulsion polymerization of a monomer mixture ofA) from 15 to 60% by weight of an acrylic or methacrylic ester having a primary or secondary C.sub.1 -C.sub.18 -alkyl group, as alcohol radical,B) from 15 to 50% by weight of an acrylic or methacrylic ester having tertiary C.sub.4 -C.sub.8 -alkyl group or a C.sub.6 -C.sub.12 -radical that is an alicyclic or aromatic group as alcohol group a methacrylic ester having a primary or secondary C.sub.2 -C.sub.4 -alkyl group as alcohol radical, acrylo- or methacrylonitrile, acryl- or meth-acrylamide, a vinyl ester of a C.sub.1 -C.sub.8 - carboxylic acid,C) from 10 to 50% by weight of one or more C.sub.8 -C.sub.12 - aromatic vinyl compounds,D) from 8 to 20% by weight of an olefinically unsaturated C.sub.3 -C.sub.5 -mono- or C.sub.4 -C.sub.8 -dicarboxylic acid or anhydride, andE) from 0 to 5% by weight of further copolymerizable monomers having functional groups in the presence of from 0.1 to 10% by weight, based on the monomer mixture of A to E, of an emulsifier mixture of(a) one or more anionic emulsified of formula I where ##STR1## M is an alkali metal or ammonium and X and Y are identical or different and each is O--(C.sub.n H.sub.2n O).sub.m --R, OM or NHR, wherein at least one of the radicals X and Y is O--(C.sub.n H.sub.2n O).sub.m --R or NHR, and(b) from 0.1 to 10 parts by weight per part by weight of (a) of at least one further different anionic emulsifier.