摘要:
A crosslinkable powder composition is provided which is redispersible in water and comprises a) from 30 to 95 parts by weight of a water-insoluble, film-forming polymer of one or more free-radically polymerizable, ethylenically unsaturated monomers, b) from 5 to 70 parts by weight of a water-soluble polymer, where at least one of the polymer components a) and b) comprises one or more comonomer units containing reactive groups which can form a chemical, nonionic bond with one another or with crosslinkers, and the parts by weight of a) and b) add up to 100 parts by weight, and c) from 0.01 to 5% by weight, based on the total weight of a) and b), of at least one phase transfer catalyst.
摘要:
A process is provided for preparing crosslinkable binders in the form of the aqueous dispersions by polymerizing vinyl ester-olefin copolymers in the presence of protective colloid, which comprises polymerizing vinyl ester-olefin copolymers having a Tg of less than −10° C. by emulsion polymerization in the presence of a protective colloid based on (meth)acrylate polymers comprising from 80 to 95% by weight, based on the overall weight of the polymer, of acrylates or methacrylates of aliphatic alcohols of 1 to 12 carbon atoms and from 5 to 20% by weight, based on the overall weight of the copolymer, of ethylenically unsaturated monocarboxylic or dicarboxylic acids, the latter copolymer having a glass transition temperature Tg of from 60 to 120° C., and, after the end of polymerization, introducing the crosslinkable groups by reacting the carboxyl groups of the (meth)acrylate polymers with ethylenically unsaturated compounds comprising functions suitable for esterifying the carboxyl group.
摘要:
The crosslinkable nematic polyorganosiloxanes are cyclic polyorganosiloxanes containing at least three different mesogenic side groups per polyorganosiloxane, where at least two mesogenic side groups per polyorganosiloxane each contain at least three radicals selected from aromatic, heteroaromatic and cycloaliphatic radicals. They contain a methacrylic or acrylic group in at least one of the mesogenic side groups. The cyclic polyorganosiloxanes have a broad nematic phase and can be readily aligned.
摘要:
A method for processing wastewater and exhaust gas condensates from the polymerization of vinyl acetate and ethylene and optionally other comonomers in an aqueous medium by suspension or emulsion polymerization employs relieving pressure after completion of the polymerization of the polymerization batch and discharging the polymer dispersion. During the relieving, the gaseous phase is removed by means of a compressor. Optionally, the gaseous phase occurring during stripping is removed by the compressor and cooled by one or more heat exchangers before entry into the compressor. The liquid phases occurring in the compressor and optionally in the heat exchanger are separated from the gaseous phase and the liquid phases are given to a rectification column, and separated into a vinyl acetate monomer phase and a wastewater phase, and the vinyl acetate monomer phase is resupplied to polymerization.
摘要:
A process for aqueous, free-radically initiated, continuous emulsion polymerization of A) at least one vinyl ester and optionally at least one (meth)acrylic ester, B) ethylene, and C) 0 to 10% by weight of one or more ethylenically unsaturated, functionalized comonomers, in the presence of 3.0 to 12.5% by weight of one or more emulsifiers, where at least 50% by weight are nonionic emulsifiers, and 0 to 10% by weight of one or more protective colloids, in a stirred tank cascade with at least two pressure reactors connected in series and with at least one low-pressure reactor connected downstream.
摘要:
Copolymers of ethylene and vinyl chloride also containing a protective colloid, optionally in conjunction with a fatty acid compound or precursor thereof or with an organosilicon compound, can be employed to increase the water repellency of hydraulically settable construction materials.
摘要:
Redispersible polymer powders which are cationically stabilized by spray drying a polymer dispersion with a cationic polymer can be used in higher concentrations in chemical building construction materials without introducing adverse properties.
摘要:
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.
摘要:
A process for preparing aqueous dispersions or water-redispersible polymer powders of polyvinyl-alcohol-stabilized polymers based on vinyl ester(s), and ethylene, by continuous emulsion polymerization with no seed latex, and optionally drying the dispersion, by a) polymerizing in at least two pressurized reactors in series at a temperature of 40 to 100° C. and a pressure of 5 to 100 bar to a residual monomer content of less than 3% by weight, and continuing polymerizing in an unpressurized reactor at 20 to 60° C. and less than 1.0 bar; b) initiating polymerization by a redox system containing oxidizing and reducing components, at least part of the reducing component introduced within the first pressurized reactor, c) metering polyvinyl alcohol into the first pressure reactor such that its proportion is ≦6% by weight, based on the monomers continuously introduced to the reactor, d) introducing 10 to 60% by weight of total vinyl ester into the second pressure reactor, e) maintaining a weight ratio of redox system oxidation component to monomer of from 0.03 to 0.07 in the first reactor, and f) a residence time of 2.5 hours or less in that reactor.
摘要:
Solventlessly preparable coating compositions for producing soiling-resistant coatings, comprise: a) at least one film-forming polymer of one or more vinyl ester, (meth)acrylate, vinylaromatic, olefin, 1,3-diene, or vinyl halide monomers, and, if desired, further monomers copolymerizable therewith, in the form of an aqueous dispersion or water-redispersible powder, b) one or more photoinitiators and/or fungicides, c) at least one pigment, d) one or more fillers, and, if desired, e) further additives, wherein the photoinitiators and fungicides b) are in the form of complexes with cyclodextrin or its derivatives.