摘要:
The present invention provides a novel one-step process for preparing an aqueous polymer dispersion by the free radical aqueous emulsion polymerization comprising mixing at least water, a dispersant, and an oil-soluble initiator; raising a temperature from the starting to the end reaction temperature while metering at least ethylenically unsaturated monomers and a water-soluble initiator into a reaction vessel, conducting polymerization of the monomers in the presence of the water-soluble initiator at a temperature up to the end reaction temperature, and when the temperature has reached the end reaction temperature, conducting polymerization by the oil-soluble initiator. The oil-soluble initiator is inactive at the starting reaction temperature and becomes more active as a temperature approaches the end reaction temperature at which the oil-soluble initiator is fully active.
摘要:
An aqueous polymer dispersion is prepared by free radical aqueous emulsion polymerization of at least one ethylenically unsaturated compound (monomer) in the presence of at least one dispersant and at least one water-soluble and one oil-soluble free radical initiator by a process in which the polymerization temperature increases from the starting reaction temperature TS to the end reaction temperature TE in the course of the polymerization reaction.
摘要翻译:在至少一种分散剂和至少一种水溶性和一种油溶性自由基引发剂的存在下,通过至少一种烯键式不饱和化合物(单体)的自由基水性乳液聚合制备聚合物水分散体,其中 在聚合反应过程中,聚合温度从起始反应温度T S S增加到最终反应温度T E E。
摘要:
The invention provides a process for preparing expandable styrene polymers which comprises the steps of:(a) adding an aqueous phase comprising a suspension stabilizer and an organic phase comprising styrene and an initiator to a reactor,(b) commencing the addition of a blowing agent at a styrene conversion in the range from 40 to 70% and adding the blowing agent over a period ranging from 30 to 60 minutes,(c) adding a stabilizer to stabilize the bead size distribution of the expandable styrene polymer at a styrene conversion in the range from 65 to 99%.
摘要:
The invention provides a process for preparing expandable styrene polymers which comprises the steps of: (a) adding an aqueous phase comprising a suspension stabilizer and an organic phase comprising styrene and an initiator to a reactor, (b) commencing the addition of a blowing agent at a styrene conversion in the range from 40 to 70% and adding the blowing agent over a period ranging from 30 to 60 minutes, (c) adding a stabilizer to stabilize the bead size distribution of the expandable styrene polymer at a styrene conversion in the range from 65 to 99%.
摘要:
Catalyst systems of the type comprising the Ziegler-Natta catalysts contain, as active components,a) a titanium-containing solid component which contains titanium, magnesium, halogen and a carboxylic ester as an electron donor, and, as a cocatalyst,b) an aluminum compound andc) if required, a further electron donor, a compound of the following formula IR.sub.m.sbsb.1 Al--(OCOR.sup.1).sub.m.sbsb.2 (I)whereR and R.sup.1 are identical or different and are each hydrogen or C.sub.1 -C.sub.8 -alkyl andm.sub.1 and m.sub.2 are each 1 or 2 and sum to give 3, being used as aluminum compound b) in the preactivation of the titanium-containing soild compound a) with the cocatalyst.
摘要:
Propylene polymers have a molecular weight ratio Q (M.sub.w /M.sub.n) of from 6 to 30 and are obtainable by Ziegler-Natta polymerization in the presence of hydrogen as molecular weight regulator and are particularly suitable for the production of films and moldings.
摘要:
The invention relates to a process for continuously preparing styrene polymers by anionic spray polymerization, which comprises i) styrene and the initiator solution being mixed in a dynamic or static mixer and then the mixture being sprayed, ii) the resultant droplets passing from the liquid monomer state to the melted polymer state during their free fall in the spraying tower, iii) the melt droplets being collected as a melt at the foot of the tower, the melt having a monomer content of below 1%, preferably below 0.1% (
摘要:
High-flow propylene/ethylene copolymers which have a melt flow index of from 2 to 200 g/min under a load of 2.16 kg at 230.degree. C. and which may be produced from the gas phase by polymerization in two stages in an agitated fixed bed in the presence of hydrogen acting as chain stoppage regulator and using a Ziegler-Natta catalyst system comprising a titaniferous solid component which contains a magnesium compound on finely divided silicon oxide or on finely divided aluminum oxide or on a finely divided aluminum silicate having the empirical formula SiO.sub.2.aAl.sub.2 O.sub.3, where a stands for a value between 0.001 and 2, and an aluminum component, by means of a procedure comprisinga) a first polymerization stage in which propylene is polymerized under a pressure of from 20 to 40 bar and at a temperature of from 60.degree. to 90.degree. C., the ratio of the partial pressure of the hydrogen to that of the propylene being adjusted to from 1:100 to 10:100, followed byb) a second polymerization stage, which consists in the polymerization, at a temperature of from 40.degree. to 100.degree. C., of a mixture of propylene and ethylene and the addition thereof, in the form of polymerized units, to the polypropylene produced in the first polymerization stage, the pressure in this second polymerization stage being from 10 to 30 bar and at least 7 bar lower than that used in the first polymerization stage, while the ratio of the partial pressure of the hydrogen to that of the propylene is adjusted to from 2:100 to 12:100 and the ratio of the weight of monomer converted in the first stage to that of monomer converted in the second stage is kept within the range of 1:1 to 20:1.
摘要:
Metallocene catalyst systems for the polymerization of C.sub.2 -C.sub.10 -alkenes are obtainable by deactivation of a preactivated metallocene catalyst system which contains, as active components, a metallocene complex of a metal of subgroup IV or V of the Periodic Table and an oligomeric alumoxane compound and, if required, subsequent reactivation.
摘要:
Propylene-ethylene copolymers are obtained by two-stage polymerization from the gaseous phase in an agitated fixed bed by means of a Ziegler-Natta catalyst system that contains in addition to a titanium-containing solid component also an aluminum compound as co-catalyst, wherein as Ziegler-Natta catalyst system a system is used which, following the reaction of the titanium-containing solid component with the co-catalyst, is deactivated by reaction with carbon dioxide. The copolymers are used for producing fibers, films and moldings.