摘要:
In a method of selecting polymerization catalysts, in particular Phillips catalysts for the polymerization of olefins, from a multiplicity of catalysts on the basis of their catalytic properties, a multiplicity of catalyst precursors or catalyst supports are converted in parallel into polymerization catalysts in a pretreatment step in an array of reactors, where the pretreatment comprises at least one thermal treatment step at from 250 to 1200° C. Furthermore, at least one starting material is converted with the aid of the respective polymerization catalysts under prescribed polymerization conditions into at least one polymer product in a polymerization step and, finally, analysis of the polymer product or products is carried out to determine its composition and/or chosen properties. This makes it possible to carry out a thermal pretreatment of polymerization catalysts quickly under defined conditions which can be varied.
摘要:
In a method of selecting polymerization catalysts, in particular Phillips catalysts for the polymerization of olefins, from a multiplicity of catalysts on the basis of their catalytic properties, a multiplicity of catalyst precursors or catalyst supports are converted in parallel into polymerization catalysts in a pretreatment step in an array of reactors, where the pretreatment comprises at least one thermal treatment step at from 250 to 1200° C. Furthermore, at least one starting material is converted with the aid of the respective polymerization catalysts under prescribed polymerization conditions into at least one polymer product in a polymerization step and, finally, analysis of the polymer product or products is carried out to determine its composition and/or chosen properties. This makes it possible to carry out a thermal pretreatment of polymerization catalysts quickly under defined conditions which can be varied.
摘要:
Polymers of ethylene are obtainable by polymerization of ethylene and, if desired, further comonomers in the presence of a catalyst system comprising as active constituents I) a Phillips catalyst, II) a solid which is different from I) and comprises a component which is derived from the metallocene complexes of the formula (A) in which the substituents and indices have the following meanings: R1 to R10 are hydrogen, C1-C10-alkyl, 5-to 7-membered cycloalkyl which may in turn bear C1-C6-alkyl groups as substituents, C6-C15-aryl or aryalkyl, where two adjacent radicals may also together form a cyclic group having from 4 to 15 carbon atoms, or Si(R11)3, where R11 is C1-C10-alkyl, C6-C15-aryl or C3-C10-cycloalkyl, or the radicals R4 and R9 together form a group —[Y(R12R13)]m—, where Y is silicon, germanium, tin or carbon, and R12, R13 are hydrogen C1-C10-alky, C3-C10-cycloalyl or C6-C15-aryl, M is a metal of transition groups IV to VIII or a metal of the lanthanide series, Z1, Z2 are fluorine, chlorine, bromine, iodine, hydrogen, C1-C20-alkyl or aryl, —OR14, —OOCR14, where R14 is hydrogen or C1-C20-alkyl; R15 is C1-C20-alkyl; m is 1,2,3 or 4; n is 0, or 2; r is 0, 1 or 2; the sum n+r is likewise 0, 1 or 2, and, if desired, III) an organometallic component selected from groups IA, IIA, IIB and IIIA of the Periodic Table of the Elements.
摘要:
Method of determining the composition of polymer mixtures comprising defined polymer components of differing mean molar masses Mn, which comprises the steps (a) recording of at least one 1H-NMR relaxation curve of the polymer mixture and (b) calculating the proportions of the polymer components by matching the measured relaxation curve with the relaxation curves of the individual polymer components. In this way, the composition of polymer mixtures can be determined quickly and simply. Furthermore, process integration for regulating the polymerization is possible.
摘要:
Method of determining the composition of polymer mixtures comprising defined polymer components of differing mean molar masses Mn, which comprises the steps (a) recording of at least one 1H-NMR relaxation curve of the polymer mixture and (b) calculating the proportions of the polymer components by matching the measured relaxation curve with the relaxation curves of the individual polymer components. In this way, the composition of polymer mixtures can be determined quickly and simply. Furthermore, process integration for regulating the polymerization is possible.
摘要:
In a low-odor polyethylene blend made from a high-molecular-weight ethylene copolymer obtainable by polymerization in the presence of a Ziegler catalyst and from a low-molecular-weight ethylene homopolymer or ethylene copolymer obtainable by polymerization in the presence of a chromocene catalyst on an oxidic support, the Al content of the high-molecular-weight component is from 5 to 60 mg/kg, the Al content of the low-molecular-weight component is from 0 to 5 mg/kg and the Al content of the blend is from 1 to 55 mg/kg. Processes are described for preparing blends of this type. Their use is described for producing moldings, in particular hollow articles and pipes. Moldings, in particular hollow articles and pipes, are produced from low-odor polyethylene blends.
摘要:
The invention relates to a method for conditioning double metal catalysts which are used in the production of polyether polyols. The conditioning enhances the performance of the catalyst, so that lower concentrations of the DMC catalyst can be used in polyether polyol production.
摘要:
When rolling sheets or strips in roll stands using working rolls, which are supported on back-up rolls or on intermediate rolls having back-up rolls, whereby the setting of the roll gap is effected by axially displacing roll pairs provided with curved contours, differences from the required profile occur in the instance of larger widths of a product range due to excessive extensions in the edge areas or in the quarter areas that are manifested in the form of so-called quarter waves in the flatness of the product. In order to rectify this problem by using a simple mechanism and to improve the setting mechanism and the strategy for creating absolutely planar strips with a predetermined thickness profile over the entire width of the rolling stock, the invention provides that for forming the roll gap set profiles (10, 11) for two selected displacing positions, the contours of the rolls of one roll pair are shaped in such a manner that they produce, in the roll gap, a profile (20, 21), which is symmetric with regard to the center of the roll and which has a profile maximum in the center of the roll that can be altered by displacing the rolls, whereas the contours of the rolls of at least one second roll pair produce, in the roll gap, a profile (22, 23), which is symmetric with regard to the center of the roll and which has two identical maxima outside of the center of the roll that can be altered by displacing the rolls.
摘要:
The present invention relates to plastic containers or moldings which have been produced by blow molding and have improved antistatic properties. The containers or moldings have an outer wall and an inner wall and contain webs of electrically conducting material running along the inner wall. The invention also relates to a process for the production of the containers or moldings and to their use.
摘要:
A multilayer composite plastics material, containing at least one layer (A), which consists, to an extent of least 90 wt %, based on the total weight of this layer, of ethylene homopolymers or copolymers, at least one barrier layer (B), which substantially consists of polybutylene terephthalate, and also, if desired, layers of adhesion promoter (C) serving to improve the adhesion between these layers.