摘要:
The invention relates to a polyethylene molding composition having a multimodal molar mass distribution particularly suitable for blow molding films having a thickness in the range from 8 to 200 μm. The molding composition has a density at a temperature of 23° C. in the range from 0.953 to 0.960 g/cm3 and an MFR190/5 of the final product after extrusion in the range from 0.10 to 0.50 dg/min. The composition comprises from 30 to 60% by weight of a first ethylene polymer fraction made of a homopolymer A having a first molecular weight, from 22 to 40% by weight of a second ethylene polymer fraction made of a further homopolymer or first copolymer B of ethylene and at least one first comonomer from the group of olefins having from 4 to 8 carbon atoms, the first copolymer B having a second molecular weight higher than the first molecular weight, and from 10 to 30% by weight of a third ethylene polymer fraction made of a second copolymer C having a third molecular weight higher than the second molecular weight. The molding composition of the invention allows to produce thin films having improved processability without impairing the mechanical properties.
摘要:
Process for the preparation of a polyolefin polymer by continuously polymerizing one or more olefin monomers in suspension at temperatures of from 40° C. to 120° C. and pressures of from 0.1 to 10 MPa in the presence of a polymerization catalyst in at least one polymerization reactor, comprising a) withdrawing a suspension of solid polyolefin particles in a suspension medium from the polymerization reactor, wherein the suspension has a temperature of from 65° C. to 120° C.; b) feeding the suspension withdrawn from the polymerization reactor to a moderating vessel; c) keeping the suspension in the moderating vessel at a temperature of from 60° C. to 85° C. for a time sufficiently long that the mean residence time of the suspension in the moderating vessel is at least 5 min; d) withdrawing suspension from the moderating vessel; e) cooling the suspension withdrawn from the moderating vessel to a temperature of from 20° C. to 55° C.; and f) mechanically separating the solid polyolefin particles from the liquid suspension medium, and method for controlling the content of hydrocarbons with from 14 to 300 carbon atoms in a polyolefin polymer prepared by polymerizing one or more olefin monomers in suspension.
摘要:
A method for transitioning from a Ziegler-Natta to a Phillips catalyst system for the olefin polymerization reaction in one reactor, preferably a gas phase reactor, is described. The method comprises the steps of a) discontinuing a first olefin polymerization reaction performed in the presence of the Ziegler-Natta catalyst system; b) performing a second olefin polymerization reaction in the presence of a further catalyst system comprising catalyst components (A) and (B) producing, respectively, a first and a second polyolefin fraction, wherein the Mw of the first polyolefin fraction is less than the Mw of the second polyolefin fraction and the initial activity of catalyst component (A) exceeds the initial activity of catalyst component (B); and c) performing a third olefin polymerization reaction the presence of the Phillips catalyst system. Thanks to this method, there is no need to empty the reactor after each olefin polymerization reaction, and the transitioning time needed to attain the desired quality of the polyolefin obtained in each olefin polymerization reaction subsequent to the first one is sufficiently short to permit a quick and reliable change of production.
摘要:
A novel PE material is devised showing excellent mechanical/optical properties and process ability, e.g. for film extrusion. The polyethylene of the invention is produced in one single e.g. gas phase reactor.
摘要:
A process for homogenizing and pelletizing a polyethylene composition comprising the steps of a) providing a polyethylene composition having a density of from 0.90 g/cm3 to 0.97 g/cm3 and a melt flow rate MFR21.6 at 190° C. under a load of 21.6 kg of from 1 g/10 min to 80 g/10 min, b) melting the polyethylene composition; c) passing the melt through a combination of screens consisting of screens having a mesh opening of at least 205 μm and comprising at least two screens having a mesh opening of from 205 μm to 350 μm; and e) pelletizing the molten polyethylene composition, the use of a polyethylene composition obtained by such a process for the preparation of films, fibers, pipes, blow-molded articles, injection-molded articles, compression-molded articles or rotomolded articles and films, fibers, pipes, blow-molded articles, injection-molded articles, compression-molded articles or rotomolded articles prepared from a polyethylene composition obtained by such a process.
摘要翻译:一种聚乙烯组合物均质和造粒的方法,包括以下步骤:a)提供密度为0.90g / cm 3至0.97g / cm 3的聚乙烯组合物和190℃下的熔体流动速率MFR 21.6, 21.6kg,从1g / 10min至80g / 10min,b)熔融聚乙烯组合物; c)使熔体通过由具有至少205μm的网孔的筛网组成的筛网组合,并且包括至少两个网孔为205μm至350μm的筛网; 和e)使熔融的聚乙烯组合物造粒,使用通过这种制备薄膜,纤维,管,吹塑制品,注射成型制品,压塑制品或滚塑制品和薄膜的方法获得的聚乙烯组合物, 纤维,管,吹塑制品,注射成型制品,压塑制品或由通过这种方法获得的聚乙烯组合物制备的滚塑制品。
摘要:
New ethylene polymers having broad molecular weight distribution and long-chain branching, above all at high molecular weight fractions; the polymers have strain hardening equal or higher than 1.4 (at constant elongational rate of 0.5 s−1, at 150° C.), branching index g′ equal or lower than 0.9 (at Mw of 2·106 g/mol). The polymers are prepared by using a mixed catalyst system comprising a polymerization catalyst based on a late transition metal component having a tridentate ligand, and a Ziegler polymerization catalyst annealed at a temperature higher than 100° C., for a time of at least 10 minutes.
摘要翻译:新的乙烯聚合物具有宽分子量分布和长链支化,首先是高分子量级分; 聚合物具有等于或高于1.4的应变硬化(在150s的恒定伸长率为0.5s -1,支化指数g'等于或等于0.9)(Mw为2·10 6 g / mol)。 通过使用包含基于具有三齿配体的后过渡金属组分的聚合催化剂和在高于100℃的温度下退火的齐格勒聚合催化剂至少10分钟的混合催化剂体系来制备聚合物 。
摘要:
A process for homogenizing and pelletizing a polyethylene composition comprising the steps of a) providing a polyethylene composition having a density of from 0.90 g/cm3 to 0.97 g/cm3 and a melt flow rate MFR21.6 at 190° C. under a load of 21.6 kg of from 1 g/10 min to 80 g/10 min, b) melting the polyethylene composition; c) passing the melt through a combination of screens consisting of screens having a mesh opening of at least 205 μm and comprising at least two screens having a mesh opening of from 205 μm to 350 μm; and e) pelletizing the molten polyethylene composition, the use of a polyethylene composition obtained by such a process for the preparation of films, fibers, pipes, blow-molded articles, injection-molded articles, compression-molded articles or rotomolded articles and films, fibers, pipes, blow-molded articles, injection-molded articles, compression-molded articles or rotomolded articles prepared from a polyethylene composition obtained by such a process.
摘要翻译:一种聚乙烯组合物均质和造粒的方法,包括以下步骤:a)提供密度为0.90g / cm 3至0.97g / cm 3的聚乙烯组合物和190℃下的熔体流动速率MFR 21.6, 21.6kg,从1g / 10min至80g / 10min,b)熔融聚乙烯组合物; c)使熔体通过由具有至少205μm的网孔的筛网组成的筛网组合,并且包括至少两个网孔为205μm至350μm的筛网; 和e)使熔融的聚乙烯组合物造粒,使用通过这种制备薄膜,纤维,管,吹塑制品,注射成型制品,压塑制品或滚塑制品和薄膜的方法获得的聚乙烯组合物, 纤维,管,吹塑制品,注射成型制品,压塑制品或由通过这种方法获得的聚乙烯组合物制备的滚塑制品。