茂金属催化剂及茂金属聚丙烯进展

介绍茂金属催化剂性能特点，发展概况及茂金属聚丙烯的工业化进展情况。     

Ziegler-Natta/茂金属复合催化剂制备双峰聚乙烯

通过把茂金属催化剂负载在Ziegler-Natta催化剂上制备了ZM复合催化剂,在单一聚合反应器内研究了ZM催化剂用于乙烯聚合制备双峰聚乙烯的性能。考察了催化剂中茂金属化合物的含量、聚合过程中反应温度、助催化剂的用量和共聚单体1-己烯的用量对催化剂乙烯聚合性能的影响规律。结果表明：采用ZM催化剂可以在单反应器内催化乙烯聚合得到分子量分布呈双峰的聚乙烯,聚乙烯的分子量分布达到155,聚合活性可达2.52×10⁷ g/molMt·h。     

茂金属聚丙烯催化剂概述

聚丙烯是一种生活中应用非常广泛的材料,其中丙烯聚合催化剂的进步是聚烯烃工业蓬勃发展的关键。具有独特性能和优势的茂金属聚丙烯催化剂在过去的几十年中引起了人们极大的研究兴趣。综述了茂金属聚丙烯催化剂的结构、组成,助催化剂以及茂金属催化丙烯聚合机理。重点介绍了非桥联茂金属催化剂以及桥联茂金属催化剂,其中桥联茂金属化合物因桥基的刚性骨架结构,使得其与聚丙烯规整度紧密相连。还详细介绍了C_2、C_(2v)、C_s、C_1不同对称性对聚丙烯规整度的影响。     

茂金属催化剂及茂金属聚乙烯现状

综述了茂金属催化剂的发展和茂金属聚乙烯(mPE)产品的工业化现状,国内外mPE生产工艺、产品牌号、应用领域及国内mPE开发现状。茂金属催化剂活性高,可精确定制聚乙烯树脂的分子结构,用其制备的聚乙烯具有较窄的相对分子质量分布。限制几何构型催化剂技术与溶液聚合工艺相结合可以在分子结构上控制短支链和长支链在主链上的分布及产品的相对分子质量分布。我国茂金属催化剂及mPE在研发和生产方面与国外公司差距较大,尤其薄膜晶点问题未能解决,影响了在薄膜领域的应用,因此,加快mPE产品的研发与生产十分必要。     

茂金属催化剂催化丙烯聚合研究进展

介绍了茂金属催化剂催化丙烯聚合的发展概况、催化剂结构与聚合物微观结构的关系、丙烯聚合机理及催化体系的结构组成对丙烯聚合的影响     

茂金属催化剂开发及应用

本文介绍了茂金属催化剂的开发以及利用茂金属合成的聚乙烯、聚丙烯、聚苯乙烯、ＥＰＤＭ等聚合物方面的进展。     

聚烯烃树脂用茂金属催化剂新进展

茂金属催化剂作为一种变革未来聚烃树脂工业的技术日益引人注目，着重叙述了茂金属催化剂在乙烯，丙烯等烯烃聚合方面的应用情况。     

茂金属催化剂的研究进展

介绍了茂金属催化剂合成技术,重点阐述了非桥联型、桥联型、限定几何构型、离子型和负载型茂金属催化剂的合成、结构及性能。     

Modification of a Ziegler-Natta catalyst with a metallocene catalyst and its olefin polymerization behavior

A Ziegler-Natta catalyst was modified with a metallocene catalyst and its polymerization behavior was examined. In the modification of the TiCl₄ catalyst supported on MgCl₂ (MgCl₂-Ti) with a rac-ethylenebis(indenyl)zirconium dichloride (rac-Et(Ind)₂ZrCl₂, EIZ) catalyst, the obtained catalyst showed relatively low activity but produced high isotactic polypropylene. These results suggest that the EIZ catalyst might block a non-isospecific site and modify a Ti-active site to form highly isospecific sites. To combine two catalysts in olefin polymerization by catalyst transitioning methods, the sequential addition of catalysts and a co-catalyst was tried. It was found that an alkylaluminum like triethylaluminum (TEA) can act as a deactivation agent for a metallocene catalyst. In ethylene polymerization, catalyst transitioning was accomplished with the sequential addition of bis(cyclopentadienyl)zirconium dichloride (Cp₂ZrCl₂)/methylaluminoxane (MAO), TEA, and a titanium tetrachloride/vanadium oxytrichloride (TiCl₄/VOCl₃, Ti-V) catalyst. Using this method, it was possible to control the molecular weight distribution (MWD) of polyethylene in a bimodal pattern. In the presence of hydrogen, polyethylene with a very broad MWD was obtained due to a different hydrogen effect on the Cp₂ZrCl₂ and Ti-V catalyst. The obtained polyethylene with a broader MWD exhibited more apparent shear thinning.     

Preparation of polypropylene/nanoclay composite fibers

Melt spinning of nanoclay (NA)/polypropylene (PP) composites into textile fibers is studied. The synthetic NA Perkalite F100 is prone to be exfoliated in PP matrix. With the help of a maleic anhydride‐grafted low‐molecular‐weight PP as compatibilizer (Epolene E43), a highly exfoliated PP/NA composite was successfully prepared. However, the prepared PP/NA composite shows a poor spinnability because of the phase separation between Epolene E43 and PP matrix. The combination of two different groups of compatibilizers, which are Polybond 1001 (acrylic acid‐grafted PP) for the dispersion of NA and Epolene G3216 (maleic anhydride‐grafted PP‐based copolymer) for the exfoliation of NA, can solve this problem. The PP/NA composite prepared by these two compatibilizers can be smoothly spun into fiber at the NA concentration below 1.9 wt%, which is found to be the percolation concentration of formation of NA network structure in PP matrix. POLYM. ENG. SCI., 53:2035–2044, 2013. © 2013 Society of Plastics Engineers     

Ziegler-Natta型丙烯聚合催化剂内给电子体复配的研究进展

简述了Ziegler-Natta催化剂内给电子体的作用,指出通过内给电子体复配可以使其优势互补,得到综合性能更优的催化剂。深入调研了国内外相关单位的研究动向,以LyondellBasell公司、DOW公司、中国石油化工股份有限公司北京化工研究院等多个研究单位为着眼点,阐述了复配内给电子体的研究进展,展望了内给电子体复配的广阔前景。     

Effect of cocatalyst on the chemical composition distribution and microstructure of ethylene-hexene copolymer produced by a metallocene/Ziegler-Natta hybrid catalyst

A silica-magnesium bisupport (SMB) was prepared by a sol-gel method for use as a support for metallocene/Ziegler-Natta hybrid catalyst. The SMB was treated with methylaluminoxane (MAO) prior to the immobilization of TiCl₄ and rac-Et(Ind)₂ZrCl₂. The prepared rac-Et(Ind)₂ZrCl₂/TiCl₄/MAO/SMB catalyst was applied to the ethylenehexene copolymerization with a variation of cocatalyst species (polymerization run 1: triisobutylaluminum (TIBAL) and methylaluminoxane (MAO), polymerization run 2: triethylaluminum (TEA) and methylaluminoxane (MAO)). The effect of cocatalysts on the chemical composition distributions (CCDs) and microstructures of ethylene-hexene copolymers was examined. It was found that the catalytic activity in polymerization run 1 was a little higher than that in polymerization run 2, because of the enhanced catalytic activity at the initial stage in polymerization run 1. The chemical composition distributions (CCDs) in the two copolymers showed six peaks and exhibited a similar trend. However, the lamellas in the ethylene-hexene copolymer produced in polymerization run 1 were distributed over smaller sizes than those in the copolymer produced in polymerization run 2. It was also revealed that the rac-Et(Ind)₂ZrCl₂/TiCl₄/MAO/SMB catalyst preferably produced the ethylene-hexene copolymer with non-blocky sequence when TEA and MAO were used as cocatalysts.     

丙烯聚合Ziegler-Natta催化剂中给电子体的作用

本文从内给电子体的作用、外给电子体的作用、内外给电子体的协同作用等方面综述了给电子体化合物在丙烯聚合Ziegler—Natta催化剂中的作用。     

Ziegler-Natta聚丙烯催化剂体系给电子体的研究进展

综述了 Ziegler-Natta聚丙烯催化剂体系中给电子体化合物的研究进展。按照给电子体化合物在催化体系中的作用及化学结构进行了详细的分类;指出了Z-N聚丙烯催化剂体系给电子体的研发趋势。     

Tacticity distribution of isotactic polypropylene prepared with heterogeneous Ziegler-Natta catalyst. 1. Fractionation of polypropylene

Two polypropylene samples, one with relatively low isotacticity and the other with high isotacticity were fractionated using a series of solvents and temperatures. For both samples 4-9 fractions were collected and characterised with differential calorimetry, size exclusion chromatography and ¹³C NMR spectroscopy. The collected fractions showed typical characteristics of a fractionation based on isotacticity, but also similarities to results from temperature rising elution fractionation (TREF), even though a separate controlled crystallisation step was not used. The melting temperatures of the fractions were found to increase linearly as a function of the meso diad fraction. A calibration, which can be used to convert DSC melting curves to wt% curves of isotacticity, was constructed for the temperature range 108-165 °C. The calibration enables quick analysis of samples in polypropylene manufacturing processes.     

Thermooxidative degradation of isotactic polypropylene prepared on metallocene catalyst and its sorption capacity

The sorption capacity and resistance to thermooxidative degradation are comparatively studied for isotactic polypropylene (PP) produced in the medium of the liquid monomer on homogeneous metallocene catalytic systems and on a heterogeneous titanium–magnesium catalyst. These polymers are characterized by different sorption capacities with respect to the phenyl‐β‐naphthylamine antioxidant and different induction periods of oxidation by molecular oxygen. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 808–811, 2006     

新型Ziegler-Natta催化剂用于丙烯多段聚合制备抗冲聚丙烯

聚丙烯（PP）质轻、价廉,具有良好的加工性能,应用范围广泛．PP的很多应用领域要求它应具有较好的韧性．均聚PP在低温时变脆,抗冲PP是通过在均聚PP中加入橡胶制备的．对PP以提高其抗冲击强度为目的的改性大多用共混的方法,将PP和两种或两种以上的其他聚合物以机械共混的方法进行混合,得到一种宏观上均匀的聚合物共混物,其性能有一定的提高．