Polymerization of propylene with highly active MgCl2-supported TiCl3 catalyst

Summary The MgCl₂ supported TiCl₃ catalyst was prepared by grinding the mixture of TiCl₃·3Py and MgCl₂ in a ball mill. The catalyst was treated either i.vac. at 50–200°C or with alkylaluminum halides to remove the residual pyridine, and propylene polymerization was conducted at 65°C using the resulting catalysts combined with triethylaluminum. The catalyst treated with diethylaluminum chloride showed an extremely high activity for the polymerization.     

Propene polymerization with MgCl2-supported TiCl4/dioctylphthalate catalyst. I. Catalyst behavior

Slurry polymerization of propene using MgCl₂-supported TiCl₄/dioctylphthalate catalysts were carried out in a semibatch reactor at a constant pressure to examine the effects of polymerization conditions on catalyst activity and polymer isotacticity. The catalysts were prepared at 80, 90, and 105°C, which gave different compositions of chemical complexes associated with the diester. Five alkyl aluminums (triethyl, triisobutyl, tri-n-hexyl, tri-n-octyl, and isoprenyl) were studied as cocatalysts. Among these, triethyl aluminum was found to be most effective for the catalysts prepared at 80 and 95°C, and tri-n-hexyl aluminum for the catalyst prepared at 105°C. Dimethoxydiphenyl silane and 2,2,6,6-tetramethylpiperidine were employed to study their effects as an external Lewis base for the catalyst prepared at 105°C. In both cases, a small amount of either base resulted in significant increase in activity and isotacticity, which can be attributed to the high level of phthaloyl chloride complex in the catalyst. © 1995 John Wiley & Sons, Inc.     

Propene polymerization with MgCl2-supported TiCl4/dioctylphthalate catalyst. II. Effects of polymerization conditions on the microstructure of isotactic polymer

Propene was polymerized over the MgCl₂-supported TiCl₄/dioctylphthalate catalyst in heptane. Polymer products obtained under different polymerization conditions were separated into isotactic and atactic polypropenes by the extraction of boiling n-heptane. The effects of polymerization time, cocatalyst type, cocatalyst/catalyst ratio, polymerization temperature, and external base/cocatalyst ratio on the isotactic triad of the isotactic portion of polypropene were investigated 2,2,6,6-Tetramethyl piperidine (TMPIP), dimethoxy diphenyl silane (DMDPS), and t-butylmethyl ether (TBME) were employed as the external Lewis base. High concentrations of the first two bases caused a decrease in isotactic triads in the isotactic polymer, while TBME showed no significant effects. The difference can be attributed to the different roles these external bases play in polymerization. © 1995 John Wiley & Sons, Inc.     

外给电子体对MgCl2负载TiCl4催化剂催化乙烯/丙烯共聚合的影响

采用邻苯二甲酸二异丁酯(DIBP)为内给电子体的Mg Cl2负载Ti Cl4催化剂,考察了在无外给电子体及以环己基甲基二甲氧基硅烷(简称C-donor)、二环戊基二甲氧基硅烷(简称D-donor)、苯基三乙氧基硅烷(简称PTES)为外给电子体的条件下,催化剂对乙烯/丙烯共聚合活性、单体竞聚率、共聚物序列分布和热性能的影响。结果表明,在不同外给电子体作用下,随着乙烯进料比的增加,聚合活性先增加后逐渐减小,并呈现出明显的"共单体效应";DIBP与D-donor有很好的协同效应,二者配合可提高催化剂活性,最高可达8.3 kg(以1 g Ti计);当乙烯/丙烯(摩尔比)为40%~65%时,共聚物链段中乙烯和丙烯分布更均匀,无规度更高,具有更短的平均序列长度;当乙烯/丙烯为50%时,所得共聚物的熔融温度最低,可达108℃,玻璃化转变温度为-48.6℃,表明聚合物具有较好的耐低温性能。     

Morphological development of impact polypropylene produced in gas phase with a TiCl4/MgCl2 catalyst

This article reports on a comprehensive study of the reaction kinetics, particle morphology development, and polymer properties of impact polypropylene produced in gas phase with a TiCl₄/MgCl₂ catalyst. Experiments were conducted over a range of copolymerization times, temperatures, monomer compositions, and hydrogen levels. The catalyst was found to exhibit a decay-type reaction rate for ethylene and propylene, but the presence of both monomers together caused an activation of the catalyst. Copolymer composition was constant over reaction time. Hydrogen was found to reversibly enhance the rate of propylene polymerization but to have no effect on ethylene. Microscopy provided evidence that the copolymer phase segregates from the homopolymer during polymerization. As copolymer content increased, product bulk density decreased because of the presence of sticky material on the particle surface. However, even at 70 wt % copolymer, enough pores were present in the particle to prevent monomer diffusion limitations. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 3085–3106, 2001     

Polymerizations of α-olefins and styrene with MgCl2-supported titanium catalyst system: MgCl2/TiCl4/PhCO2Et with AlEt3PhCO2Et

Summary Kinetic analysis was performed in a short time polymerizations of 1-butene,4-methyl-1-pentene and styrene by using a catalyst system composed of MgCl₂/TiCl₄/PhCO₂Et with AlEt₃/PhCO₂Et which is known as a highly active and highly stereospecific catalyst system in olefin polymerization. The concentration of the active centers, [C ^*], the propagation rate constant, k _p, and the chain transfer rate, r _tr, were determined for each monomer. It was found that the values of [C ^*] were almost same for every monomer, but the values of k _p changes widely in the following order: propylene>1-butene>4-methyl-1-pentene>styrene.     

球形MgCl2载体催化剂催化1-丁烯聚合

在以三乙基铝(AlEt3)为助催化剂、n(Al)/n(Ti)为300、聚合压力为0.10 MPa、聚合温度为30℃、通入氢气3 mL、环己基甲基二甲氧基硅烷(CHMMS)与Al的摩尔比为0.033、聚合2h的条件下,球形MgCl2载体催化刺的活性为607g/g,聚1-丁烯的等规指数为82.3%.依催化剂活性大小,外给电...     

TiCl4/MgCl2催化剂载体掺杂的研究进展

综述了用于烯烃配位聚合的MgCl_2载体掺杂负载型Ziegler-Natta(Z-N)催化剂的研究进展,讨论了此类催化剂用于烯烃聚合的催化活性、活性中心分布、聚合产物的相对分子质量分布及立构规整性的变化等。掺杂MgCl_2负载的Z-N催化剂比常规负载的Z-N催化剂生产的聚烯烃的相对分子质量分布宽,催化活性也有一定的改变。     

MgCl2-BuOH/TiCl4催化剂催化乙烯聚合

研究了自制MgCl2-BuOH/TiCl4催化剂在不同条件下用于乙烯均聚合和共聚合的性能,考察了不同的氢气分压、铝钛摩尔比和共聚单体浓度对催化剂活性和聚合反应动力学的影响,测试了聚合产品的熔体流动速率、堆密度及拉伸性能等,表征了聚合产品的相对分子质量及其分布、分子链结构,得出了聚合条件对MgCl2-BuOH/TiCl4催化剂及其产品性能影响的一般规律.     

Synthesis,structure, and thermal properties of new polypropylene nanocomposites prepared by using MgCl2‐mica/TiCl4 based catalyst

Preparation of polypropylene/mica nanocomposites via in situ polymerization is investigated. The nanocomposites were successfully synthesized using a Ziegler‐Natta catalyst based on MgCl₂/modified mica/TiCl₄. Muscovite mica was organically modified with quaternary ammonium salt, and with triethylaluminum. The treatment with triethylaluminum increased the disorder in the stacking of clay layers, producing a more active catalyst for propylene polymerization, although the mica containing catalysts had lower activity than the standard one prepared without clay. The nanostructure of the composites was characterized by X‐ray diffraction. The results showed that part of the mica layers were exfoliated in the polymer matrix, although tactoids were still present. Small‐angle X‐ray scattering analysis was used to determine how mica and its concentration influence the size of the polymer nanocrystals. Differential scanning calorimetry was used to investigate both melting and crystallization temperatures, as well as the crystallinity of the nanocomposite samples. Thermogravimetric analysis showed that polypropylene/mica nanocomposites presented much higher thermal stability than the polypropylene without mica, which means that mica had a barrier effect against heat. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45587.     

Propylene polymerization over MgCl2‐supported TiCl4 catalysts bearing different amounts of a diether internal electron donor: Extrapolation to the role of internal electron donor on active site

In this work, the composition of MgCl₂‐supported Ziegler‐Natta (ZN) catalysts bearing different amounts of 9,9‐bis(methoxymethyl)fluorine (BMMF) and the propylene polymerization over these catalysts are investigated. Based on the experimental results, the models of active sites suitable for ZN catalysts with/without internal donor BMMF are established, and they can be described as follows: atactic site (I)—isolated TiCl₄ monomeric species on the (110) lateral cut (around which there is no complexes), weakly isospecific site (II)—semi‐isolated and surrounded TiCl₄ monomeric species on the (110) lateral cut (in the vicinity of which BMMF or other TiCl₄ is adsorbed), and highly isospecific site (III)—dimeric TiCl₄ species (Ti₂Cl₈) on the (104) lateral cut. Meanwhile, the mechanism underlying the role of BMMF on active sites is revealed (i) convert atactic sites (I) to weakly isospecific site (II) by occupying either or both of L₁ or/and L₂ vacancies around site; (ii) improve the isotacticity of weakly isospecific site (II) in donor‐free ZN catalyst by adsorbing at L₂ vacancy or/and replacing the Cl for TiCl₄ at L₁; and (iii) replace highly isospecific site (III). In addition, these roles of BMMF are successively achieved according to the amount of BMMF added. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Propene polymerization with MgCl2-supported TiCl4/dioctylphthalate catalyst. III. Effects of polymerization conditions on molecular weights and molecular weight distribution

In propene polymerization over the MgCl₂-supported TiCl₄/dioctylphthalate (DOP) catalyst, the weight- and number-average molecular weights and the molecular weight distribution (MWD) of polypropene products and of the isotactic and atactic polymer portions were studied. The average molecular weights and MWD were found to be independent of time. The isotactic polymer had higher molecular weight and broader distribution than the atactic portion by almost an order of magnitude. An increase in temperature and cocatalyst/catalyst ratio resulted in lowering molecular weight due to increasing transfer reaction. Alkyl aluminum was used as a cocatalyst, and the molecular weight did not vary significantly with different alkyl groups. Of the three external bases studied, 2,2,6,6-tetramethyl piperidine (TMPIP), dimethoxydiphenyl silane (DMDPS), and t-butylmethyl ether (TBME), the addition of a small amount of one of the first two bases caused a substantial increase in both molecular weight and polydispersity of the isotactic polymer. Those increases leveled off quickly with increasing amounts of the external base. On the other hand, both average molecular weights and polydispersity of the atactic polymer decreased with a net increase in the molecular weight of the whole polymer. TBME, however, has no significant effect on either molecular weight or MWD. These effects are discussed in the context of the roles of the external base in propene polymerization. © 1995 John Wiley & Sons, Inc.     

MgCl2-BuOH/TiCl4催化剂催化乙烯聚合动力学

研究了MgCl2-正丁醇/TiCl4催化剂常压下催化乙烯聚合的性能和动力学行为.考察了n(Al)/n(Ti)、聚合温度、共聚单体浓度、氢气分压对催化剂性能的影响.研究表明:三乙基铝为助催化剂,n(Al)/n(Ti)为200,聚合压力为0.1 MPa,温度为50℃,聚合时间为2 h时,该催化剂具有较高的活性:聚合动力学行为平稳,活性衰减较慢,活性可达1 550.2 g/g;该催化剂具有良好的乙烯均聚合和共聚合性能以及氢调性能.     

Ethylene-propylene copolymers by a supported Ziegler-Natta catalyst based on TiCl4/MgCl2

Ethylene-propylene copolymers have been prepared by using Ziegler-Natta catalysts based on TiCl₄, MgCl₂, PCl₃ and (n-Bu)₃PO₄. The catalysts TiCl₄/MgCl₂/PCl₃ and TiCl₄/MgCl₂/(n-Bu)₃PO₄ were prepared by reacting TiCl₄ with pretreated MgCl₂. The support was prepared by ball milling of MgCl₂ with varied amounts of PCl₃ or (n-Bu)₃PO₄. The addition of PCl₃ has remarkably increased the MgCl₂ surface area in comparison with (n-Bu)₃PO₄. The effects of PCl₃ and (n-Bu)₃PO₄ on ethylene homopolymerization, ethylene-propylene copolymerization and on copolymer properties were evaluated. The catalyst system containing PCl₃ permitted to synthesize propylene-ethylene copolymers with up to 75% (w/w) of propylene and provided control of copolymer crystallinity. The reduction of the copolymer molecular weight distribution suggested that PCl₃ acted as an internal donor, poisoning some active catalytic sites. Received: 2 April 1997/Revised: 6 June 1997/Accepted: 18 June 1997     

The influence of aluminum alkyls on the polymerization of ethylene with SiO2/MgCl2-supported TiCl4 catalysts

The influence of different aluminum alkyls (diethylaluminum chloride, triethylaluminum, triisobutylaluminum, tri-n-hexylaluminum, tri-n-octylaluminum and isoprenylaluminum) on the ethylene polymerization activity of a laboratory prepared high-activity SiO₂/MgCl₂-supported TiCl₄ catalyst has been investigated. A slurry reactor (decane diluent) was used for measuring rates of polymerization. The average molar mass, the breadth of the molar mass distribution, the polymerization activity, and the shapes of the activity-time profiles, were strongly dependent on the nature of the aluminum alkyl. For several of the cocatalysts used, the catalytic activity approached a constant value after a certain amount of time under reaction conditions. In this constant activity region, a first-order dependence of the polymerization rate on the monomer concentration was found for all of the systems examined. However, the activation energy of the polymerization reaction was found to depend strongly on the type of cocatalyst which was used.     

Solution copolymerization of ethylene with α-olefins by a MgCl2 supported TiCl4 catalyst

Summary Copolymerization of ethylene with -olefins, i.e. propylene, butene-1, 4-methyl-pentene-1(4-MP-1), was carried out by a MgCl₂ supported TiCl₄ catalyst in combination with Et₃Al at a temperature as high as 170 °C at which the polymerization system was homogeneous. This catalytic system showed very a high activity and produced copolymers having a density of 0.91–0.94 g/ml. Of these three kinds of comonomers, propylene showed the highest reactivity and caused most frequently the termination of a polymer growing by chain transfer reaction and produced copolymers having the broadest MWD.     

Studies on propylene polymerization with a highly active MgCl2 supported TiCl4 catalyst system

Summary Propylene polymerization was performed with a highly active MgCl supported TiCl₄ in conjunction with Et₃Al and ethyl benzoate (EB). The obtained polypropylene sample was separated into four fractions by successive extraction with pentane, heptane and trichloroethylene (trichlene). Yield, Mn, Tm and microtacticity of each fraction were determined, and the effects of the concentration of EB on these items of results were investigated. It has been found that EB enhances yield, Mn and stereospecificity of trichlene insoluble (the most stereospecific) fraction, and in contrast, it decreases rapidly yields of other three fractions without changing the character of the polymers. From these findings, the functions of EB to the active centers were discussed.