几种Ziegler-Natta催化剂催化丙烯聚合的反应动力学

研究了4种Ziegler-Natta催化剂在淤浆聚合条件下,助催化剂和外给电子体对其催化丙烯聚合反应动力学行为的影响。结果表明:4种催化剂都有一个短暂的活性中心形成阶段,聚合动力学曲线均为上升-衰减型;4种催化剂活性均随烷基铝用量的增加而降低;所制聚丙烯的等规指数均随烷基铝用量的增加而降低,随外给电子体用量的增加而升高;助催化剂为三乙基铝[n(Al)∶n(Ti)=100],外给电子体为二环戊基二甲氧基硅烷[n(Si)∶n(Ti)=5]时,4种催化剂都具有较高的活性及较慢的聚合反应速率衰减;用催化剂4制备的聚丙烯的等规指数受助催化剂及外给电子体的影响较小。     

Ziegler-Natta催化剂制备低相对分子质量聚乙烯的研究

采用化学法对MgCl_2载体进行改性,负载TiCl_4活性组分,制备了Ziegler-Natta催化剂,并用于乙烯聚合制备低相对分子质量聚乙烯。结果表明:乙烯聚合时,同时使用内外给电子体时的聚合活性最高。选用该高效负载催化剂为主催化剂,三乙基铝为助催化剂,温度为100 ℃,压力为1.9 MPa,所制聚乙烯的黏均分子量为(1～2)× 10~4,催化剂活性可达972 g/(g·h)。     

PE-UHMW聚合用氧基硅烷内给电子体Ziegler-Natta催化剂的制备及应用

采用实验室自制的两种复合型氧基硅烷内给电子体：二甲基二(2-酚基乙氧基)硅烷(IED1)和二甲基二(2-氯乙氧基)硅烷(IED2),将两种内给电子体配置Ziegler-Natta催化剂并进行乙烯的催化聚合以制备超高分子量聚乙烯(PE-UHMW)。考察了两种内给电子体加入对Ziegler-Natta催化剂的载钛量、催化剂活性、催化剂的微观形貌及聚合物分子量等因素的影响,并考察催化剂加入量、聚合温度、聚合时间、助催化剂加入量对PE-UHMW聚合效果的影响。由于IED1结构中含有4个含氧基团,电子云密度高于IED2,因此IED1对催化剂活性以及聚合物分子量影响较大。最终确定PE-UHMW聚合工艺条件为：以IED1为内给电子体,催化剂加入量为12 mg/L,IED1与载体氯化镁的物质的量之比为1∶4,聚合温度为75℃,聚合时间为2 h,催化剂中Al/Ti物质的量之比为80。在此工艺条件下催化剂的催化效率为17.1 kg/(g·h),催化剂载钛量为5.8%,PE-UHMW堆密度为0.3 g/cm³,PE-UHMW分子量为4.0×10⁶。     

新型MgCl2/PET复合载体催化剂及丙烯聚合Ⅱ.丙烯聚合

用MgCl2和聚对苯二甲酸乙二酯（PET）制备了一种新型复合载体,负载钛后应用于丙烯催化聚合。考察了聚合温度、助催化剂用量、氢气加入量及外给电子体种类等对催化剂和产物性能的影响。聚合温度为70℃、n（Al）／n（Ti）为200、氢气加入量为1L,采用环己基甲基二甲氧基硅烷作为外给电子体时,催化剂具有较高的催化活性,同时聚丙烯具有较高的等规指数,相对分子质量分布宽。     

SC型高效催化剂丙烯液相本体聚合

SC型高效催化剂是用无水MgCl_2、醇、蘸、TiCl_4以及添加剂制备的,SC型催化剂和A1Et_3助催化剂、Ph_2Si(OMe)_2外给电子体,用于丙烯液相本体聚合,丙烯在70℃聚合2h具有高效率(大于3万gPP/gCat),得到的聚丙烯等规度(大于98％)和堆密度(大于0.45g/cm~3)高,颗粒形态好,粒度分布窄,聚丙烯的MFR容易用氢调节。     

一种超高分子量聚乙烯复合材料的制备方法

本发明涉及一种超高分子量聚乙烯复合材料的制备方法,其特征在于：选用两种烯烃聚合催化剂,其中一种是可生产超高分子量聚乙烯的超高分子量催化剂,另一种是生产低分子量聚乙烯的低分子量催化剂;以表面带有羟基和丙烯酸酯异丁基的POSS 分子为载体,先将低分子量催化剂负载于 POSS 分子上,经聚合反应得到低分子量聚乙烯;然后将超高分子量催化剂负载于POSS 分子上,加入助催化剂,通入乙烯,经聚合反应后获得超高分子量聚乙烯/POSS/低分子量聚乙烯共混的纳米复合材料。本发明制备方法工艺简单、效率高、能耗低,可通过原位聚合制备分子尺度混合均匀的纳米复合材料。     

新型MgCl_2负载钛催化剂在丙烯聚合中的应用

用优化乳化法制备了MgCl_2负载钛催化剂,考察了催化剂的形态结构并将其应用于丙烯催化聚合。聚合温度70℃、氢气加入量为1 L,采用二异丁基二甲氧基硅烷作为外给电子体时,催化剂具有较高的催化活性,同时聚丙烯具有较高的等规指数。     

中国专利

用于烯烃聚合的催化剂组分及其制备方法本发明提供了一种用于烯烃聚合的催化剂组分的制备方法及其获得的催化剂组分。该方法中采用以球形卤化镁加合物为载体,并采用以二醇酯类化合物与1,3-二醚类化合物复配作为内给电子体所制备的球形催化剂,通过控制内给电子体的反应温度及控制催化剂的洗涤程度使所得催化剂在用于烯烃聚合,尤其是丙烯聚合时,显示了超高的聚合活性和较高的立构定向性,并且即使在较低烷基铝浓度下仍保持了很高的活性,所得聚合物的相对分子质量分布较宽,灰分相对较低。     

高相对分子质量聚丙烯的研究

介绍了几种Z－N型催化剂体系用液相本体聚合制备的高相对分子质量聚丙烯及利用其制备的双峰聚丙烯，讨论了催化剂体系中助催化剂烷基铝用量，不同的给电子体，聚合温度的变化对催化剂活性，聚丙烯相对分子质量的影响。     

外给电子体CMMS、DCPMS制备高结晶度聚丙烯的研究

CMMS、DCPMS外给电子体分别与CS 1型、CS 2型聚丙烯主催化剂进行丙烯聚合评价,结果表明DCPMS是高效催化剂的有效助催化剂,能够有效提高聚丙烯的真实等规度、结晶度,DCPMS更适宜制备相对高结晶性聚丙烯。     

Dimethylsilylbis(1‐indenyl) zirconium dichloride/methylaluminoxane catalyst supported on nanosized silica for propylene polymerization

A dimethylsilylene‐bridged metallocene complex, (CH₃)₂Si(Ind)₂ZrCl₂, was supported on a nanosized silica particle, whose surface area was mostly external. The resulting catalyst was used to catalyze the polymerization of propylene to polypropylene. Under identical reaction conditions, a nanosized catalyst exhibited much better polymerization activity than a microsized catalyst. At the optimum polymerization temperature of 55°C, the former had 80% higher activity than the latter. In addition, the nanosized catalyst produced a polymer with a greater molecular weight, a narrower molecular weight distribution, and a higher melting point in comparison with the microsized catalyst. The nanosized catalyst's superiority was ascribed to the higher monomer concentration at its external active sites (which were free from internal diffusion resistance) and was also attributed to its much larger surface area. Electron microscopy results showed that the nanosized catalyst produced polymer particles of similar sizes and shapes, indicating that each nanosized catalyst particle had uniform polymerization activity. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

A comparative study of ethylene and propylene polymerization over titanium–magnesium catalysts of different composition

New data on the molecular weight characteristics of polypropylene (PP) and polyethylene (PE) were obtained from the polymerization over supported titanium–magnesium catalysts differing in their compositions (presence and absence of internal and external donors). Internal and external donors were found to affect the molecular weight of polymers in a different manner for ethylene and propylene polymerization. The introduction of the internal donor increases the molecular weight of PP and does not affect the molecular weight of PE. The effect of external donor introduced to catalytic system on the polymer molecular weight depends on catalyst composition: for a catalyst without internal donor, the introduction of the external donor increases the molecular weight of PP and does not affect that of PE. In the case of catalyst with the internal donor, the introduction of the external donor increases the molecular weight of PP and substantially decreases that of PE. The data on polymerization degree of the polymers produced under conditions when chain transfer with hydrogen was the dominant reaction were used to calculate the values for ethylene polymerization over the catalysts of different composition. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40658.     

琥珀酸酯为内给电子体的新型MgCl2载体催化剂用于丙烯聚合

A novel MgCl2-supported Ziegler-Natta catalyst containing diethyl diisopropylsuccinate donor was prepared and propylene polymerizations with the combination of such catalyst and four external donors were investigated in detail. The catalyst was compared with a commercial one with phthalate as internal donor in terms of catalytic activity, hydrogen sensitivity and stereospecificity in propylene polymerization. The molecular weight, molecular weight distribution and microstructure of the produced polypropylenes were compared also. It was found that the novel catalyst containing succinate internal donor showed higher activity and higher stereospecificity than those with phthalate as internal donor. Consequently, polypropylenes obtained by the succinate-based catalyst showed high molecular weight, high melting temperature, high isotactic index and broad molecular weight distribution than those obtained with the commercial catalyst.     

Synthesis of polypropylene with varied microstructure and molecular weights characteristics using supported titanium catalyst system

Propylene polymerizations were conducted in slurry phase batch process using different dialkyldimethoxysilanes as an external donor with magnesium dichloride (MgCl₂) supported titanium tetrachloride (TiCl₄) catalyst having diisobutylphthalate (DIBP) as an internal donor. The dialkyl group of the external donors like dimethyldimethoxysilane (DMDMS), diisopropyldimethoxysilane (DIPDMS) and dicyclopentyldimethoxysilane (DCPDMS) were found to influence on the microstructure and the molecular weight characteristics of synthesized polypropylene in addition to the initial rate of polymerization and decay index. DCPDMS gave highest productivity and high molecular weight polypropylene with improved kinetics while DMDMS gave lowest productivity in comparison. The molar equivalent combination of DCPDMS with DIPDMS and DMDMS respectively, resulted in producing polypropylene with tacticity pattern and molecular weight characteristics in between the individual alkoxysilane based system indicating the effect of alkyl group on the catalyst performance.     

Alternating copolymerization of butadiene and propylene

An alternating copolymer of propylene and butadiene is prepared with vanadium or titanium compounds and alkylaluminum compounds as the polymerization catalyst. The catalyst should be prepared at extremely low temperature as?70°C and halogen atom is essential to the catalyst activity. Carbonyl compounds such as ketone, acid, ester, acid anhydride, and acid peroxide are very effective additives to the catalyst for enhancement of the molecular weight of the polymer. The potentiometric titration and the ESR study suggest that a divalent vanadium compound associated to form the dimer through chlorine bridge is a precursor of the active species. An anionic copolymerization mechanism involving the alternating coordination of monomers is proposed. The copolymer is always of a 1 : 1 composition irrespective of the composition of monomer feed and the alternating structure of polypropylene and trans-1,4-polybutadiene is estimated from IR and NMR data. The copolymer seems to be a new versatile synthetic rubber having excellent low temperature properties, high rebound, good compatibility with conventional rubbers and high resistance toward aging.     

溶液聚合法制备聚乳酸的研究

以L-乳酸单体为原料,应用溶液聚合法制备聚乳酸,其中二苯醚为溶剂,采用分阶段脱水的工艺方法。探讨了反应时间,反应温度,催化剂种类及其用量,反应体系的真空度,分子筛等因素对聚合物相对分子质量的影响。采用乌式黏度法测量其相对分子质量,并用FTIR测试手段对聚合物进行结构表征。结果表明,最佳的反应条件为,反应温度170℃,催化剂用量为0.25wt%,聚合反应后期加入分子筛脱水,聚合时间为20h。     

聚乳酸基离聚物的合成与表征

聚乳酸是一种绿色环保高分子材料。以丙交酯为单体,辛酸亚锡为催化剂,N-甲基二乙醇胺为引发剂通过丙交酯的开环聚合法制备了聚合物分子链中含有氨基官能团的双端羟基聚乳酸,然后以异佛尔酮二异氰酸酯作为扩链剂进行溶液扩链反应制备了聚乳酸基聚氨酯,然后再与冰醋酸、碘甲烷、溴乙烷反应,制备了以聚乳酸基聚氨酯为基体的离聚物。并采用特性粘数测定、GPC、差示扫描量热法、热重分析法、X射线衍射等方法对聚合物进行了表征。结果表明,聚乳酸基聚氨酯离聚物的特性粘数高于聚乳酸基聚氨酯,离聚物的热稳定性优于聚乳酸及聚乳酸基聚氨酯。     

复合载体负载型催化剂制备UHMWPE动力学行为

研究了采用氯化镁和硅胶复合载体负载Mg-Ti型催化剂催化乙烯聚合的性能和动力学行为,考察了聚合温度、时间、压力、助催化剂对催化剂性能的影响,以及链转移反应在其中所起到的作用。结果表明,温度对聚乙烯的相对分子质量影响最大,乙烯分压和聚合温度对催化剂的活性有明显影响,存在一个使催化剂高活性的最适宜铝钛物质的量之比。     

Supported hybrid early and late transition metal catalysts for the synthesis of polyethylene with tailored molecular weight and chemical composition distributions

Supported hybrid catalysts using metallocenes and a nickel diimine catalyst were synthesized and used for ethylene slurry polymerization and ethylene/1-hexene copolymerization. Two types of metallocenes, together with a nickel diimine catalyst were supported onto SiO₂ through chemical bonding, and a borate compound was physisorbed for the activation of the catalysts. These supported hybrid catalysts had high catalyst activities and made free-flowing polymer particles. The chemical composition distribution, molecular weight averages and distributions of resultant polymers were controlled by catalyst structure and polymerization conditions such as reaction temperature and the use of α-olefin. According to GPC-IR, ¹³C NMR and CEF characterization results of some polymers, more 1-hexene was incorporated in the high molecular weight region, short chain branches were generated by the chain walking mechanism in low molecular weight region. The morphologies of the resulting particles were investigated by SEM.