Ansa-茂锆催化剂对乙烯/1-辛烯共聚合研究

乙烯与α 烯烃共聚合可制得线性低密度聚乙烯等重要塑料产品．用茂金属催化剂与甲基铝氧烷（ＭＡＯ）助催化剂合成的乙烯／α 烯烃共聚物具有共单体分布均匀，分子量分布窄等特点，其性能比传统的Ｚｉｅｇｌｅｒ Ｎａｔａ催化剂体系所得共聚物优越．茂金属化合物的结构...     

β-二酮锆/AlEt2Cl/MAO催化乙烯原位共聚合成支化聚乙烯

以β-二酮锆为唯一主催化剂, 以AlEt2Cl和MAO为助催化剂, 使之分别与主催化剂作用形成两种不同功能的催化活性中心, 考察乙烯原位共聚合成支化聚乙烯.     

Synthesis, molecular structure, and polymerization reactivity of ethylenebis(1,3-dimethylcyclopentadienyl)zirconium dichloride

An ethylene-bridged zirconocene complex bearing methyl substituents only on the cyclopentadienyl carbons adjacent to bridge point, ethylenebis(1,3-dimethylcyclopentadienyl)zirconium dichloride (5) was synthesized. Crystal structure of 5 was determined. The complex, 5, when activated with MAO, shows better comonomer incorporation ability than [Ph₂C(Fluo)(Cp)]ZrCl₂ in the ethylene–norbornene copolymerization but it is not better than rac-Et(Ind)₂ZrCl₂ for the ethylene-1-hexene copolymerization in terms of activity and comonomer incorporation.     

C-NMR study of Ti(IV) species formed by Cp*TiMe3 and Cp*TiCl3 activation with methylaluminoxane (MAO)

Using ¹³C- and ¹H-NMR spectroscopy, titanium(IV) species formed in the catalytic systems Cp*TiMe₃/MAO and Cp*TiCl₃/MAO (Cp*=C₅(CH₃)₅) in toluene and chlorobenzene were studied within the temperature range 253-293 K and at Al/Ti ratios 30-300. It was shown that upon activation of Cp*TiMe₃ with methylaluminoxane (MAO) mainly the ‘cation-like’ intermediate Cp*Me₂Ti⁺←Me⁻Al(MAO) (2) is formed. Three types of titanium(IV) complexes were identified in Cp*TiCl₃/MAO catalytic system. They are methylated complexes Cp*TiMeCl₂ and Cp*TiMe₂Cl, and the ‘cation-like’ intermediate 2. Complex 2 dominates in Cp*TiCl₃/MAO system in conditions approaching to those of practical polymerization (Al/Ti ratios more than 200). According to the EPR measurements, the portion of EPR active Ti(III) species in the Cp*TiCl₃/MAO system is smaller than 1% at Al/Ti=35, and is about 10% at Al/Ti=700.     

新型单茂钛催化剂乙烯均聚反应合成支化聚乙烯

单茂钛化合物Ｃｐ′ＴｉＬ3(Ｃｐ′为 η5 环戊二烯基或取代 η5 环戊二烯基 ;Ｌ为卤素、氢、烃基、烃氧基等 )和甲基铝氧烷 (ＭＡＯ)组成的催化剂催化苯乙烯聚合 ,表现出非常高的催化活性和间规立构选择性[1～ 3] .这类催化剂也可用于丙烯、丁烯等α 烯烃聚合 ,合成无规或立构嵌段聚合物[4～ 6] ;但用单茂钛 /ＭＡＯ催化剂进行乙烯均聚合研究[7] 较少 .本文报道用三甲基铝 (ＴＭＡ)含量不同的改性ＭＡＯ(ｍＭＡＯ)作助化催剂激活 1 ,2 ,3,4,5 五甲基茂基三苄氧基钛 [Ｃｐ Ｔｉ(ＯＢｚ) 3]催化乙烯均聚合 ,对聚合产物结构性能进行表征 ;发现…     

COPOLYMERIZATION OF ETHYLENE AND PROPYLENE WITH CpCH2CH2CH=CH2)2MCl2(M=Zr,Hf)AND Cp2ZrCl2 CATALYSTS

(CpCH_2CH_2CH = CH_2)_2MCl_2(M=Zr, Hf)/MAO and Cp_2ZrCl_2/MAO (Cp=cyclopentadienyl; MAO=methylaluminoxane) catalyst systems have been compared for ethylene copolymerization to investigate the influence of theligand and transition metal on the polymerization activity and copolymer properties. For both CH_2CH_2CH=CH_2 substitutedcatalysts the catalytic activity decreased with increasing propene concentration in the feed. The activity of the hafnocenecatalyst was 6～8 times lower than that of the analogous zirconocene catalyst, ~(13)C NMR analysis showed that the copolymerobtained using the unsubstituted catalyst Cp_2ZrCl_2 has greater incorporatien of propene than those produced byCH_2CH_2CH=CH_2 substituted Zr and Hf catalysts. The melting point, crystallinity and the viscosity-average molecularweight of the copolymer decreased with an increase of propenc concentration in the feed. Both CH_2CH_2CH= CH_2 substitutedZr and Hf catalysts exhibit little or no difference in the melting point and crystallinity of the produced copolymers. However,there are significant differences between the two zirconocene catalysts. The copolymer produced by Cp_2ZrCl_2 catalyst havemuch lower T_m and X_c than those obtained with the (CpCH_2CH_2CH=CH_2)_2ZrCl_2 catalyst. The density and molecular weightof the copolymer decreased in the order: (CpCH_2CH_2CH=CH_2)_2HfCl_2>(CpCH_2CH_2CH=CH_2)_2ZrCl_2>Cp_2ZrCl_2. The kineticbehavior of copolymerizaton with Hf catalyst was found to be different from that with Zr catalyst.     

单茂钛催化剂的苯乙烯间规聚合和乙烯聚合的比较

考察三甲基铝（ＴＭＡ） 部分水解法制备固体改性甲基铝氧烷（ｍ ＭＡＯ） 时,反应物Ｈ２Ｏ 和ＴＭＡ 的摩尔比对ｍ ＭＡＯ 的产量及ｍ ＭＡＯ 中ＴＭＡ 含量的影响;以五甲基茂基三苄氧基钛［Ｃｐ ＊ Ｔｉ（ＯＢｚ）３］／ｍ ＭＡＯ 组成的均相催化体系,分别考察ｍ ＭＡＯ 的用量［ 即Ａｌ／Ｔｉ 摩尔比］ 及ｍ ＭＡＯ 中ＴＭＡ 含量对苯乙烯间规聚合和乙烯聚合的影响．通过分析Ｃｐ ＊ Ｔｉ（ＯＢｚ）３／ｍ ＭＡＯ 催化体系钛氧化态的分布,发现Ｔｉ（ Ⅲ） 活性中心有利于合成间规聚苯乙烯;而Ｔｉ（ Ⅳ） 活性中心有利于合成聚乙烯．苯乙烯间规聚合时,外加三异丁基铝（ＴＩＢＡ） ,将提高催化活性,同时可节省ＭＡＯ 用量．     

单茂钛/甲基铝氧烷催化剂乙烯/丙烯共聚合研究

改性甲基铝氧烷(mMAO)激活五甲基茂基三氯化钛(Cp TiCl3)催化乙烯 丙烯共聚合,控制两种单体的进料配比,得到单元序列分布不同的共聚物.混合单体中含有少量丙烯,共聚合活性高于相同聚合条件下乙烯均聚合的活性.用1 3C -NMR测定共聚物分子链的微观结构和单元序列分布,计算出单体的竞聚率;结果表明共聚物分子链中两种单体的序列分布均匀.混合单体中丙烯含量较大时,共聚物为完全无规共聚物;而当丙烯含量少时,丙烯链节或短的聚丙烯链段均匀分布于聚乙烯链段之间.共聚物经DSC分析,也证明不存在长序列的聚乙烯链段;因此,即便在进料气体中丙烯含量很少的情况下,共聚物仍然没有明显的熔融温度和结晶性.     

用甲基铝氧烷活化的氯化稀土催化剂合成高顺式窄分布聚丁二烯

以NdCl3.4L(配体L为膦酸三丁酯TBP、膦酸三苯酯TPP、膦酸二异辛酯P204)为主催化剂(简称[Nd])、甲基铝氧烷(MAO,简称[Al])为助催化剂和环己烷为溶剂,进行1,3-丁二烯聚合的研究.考察了配体对丁二烯聚合反应活性的规律及MAO用量、催化剂陈化时间、溶剂种类对聚合的影响;并对聚合物进行NMR,IR和GPC的表征.结果表明,3种配体的聚合活性顺序为TBP>P204>TPP;当[Al]/[Nd]为30时,聚合物的分子量分布指数达到1.20;30℃陈化时,聚丁二烯cis-1,4结构均大于97%;与正己烷、甲苯溶剂对比来看,环己烷体系所得聚合产物的分子量分布相对较窄、产率较高.     

The effect of polymerization conditions on crystalline of polybutene-1 catalyzed by metallocene catalyst

Polybutene-1 was synthesized stereoselectively with the precursorη5-(pentamethyl-cyclopentadienyl) tribenzyloxide titanium (Cp*Ti(OBz)3) and methylaluminoxane (MAO). The effects of polymerization conditions, trimethyl alumina (TMA) content in MAO and temperature on the crystalline and molecular weight of the products, and catalytic activity were investigated. The structural properties of the polybutene-1 were characterized with 13C NMR and WAXD.