This invention relates to high melting polyolefin copolymers suitable as thermoplastic elastomers and catalysts and methods for their synthesis. These elastomeric olefin copolymers are characterized by a mole fraction of crystallizable component X
c
from about 30 to about 99%; low glass transition temperatures, below −20° C., and typically below −50 ° C.; melting points above about 90° C.; high molecular weights; a molecular weight distribution M
W
/M
n
=10; and a narrow composition distribution between chains of =15%. The novel copolymers of the invention range from reactor blends to multiblock copolymers that can be sequentially fractionated into fractions of differing crystallinities, which fractions nevertheless show compositions of comonomers which differ by less than 15% from the parent polymer (reactor product). The invention also relates to a process for producing such copolymers by utilizing an unbridged, substituted or unsubstituted cyclopentadienyl metallocene catalyst that is capable of interconverting between states with different copolymerization characteristics, which interconversion is controlled by selecting the substituents of the cyclopentadienyl ligands so that the rate of interconversion of the two states is within several orders of magnitude of the rate of formation of a single polymer chain. Where r
i
>r
f
the polymer can be characterized as multiblock; where r
i
本发明涉及高熔点聚烯烃共聚物,适用于热塑性弹性体和催化剂,并提供其合成方法。这些弹性聚烯烃共聚物的结晶组分摩尔分数Xc大约在30%至99%之间;玻璃化转变温度低,低于-20℃,通常低于-50℃;熔点高于大约90℃;具有高分子量;分子量分布MW/Mn≤10;链之间的组成分布狭窄,≤15%。本发明的新型共聚物从反应器混合物到多嵌段共聚物,可以被分离成不同结晶度的分数,但这些分数的共聚单体组成与母体聚合物(反应器产物)相差不到15%。本发明还涉及一种通过利用能够在具有不同共聚特性的状态之间相互转换的未桥联、取代或未取代的环戊二烯基金属茂催化剂来生产这种共聚物的方法,该相互转换由选择环戊二烯基配体的取代基来控制,使得两种状态之间的相互转换速率与单一聚合物链的形成速率相差不超过几个数量级。其中,如果ri>rf,则聚合物可被表征为多嵌段;如果ri
Catalyst systems for high melting thermoplastic elastomeric alpha-olefin polymers and plastomers
申请人:The Board of Trustees of the Leland Stanford Junior University
公开号:US20030195308A1
公开(公告)日:2003-10-16
This invention relates generally to low ethylene insertions into &agr;-olefin polymers and processes for production of such polymers using unbridged fluxional metallocenes, primarily substituted aryl indenyl metallocenes, and more particularly to use of unbridged, fluxional, cyclopentadienyl or indenyl metallocene catalyst systems in methods of production of high melting point &agr;-olefin homo- and co-polymers, particularly elastomeric crystalline and amorphous block homo- and co-polymers of &agr;-olefins. The activity of fluxional unbridged metallocene polymerization catalysts containing at least one 2-arylindene ligand is increased 10× or more by the addition of small (typically 0.1-10 wt. %) amounts of ethylene to the polymerization system, which increase is termed the Polymerization Rate-Enhancement effect (PRE), which is measured in terms of an Ethylene Enhancement Factor (EEF) as a dimensionless ratio in the range of from about 1.1 to about 10 or above. The amount of ethylene included in the reaction system can be selected and controlled to be so small as to result in essentially minimal (<2 mole %) incorporation of ethylene units into the resulting elastomeric polymer and the molecular weight may be increased. Amounts of ethylene to generate the PRE effect may be greater than 0.1 wt. % and preferably range up to about 2 wt. %. However, if a polymer with more ethylene is desired, additional ethylene may be incorporated into the polymerization feed, including up to 10 to about 50 mole % based on olefin units. A second important aspect of this invention is the ability to use a PRE activity-enhancing amount of ethylene in an olefin polymerization without substantially affecting the physical properties of the elastomer. In a third important aspect of this invention, &agr;-olefin elastomers are produced through incorporation of ethylene using unbridged fluxional catalyst systems which may not otherwise produce acceptable elastomeric homopolymers. This effect is termed the EPE effect, for Elastomeric Property-Enhancing effect. The EPE amount of ethylene required to produce such elastomers typically overlaps the PRE activity-enhancing amount. Incorporation of up to about 5 mole % or more of ethylene typically will produce an elastomeric polymer using such catalyst systems. Typical useful amounts of incorporated ethylene include about 1 to 3 mole %. Preferred polymers of this invention retain sufficient crystallinity to provide a high melting point (by DSC) of about 80° C., preferably above 100° C., including in the range of from about 120° C. to about 140° C. and above. Novel flexible &agr;-olefin homo and copolymers having elongation in excess of 600% and substantially no retained force are disclosed.
本发明涉及低乙烯插入到α-烯烃聚合物中以及使用未桥联流动金属芳基茚基金属烯催化剂,尤其是取代芳基茚基金属烯催化剂的方法生产这种聚合物的过程,更特别地,使用未桥联、流动的环戊二烯基或茚基金属烯催化剂体系在生产高熔点α-烯烃均聚物和共聚物的方法中,特别是α-烯烃弹性结晶和非晶块状均聚物和共聚物的方法。至少含有一个2-芳基茚烯配体的流动未桥联金属烯聚合催化剂的活性通过向聚合体系中添加少量(通常为0.1-10重量%)乙烯而增加10倍或更多,这种增加被称为聚合速率增强效应(PRE),以无量纲比例的乙烯增强因子(EEF)的形式进行测量,范围为约1.1至约10或以上。可以选择和控制反应系统中包含的乙烯量非常小,以致于在所得到的弹性聚合物中几乎不包含(<2摩尔%)乙烯单元,分子量可以增加。产生PRE效应的乙烯量可能大于0.1重量%,并且最好在约2重量%范围内。但是,如果需要含更多乙烯的聚合物,可以将额外的乙烯并入聚合物化反馈中,包括基于烯烃单位的10至约50摩尔%。本发明的第二个重要方面是,在α-烯烃聚合中使用PRE活性增强量的乙烯而几乎不影响弹性体的物理性质。在本发明的第三个重要方面中,通过使用未桥联流动催化剂体系并将乙烯并入其中,可以生产α-烯烃弹性体,而该催化剂体系可能不会产生可接受的弹性体均聚物。这种效应称为EPE效应,用于弹性物性增强效应。通常需要并入约5摩尔%或更多的乙烯来使用这种催化剂体系生产弹性聚合物。通常有用的并入乙烯量包括约1至3摩尔%。本发明的优选聚合物保持足够的结晶性,以提供高熔点(通过DSC)约80℃,优选高于100℃,包括约120℃至约140℃以上的范围。还公开了具有超过600%的延伸率和基本无保留力的新型柔性α-烯烃均聚物和共聚物。
Methods of production of ethylene copolymers having narrow composition distributions and high melting temperatures
申请人:The Board of Trustees of the Leland Stanford Junior University
公开号:US20020115805A1
公开(公告)日:2002-08-22
A copolymer of ethylene and at least one comonomer containing at least 4 carbon atoms is characterized by a polydispersity greater than 2, a broad melting point transition as measured by differential scanning calorimetry, and a narrow composition distribution. Ethylene/C
4+
copolymers also may show at least one peak melting point above the peak melting point of a random copolymer of the same monomer unit composition. These copolymers are made by contacting ethylene and a comonomer under polymerization conditions in the presence of a suitable fluxional catalyst system.
乙烯和至少一个含有至少4个碳原子的共聚单体的共聚物具有聚分散度大于2、宽的熔点转变(通过差示扫描量热法测量)和窄的组成分布的特征。乙烯/C4+共聚物还可能显示出至少一个峰值熔点高于相同单体单位组成的随机共聚物的峰值熔点。这些共聚物是在适当的流动催化剂体系存在下,在聚合条件下接触乙烯和共聚单体制成的。
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