CA2379607A1

CA2379607A1 - Manufacture of polyethylenes

Info

Publication number: CA2379607A1
Application number: CA002379607A
Authority: CA
Inventors: Lin Wang; Maria Spinu; Joel David Citron
Original assignee: Individual
Current assignee: EIDP Inc
Priority date: 1999-09-29
Filing date: 2000-09-28
Publication date: 2001-04-05
Also published as: CN1939934B; US20040048989A1; EP1228110B1; WO2001023443A1; CN1939934A; JP2003510427A; DE60016014D1; US6555631B1; CN1377377A; BR0017587B1; BR0014639A; DE60016014T2; BR0014639B1; US6921795B2; US20030149182A1; AU7726800A; KR20020037364A; EP1228110A1; ATE282645T1

Abstract

Blends of two or more polyethylenes are made by reacting ethylene with an oligomerization catalyst that forms .alpha.-olefins, and two polymerization catalysts, one of which under the process conditions copolymerizes ethylene and .alpha.-olefins, and the other of which under process conditions does not readily copolymerize ethylene and .alpha.-olefins. The blends may have improved physical properties and/or processing characteristics.

Description

TITLE
MANUFACTURE OF POLYETHYLENES
FIELD OF THE INVENTION
Blends of polyethylenes may be manufactured by using various combinations of ethylene polymerization catalysts that may or may not copolymerize a.-olefins and ethylene, and ethylene oligomerization catalysts that produce a-olefins.
TECHNICAL BACKGROUND
Polyethylenes are important items of commerce, these being produced in larger volumes than any other polymer.
Many different grades of this polymer type are produced, these differing grades varying in many properties, including i5 cost. For an overview of polyethylenes, see B. Elvers, et al., Ed., Ullmann's Encyclopedia of Industrial Chemistry, 5th Ed., Vol. A21, VCH Verlagsgesellschaft, Weinheim, 1992, p.
488-518; and H. Mark et al., Ed., Encyclopedia of Polymer Science and Engineering, Vol. 6, John Wiley & Sons, New York, 1986, p. 383-489.
Aside from cost the two major property areas of concern to most users (polymer processors) are final polymer physi-cal properties, that is does the polymer have physical prop-erties suitable for the end use, and how difficult is it to form the polymer into the final article, often called proc-essability. In some instances polyethylene compositions having desirable properties are obtained by blending two or more polyolefins, at least one of which is a polyethylene, together. These blends may be formed by melt blending the separate blend polymers, or by forming two or more of the blend polymers in a single polymerization system (these may be sequential or simultaneous polymerizations). The latter is often preferred because such blends are often more uni-form, and the cost of a separate mixing step is avoided.
Blends may be formed to improve physical properties and/or processing properties. For instance, high density polyethylene is sometimes not as tough as desired, so it may be blended with a less crystalline polymer, such as a lower melting (even elastomeric) copolymer of ethylene and an a,-olefin (or other polyolefin), to toughen the resulting prod-uct. Therefore improved methods of making blends of poly-l0 ethylene polymers are of interest.
Various reports of "simultaneous" oligomerization and polymerization of ethylene to form (in most cases) branched polyethylenes have appeared in the literature, see for in-stance W090/15085, W099/50318, US5753785, US5856610, US5686542, US5137994 and US5071927; C. Denger, et al, Makro-mol. Chem. Rapid Commun., vol. 12, p. 697-701 (1991), and E.
A. Benham, et al., Polymer Engineering and Science, vol. 28, p. 1469-1472 (1988). All of the above are incorporated by reference herein for all purposes as if fully set forth.
None of these references specifically describes any of the processes or branched homopolyethylenes of the present invention.
SUMMARY OF THE INVENTION
This invention concerns a process for producing a blend of two or more polyethylenes, characterized in that said process comprises the step of contacting:
(1) ethylene;

(2) an active ethylene oligomerization catalyst under conditions to oligomerize at least a portion of the ethylene to one or more a,-olefins of the general formula R18CH=CHz, wherein R18 is an alkyl containing an even number of carbon atoms;

(3) a first active polymerization catalyst under con-ditions to copolymerize ethylene and the a-olefins generated from the active ethylene oligomerization catalyst; and (4) a second active polymerization catalyst under con-s ditions to polymerize ethylene, but not readily copolymerize ethylene and a-olefins.
This invention also concerns a polymerization catalyst component, comprising:
(a) an oligomerization catalyst that oligomerizes eth-l0 ylene to one or more a-olefins of the formula HzC=CHRla, wherein Rl$ is an alkyl containing an even number of carbon atoms; and (b) a first polymerization catalyst that is capable of copolymerizing ethylene and one or more a-olefins of the 15 formula H2C=CHRle;
(c) a second polymerization catalyst chemically differ-ent than the first active polymerization catalyst that is capable of polymerizing ethylene but does not readily co-polymerize ethylene and a-olefins;
20 (d) optionally, one or more catalyst supports onto which one or more of (a), (b) and/or (c) has been supported;
and (e) optionally one or more catalyst activators for (a), (b) and/or (c) .
25 This invention also concerns a first polymer blend com-prising:
(a) a first polyethylene that contains at least three different branches of the formula -(CHzCH2)nH, wherein n is an integer of 1 or more, and 30 (b) a second polyethylene that is different from the first polyethylene, in a weight ratio of about 1:4 to about 4:1 based on the to-tal weight of the first and second polyethylenes, and pro-vided that said second polyethylene has a melting point at least 20°C higher than said first polyethylene, or said sec-ond polyethylene has a heat of fusion at least 50 J/g greater than said first polyethylene, or both.
Also described herein is a second polymer blend com-prising:
(a) a third polyethylene having a density of less than 0.93 g/mL, containing at least 2 ethyl branches, at least 2 hexyl or longer branches and at least one butyl branch per 1000 methylene groups, and provided that said third polyeth-ylene has fewer than 5 methyl branches per 1000 methylene groups; and (b) a fourth polyethylene having a density of 0.93 g/mL
or more.
This invention also includes a third polymer blend com-prising:
(a) a fifth polyethylene containing about 20 to about 150 branches of the formula -(CHZCHz)nH per 1000 methylene groups, wherein n is an integer of 1 to 100, provided that said fifth polyethylene has less than about 20 methyl branches per 1000 methylene groups; and (b) a sixth polyethylene that is different from the fifth polyethylene and has a density of about 0.93 g/mL or more.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Herein certain terms are used which are defined below.
By "hydrocarbyl" is meant a univalent radical contain-ing only carbon and hydrogen. As examples of hydrocarbyls may be mentioned unsubstituted alkyls, cycloalkyls and aryls. If not otherwise stated, it is preferred that the hydrocarbyl groups herein contain 1 to 30 carbon atoms, and more preferably 1 to 20 carbon atoms.

By "substituted hydrocarbyl" herein is meant a hydro-carbyl group that contains one or more "inert functional groups" that are inert under the process conditions to which the compound containing these groups is subjected. The in-s ert functional groups also do not substantially interfere with the oligomerization/polymerization process. For exam-ple, in cases in which the inert functional group may be near the complexed iron atom, such as R4 or RS in formula (I) (shown below) , or as a substituent on R4, R5, R6 or R', the l0 inert functional group should not coordinate to the iron atom more strongly than the three depicted N groups in (I) which are the desired coordinating groups - that is, the functional group should not displace one or more of the de-sired coordinating N groups. The hydrocarbyl may be com-15 pletely substituted, as in trifluoromethyl. If not other-wise stated, it is preferred that substituted hydrocarbyl groups herein contain 1 to about 30 carbon atoms. Included in the meaning of "substituted" are heterocyclic rings.
Examples of inert functional groups include halo 20 (fluoro, chloro, bromo and iodo), ester, keto (oxo), amino, amino, carboxyl, phosphate, phosphonite, phosphine, phosphi-nite, thioether, amide, nitrite, and ether. Preferred inert functional groups are halo, ester, amino, amino, carboxyl, phosphate, phosphonite, phosphine, phosphinite, thioether, 25 and amide. With respect to catalysts based on ligands (I) and (II) described below, which inert functional groups are useful in which oligomerizations/polymerizations may in some cases be determined by reference to US5955555, US6103946 and W098/30612, all of which are hereby incorporated by refer-30 ence for all purposes as if fully set forth.
By an oligomerization or polymerization "catalyst acti-vator" is meant a compound that reacts with a transition metal compound to form an activated catalyst species. A

preferred catalyst activator is an alkylaluminum compound, that is, a compound which has at least one alkyl group bound to an aluminum atom.
By "relatively noncoordinating" (or "weakly coordinat-ing") anions are meant those anions as are generally re-ferred to in the art in this manner, and the coordinating ability of such anions is known and has been discussed in the literature. See, for instance, W. Beck et al., Chem.
Rev., vol. 88, pp. 1405-1421 (1988), and S.H. Strauss, Chem.
Rev., vol. 93, pp. 927-942 (1993), both of which are hereby included by reference. Among such anions are those formed from aluminum compounds (such as those described in the im-mediately preceding paragraph) and X- (an anion as discussed in further detail below) , including (R29) 3A1X-, (R29) 2AlClX-, RZ9A1C12X-, and Rz9AlOX-, wherein R29 is alkyl. Other useful noncoordinating anions include BAF- (BAF = tetrakis[3,5-bis (trifluoromethyl) phenyl] borate , SbF6-, PF6-, and BF4-, trifluoromethanesulfonate, p-toluenesulfonate, (RfSOz)zN-, and (CsFs)4B
By a "primary carbon group" herein is meant a group of the formula -CHz---, wherein the free valence --- is to any other atom, and the bond represented by the solid line is to a ring atom of an aryl or substituted aryl to which the pri-mary carbon group is attached. Thus the free valence ---may be bonded to a hydrogen atom, a halogen atom, a carbon atom, an oxygen atom, a sulfur atom, etc. In other words, the free valence --- may be to hydrogen, hydrocarbyl, sub-stituted hydrocarbyl or a functional group. Examples of primary carbon groups include -CH3, -CHZCH (CH3) 2, -CHZCl, -CH2C6H5, -OCH3 and -CH20CH3.
By a secondary carbon group is meant the group , CH

wherein the bond represented by the solid line is to a ring atom of an aryl or substituted aryl to which the secondary carbon group is attached, and both free bonds represented by the dashed lines are to an atom or atoms other than hydrogen. These atoms or groups may be the same or different. In other words the free valences represented by the dashed lines may be hydrocarbyl, substituted hydrocarbyl or inert functional groups. Examples of secondary carbon groups include -CH (CH3) 2, -CHC12, -CH (C6H5) 2, cyclohexyl, - CH ( CH3 ) OCH3 , and - CH=CCH3 .
By a "tertiary carbon group" is meant a group of the formula ,, C;' ., wherein the bond represented by the solid line is to a ring atom of an aryl or substituted aryl to which the tertiary carbon group is attached, and the three free bonds represented by the dashed lines are to an atom or atoms other than hydrogen. In other words, the bonds represented by the dashed lines are to hydrocarbyl, substituted hydrocarbyl or inert functional groups. Examples of tetiary carbon groups include -C (CH3) 3, -C (C6H5) 3, -CC13, -CF3, -C (CH3) ZOCH3, -C=CH, -C (CH3) ZCH=CH2, aryl and substituted aryl such as phenyl and 1-adamantyl.
By "aryl" is meant a monovalent aromatic group in which the free valence is to the carbon atom of an aromatic ring.
An aryl may have one or more aromatic rings which may be fused, connected by single bonds or other groups.
By "substituted aryl" is meant a monovalent aromatic group substituted as set forth in the above definition of "substituted hydrocarbyl". Similar to an aryl, a substi-tuted aryl may have one or more aromatic rings which may be fused, connected by single bonds or other groups; however, when the substituted aryl has a heteroaromatic ring, the free valence in the substituted aryl group can be to a het-eroatom (such as nitrogen) of the heteroaromatic ring in-s stead of a carbon.
Herein two or more polyethylenes are made. By a "poly-ethylene" is meant a polymer in which at least 50 mole per-cent, preferably at least 70 mole percent, and more prefera-bly at least 80 mole percent of the repeat units are derived from ethylene in the polymerization process. By a "homo-polyethylene" herein is meant a polymer in which substan-tially all of the repeat units are derived from ethylene in the polymerization process. "Derived from ethylene" in-cludes any comonomers generated in situ (either simultane-ously with or in series with the actual polymerization) from ethylene such as, for example, those ethylene oligomers formed by the ethylene oligomerization catalyst.
The comonomer, whether formed in situ or added sepa-rately to the polymerization, is a series of a-olefins of the formula H2C=CHR18, wherein R1$ is an alkyl containing an even number of carbon atoms. Other a-olefins, such as those in which R1a contains an odd number of carbons may optionally be present. It is preferred that the series of a-olefins comprises individual a-olefins in which R18 contains 2, 4, 6, 8, 10, 12, I4, 16 and optionally higher carbon atoms. It is also preferred that the series of cc-olefins comprises 5 mole percent or more, more preferably 10 mole percent or more, and especially preferably 15 mole percent or more, of a-olefins in which R1$ contains 10 or more carbon atoms, based on the total moles of a-olefins in the series. Preferably the oligomerization catalyst produces an a.-olefin mixture that has an average degree of oligomerization (that is the average number of ethylene units per molecule) of 30 or less, more preferably 15 or less.
If the series of olefins is added to the polymerization (i.e., it is not a homopolyethylene) or the olefins are made first in series with the polymerization reaction and thus may be sampled, the olefin series being used may be ana-lyzed, as by gas chromatography, to see if any of the above compositional limits on the olefin series are being met. If the olefin series is produced in situ simultaneously with l0 the polymerization reaction, it may not be possible to ob-taro a representative sample of the olefin series. Gener-ally the olefin series will be produced in situ by an ethyl-ene oligomerization catalyst which forms the requisite ole-fins from ethylene, and is active in the absence of the first and second polymerization catalysts (see below). In this instance an oligomerization may be run in the absence of the polymerization catalysts) to produce only the series of olefins, under conditions which reasonably mimic the com-bined oligomerization/polymerization. The series of olefins thus obtained is then analyzed (as by gas chromatography) to determine if it meets appropriate limitations. Typical analyses of such series of olefins may be found in previ-ously incorporated US6103946. It is assumed herein that the incorporation of a-olefins into a branched polyethylene is in proportion to the relative amounts in which they are pre-sent in the polymerization process. This may not be totally correct in the event, for example, that a volatile olefin such as 1-butene is partially "lost" to the polymerization reaction.
Oftentimes when such a series of olefins is made from ethylene a measure of the molecular weights of the olefins obtained is factor K from the Schulz-Flory theory (see for instance B. Elvers, et al., Ed. Ullmann's Encyclopedia of Industrial Chemistry, Vol. A13, VCH Verlagsgesellschaft mbH, Weinheim, 1989, p. 243-247 and 275-276. This is defined as:
K = n(Cn+2 olefin)/n(Cn olefin) wherein n(Cn olefin) is the number of moles of olefin con-taming n carbon atoms, and n(Cn+2 olefin) is the number of moles of olefin containing n+2 carbon atoms, or in other words the next higher oligomer of Cn olefin. From this can be determined the weight (mass) fractions of the various olefins in the resulting oligomeric reaction product mix-ture. The K factor is preferred to be in the range of about 0.55 to about 0.90, more preferably 0.65 to about 0.80. The K factor may also be varied by changing oligomerization con-ditions and/or the oligomerization catalyst, see for in-stance previously incorporated US6103946. By analyzing the branching pattern of the polymer produced one can roughly back calculate the K factor for the oligomerization to a-olefin, although there are possible errors (see below).
In one preferred embodiment, the polymer made is a ho-mopolyethylene, and/or the series of olefins is prepared si-multaneously with the polymerization reactions.
A preferred oligomerization catalyst for the prepara-tion of the olefins is described in previously incorporated US6103946. More preferably, the oligomerization catalyst is an Fe complex (Fe [II] or Fe [III] ) of a ligand of the general formula (I) Rs R (I) wherein:
R1, R2, R3, R4 and RS are each independently hydrogen, hydrocarbyl, substituted hydrocarbyl, or an inert func-tional group, provided that any two of R1, R2 and R3 vicinal to one another, taken together may form a ring;
and R6 and R' are aryl or substituted aryl.
More specifically, the preferrred oligomerization cata lyst is an Fe complex (Fe[II] or Fe[III]) of a ligand of the general formula (I), wherein:
R1, R2 and R3 are each independently hydrogen, hydrocar-byl, substituted hydrocarbyl or an inert functional group, provided that any two of R1, R2 and R3 vicinal to one another taken together may form a ring;
R4 and RS are each independently hydrogen, hydrocarbyl, substituted hydrocarbyl or an inert functional group;
R6 and R' are each independently an aryl or substituted aryl having a first ring atom bound to the imino nitrogen, provided that:
in R6, a second ring atom adjacent to said ffirst ring atom is bound to a halogen, a primary carbon group, a secon-dary carbon group or a tertiary carbon group; and further provided that in R6, when said second ring atom is bound to a halogen or a primary carbon group, none, one or two of the other ring atoms in R6 and R' adjacent to said first ring atom are bound to a halogen or a primary carbon group, with the re-mainder of the ring atoms adjacent to said first ring atom being bound to a hydrogen atom; or in R6, when said second ring atom is bound to a secon-dary carbon group, none, one or two of the other ring atoms in R6 and R' adjacent to said first ring atom are bound to a halogen, a primary carbon group or a secondary carbon group, with the remainder of the ring atoms adjacent to said first ring atom being bound to a hydrogen atom; or in R6, when said second ring atom is bound to a tertiary carbon group, none or one of the other ring atoms in R6 and R' adjacent to said first ring atom are bound to a tertiary carbon group, with the remainder of the ring atoms adjacent to said first ring atom being bound to a hydrogen atom.
By a "first ring atom in R6 and R' bound to an imino ni trogen atom" is meant the ring atom in these groups bound to an imino nitrogen shown in (I), for example C/ \ C
c~ c C\ /C
\C N
(III) or N (IV) the atoms shown in the 1-position in the rings in (III) and (IV) are the first ring atoms bound to an imino carbon atom (other groups which may be substituted on the aryl groups are not shown). Ring atoms adjacent to the first ring atoms are shown, for example, in (V) and (VI), where the open va-lencies to these adjacent atoms are shown by dashed lines (the 2,6-positions in (V) and the 2,5-positions in (VI)).
c~ ~ c C-C
.cue ,c_ -N (V) or N (VI ) Particularly preferred is a ligand of the formula (II):

R9 Rio R8 ~ Ro Ra ~a (II) wherein:
each of R1, R2, R3, Ra, R5, R9, R1°, Rll, R14' Rls and R16 is independently selected from the group consisting of hy drogen, hydrocarbyl, substituted hydrocarbyl and an in ert functional group; and R8 is halogen, a primary carbon group, a secondary car-bon group or a tertiary carbon group;
provided that:
l0 when Re is halogen or a primary carbon group none, one or two of R'-z, Ri3 and R1' are independently a primary carbon group, an inert functional group or a trihalo tertiary carbon group, and the remainder of Rlz, Ris and R1' are hydrogen;
when R8 is a secondary carbon group, none or one of R12, R13 and R1' is a primary carbon group, a secondary carbon group, a trihalo tertiary carbon group or an inert functional group, and the remainder of Rlz, R13 and R1' are hydrogen;
when R8 is a tertiary carbon group all of R12, R13 and R1' are hydrogen;

any two of Rl, RZ and R3 vicinal to one another, taken together may form a ring; and any two o f R8 , R9 , Rl ° , R11 ~ R12 , R13 , R14 , Rl s ~ R16 and R1' vicinal to one another, taken together may form a ring.
In one preferred embodiment of ligand (II), R4 and Rs are methyl or hydrogen; and/or R1, R2, and R3 are all hydro-gen; and/or R9, R1°, Rll, R14, Rls and R16 are all hydrogen;
and/or Rl' is selected from the group consisting of methyl, ethyl, propyl isopropyl, halo and trihalomethyl; and/or Rla l0 is selected from the group consisting of hydrogen, methyl, ethyl, propyl, isopropyl, halo and trihalomethyl. In cer-tain more preferred embodiments, both R12 and R1' are methyl or ethyl. In all such cases, R8 is a primary carbon group, and R13 i s hydrogen .
In specific preferred embodiments of ligand (II):
R4 and Rs are meth 1 ~ R9 R1° Rll R13 14 15 16 y , , , , , R , R and R
are all hydrogen; R12 is hydrogen or methyl; Rl' is methyl;
and Re is a primary carbon group; or R4 and Rs are methyl; R9, R1°, Rll, R13, R14, Ris and Rls are all hydrogen; R12 is hydrogen or ethyl; Rl' is ethyl; and R8 is a primary carbon group; or R4 and RS are methyl; Rg, R1°, Rl, R13, R14, Rls and R16 are all hydrogen; R12 is hydrogen or isopropyl; Rl' is isopro-pyl; and Re is a primary carbon group; or R4 and RS are methyl ; R9 , R1° , R11 ~ R13 , R14 , R15 and R16 are all hydrogen; R12 is hydrogen or n-propyl; Rl' is n-propyl; and Re is a primary carbon group; or R4 and R5 are meth 1 - R9 R1° R11 13 14 15 16 y , , , , R , R , R and R
are all hydrogen; Rl2 is hydrogen or chloro; Rl' is chloro;
and RB is a primary carbon group; or R4 and RS are methyl ; R9 , R1° , R11, R13 , Ri4 , Rls and RIs are all hydrogen; R12 is hydrogen or trifluoromethyl; Rl' is trifluoromethyl; and R$ is a primary carbon group.

In another preferred embodiment of ligand (II), Rl, R2, R3, R4, R5, R9, R1°, Rll, R14, Rls and R16 are as just defined, and if R8 is a primary carbon group, R12 and Rl' are hydrogen, and R13 is a primary carbon group; or if R8 is a secondary carbon group, R1z and R1' are hydrogen, and R13 is a primary carbon group or a secondary carbon group.
Also preferred is when Re is a primary carbon group, preferably selected from methyl, ethyl, propyls and butyls.
There are two types of polymerization catalysts em-ployed in the process herein, a first polymerization cata-lyst and a second polymerization catalyst. Although these will often be different chemically, it is possible that they are the same chemically but under different physical and/or process conditions that favor one type of polymerization over another. The terms "favor" one type of polymerization over another is relative in nature, and refers to the actual result (polymer) obtained from each of the catalysts under the process conditions.
For example, if the process is carried out as a con-tinuous gas phase polymerization, the oligomerization cata-lyst and the polymerization catalysts will often be sup-ported on fine particulate solids (such as silica, alumina, another organic polymer, magnesium chloride, sodium chlo ride, etc.). One may support the first polymerization and the oligomerization catalyst onto the same support parti-cles, while supporting the second polymerization catalyst on different support particles (the support particles for each may the same or different materials). In this instance each support particle may be thought of as a minireactor, that is h;:3seous or other reactants, once reacted by the catalysts) on that support stay there, and may be further reacted if they are still reactive (i.e. a-olefin). Thus the particles having the oligomerization catalyst and first polymerization catalyst are reactive towards forming a-olefin, which may then be copolymerized with ethylene by the first polymeriza-tion catalyst. The second polymerization catalyst, although it may be able to copolymerize ethylene and a-olefins, just makes a homopolyethylene containing at most a relatively small amount of branching due to a-olefin incorporation, be-cause the in situ generated a-olefin is not readily avail-able to this second catalyst for copolymerization. This is illustrated by Example 2 (below). In Example 2 the first l0 and second polymerization catalysts are an identical metal-locene which is capable of copolymerizing ethylene and a-olefins. Yet a semicrystalline polyethylene is part of the product. The melting point of this semicrystalline polyeth-ylene indicates that it may have some branching due to in-corporation of some a-olefin, but it does not have as much branching as the polyethylene produced by the combination of the oligomerization catalyst and the first polymerization catalyst (present on the same support particles). The "leakage" of a-olefin to the second polymerization catalyst particles is probably due to vaporization of lower molecular weight a-olefins, such as 1-butene, into the ethylene gas present, and subsequent copolymerization by the second po-lymerization catalyst.
It would therefore be preferable, if it is desired that the relatively higher melting point and nonbranched polyeth-ylene produced by this process is or is very close to high density polyethylene (HDPE) with little or no branching (in-corporation of a-olefin), to use as a second polymerization catalyst a material which has no or a reduced tendency to copolymerize ethylene with a-olefins. Such a second polym-erization catalyst was used in Example 3, and it can be seen that although the overall polymer product has 25 branches/1000 CH2 groups, the melting point of the overall polymer indicates that the relatively unbranched polymer contained therein (made by the second polymerization cata-lyst) is essentially HDPE.
The first polymerization catalyst for the copolymeriza-tion of the ethylene and the olefin series should be a cata-lyst that can copolymerize ethylene and cc-olefins so that the relative rate of copolymerization of these two types of monomers are similar. Such catalysts include Ziegler-Natta-type catalysts and metallocene catalysts. These types of catalysts are well known in the polyolefin field, see for instance Angew. Chem., Int. Ed. Engl., vol. 34, p. 1143-1170 (1995), EP-A-0416815 and US5198401 for information about metallocene-type catalysts; and J. Boor Jr., Ziegler-Natta Catalysts and Polymerizations, Academic Press, New York, 1979 for information about Ziegler-Natta-type catalysts, all of which are hereby incorporated by reference herein for all purposes as if fully set forth. Certain late transition metal catalysts may also be suitable, such as found in US5880241, US5955555 and US5714556, all of which are hereby incorporated by reference herein for all purposes as if fully set forth.
Many of the useful polymerization conditions for these types of catalysts and the oligomerizations catalysts coin-cide, so conditions for the polymerization are easily acces-sible. Oftentimes the "co-catalyst" or "activator" is needed for the copolymerization catalyst, much as W is some-times needed for the oligomerization catalysts (as described below). In many instances the same compound, such as an al-kylaluminum compound, may be used for these purposes for both types of catalysts.
Suitable catalysts for the copolymerization catalyst also include metallocene-type catalysts, as described in US5324800 and EP-A-0129368; particularly advantageous are bridged bis-indenyl metallocenes, for instance as described in US5145819 and EP-A-0485823. Another class of suitable catalysts comprises the well-known constrained geometry catalysts, as described in EP-A-0416815, EP-A-0420436, EP-A-0671404, EP-A-0643066 W091/04257. Also the class of transi-tion metal complexes described in, for example, W098/30609, US5880241, US6060569 and US5714556 can be used. Also useful are transition metal complexes of bis(carboximidamida-tonates), as described in WO00/12568. All of the aforemen-tinned publications are incorporated by reference herein for all purposes as if fully set forth. Of the above, metallo cene-type catalysts are preferred.
As noted above the second polymerization catalyst may be the same as, or different than the first polymerization catalyst, and therefore the second polymerization catalyst includes all those materials useful as first polymerization catalyst. As also noted above however the second polymeri-zation may also be an ethylene polymerization catalyst that does not readily copolymerize ethylene and a-olefins, and these polymerization catalysts are preferred second polym-erization catalysts. By "does not readily" is meant the second catalyst does not incorporate a-olefins in a copoly-mer with ethylene as well as the first polymerization cata-lyst and preferably has little or no tendency to do so, but it may incorporate some a-olefin in the polyethylene it makes. Preferably it incorporates less than 5 mole percent of a-olefin (of the total repeat units), more preferably less than 1 mole percent and especially preferably less than 0.2 mole percent of these repeat units. Such incorporation may be measured by 13C NP~IR, especially after separating the polymers by TREE (see below).

A preferred second polymerization catalyst is an iron complex of a compound of the formula (III) Rs N
N
R' (III) wherein:
R1, R2, R3, R4 and RS are each independently hydrogen, hydrocarbyl, substituted hydrocarbyl, or an inert func-tional group, provided that any two of R1, RZ and R3 vicinal to one another, taken together may form a ring;
and R6 and R' are aryl or substituted aryl.
In (III) it is preferred that R6 is R9 Rio R' (IV) ;
and R' is ,.2o Rya R,o ~~5 (v) wherein:
Rz° and R22 are each independently hydrocarbyl, substi-tuted hydrocarbyl or an inert functional group;
Rs ~ Rlo ~ Rll ~ Ri4 , Rls and R16 are as de f fined above ;

Rl9 and Rzl are each independently hydrogen, hydrocarbyl, substituted hydrocarbyl or an inert functional group;
and provided that any two of R9, R1°, Rll, R14, Rls R16, Rls~ Rzo~ Rzl and Rzz that are vicinal to one another, taken together may form a ring.
It will be noted that, in the general description, (I) and (II) are subsets of (III), and therefore when choosing (III) (or its iron complex), an oligomerization catalyst should not be chosen as the second polymerization catalyst.
Useful and preferred systems are described in, for example, previously incorporated US5955555, as well as in W099/12981, W099/46302, W099/46303, W099/46304, W099/46308, W099/62963, WO00/15646, WO00/24788, WO00/32641 (all of which are incor-porated by reference herein for all purposes as if fully set forth), and reference may be had thereto for further de-tails.
The process may be run in any way in which all three (or more, if present) of the catalysts are active for their intended use. For instance, if each of the catalysts is a metal halide (or other anion X- such as carboxylate, ace-tylacetonate, etc.) complex the process may be run at a tem-perature of about -100°C to about +200°C, more preferably about 0°C to about 100°C.
The "pure" Fe complexes of (I), (II) and (III) may be exempt i f ied by the formulas ( I ) FeXn, ( I I ) FeXn and ( I I I ) FeXn, wherein each X is an anion, n is 1, 2 or 3 so that the total number of negative charges on the X groups is equal to the oxidation state of the Fe in the pure Fe complex. Prefera-bly, each X is a monovalent anion, more preferably selected from the group consisting of halide and carboxylate, and es-pecially a halide such as chloride or bromide.
The various complexes (such as the pure Fe complexes) may in and of themselves be active catalysts, or they may be activated (or made more active) preferably by preparation in situ by contact with a catalyst activator in a variety of methods. Generally, it has been found that the most active catalysts are those that have been contacted with a catalyst activator.
The various complexes may be activated by contact with a first compound W, which is a neutral Lewis acid capable of abstracting X- to form WX-, provided that the anion formed is a weakly coordinating anion; or a cationic Lewis or Bronsted acid whose counterion is a weakly coordinating anion.
In those instances in which the Fe complex of (I), (II) or (III) does not contain an alkyl, hydride, or other group which may be displaced by ethylene already bonded to the metal (i.e., X is not alkyl or hydride), a neutral Lewis acid or a cationic Lewis or Bronsted acid may also alkylate or add a hydride to the metal, i.e., causes an alkyl group or hydride to become bonded to the metal atom, or a separate compound is added to add the alkyl or hydride group.
A preferred neutral Lewis acid, which can alkylate the metal, is a selected alkyl aluminum compound, such as R3°3A1, R3°3A1C1, R3°A1C12, and "R3°A10" (alkylaluminoxanes) , wherein R3° is alkyl containing 1 to 25 carbon atoms, preferably 1 to 4 carbon atoms. Suitable alkyl aluminum compounds include methylaluminoxane (which is an oligomer with the general formula [MeAlO] n) , (C2H5) ZA1C1, (C2H5) AlClz and [(CH3)ZCHCHz]3A1. Metal hydrides such as NaBH4 may be used to bond hydride groups to the metal M.
In the process of the present invention at least two polymers are produced, and both of them may be thought of as homopolyethylenes (assuming no other olefins are introduced and copolymerized in the process). Other olefins, such as propylene or 1-butene may also optionally be added to the process and may be copolymerized into the lower density polyethylene, but these other olefins should not be exten-sively copolymerized into the relatively higher density (containing less branching) polyethylene.
However it is to be understood that (at least) one of polymers produced, the relatively lower density and/or more highly branched polyethylene, is not made by the direct po-lymerization of ethylene alone, but by the copolymerization of ethylene and one or more a.-olefins which may be, and preferably are, produced in situ. This polymer (the first, third and where applicable fifth polyethylenes herein) usu-ally contain (assuming no other olefins added to the proc-ess) only branches of the formula (excluding end groups) -(CH2CH2)nH wherein n is 1 or more, preferably 1 to 100, more preferably 1 to 30, of these branches per 1000 methyl-ene atoms. Normally there will be branches with a range of "n" in the polymer. The amount of these branches (as meas-ured by total methyl groups) in the polymer preferably ranges from about 2 to about 200, especially preferably about 5 to about 175, more preferably about 10 to about 150, very preferably about 20 to about 150, and particularly preferably 25 to 100 branches per 1000 methylene groups in the polymer. For the method of measurement (13C NMR) and cal-culation, see previously incorporated US5880241. Another preferable range for these branches is about 50 to about 200 methyl groups per 1000 methylene carbon atoms. It is also preferable (either alone or in combination with the other preferable features above) that in the first, third and fifth polyethylenes there are at least 2 branches each of ethyl and n-hexyl or longer and at least one n-butyl per 1000 methylene groups, more preferably at least 4 branches each of ethyl and n-hexyl or longer and at least 2 n-butyl branches per 1000 methylene groups, and especially prefera-bly at least 10 branches each of ethyl and n-hexyl or longer and at least 5 n-butyl branches per 1000 methylene groups.
It is also preferred that there are more ethyl branches than butyl branches. In another preferred first, third or fifth polyethylene (alone or in combination with any of the above preferred features) there is less than 20 methyl branches, more preferably less than 2 methyl branch, and especially preferably less than 2 methyl branches (all after correction for end groups) per 1000 methylene groups.
The other polymer produced, the higher density and/or l0 lower branching level second, fourth or sixth polyethylenes are preferably relatively unbranched, more preferably having less than 15 branches (as measured by total methyl groups, corrected for end groups) per 1000 CH2 groups, more prefera-bly less than less than 5 branches/1000 CH2 groups. It is also preferred that this polymer have a melting point of about 115°C or higher, more preferably about 125°C or higher, and/or have a density of about 0.93 g/mL or more, more pref-erably about 0.94 g/mL or more, and/or the more branched (first, third or fifth) polyethylene have a density of less than 0.93 g/mL, more preferably less than about 0.92 g/mL.
Any of the above preferred limitations on any of the polyethylenes may be combined with any other limitation, so long as these limitations do not conflict with each other or with limitations on the blends described herein. It is also to be understood that branches containing an odd number of carbon atoms may also be present in these polyethylenes from addition of olefins containing an odd number of carbon atoms to the polymerization. These latter polyethylenes will not be homopolyethylenes, but may otherwise be covered herein.
If present, preferably less than about 5 mole percent, more preferably less than about 2 mole percent, and especially preferably less than about 1 mole percent of the copolymer-ized olefins will be olefins with an odd number of carbon atoms.
In the first polymer blend herein it is preferred that the weight ratio of the first and second polyethylenes is in the range of from about 1:4 to about 2:1, more preferably in the range of from about 1:4 to about 1:1, based on the com-biped weight of the first and second polyethylenes; and/or said second polyethylene has a melting point at least about 30°C, more preferably 50°C higher than said first polyethyl-l0 ene; and/or said second polyethylene has a heat of fusion at least about 100 J/g greater than the heat of fusion of said first polyethylene.
In the first through sixth polyethylenes here it is preferred that they are homopolyethylenes. Furthermore in the polymerization process herein and in preparation of the first, second and third polymer blends herein it is also preferred that the oligomerization of ethylene and the po-lymerization carried out by the first and second polymeriza-tion catalysts be carried out essentially simultaneously in the same reactor(s).
In one preferred method, the oligomerization catalyst and the first polymerization catalyst are supported on the same support particles, and the second polymerization cata-lyst is supported on other support particles, each "set" of support particles being the same or different materials.
Using this method it is especially preferred that the proc-ess is carried out in the gas phase.
In another preferred method the oligomerization cata-lyst, first polymerization catalyst and second polymeriza-tion catalyst are all supported on the same catalyst parti-cles. While gas phase polymerization is again preferred, this process may also be carried out in solution or slurry polymerization. The second polymerization catalyst prefera-bly has little or no tendency to copolymerize ethylene and a-olefins.
In another preferred process the process is carried out in solution or slurry with one or more, preferably all of the catalysts, being unsupported. Again the second polym-erization catalyst preferably has little or no tendency to copolymerize ethylene and a-olefins.
In all of the processes, it is preferred that the sec-ond polymerization catalyst has little or no tendency to co-l0 polymerize ethylene and a-olefins.
It is preferred that one or more of the catalysts be present as a complex with the appropriate transition metal and that the anions for the transition metal be monoanions, such as halide, especially chloride or bromide, carboxylate, acetylacetonate, etc. In such a case, as indicated above, a cocatalyst or activator is usually needed, such as an al-kylaluminum compound. If a support is used, the alkylalumi-num compound may also be present (supported) on the support.
Other items normally present in transition metal complex catalyzed polymerization of ethylene, such as hydrogen to regulate the molecular weight of the polymers formed, may also be present.
The polymerization catalyst component comprises an oli-gomerization catalyst and two polymerization catalysts (which may be chemically identical but produce different polymers). This component may be a "single" material, i.e., a support particles having on them all three catalysts (plus optionally one or more cocatalysts), or may be a mixture of two materials such as support particles having the oli-gomerization catalyst and the first polymerization catalyst supported thereon, and other support particles having the second polymerization catalyst supported thereon, and op-tionally one or more cocatalysts supported on one or both sets of particles. It may be a solution or slurry of all three catalysts. In these catalyst components (and in the polymerization/oligomerization process) preferred cocata-lysts are alkylaluminum compounds, and methylaluminoxane is especially preferred.
In many instances, in order to measure the melting point, heat of fusion, branching levels and/or branching distributions of the polymer blends produced herein accu-rately, it is first necessary to separate the polymers in the blend. This may conveniently done by TREF, Temperature-Rising Elution Fractionation, which basically separates polymers on the basis of melting point (crystallinity). The fractions may be quantitated by various detectors, and these fractions detected and analyzed, for example for density, and by DSC, NMR, and GPC. If enough polymer is not col-lected in one TREE run, several runs may be made to collect enough polymer for various analyses desired. The fractions for the purposes of determining the amount of each polymer in the blend may be grouped together, for example the two polymers giving a bimodal distribution may be collected as several fractions each, but these fractions may be grouped together to determine how much, for example, of a higher melting and lower melting polymer there is. The shape of the TREF curve may be used, and mathematical modeling may be used to determine the amounts of each fraction on overlap-ping TREE peaks. A description of TREF may be found in L.
Wild, Adv. Polym. Sci., vol. 98, p. 1-47 (1990); G. Glock-ner, J. Appl. Polym. Sci., Polym. Symp., vol. 45, p. 1 et seq. (1990); L. G. Hazlitt, J. Appl. Polym. Sci., Appl.
Polym. Symp., vol. 45, p. 25 et seq., (1990); I Mingozzi, et al., J. Polym. Anal. Charact., vol. 3, p. 293 et seq., (1997); and the first 2 chapters in R. A. Petrick, et al., Ed., Modern Techniques for Polymer Characterization, John Wiley & Sons, Chichester, 1999.
Density is determined by ASTM Method D1928, Method C
with the following changes. Polytetrafluororethylene coated aluminum foil is used for the parting sheets, backing plates are not used, and the samples is heated for 1.5 min at 180°C.
The sandwich of A1 foil and the Teflon~ FEP fluoropolymer chase are placed directly on the platens of the hot press.
Density is measured using the method of ASTM D1505. Melting point and heat of fusion of polymers is measured using the method of ASTM D3417-97, on the second heat and using a heating rate of 10°C/min, taking the maximum of the melting endotherm as the melting point.
The number of branches in a polyethylene is measured taken as the total number of methyl groups per 1000 methyl-ene (CHZ) groups, after correction for end groups (in other words, end groups are not included in the total). Branching distribution is measured by 13C NMR and is corrected for end groups (although herein corrected results are not given).
Methods for both these NMR measurements are found in previ-ously incorporated US5880241.
Molecular weights are measured using Gel Permeation Chromatography using appropriate standards.
In the Examples, all pressures are gauge pressures.
The following abbreviations are used:
OHf - heat of fusion DSC - differential scanning calorimetry GC - gas chromatography GPC - gel permeation chromatography MAO - methylaluminoxane Me - methyl Mw - weight average molecular weight PE - polyethylene PDI - weight average molecular weight/number average molecular weight RT - room temperature TCE - trichloroethylene In the Examples, the following compounds were used:
,I ~ ~I
Z~C12 - N- I I \
\ / ~~
ci ci c~ ci A B C
Example 1 General procedure for making silica supported cata-lysts:
In a drybox, A (0.1 wt o in biphenyl, the weight in Ta-ble 1 are the solution weights), B and/or C, and silica sup-ported methylaluminoxane (0.358, 18 wt% in A1, Albamarle) were mixed with 15 mL of toluene in a 20 mL vial. The vial was shaken for 30 min at RT. The solid was filtered, washed with 3X5mL toluene and dried in vacuo for 1 h. It was then stored in a freezer in the drybox and was used the same day.
Details of catalyst components are listed in Table 1.
Examples 2-5 and Comparative Examples A-C
In a drybox, supported catalysts (total 5.0 mg) were weighed in GC vials. They were placed in a multitube block reactor (more than one polymerization could be run at once).
The reactor was brought out of the drybox and was charged with 1.21 MPa of ethylene. It was then placed in a 90°C oil bath for 1 h under 1.21 MPa of ethylene. Polymers were iso-lated, weighed and then analyzed without purification by 1HNMR (TCE-d2, 120°C), GPC and DSC. Results of the various polymerization runs are given in Table 2.

Table 1 Cata- Com- Amount of Silica Tolu- A1:M:A

lyst pounds) A (O.lwt % Supported ene Ratio and amount in MAO (mL) M=Zr, Fe biphenyl) (18 wt s) I B, l.Omg 0 0.35g 15 1000:1:0 II C, l.2mg 0 0.358 15 1000:1:0 III B, l.Omg 27.3mg 0.35g 15 1000:1:0.025 IV B, l.Omg 109.2mg 0.358 15 1000:1:0.1 V B, l.Omg 54.6mg 0.358 15 1000:1Zr, C, l.2mg lFe:0.05 Table 2 Ex. Cata- PE TON* #Me/ Mw/PDI m .p.
lyst(s) yield 1000 [C/OHf(J/g)]
And Amount (g) CH2 2 I, 2.5mg 0.175 180,000 21 198,985/5.1 116/106.0 IV, 2.5mg 3 II, 2.5mg 0.340 350,000 25 124,009/5.2 132/101.8 IV, 2.5mg 4 III, 2.5mg 0.389 400,000 26 183,845/5.2 119**/100.4 IV, 2.5mg V, 5mg 0.417 440,000 23 169,050/7.3 116**/98.6 A II, 5mg 0.243 270,000 2 147,758/7.9 133/212.5 B III, 5mg 0.351 370,000 14 222,394/4.4 117/105.7 C IV, 5mg 0.125 120,000 59 50,342/26.2 124/17.2 * moles of ethylene/mole of catalyst(s).hr ** large shoulder

Claims

What is claimed is:

1. A polymerization catalyst component, comprising:
(a) an oligomerization catalyst that oligomerizes eth-ylene to one or more .alpha.-olefins of the formula H2C=CHR18, wherein R18 is an alkyl containing an even number of carbon atoms;
(b) a first polymerization catalyst that is capable of copolymerizing ethylene and one or more .alpha.-olefins of the formula H2C=CHR18; and (c) a second polymerization catalyst chemically differ-ent than the first active polymerization catalyst, that is capable of polymerizing ethylene but does not readily co-polymerize ethylene and .alpha.-olefins.

2. The polymerization catalyst component as recited in claim 1, characterized in that the ethylene oligomerization catalyst is an Fe complex of a ligand of the general formula (I) wherein:
R1, R2 and R3 are each independently hydrogen, hydrocar-byl, substituted hydrocarbyl or an inert functional group, provided that any two of R1, R2 and R3 vicinal to one another taken together may form a ring;
R4 and R5 are each independently hydrogen, hydrocarbyl, substituted hydrocarbyl or an inert functional group;

R6 and R7 are each independently an aryl or substituted aryl having a first ring atom bound to the imino nitrogen, provided that:
in R6, a second ring atom adjacent to said first ring atom is bound to a halogen, a primary carbon group, a secon-dary carbon group or a tertiary carbon group; and further provided that in R6, when said second ring atom is bound to a halogen or a primary carbon group, none, one or two of the other ring atoms in R6 and R7 adjacent to said first ring atom are bound to a halogen or a primary carbon group, with the re-mainder of the ring atoms adjacent to said first ring atom being bound to a hydrogen atom; or in R6, when said second ring atom is bound to a secon-dary carbon group, none, one or two of the other ring atoms in R6 and R7 adjacent to said first ring atom are bound to a halogen, a primary carbon group or a secondary carbon group, with the remainder of the ring atoms adjacent to said first ring atom being bound to a hydrogen atom; or in R6, when said second ring atom is bound to a tertiary carbon group, none or one of the other ring atoms in R6 and R7 adjacent to said first ring atom are bound to a tertiary carbon group, with the remainder of the ring atoms adjacent to said first ring atom being bound to a hydrogen atom.

3. The polymerization catalyst component as recited in claim 2 wherein the ethylene oligomerization catalyst is an Fe complex of a ligand of the general formula (II):

wherein:
each of R1, R2, R3, R4, R5, R9, R10, R11, R14, R15 and R16 is independently selected from the group consisting of hy-drogen, hydrocarbyl, substituted hydrocarbyl and an in-ert functional group; and R8 is a primary carbon group, a secondary carbon group or a tertiary carbon group;
provided that:
when R8 is a primary carbon group none, one or two of R12, R13 and R17 are independently a primary carbon group, an inert functional group or a trihalo tertiary carbon group, and the remainder of R12, R13 and R17 are hydrogen;
when R8 is a secondary carbon group, none or one of R12, R13 and R17 is a primary carbon group, a secondary carbon group, a trihalo tertiary carbon group or an inert functional group, and the remainder of R12, R13 and R17 are hydrogen;
when R8 is a tertiary carbon group all of R12, R13 and R17 are hydrogen;

any two of R1, R2 and R3 vicinal to one another, taken together may form a ring; and any two of R8, R9, R10, R11, R12, R13, R14, R15, R16 and 17 vicinal to one another, taken together may form a ring.

4. The polymerization catalyst component as recited in claim 1, characterized in that the second active polymeriza-tion catalyst is an Fe complex of a ligand of the general formula (III) wherein:
R1, R2, R3, R4 and R5 are each independently hydrogen, hydrocarbyl, substituted hydrocarbyl, or an inert func-tional group, provided that any two of R1, R2 and R3 vicinal to one another, taken together may form a ring;
and R6 and R7 are aryl or substituted aryl.

5. The polymerization catalyst component as recited in claim 1, characterized in that the first polymerization catalyst is a metallocene-type catalyst.

6. The polymerization catalyst component as recited in claim 1, characterized in that the first polymerization catalyst is a metallocene-type catalyst, and the second ac-tive polymerization catalyst is an Fe complex of a ligand of the general formula (III):

wherein:
R1, R2, R3, R4 and R5 are each independently hydrogen, hydrocarbyl, substituted hydrocarbyl, or an inert func-tional group, provided that any two of R1, R2 and R3 vicinal to one another, taken together may form a ring;
and R6 and R7 are aryl or substituted aryl.

7. The polymerization catalyst component of any one of claims 1-6, characterized in that it further comprises (d) one or more catalyst supports onto which one or more of (a), (b) and/or (c) has been supported.

8. A process for producing a blend of two or more poly-ethylenes, characterized in that said process comprises the step of contacting:
(1) ethylene;
(2) an active ethylene oligomerization catalyst under conditions to oligomerize at least a portion of the ethylene to one or more .alpha.-olefins of the general formula R18CH=CH2, wherein R18 is alkyl containing an even number of carbon at-oms;

(3) a first active polymerization catalyst under con-ditions to copolymerize ethylene and the .alpha.-olefins generated from the active ethylene oligomerization catalyst; and (4) a second active polymerization catalyst under con-ditions to polymerize ethylene, but not readily copolymerize ethylene and .alpha.-olefins.

9. The process as recited in claim 8, characterized in that the active ethylene oligomerization catalyst is an Fe complex of a ligand of the general formula (I) wherein:
R1, R2 and R3 are each independently hydrogen, hydrocar-byl, substituted hydrocarbyl or an inert functional group, provided that any two of R1, R2 and R3 vicinal to one another taken together may form a ring;
R4 and R5 are each independently hydrogen, hydrocarbyl, substituted hydrocarbyl or an inert functional group;
R6 and R7 are each independently an aryl or substituted aryl having a first ring atom bound to the imino nitrogen, provided that:
in R6, a second ring atom adjacent to said first ring atom is bound to a halogen, a primary carbon group, a secon-dary carbon group or a tertiary carbon group; and further provided that in R6, when said second ring atom is bound to a halogen or a primary carbon group, none, one or two of the other ring atoms in R6 and R7 adjacent to said first ring atom are bound to a halogen or a primary carbon group, with the re-mainder of the ring atoms adjacent to said first ring atom being bound to a hydrogen atom; or in R6, when said second ring atom is bound to a secon-dary carbon group, none, one or two of the other ring atoms in R6 and R7 adjacent to said first ring atom are bound to a halogen, a primary carbon group or a secondary carbon group, with the remainder of the ring atoms adjacent to said first ring atom being bound to a hydrogen atom; or in R6, when said second ring atom is bound to a tertiary carbon group, none or one of the other ring atoms in R6 and R7 adjacent to said first ring atom are bound to a tertiary carbon group, with the remainder of the ring atoms adjacent to said first ring atom being bound to a hydrogen atom.

10. The process as recited in claim 9, characterized in that the active ethylene oligomerization catalyst is an Fe complex of a ligand of the general formula (II):

wherein:
each of R1, R2, R3, R4, R5, R9, R10, R11, R14, R15 and R16 is independently selected from the group consisting of hy-drogen, hydrocarbyl, substituted hydrocarbyl and an in-ert functional group; and R8 is a primary carbon group, a secondary carbon group or a tertiary carbon group;
provided that:
when R8 is a primary carbon group none, one or two of R12, R13 and R17 are independently a primary carbon group, an inert functional group or a trihalo tertiary carbon group, and the remainder of R12, R13 and R17 are hydrogen;
when R8 is a secondary carbon group, none or one of R12, R13 and R17 is a primary carbon group, a secondary carbon group, a trihalo tertiary carbon group or an inert functional group, and the remainder of R12, R13 and R17 are hydrogen;
when R8 is a tertiary carbon group all of R12, R13 and R17 are hydrogen;
any two of R1, R2 and R3 vicinal to one another, taken together may form a ring; and any two of R8, R9, R10, R11, R12, R13, R14, R15, R16 and R17 vicinal to one another, taken together may form a ring.

11. The process as recited in claim 8, characterized in that the second active polymerization catalyst is chemically different than the first active polymerization catalyst, and has little or no tendency to copolymerize ethylene and .alpha.-olefins.

12. The process as recited in claim 8, characterized in that the second active polymerization catalyst is an Fe com-plex of a ligand of the general formula (III):

wherein:
R1, R2, R3, R4 and R5 are each independently hydrogen, hydrocarbyl, substituted hydrocarbyl, or an inert func-tional group, provided that any two of R1, R2 and R3 vicinal to one another, taken together may form a ring;
and R6 and R7 are aryl or substituted aryl.

13. The process as recited in claim 8, characterized in that the first polymerization catalyst is a metallocene-type catalyst.

14. The process as recited in claim 8, characterized in that the oligomerization catalyst, first polymerization catalyst and second polymerization catalyst are supported.

15. The process as recited in claim 14 carried out in the gas phase.

16. The process as recited in claim 8, characterized in that the polymerization catalyst component as set forth in any one of claims 1-6 is used.

17. The process as recited in any one of claims 8-15, characterized in that the polyethylenes are homopolyethyl-enes.

18. The process as recited in claim 16, characterized in that the polyethylenes are homopolyethylenes.

19. A polymer blend comprising:
(a) a first polyethylene that contains at least three different branches of the formula -(CH2CH2)n H, wherein n is an integer of 1 or more, and (b) a second polyethylene that is different from the first polyethylene, in a weight ratio of about 1:4 to about 4:1 based on the to-tal weight of the first and second polyethylenes, and pro-vided that said second polyethylene has a melting point at least 20°C higher than said first polyethylene, or said sec-ond polyethylene has a heat of fusion at least 50 J/g greater than said first polyethylene, or both.

20. The polymer blend of claim 29, characterized in that the first and second polyethylenes are homopolyethyl-enes.

21. A polymer blend comprising:
(a) a third polyethylene having a density of less than 0.93 g/mL, containing at least 2 ethyl branches, at least 2 hexyl or longer branches and at least one butyl branch per 1000 methylene groups, and provided that said third polyeth-ylene has fewer than 5 methyl branches per 1000 methylene groups; and (b) a fourth polyethylene having a density of 0.93 g/mL
or more.

22. The polymer blend of claim 21, characterized in that the third and fourth polyethylenes are homopolyethyl-enes.

23. A polymer blend comprising:
(a) a fifth polyethylene containing about 20 to about 150 branches of the formula -(CH2CH2)n H per 1000 methylene groups, wherein n is an integer of 1 to 100, provided that said fifth polyethylene has less than about 20 methyl branches per 1000 methylene groups; and (b) a sixth polyethylene that is different from the fifth polyethylene and has a density of about 0.93 g/mL or more.

24. The polymer blend of claim 23, characterized in that the fifth and sixth polyethylenes are homopolyethyl-enes.

25. The polymer blend of any one of claims 19-24, ob-tainable by the process as set forth in claim 8.