Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Polymers from only ethylenic monomers or processes of...
Reexamination Certificate
2001-05-02
2004-01-20
Harlan, Robert (Department: 1713)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Polymers from only ethylenic monomers or processes of...
C526S160000, C526S161000, C526S348600, C526S905000, C526S916000, C526S943000, C502S152000, C502S155000
Reexamination Certificate
active
06680361
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to shear thinning ethylene/&agr;-olefin (EAO) interpolymers. The interpolymers have a Processing Rheology Ratio (PRR) of at least 4, an indication that long chain branching (LCB) is present. The interpolymers attain such a PRR in the absence of a conventional LCB monomer such as norbornadiene (NBD). The alpha-olefin (&agr;-olefin) suitably contains three to 20 carbon atoms (C
3
-C
20
) and is preferably propylene (C
3
), 1-butene, 1-hexene or 1-octene (C
8
). The interpolymers desirably include a diene (diolefin) monomer, preferably a nonconjugated diene monomer such as 5-ethylidene-2-norbornene (ENB). The diene-containing EAO interpolymers are generically referred to as “EAODM interpolymers”. EAO and EAODM interpolymers are collectively referred to as “EAO(D)M interpolymers”. This invention also relates to preparation of such interpolymers, compositions that include such interpolymers and articles of manufacture that include at least one part or portion fabricated from such interpolymers or compositions.
SUMMARY OF THE INVENTION
A first aspect of the invention is a shear thinning EAO(D)M interpolymer, the interpolymer having polymerized therein ethylene, at least one &agr;-olefin monomer and, optionally, at least one diene monomer and being characterized by a PRR of at least four. The interpolymer desirably has an ethylene (C
2
) content of from 20 to 95 weight percent (wt %), an &agr;-olefin content of from 80 to 5 wt %, the &agr;-olefin being a C
3-20
&agr;-olefin and, optionally, a diene monomer content within a range of from greater than 0 to 25 wt %, all percentages being based on interpolymer weight and totaling 100 wt %. The EAO(D)M interpolymer attains such a PRR in the absence of NBD or any other conventional LCB monomer.
Interpolymer viscosity is conveniently measured in poise (dyne-second/square centimeter (d-sec/cm
2
)) at shear rates within a range of 0.1-100 radian per second (rad/sec) and at 190° C. under a nitrogen atmosphere using a dynamic mechanical spectrometer such as a RMS-800 or ARES from Rheometrics. The viscosities at 0.1 rad/sec and 100 rad/sec may be represented, respectively, as V
0.1
and V
100
with a ratio of the two referred to as RR and expressed as V
0.1
/V
100
. PRR=RR+[3.82−interpolymer Mooney Viscosity (ML
1+4
at 125° C.)]×0.3.
A second aspect of the invention is a process for preparing the EAO(D)M interpolymer of the first aspect, the process comprising: contacting ethylene, at least one &agr;-olefin monomer and, optionally, at least one diene monomer with a catalyst and an activating cocatalyst under conditions sufficient to attain an ethylene conversion of at least 60 weight percent, the conditions including a temperature of at least 70° C., more preferably at least 80° C., and, optionally, in the presence of an effective amount of hydrogen, the amount being sufficient to maintain an interpolymer PRR of at least 4, the catalyst being at least one constrained geometry metal complex. The &agr;-olefin monomer is suitably a C
3-20
&agr;-olefin monomer. The process is especially useful for the solution polymerization of EAO(D)M interpolymers wherein the diene or polyene is ENB, 1,4-hexadiene or a similar nonconjugated diene or a conjugated diene such as 1,3-pentadiene. The diene is preferably ENB or 7-methyl-1,6-octadiene. As in the first aspect, the interpolymer PRR is achieved in the absence of a conventional LCB monomer.
A third aspect of the invention is a polymer blend composition that comprises the interpolymer of the first aspect and an amount of a crystalline polyolefin resin, desirably a propylene polymer or copolymer, preferably polypropylene (PP). The interpolymer is desirably present in an amount of less than 50 parts by weight (pbw) and the crystalline polyolefin resin is desirably present in an amount of more than 50 pbw. When the interpolymer is an EAODM interpolymer, the polymer blend is referred to as a thermoplastic elastomer or TPE. When the interpolymer is an EAO interpolymer, the polymer blend is referred to as a thermoplastic polyolefin or TPO.
A fourth aspect of the invention is a polymer blend composition that comprises an interpolymer of the first aspect that is at least partially crosslinked (also referred to as cured or vulcanized) and a crystalline polyolefin resin, again desirably a propylene polymer or copolymer, preferably PP. The interpolymer is desirably present in an amount of from 40 to 90 pbw and the crystalline polyolefin is desirably present in an amount of from 60 to 10 pbw. The interpolymer is preferably crosslinked sufficiently to provide a gel content of at least 70%, based on interpolymer weight.
In both the third and fourth aspects, the amounts of interpolymer and crystalline polyolefin resin are based on total weight of interpolymer plus crystalline polyolefin and, when added together, equal 100 pbw.
DESCRIPTION OF PREFERRED EMBODIMENTS
All references to the Periodic Table of the Elements herein refer to the Periodic Table of the Elements, published and copyrighted by CRC Press, Inc., 1989. Also, any reference to a Group or Groups shall be to the Group or Groups as reflected in this Periodic Table of the Elements using the IUPAC system for numbering groups.
Neat EAO(D)M interpolymers of the present invention have three distinct characteristics. One is a PRR of at least four. The PRR is desirably within a range of from 4 to 350, preferably from 4 to 250, most preferably from 8 to 150. A second is a Mooney Viscosity or MV (ML
1+4
@125° C., ASTM D1646-94) within a range of from 0.5 to 200, preferably from 5 to 120, and more preferably from 10 to 85. A third is a molecular weight distribution (MWD or M
w
/M
n
) within a range of from 2 to 5, preferably from 2.0 to 3.8, and more preferably from 2.2 to 3.2. Given these characteristics, preferred EAO(D)M interpolymers have a MWD of at least 2.5 and a PRR of at least 8. Preferred EAODM interpolymers have a MWD of at least 2.2, a MV of at least 15 and a PRR of at least 10. When the EAO is a C
2
/C
8
(EO) copolymer, the MWD is at least 2.3, the MV is at least 5 and the PRR is preferably greater than 4.
In solution polymerization processes, a known and predominant mode of controlling molecular weight is chain termination via thermal termination, hydrogen termination or both. It is believed that thermal termination yields a chain end with a reactive vinyl group whereas hydrogen chain termination yields a non-reactive saturated end group. In most cases, thermal termination competes with hydrogen termination. It is also believed that the formation of reactive vinyl end groups and subsequent reinsertion thereof into a growing polymer backbone under the process conditions detailed above yields a polymer product with in situ LCB. As such, reactor condition combinations that favor forming reactive vinyl end groups, such as little or no hydrogen and elevated polymerization temperatures, are believed to favor incorporation of the reactive vinyl end groups which in turn leads to an increased LCB level as reflected by a PRR increase.
The EAO(D)M interpolymers of the present invention have polymerized therein C
2
, at least one C
3-20
&agr;-olefin (ethylenically unsaturated) monomer and, optionally, a C
4-40
diene monomer (other than NBD or another conventional LCB monomer). The &agr;-olefin may be either an aliphatic or an aromatic compound and may contain vinylic unsaturation or a cyclic compound, such as styrene, p-methyl styrene, cyclobutene, cyclopentene, and norbornene, including norbornene substituted in the 5 and 6 position with C
1-20
hydrocarbyl groups. The &agr;-olefin is preferably a C
3-20
aliphatic compound, more preferably a C
3-16
aliphatic compound. Preferred ethylenically unsaturated monomers include 4-vinylcyclohexene, vinylcyclohexane, and C
3-10
aliphatic &agr;-olefins (especially ethylene, propylene, isobutylene, 1-butene, 1-pentene, 1-hexene, 3-methyl-1-pentene, 4-methyl-1-pentene, 1-octene, 1-decene and 1-dodecene). A more preferred C
Cady Larry Duane
Hughes Morgan Mark
Laughner Michael Kenneth
Meiske Larry Alan
Parikh Deepak Rasiklal
DuPont Dow Elastomers LLC
Harlan Robert
LandOfFree
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