Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Polymers from only ethylenic monomers or processes of...
Reexamination Certificate
1999-12-27
2002-10-15
Wu, David W. (Department: 1713)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Polymers from only ethylenic monomers or processes of...
C526S281000, C526S282000, C526S283000, C526S336000, C526S348600, C526S901000, C526S916000, C502S117000, C502S104000
Reexamination Certificate
active
06465584
ABSTRACT:
The invention relates to an elastomeric copolymer derived from components comprising
a) ethylene,
b) an &agr;-olefin,
c) a non-conjugated polyene (C) having one C═C bond that is copolymerizable using a Ziegler-Natta catalyst, and
d) optionally a non-conjugated polyene (D) which in the molecule contains two or more C═C bonds that are copolymerizable using a Ziegler-Natta catalyst; the invention also relates to a process for the preparation of such an elastomeric copolymer.
An elastomeric copolymer of ethylene, an &agr;-olefin and one or more non-conjugated polyenes is already known and described in EP 94.051 A. Such a product has rubber-like properties and is here and hereinafter denoted as EADM (products based on ethylene, an &agr;-olefin and a diene). An elastomeric copolymer is here and hereinafter understood to be a copolymer which, at room temperature and higher temperatures, has a crystallinity of at most 5%, measured by means of DSC (differential scanning calorimetry).
Elastomeric copolymers are characterized by a number of parameters. Besides the weight percentage of the monomer units there is the molecular weight (expressed as number average (Mn) or weight-average molecular weight (Mw)), the molecular weight distribution (MWD, defined as Mw/Mn), as well as the degree of branching. The value of the degree of branching is determined by means of the Mark-Houwink equation, which gives the relation between the molecular weight (M) and the intrinsic viscosity (&eegr;) of the copolymer. For a pure copolymer without long chain branching the relation between log (&eegr;) and log (M) is described by a linear relation. Long chain branching results in a deviation of the linear relation between log (&eegr;) and log (M). The relation between log (&eegr;) and log (M) becomes less linear as the degree of branching increases.
A Size Exclusion Chromatography—Differential Viscometry combination (SEC-DV) is used to determine molecular weight distributions (MWDs) and degree of branching for the elastomeric copolymers in conformity with the universal calibration principle as described in Z. Grubistic, R. Rempp, H. Benoit, J. Polym. Sci., Part B, 5, 573 (1967). It holds that log [&eegr;
i
]*M
i
) vs retention volume=constant, (with [&eegr;
i
] representing the intrinsic viscosity, M
i
the molecular weight and “i” being the i
th
-elution fraction in the SEC-DV chromatogram). The experimental Mark-Houwink equation yields information on the degree of branching if this equation is compared with the Mark-Houwink equation for linear polymers, which is used as reference. Branching is understood to be a branch in the polymer chain, which is longer than a branch produced by the incorporation of a single molecule of the &agr;-olefin or of a polyene. The reference Mark-Houwink equation is dependent on the average ethylene/&agr;-olefin composition of the polymer. According to Th. G. Scholte, N. L. J. Meijerink, H. M. Schoffeleers, A. M. G. Brands, J. of Appl. Pol. Sci., Vol, 29, 3763-3782 (1984) the following holds for the Mark-Houwink equation of a linear ethylene-propylene (EP) copolymer:
[&eegr;]*=(1−⅓*
W
3
)
(1+a)
.K
PE
.(
M
v
*)
a
(I)
where:
[&eegr;]*=apparent weight-average intrinsic viscosity of a linear copolymer with an ethylene/&agr;-olefin composition corresponding to that of the elastomeric copolymer (in dl/g)
W
3
=propylene weight fraction
K
PE
=Mark-Houwink constant for linear polyethylene (PE) (=4.06.10
−4
), measured in 1,2,4-trichlorobenzene at 135° C.
a=Mark-Houwink constant for linear polyolefinic copolymers (=0.725), measured in 1,2,4-trichlorobenzene at 135° C.
M
V
*=apparent, viscosity-average molecular weight, defined as:
M
v
*
=
(
∑
w
i
(
M
i
*
)
a
∑
w
i
)
1
/
a
(
II
)
where:
w
i
=weight fraction belonging to elution fraction i
M*
i
=apparent molecular weight, for elution fraction i
W
3
is calculated for such a copolymer according to the formula:
W
3
=C
3
/(
C
3
+C
2
) (III)
where C
2
and C
3
represent, respectively, the ethylene content and the propylene content of the EP copolymer (in mass %).
For other &agr;-olefin copolymers the value of [&eegr;]* is corrected according to the guidelines presented in the above-mentioned article by Scholte c.s.
The degree of branching is quantified according to the branching parameter, g′ (III), defined as:
g′ (III) degree of branching=([&eegr;]/[&eegr;]*)
1.725
(IV)
[&eegr;]=measured weight-average intrinsic viscosity (in dl/g)
[&eegr;]*=apparent weight-average intrinsic viscosity of a linear copolymer with an ethylene/&agr;-olefin composition corresponding to that of the elastomeric copolymer (dl/g).
For this, see: L. I. Kulin, N. L. Meijerink, P. Starck, Pure & Appl. Chem., vol. 60, No. 9, 1403-1415 (1988) and S. Shiga, Polym. Plast. Technol. Eng., 28(1), 17-41 (1989).
Elastomeric copolymers have now been found, and these are the subject of the present invention, which had not been known hitherto and which display different branching characteristics. Thus the invention relates to elastomeric copolymers having a strongly deviating rheological behaviour as a function of the composition compared with the known copolymers.
The elastomeric copolymer according to the invention is characterized in that the elastomeric copolymer has the following properties:
i the weight ratio between the ethylene content and the &agr;-olefin content is between 80/20 and 40/60
ii the polyene (C) content is 4 to 30 wt. %
iii the polyene (D) content is 0 to 5 wt. %
iv a branching coefficient BC, for which the following holds:
0.57−0.022*[
C]≦BC≦
0.7 (V)
where
BC
=
g
′
(
III
)
MWD
+
0.25
*
RBE
*
[
D
]
0.5
+
0.0855
*
[
DCPD
]
(
VI
)
[C]=polyene (C) content of the polymer (wt. %, relative to the total weight of the polymer),
[D]=polyene (D) content of the polymer (wt. %, relative to the total weight of the polymer),
RBE=relative branching efficiency of the polyene (D) relative to vinyl norbornene (VNB).
[DCPD]=dicyclopentadiene content of the polymer (wt. %, relative to the total weight of the polymer).
Preferably, the elastomeric copolymer according to the invention is characterized in that the elastomeric copolymer has the following properties:
i the weight ratio between the ethylene content and the &agr;-olefin content is between 80/20 and 40/60
ii the polyene (C) content is 4 to 30 wt. %
iii the polyene (D) content is 0 to 5 wt. %
iv a branching coefficient BC*, for which the following holds:
0.57−0.022*[
C]≦BC*≦
0.7 (VII)
where
BC
*
=
g
′
(
III
)
MWD
+
Σ
D
(
0.25
*
[
D
]
0.5
)
(
VIII
)
[C]=polyene (C) content of the polymer (wt. %, relative to the total weight of the polymer),
[D]=polyene (D) content of the polymer (wt. %, relative to the total weight of the polymer).
&Sgr;
D
=sommation of all contributions to BC* of the polyenes D present in the elastomeric copolymer.
An even more preferred embodiment of the present invention is an elastomeric copolymer having a branching coefficient which satisfies the relation:
0.6−0.022*[
C]≦BC≦
0.7 (IX)
Formula IX is also valid for BC*.
Such copolymers have a relation between the degree of branching, the molecular weight distribution and composition that is totally different from that of the products described hitherto.
Surprisingly, the copolymers according to the invention have a much higher BC than state of the art copolymers having a comparable composition.
The copolymers according to the invention contain ethylene and an &agr;-olefin, the ratio between ethylene and the &agr;-olefin being between 80/20 and 40/60 (parts by weight). Preferably the ratio is between 70/30 and 40/60. More pre
Beelen Henri J. H.
Evens Georges G.
Oosterlaken Andreas A.
Pijpers Emanuel M. J.
Renkema Jacob
DSM N.V.
Harlan R.
Pillsbury & Winthrop LLP
Wu David W.
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