U.S. patent application number 10/364056 was filed with the patent office on 2004-08-12 for diene-modified propylene polymer nucleating agents.
Invention is credited to Agarwal, Pawan K., Dekmezian, Armenag, Mehta, Aspy K., Weng, Weiqing.
Application Number | 20040157999 10/364056 |
Document ID | / |
Family ID | 32824347 |
Filed Date | 2004-08-12 |
United States Patent
Application |
20040157999 |
Kind Code |
A1 |
Agarwal, Pawan K. ; et
al. |
August 12, 2004 |
DIENE-MODIFIED PROPYLENE POLYMER NUCLEATING AGENTS
Abstract
This invention relates to compositions derived from polyolefins
combined with polymeric nucleating agent. The nucleating agent is
specifically a diene-propylene copolymer.
Inventors: |
Agarwal, Pawan K.; (Houston,
TX) ; Dekmezian, Armenag; (Kingwood, TX) ;
Mehta, Aspy K.; (Humble, TX) ; Weng, Weiqing;
(Houston, TX) |
Correspondence
Address: |
EXXONMOBIL CHEMICAL COMPANY
P O BOX 2149
BAYTOWN
TX
77522-2149
US
|
Family ID: |
32824347 |
Appl. No.: |
10/364056 |
Filed: |
February 11, 2003 |
Current U.S.
Class: |
525/240 |
Current CPC
Class: |
C08L 23/12 20130101;
C08L 2205/02 20130101; C08L 23/16 20130101; C08L 23/10 20130101;
C08L 23/16 20130101; C08L 23/145 20130101; C08L 23/06 20130101;
C08L 23/145 20130101; C08L 23/02 20130101; C08L 23/06 20130101;
C08L 23/10 20130101; C08L 23/12 20130101; C08L 2666/04 20130101;
C08L 2666/04 20130101; C08L 2666/04 20130101; C08L 2666/04
20130101; C08L 2666/06 20130101 |
Class at
Publication: |
525/240 |
International
Class: |
C08L 023/00; C08L
023/04 |
Claims
What is claimed is:
1. A polymer composition comprising a blend of: a) from 0.01 to 30
weight percent diene-propylene copolymer based on the total polymer
composition weight; and b) crystallizable polyolefin comprising
from a minimum of 0 to less than 100 percent by weight propylene
derived units.
2. The polymer of claim 1 prepared by combining the diene-propylene
copolymer of a) with at least 50 weight percent of the
crystallizable polyolefin of b) based on the total weight of the
polymer composition.
3. The polymer of claim 1 wherein the blend has a Tc of at least
3.degree. C. greater than that of the crystallizable polyolefin
alone.
4. The polymer of claim 1 wherein the crystallizable polyolefin is
selected from the group consisting of: syndiotactic propylene
homopolymer, isotactic propylene-ethylene copolymers, syndiotactic
propylene-ethylene copolymer, isotactic C.sub.4-C.sub.10
homopolymer, isotactic propylene- alpha olefin (C.sub.4-C.sub.18)
copolymer, polyethylene homopolymer, polyethylene-ethylene alpha
olefin (C.sub.4-C.sub.18) copolymers, propylene-ethylene-alpha
olefin (C.sub.4-C.sub.18) terpolymers, and propylene impact
copolymers.
5. The polymer of claim 1 wherein the crystallizable polyolefin is
selected from the group consisting of: isotactic propylene-ethylene
copolymers, isotactic propylene- alpha olefin (C.sub.4-C.sub.18)
copolymer, polyethylene homopolymer, ethylene alpha olefin
(C.sub.4-C.sub.18) copolymers, propylene-ethylene-alpha olefin
(C.sub.4-C.sub.18) terpolymers, and propylene impact
copolymers.
6. The polymer composition of claim 1 wherein the crystallizable
polyolefin comprises at least 60 weight percent propylene derived
units, and at least 5 weight percent ethylene derived units based
on the total composition weight.
7. The polymer composition of claim 1 wherein the crystallizable
polyolefin comprises at least 80 weight percent propylene derived
units based on the total composition weight.
8. The polymer composition of claim 1 wherein the crystallizable
polyolefin comprises at least 90 weight percent propylene derived
units based on the total composition weight.
9. The polymer composition of claim 1 wherein the crystallizable
polyolefin comprises at least 95 weight percent propylene derived
units based on the total composition weight.
10. The polymer composition of claim 1 wherein the crystallizable
polyolefin comprises an ethylene-propylene copolymer elastomer
comprising 5 to 25% by weight ethylene-derived units and 95 to 75%
by weight propylene-derived units, and has a melting point of less
than 90.degree. C.
11. The polymer composition of claim 10 wherein the crystallizable
polyolefin has a heat of fusion of from 1.0 J/g to 37 J/g and a
molecular weight distribution (Mw/Mn) of from 1.5 to 5.
12. The polymer composition of claim 1 prepared by combining from
0.15 to 10 weight percent of the diene-propylene copolymer of a)
with the crystallizable polyolefin of b).
13. The polymer composition of claim 1 prepared by combining from
0.15 to 8 weight percent of the diene-propylene copolymer of a)
with the crystallizable polyolefin of b).
14. The polymer composition of claim 1 prepared by combining from
0.15 to 5 weight percent of the diene-propylene copolymer of a)
with the crystallizable polyolefin of b).
15. The polymer composition of claim 1 prepared by combining from
0.20 to 5 weight percent of the diene-propylene copolymer of a)
with the crystallizable polyolefin of b).
16. The polymer composition of claim 1 wherein the diene-propylene
copolymer of a) comprises propylene derived units and from 0.001 to
2.0 weight percent diene derived units.
17. The polymer composition of claim 1 wherein the diene-propylene
copolymer of a) comprises propylene derived units and from 0.003 to
1.5 weight percent diene derived units.
18. The polymer composition of claim 1 wherein the diene-propylene
copolymer of a) comprises propylene derived units and from 0.005 to
1.0 weight percent diene derived units.
19. The polymer composition of claim 1 wherein the diene-propylene
copolymer of a) consists essentially of propylene derived units and
from 0.01 to 2.0 weight percent diene derived units.
20. A polymer composition comprising a blend of: a) from 0.01 to 10
weight percent diene-propylene copolymer based on the total polymer
composition weight; and b) crystallizable polyolefin comprising at
least 5% by weight ethylene derived units.
21. The polymer of claim 20 prepared by combining the
diene-propylene copolymer of a) with at least 50 weight percent of
the crystallizable polyolefin of b) based on the total weight of
the polymer composition.
22. The polymer of claim 20 wherein the blend has a Tc of at least
3.degree. C. greater than that of the crystallizable polyolefin
alone.
23. The polymer of claim 20 wherein the crystallizable polyolefin
is selected from the group consisting of: isotactic
propylene-ethylene copolymers, polyethylene homopolymers, isotactic
terpolymers, polyethylene copolymers, polyethylene terpolymers, and
propylene impact copolymers.
24. The polymer composition of claim 20 wherein the crystallizable
polyolefin comprises at least 72 weight percent propylene derived
units, and at least 5 weight percent ethylene derived units based
on the total composition weight.
25. The polymer composition of claim 20 wherein the crystallizable
polyolefin comprises at least 80 weight percent propylene derived
units based on the total composition weight.
26. The polymer composition of claim 20 wherein the crystallizable
polyolefin comprises at least 90 weight percent propylene derived
units based on the total composition weight.
27. The polymer composition of claim 20 wherein the crystallizable
polyolefin comprises at least 95 weight percent propylene derived
units based on the total composition weight.
28. The polymer composition of claim 20 wherein the crystallizable
polyolefin comprises an ethylene-propylene copolymer elastomer
comprising 5 to 25% by weight ethylene-derived units and 95 to 75%
by weight propylene-derived units, and has a melting point of less
than 90.degree. C.
29. The polymer composition of claim 28 wherein the crystallizable
polyolefin has a heat of fusion from 1.0 J/g to 37 J/g and a
molecular weight distribution (Mw/Mn) from 1.5 to 5.
30. The polymer composition of claim 20 prepared by combining from
0.15 to 10 weight percent of the diene-propylene copolymer of a)
with at least 50 weight percent of the crystallizable polyolefin of
b).
31. The polymer composition of claim 20 prepared by combining from
0.15 to 8 weight percent of the diene-propylene copolymer of a)
with at least 50 weight percent of the crystallizable polyolefin of
b).
32. The polymer composition of claim 20 prepared by combining from
0.15 to 5 weight percent of the diene-propylene copolymer of a)
with at least 50 weight percent of the crystallizable polyolefin of
b).
33. The polymer composition of claim 20 prepared by combining from
0.20 to 5 weight percent of the diene-propylene copolymer of a)
with at least 50 weight percent of the crystallizable polyolefin of
b).
34. The polymer composition of claim 20 wherein the diene-propylene
copolymer of a) comprises propylene derived units and from 0.001 to
2.0 weight percent diene derived units.
35. The polymer composition of claim 20 wherein the diene-propylene
copolymer of a) comprises propylene derived units and from 0.003 to
1.5 weight percent diene derived units.
36. The polymer composition of claim 20 wherein the diene-propylene
copolymer of a) comprises propylene derived units and from 0.005 to
1.0 weight percent diene derived units.
37. The polymer composition of claim 20 wherein the diene-propylene
copolymer of a) consists essentially of propylene derived units and
from 0.01 to 2.0 weight percent .alpha.,.omega.-diene derived
units.
38. A polymer composition obtained by blending: a) from 0.01 to 30
weight percent diene-propylene copolymer based on the total polymer
composition weight; and b) at least 50 weight percent
crystallizable polyolefin comprising at least 5% by weight ethylene
derived units; wherein the polymer composition has a Tc at least
3.degree. C. greater than that of the crystallizable polyolefin
alone.
39. The polymer of claim 38 prepared by combining the
diene-propylene copolymer of a) with at least 50 weight percent of
the crystallizable polyolefin of b) based on the total weight of
the polymer composition.
40. The polymer of claim 38 wherein the blend has a Te of at least
5.degree. C. greater than that of the crystallizable polyolefin
alone.
41. The polymer of claim 38 wherein the crystallizable polyolefin
is selected from the group consisting of: isotactic
propylene-ethylene copolymers, isotactic propylene- alpha olefin
(C.sub.4-C.sub.18) copolymer, polyethylene homopolymer, ethylene
alpha olefin (C.sub.4-C.sub.18) copolymers,
propylene-ethylene-alpha olefin (C.sub.4-C.sub.18) terpolymers, and
propylene impact copolymers.
42. The polymer composition of claim 38 wherein the crystallizable
polyolefin comprises at least 72 weight percent propylene derived
units, and at least 5 weight percent ethylene derived units based
on the total composition weight.
43. The polymer composition of claim 38 wherein the crystallizable
polyolefin comprises at least 80 weight percent propylene derived
units based on the total composition weight.
44. The polymer composition of claim 38 wherein the crystallizable
polyolefin comprises at least 90 weight percent propylene derived
units based on the total composition weight.
45. The polymer composition of claim 38 wherein the crystallizable
polyolefin comprises at least 95 weight percent propylene derived
units based on the total composition weight.
46. The polymer composition of claim 38 wherein the crystallizable
polyolefin comprises an ethylene-propylene copolymer elastomer
comprising 5 to 25% by weight ethylene-derived units and 95 to 75%
by weight propylene-derived units, and has a melting point of less
than 90.degree. C.
47. The polymer composition of claim 46 wherein the crystallizable
polyolefin has a heat of fusion of from 1.0 J/g to 37 J/g and a
molecular weight distribution (Mw/Mn) of from 1.5 to 5.
48. The polymer composition of claim 38 prepared by combining from
0.15 to 10 weight percent of the diene-propylene copolymer of a)
with at least 50 weight percent of the crystallizable polyolefin of
b).
49. The polymer composition of claim 38 prepared by combining from
0.15 to 8 weight percent of the diene-propylene copolymer of a)
with at least 50 weight percent of the crystallizable polyolefin of
b).
50. The polymer composition of claim 38 prepared by combining from
0.15 to 5 weight percent of the diene-propylene copolymer of a)
with at least 50 weight percent of the crystallizable polyolefin of
b).
51. The polymer composition of claim 38 prepared by combining from
0.20 to 5 weight percent of the diene-propylene copolymer of a)
with at least 50 weight percent of the crystallizable polyolefin of
b).
52. The polymer composition of claim 38 wherein the diene-propylene
copolymer of a) comprises propylene derived units and from 0.001 to
2.0 weight percent diene derived units.
53. The polymer composition of claim 38 wherein the diene-propylene
copolymer of a) comprises propylene derived units and from 0.003 to
1.5 weight percent diene derived units.
54. The polymer composition of claim 38 wherein the diene-propylene
copolymer of a) comprises propylene derived units and from 0.005 to
1.0 weight percent diene derived units.
55. The polymer composition of claim 38 wherein the diene-propylene
copolymer of a) consists essentially of propylene derived units and
from 0.01 to 2.0 weight percent .alpha.,.omega.-diene derived
units.
Description
FIELD
[0001] This invention relates to compositions derived from
polyolefins combined with a polymeric nucleating agent. The
nucleating agent is specifically a diene-propylene copolymer.
BACKGROUND
[0002] It is a common practice to use nucleating agents to increase
the crystallization temperature (Tc) of polyolefins and/or to
otherwise improve polyolefins by modifying their crystalline
morphology. One reason for doing this is to increase melt
processing efficiency and subsequent solid state strength-related
properties. By increasing Tc, polyolefins crystallize or "freeze"
at very near their melting temperature so that, for example, in
molding processes, the polymer sets quickly after being injected
into the mold.
[0003] There are many different types of nucleating agents used to
increase the Tc of polyolefins. But because such agents are
expensive and often impair other important polyolefin features,
compounders and processors are constantly searching for nucleating
agents that are economical and sufficiently increase Tc while not
degrading other desirable polyolefin properties or introducing
unwanted characteristics. The measurement of Tc is conveniently
done utilizing differential scanning calorimetry (DSC)
techniques.
[0004] Examples of common nucleating agents include inorganic
substances such as talc, silicates, calcium carbonates, sodium
phosphates, and stearates. Organic nucleating agents include
polyesters, diacetals, dibenzylidene sorbitols, sodium benzoates,
metal salts of carboxylic acids or alkyl-substituted derivatives
thereof such as salts of stearic acids, adipic acid and sebacic
acid, chromium p-tert-butyl benzoate and aluminum monophenyl
acetate. Most common nucleating agent currently being used and
recommended, specially for polypropylene family of polymers, are
talc, sodium benzoate, and sorbitols.
[0005] We have discovered that diene-propylene copolymers serve as
excellent nucleating agents for polyolefins, particularly propylene
and ethylene based polyolefins.
SUMMARY
[0006] In one embodiment the present invention is a polymer
composition comprising a blend of: a) from 0.01 to 30 weight
percent diene-propylene copolymer based on the total polymer
composition weight; and b) crystallizable polyolefin comprising
from a minimum of 0 to less than 100 percent by weight propylene
derived units.
[0007] In another embodiment the present invention is a polymer
composition comprising a blend of: a) from 0.01 to 10 weight
percent diene-propylene copolymer based on the total polymer
composition weight; and b) crystallizable polyolefin comprising at
least 5% by weight ethylene derived units.
[0008] In another embodiment the present invention is a polymer
composition obtained by blending: a) from 0.01 to 30 weight percent
diene-propylene copolymer based on the total polymer composition
weight; and b) at least 50 weight percent crystallizable polyolefin
comprising at least 5% by weight ethylene derived units; wherein
the polymer composition has a Tc at least 3.degree. C. greater than
that of the crystallizable polyolefin alone.
[0009] In another embodiment one or more of the above compositions
is prepared by combining the diene-propylene copolymer of a) with
at least 50 weight percent of the crystallizable polyolefin of b)
based on the total weight of the polymer composition.
[0010] In another embodiment one or more of the above blends has a
Tc of at least 3.degree. C. greater than that of the crystallizable
polyolefin alone.
[0011] In one or more of the above compositions the crystallizable
polyolefin is selected from the group consisting of: syndiotactic
propylene homopolymer, isotactic propylene-ethylene copolymers,
syndiotactic propylene-ethylene copolymer, isotactic
C.sub.4-C.sub.10 homopolymer, isotactic propylene- alpha olefin
(C.sub.4-C.sub.18) copolymer, polyethylene homopolymer,
polyethylene-ethylene alpha olefin (C.sub.4-C.sub.18) copolymers,
propylene-ethylene-alpha olefin (C.sub.4-C.sub.18) terpolymers, and
propylene impact copolymers.
[0012] In one or more of the above compositions the crystallizable
polyolefin is selected from the group consisting of: isotactic
propylene-ethylene copolymers, isotactic propylene- alpha olefin
(C.sub.4-C.sub.18) copolymer, polyethylene homopolymer, ethylene
alpha olefin (C.sub.4-C.sub.18) copolymers,
propylene-ethylene-alpha olefin (C.sub.4-C.sub.18) terpolymers, and
propylene impact copolymers.
[0013] In one or more of the above compositions the crystallizable
polyolefin comprises at least 60 weight percent propylene derived
units, and at least 5 weight percent ethylene derived units based
on the total composition weight.
[0014] In one or more of the above compositions the crystallizable
polyolefin comprises at least 80 weight percent propylene derived
units based on the total composition weight.
[0015] In one or more of the above compositions the crystallizable
polyolefin comprises at least 90 weight percent propylene derived
units based on the total composition weight.
[0016] In one or more of the above compositions the crystallizable
polyolefin comprises at least 95 weight percent propylene derived
units based on the total composition weight.
[0017] In one or more of the above compositions the crystallizable
polyolefin comprises an ethylene-propylene copolymer elastomer
comprising 5 to 25% by weight ethylene-derived units and 95 to 75%
by weight propylene-derived units, and has a melting point of less
than 90.degree. C.
[0018] In one or more of the above compositions the crystallizable
polyolefin has a heat of fusion of from 1.0 J/g to 37 J/g and a
molecular weight distribution (Mw/Mn) of from 1.5 to 5.
[0019] One or more of the above compositions is prepared by
combining from 0.15 to 10 weight percent of the diene-propylene
copolymer of a) with the crystallizable polyolefin of b).
[0020] One or more of the above compositions is prepared by
combining from 0.15 to 8 weight percent of the diene-propylene
copolymer of a) with the crystallizable polyolefin of b).
[0021] One or more of the above compositions is prepared by
combining from 0.15 to 5 weight percent of the diene-propylene
copolymer of a) with the crystallizable polyolefin of b).
[0022] One or more of the above compositions is prepared by
combining from 0.20 to 5 weight percent of the diene-propylene
copolymer of a) with the crystallizable polyolefin of b).
[0023] In one or more of the above compositions the diene-propylene
copolymer of a) comprises propylene derived units and from 0.001 to
2.0 weight percent diene derived units.
[0024] In one or more of the above compositions the diene-propylene
copolymer of a) comprises propylene derived units and from 0.003 to
1.5 weight percent diene derived units.
[0025] In one or more of the above compositions the diene-propylene
copolymer of a) comprises propylene derived units and from 0.005 to
1.0 weight percent diene derived units.
[0026] In one or more of the above compositions the diene-propylene
copolymer of a) consists essentially of propylene derived units and
from 0.01 to 2.0 weight percent diene derived units.
DRAWINGS
[0027] FIG. 1 shows the crystallization temperature of metallocene
ethylene/propylene copolymers with various nucleating agents
including the diene-PP.
[0028] FIG. 2 demonstrates the influence of diene-PP concentration
on crystallization temperature of the blends.
DEFINITIONS
[0029] Polyolefins are one or more substances formed by the
polymerization in any process of one or more olefins of the
formula: R.sub.1R.sub.2C.dbd.CH.sub.2 wherein: R.sub.1 and R.sub.2
are the same or different and are hydrogen or substituted or
unsubstituted alkylphenyl, cycloalkyl, phenylalkyl or alkyl.
[0030] Crystallizable means that the polyolefin displays a
measurable melting point (Tm) and crystallization temperature (Tc)
when analyzed by techniques such as differential scanning
calorimetry (DSC).
[0031] Copolymers are polymers having units derived from two or
more monomer types which may be arranged randomly, in blocks or in
multiple phases such as occurs in impact copolymers. When referring
to a specific type of copolymer, the first named olefin makes up a
majority of the copolymer. For example, a "propylene-ethylene"
copolymer will have more than 50 weight percent propylene derived
units based on the total weight of the copolymer.
[0032] Terpolymers are polymers having units derived from three or
more monomer types which may be arranged randomly, in blocks or in
multiple phases such as occurs in impact copolymers.
[0033] Dienes are nonconjugated diolefins which may be incorporated
in polymers to create long branches or to facilitate light chemical
crosslinking reactions. "Substantially free of diene" is defined to
be less than 1% diene, or less than 0.5% diene, or less than 0.1%
diene, or less than 0.05% diene, or equal to 0%. All of these
percentages are by weight in the copolymer. The presence or absence
of diene can be conventionally determined by infrared, rheological
or other techniques, well known to those skilled in the art.
[0034] In the description of the copolymer, and particularly when
describing the constituents of the copolymer, in some instances,
monomer terminology may be used. For example, terms such as
"olefin", "propylene", ".alpha.,.omega.-diene", "ethylene" and
other .alpha.-olefins can be used. When such monomer terminology is
used to describe the copolymer constituents, it means the
polymerized units of such monomers is present in the copolymer.
DESCRIPTION
[0035] The following is a description of specific embodiments of
this invention. Examples are not intended to be limited thereby.
Generally this invention is directed to compositions containing a
blend of at least two components: (1) a diene-propopylene
copolymer; and (2) a different crystallizable polyolefin. The
purpose of the diene-propylene copolymer is to act as a nucleating
agent for the crystallizable polyolefin. Thus the blend will
contain a majority of crystallizable polyolefin and a minority of
nucleating agent.
[0036] Suitable crystallizable polyolefins include: polystyrene,
polyethylene, polypropylene (isotactic and syndiotactic),
ethylene-propylene copolymers, propylene-ethylene copolymers,
propylene-higher alpha olefin (C.sub.4-C.sub.18) copolymers,
ethylene-higher alpha olefin (C.sub.4-C.sub.18) copolymers,
polyisobutylene, poly(1-pentene), poly(2-methylstyrene),
poly(4-methylstyrene), poly(1-hexene), poly(5-methyl-1-hexene),
poly(4-methylpentene), poly(1-butene), poly(3-methyl-1-butene),
poly(3-phenyl-1-propene), poly(1-octadecene), poly(vinyl
cyclopentane), poly(vinylcyclohexane), poly(a-vinylnaphthalene),
and blends of any two or more of these.
[0037] Preferred crystallizable polyolefins include: polyethylene,
ethylene-propylene copolymers, propylene-ethylene copolymers,
propylene-higher alpha olefin (C.sub.4-C.sub.18) copolymers,
ethylene-higher alpha olefin. (C.sub.4-C.sub.18) copolymers,
poly(1-butene), poly(1-pentene), poly(1-hexene), poly(1-octene),
and blends of any two or more of these.
[0038] Suitable crystallizable polyolefins may have weight average
molecular weights that vary widely, for example from at least 1000,
preferably to upwards of 1,000,000, as long as the polyolefin is
crystallizable as defined above. Preferably, the polyolefin has a
conventional DSC melting point (Tm) of from 50.degree. C. to
230.degree. C., more preferably from 60.degree. C. to 175.degree.
C.
[0039] The crystallizable polyolefins suitable for use in this
invention may be prepared by any process (for example: gas phase,
solution, slurry, bulk, single and multiple stage processes using
conventional, Ziegler-Natta, or metallocene catalysts and mixtures
thereof). Many such polyolefins are available from commercial
sources, but polyolefins produced with metallocene or single-site
catalysts offer particular advantages. Primarily this derives from
the molecular consistency of such polymers. Molecular weight
distributions, at least of homopolymers, are narrow
(Mw/Mn=1.5-4.0), and comonomers are more randomly distributed than
would be obtained with multiple-site or Ziegler-Natta catalysts. In
addition, for higher-alpha olefins (C.sub.3-C.sub.10), regio and
insertion errors and defects can be reduced or at least controlled
using metallocene or single-site catalysts. Many benefits derive
from these and other basic characteristics, and it is certainly
within the scope of this invention to take advantage of such
benefits.
[0040] In one preferred embodiment, the crystallizable polyolefin
contains from 0 to less than 100 weight percent propylene derived
units.
[0041] In some embodiments, the crystallizable polyolefin is
selected from thermoplastic polymer compositions composed of a
majority of propylene with a minor amount of ethylene. These
polymer compositions include a linear, homogeneous macromolecular
copolymer structure. These polymers will have a Tc but a reduced
level of crystallinity due to ethylene comonomer units in addition
to the propylene units.
[0042] These thermoplastic polymer compositions include from a
lower limit of 2% or 5% or 6% or 8% or 10% by weight to an upper
limit of 20% or 25% or 28% by weight ethylene-derived units. These
embodiments will also include propylene-derived units present in
the range of from a lower limit of 72% or 75% or 80% by weight to
an upper limit of 98% or 95% or 94% or 92% or 90% by weight. These
percentages by weight are based on the total weight of the
propylene and ethylene-derived units; i.e., based on the sum of
weight percent propylene-derived units and weight percent
ethylene-derived units being 100%. These compositions can comprise
random copolymers or impact copolymers.
[0043] These thermoplastic polymer compositions include low
crystallinity polymers having a heat of fusion, as determined by
DSC, ranging from a lower limit of 1.0 J/g, or 3.0 J/g, or 5.0 J/g,
or 10.0 J/g, or 15.0 J/g, or 20.0 J/g, to an upper limit of 125
J/g, or 100 J/g, or 75 J/g, or 57 J/g, or 50 J/g, or 47 J/g, or 37
J/g, or 30 J/g. As used herein, "heat of fusion" is measured using
Differential Scanning Calorimetry (DSC), which can be measured
using the ASTM E-794-95 procedure. About 2 mg to about 15 mg of a
sheet of the polymer pressed at approximately 200.degree. C. to
230.degree. C. is removed with a punch die and is annealed at room
temperature for 48 hours. At the end of the period, the sample is
placed in a Differential Scanning Calorimeter (e.g. Perkin Elmer 7
Series Thermal Analysis System) and cooled to about -50.degree. C.
to -70.degree. C. The sample is then heated at about 10.degree.
C./min to attain a final temperature of about 180.degree. C. to
about 200.degree. C. The thermal output is recorded as the area
under the melting peak of the sample which is typically at a
maximum peak at about 30.degree. C. to about 175.degree. C. and
occurs between the temperatures of about 0.degree. C. and about
200.degree. C. The thermal output is measured in joules/gram as a
measure of the heat of fusion. The melting point is recorded as the
temperature of the greatest heat absorption within the range of
melting temperature of the sample. Without wishing to be bound by
theory, we believe that in many cases these low crystallinity
polymers have generally isotactic crystallizable propylene
sequences, and the above heats of fusion are believed to be due to
the melting of these crystalline segments.
[0044] The crystallinity of these low crystallinity thermoplastic
polymers may also be expressed in terms of crystallinity percent.
For example, the thermal energy for the highest order of isotactic
polypropylene crystallinity is estimated at 189 J/g. That is, 100%
isotactic crystallinity is equal to 189 J/g. Therefore, according
to the aforementioned heats of fusion, the low crystallinity
polymer has a polypropylene crystallinity within the range having
an upper limit of 40%, or 30%, or 25%, or 20% and a lower limit of
3%, or 5%, or 7%, or 8%.
[0045] The level of crystallinity is also reflected in the melting
point. The term "melting point" as used herein is the highest peak
among principal and secondary melting peaks as determined by DSC,
discussed above. The preferred low crystallinity thermoplastic
polymers suitable for use in our invention, have a single melting
point. Typically a sample of the polypropylene copolymer will show
secondary melting peaks adjacent to the principal peak; the highest
of these peaks is considered the melting point. The low
crystallinity polymer preferably has a melting point by DSC ranging
from an upper limit of 110.degree. C., or 105.degree. C., or
90.degree. C., or 80.degree. C., or 70.degree. C.; to a lower limit
of 20.degree. C., or 25.degree. C., or 30.degree. C., or 35.degree.
C., or 40.degree. C. or 45.degree. C.
[0046] In some embodiments, the low crystallinity thermoplastic
polymer has a weight average molecular weight (Mw) of from
10,000-5,000,000 g/mol, or from 20,000 to 1,000,000 g/mol, or from
80,000 to 500,000 g/mol and a molecular weight distribution Mw/Mn
(MWD), sometimes referred to as a "polydispersity index" (PDI),
ranging from a lower limit of 1.5 or 1.8 to an upper limit of 40 or
20 or 10 or 5 or 3. The Mw and MWD, as used herein, can be
determined by a variety of methods, including those in U.S. Pat.
No. 4,540,753 to Cozewith, et al., and references cited therein, or
those methods found in Verstrate et al., Macromolecules, v. 21, p.
3360 (1988), the descriptions of which are incorporated by
reference.
[0047] In some embodiments, this low crystallinity polymer has a
Mooney viscosity ML (1+4)@125.degree. C. of 100 or less, preferably
75 or less, more preferably 60 or less, and more preferably 30 or
less. Mooney viscosity, as used herein, can be measured as ML/1+4
at 125.degree. C. according to ASTM D1646, unless otherwise
specified.
[0048] The tacticity index, expressed herein as "m/r", is
determined by .sup.13C nuclear magnetic resonance (NMR). The
tacticity index m/r is calculated as defined in H. N. Cheng,
Macromolecules, 17, 1950 (1984). The designation "m" or "r"
describes the stereochemistry of pairs of contiguous propylene
groups, "m" referring to meso and "r" to racemic. An m/r ratio of
1.0 generally describes a syndiotactic polymer, and an m/r ratio of
2.0 an atactic material. An isotactic material theoretically may
have a ratio approaching infinity, and many by-product atactic
polymers have sufficient isotactic content to result in ratios of
greater than 50. The low crystallinity elastomers used in the
invention can have a tacticity index m/r ranging from a lower limit
of 4 or 6 to an upper limit of 8 or 10 or 12.
[0049] An ancillary procedure for the description of the tacticity
of propylene units is the use of triad tacticity. The triad
tacticity of a polymer is the relative tacticity of a sequence of
three adjacent propylene units, a chain consisting of head to tail
bonds, expressed as a binary combination of m and r sequences. It
is usually expressed for copolymers as the ratio of the number of
units of the specified tacticity to all of the propylene triads in
the copolymer.
[0050] The triad tacticity (mm fraction) of a propylene copolymer
can be determined from a .sup.13C NMR spectrum of the propylene
copolymer and the following formula: 1 m m Fra ction = PPP ( m m )
PPP ( m m ) + PPP ( mr ) + PPP ( rr )
[0051] where PPP(mm), PPP(mr) and PPP(rr) denote peak areas derived
from the methyl groups of the second units in the following three
propylene unit chains consisting of head-to-tail bonds: 1
[0052] The .sup.13C NMR spectrum of the propylene copolymer is
measured as described in U.S. Pat. No. 5,504,172. The spectrum
relating to the methyl carbon region (19-23 parts per million
(ppm)) can be divided into a first region (21.2-21.9 ppm), a second
region (20.3-21.0 ppm) and a third region (19.5-20.3 ppm). Each
peak in the spectrum was assigned with reference to an article in
the journal Polymer, Volume 30 (1989), page 1350. In the first
region, the methyl group of the second unit in the three propylene
unit chain represented by PPP (mm) resonates. In the second region,
the methyl group of the second unit in the three propylene unit
chain represented by PPP (mr) resonates, and the methyl group
(PPE-methyl group) of a propylene unit whose adjacent units are a
propylene unit and an ethylene unit resonates (in the vicinity of
20.7 ppm). In the third region, the methyl group of the second unit
in the three propylene unit chain represented by PPP (rr)
resonates, and the methyl group (EPE-methyl group) of a propylene
unit whose adjacent units are ethylene units resonates (in the
vicinity of 19.8 ppm).
[0053] The calculation of the triad tacticity is outlined in the
techniques shown in U.S. Pat. No. 5,504,172. Subtraction of the
peak areas for the error in propylene insertions (both 2,1 and 1,3)
from peak areas from the total peak areas of the second region and
the third region, the peak areas based on the 3 propylene
units-chains (PPP(mr) and PPP(rr)) consisting of head-to-tail bonds
can be obtained. Thus, the peak areas of PPP(mm), PPP(mr) and
PPP(rr) can be evaluated, and hence the triad tacticity of the
propylene unit chain consisting of head-to-tail bonds can be
determined.
[0054] In some embodiments, the low crystallinity polymers useful
as the crystallizable polyolefin in our invention have a triad
tacticity of three propylene units, as measured by .sup.13C NMR, of
greater than 75%, or greater than 80%, or greater than 82%, or
greater than 85%, or greater than 90%.
[0055] In one embodiment, the low crystallinity thermoplastic
polymer further includes a non-conjugated diene monomer to aid in
the vulcanization and other chemical modification of the polymer
blend composition. The amount of diene is preferably less than 10
weight %, and more preferably less than 5 weight %. The diene may
be any non-conjugated diene which is commonly used for the
vulcanization of ethylene propylene rubbers including, but not
limited to, ethylidene norbornene, vinyl norbornene, or
dicyclopentadiene.
[0056] In other embodiments of the present invention, these low
crystallinity thermoplastic polymers are substantially free of
diene-derived units.
[0057] The low crystallinity polymer may be produced by any process
that provides the desired polymer properties, in heterogeneous
polymerization on a support, such as slurry or gas phase
polymerization, or in homogeneous conditions in bulk polymerization
in a medium comprising largely monomer or in solution with a
solvent as diluent for the monomers. For industrial uses,
continuous polymerization processes are preferred. Homogeneous
polymers are often preferred in the invention. For these polymers,
preferably the polymerization process is a single stage, steady
state, polymerization conducted in a well-mixed continuous feed
polymerization reactor. The polymerization can be conducted in
solution, although other polymerization procedures such as gas
phase or slurry polymerization, which fulfil the requirements of
single stage polymerization and continuous feed reactors, are
contemplated.
[0058] The low crystallinity polymers may be made advantageously by
the continuous solution polymerization process described in WO
02/34795, advantageously in a single reactor and separated by
liquid phase separation from the alkane solvent.
[0059] The low crystallinity polymers of the present invention may
be produced in the presence of a chiral metallocene catalyst with
an activator and optional scavenger. The use of single site
catalysts is preferred to enhance the homogeneity of the low
crystallinity polymer. As only a limited tacticity is needed, many
different forms of single site catalyst may be used. Possible
single site catalysts are metallocenes, such as those described in
U.S. Pat. No. 5,026,798, which have a single cyclopentadienyl ring,
advantageously substituted and/or forming part of a polycyclic
structure, and a hetero-atom, generally a nitrogen atom, but
possibly also a phosphorus atom or phenoxy group connected to a
group 4 transition metal, preferably titanium but possibly
zirconium or hafnium. A further example is Me.sub.5 CpTiMe.sub.3
activated with B(CF).sub.3 as used to produce elastomeric
polypropylene with an Mn of up to 4 million. See Sassmannshausen,
Bochmann, Rosch, Lilge, J. Organomet. Chem. (1997), vol 548, pp.
23-28.
[0060] Other possible single site catalysts are metallocenes which
are bis cyclopentadienyl derivatives having a group 4 transition
metal, preferably hafnium or zirconium. Such metallocenes may be
unbridged as in U.S. Pat. No. 4,522,982 or U.S. Pat. No. 5,747,621.
The metallocene may be adapted for producing the low crystallinity
polymer comprising predominantly propylene derived units as in U.S.
Pat. No. 5,969,070 which uses an unbridged bis(2-phenyl indenyl)
zirconium dichloride to produce a homogeneous polymer having a
melting point of above 45.degree. C. The cyclopentadienyl rings may
be substituted and/or part of polycyclic systems as described in
the above U.S. Patents.
[0061] Other possible metallocenes include those in which the two
cyclopentadienyls are connected through a bridge, generally a
single atom bridge such as a silicon or carbon atom with a choice
of groups to occupy the two remaining valencies. Such metallocenes
are described in U.S. Pat. No. 6,048,950 which discloses
bis(indenyl)(dimethylsilyl) zirconium dichloride and MAO; WO
98/27154 which discloses a dimethylsilyl bridged bisindenyl hafnium
dimethyl together with a non-coordinating anion activator; EP
1070087 which discloses a bridged biscyclopentadienyl catalyst
which has elements of asymmetry between the two cyclopentadienyl
ligands to give a polymer with elastic properties; and the
metallocenes described in U.S. Pat. Nos. 6,448,358 and
6,265,212.
[0062] The manner of activation of the single site catalyst can
vary. Alumoxane and preferably methyl alumoxane (MAO) may be used.
Higher molecular weights may be obtained using non-or weakly
coordinating anion activators (NCA) derived and generated in any of
the ways amply described in published patent art such as EP 277004,
EP 426637, and many others. Activation generally is believed to
involve abstraction of an anionic group such as the methyl group to
form a metallocene cation, although according to some literature
zwitterions may be produced. The NCA precursor may be an ion pair
of a borate or aluminate in which the precursor cation is
eliminated upon activation in some manner, e.g. trityl or ammonium
derivatives of tetrakis pentafluorophenyl boron (See EP 277004).
The NCA precursor may be a neutral compound such as a borane, which
is formed into a cation by the abstraction of and incorporation of
the anionic group abstracted from the metallocene (See EP
426638).
[0063] In one embodiment, the low crystallinity polymer used in the
present invention is described in detail as the "Second Polymer
Component (SPC)" in WO 00/69963, WO 00/01766, WO 99/07788, WO
02/083753, and described in further detail as the "Propylene Olefin
Copolymer" in WO 00/01745, all of which are fully incorporated by
reference.
[0064] Certain specific embodiments include a copolymer with a
specified ethylene composition. The ethylene composition of a
polymer can be measured as follows. A thin homogeneous film is
pressed at a temperature of about 150.degree. C. or greater, then
mounted on a Perkin Elmer PE 1760 infrared spectrophotometer. A
full spectrum of the sample from 600 cm.sup.-1 to 4000 cm.sup.-1 is
recorded and the monomer weight percent of ethylene can be
calculated according to the following equation: Ethylene wt
%=82.585-111.987X+30.045 X.sup.2, wherein X is the ratio of the
peak height at 1155 cm.sup.-1 and peak height at either 722
cm.sup.-1 or 732 cm.sup.-1, whichever is higher. The concentrations
of other monomers in the polymer can also be measured using this
method.
[0065] Comonomer content of discrete molecular weight ranges can be
measured by Fourier Transform Infrared Spectroscopy (FTIR) in
conjunction with samples collected by GPC. One such method is
described in Wheeler and Willis, Applied Spectroscopy, (1993), vol.
47, pp. 1128-1130. Different but similar methods are equally
functional for this purpose and well known to those skilled in the
art.
[0066] Comonomer content and sequence distribution of the polymers
can be measured by .sup.13C nuclear magnetic resonance (.sup.13C
NMR), and such method is well known to those skilled in the
art.
[0067] Again, this invention is directed to compositions containing
a blend of the crystallizable polyolefin component of which various
embodiments are described above, and a diene-propopylene copolymer
that acts as a nucleating agent. Examples of diene-propylene
copolymers include those described in U.S. Patent Application Nos.
20010007896 and 20020013440 as well as U.S. Pat. No. 5,670,595,
each of which is fully incorporated herein by reference.
[0068] Preferred diene-propylene copolymers include
copolymerization reaction products, preferably metallocene-based
copolymerization reaction products, of one or more olefin monomers,
in which one such olefin monomer is propylene, and one or more
diene monomers. The preferred dienes are .alpha.,.omega.-diene
dienes.
[0069] Generally, olefins are present in the copolymer at from 98
to 99.999 wt %. In most embodiments, the diene content of the
copolymer is greater than or equal to 0.001 wt % up to and
including 5 wt %. But specific embodiments can have a variety of
diene contents. For example, embodiments with minimum diene
contents of 0.003 and 0.005 wt % are within the invention's scope.
Similarly, embodiments with maximum diene contents of 5, 1 and 1.5
wt % are also within the invention's scope.
[0070] Some embodiments that have two or more different olefin
units have propylene olefin units, which may be present in the
copolymer in the range from 90.05 wt % to 99.999 wt % of the
copolymer. These embodiments may additionally have other olefin
units such as ethylene. These embodiments typically have
other-olefin content from 0.05 to 8 wt %. But specific embodiments
have other-olefin content minimums of 0.1 wt % and 0.5 wt %.
Similarly, some embodiments have other-olefin content maximums 6 wt
% and 3 wt % of the copolymer. .alpha.,.omega.-diene(s) typically
are present at from 0.001 wt % to 2 wt % of the copolymer. But
specific embodiments have .alpha.,.omega.-diene(s) content minimums
of from 0.003 wt % and from 0.005 wt %. Similarly, other
embodiments have .alpha.,.omega.-diene(s) content maximums of 5 wt
%, 1.5 wt % and 1.0 wt % of the copolymer
[0071] Still more preferably, the copolymer includes: propylene
units in the range from 90 wt % to 99.999 wt % of the copolymer;
C.sub.2 or other .alpha.-olefin(s) units in the range from 0.00 wt
% to 8 wt %, more preferably in the range from 0.1 to 6 wt % and
even more preferably in the range from 0.5 wt % to 3 wt % of the
copolymer. The .alpha.,.omega.-diene(s) units are present in the
copolymer in the range from 0.001 wt % to 2 wt %, more preferably
in the range from 0.003 wt % to 1.5 wt % and more still more
preferably in the range from 0.005 wt % to 1.0 wt % of the
copolymer.
[0072] The copolymer preferably has a weight average molecular
weight in the range from 50,000 to 2,000,000, more preferably from
70,000 to 1,000,000 and even more preferably from 100,000 to
750,000. The copolymer has a molecular weight distribution (MWD) in
the range from 1.5 to 15, more preferably from 2 to 10, and even
more preferably from 2 to 8.
[0073] The copolymer preferably has a crystallization temperature
(without externally added nucleating agents) in the range from
100.degree. C. to 135.degree. C., and more preferably from
105.degree. C. to 130.degree. C., and still more preferably from
110.degree. C. to 126.degree. C. The copolymer may have two
crystalline populations. Preferably in such cases, the melting
point range of one of the crystalline populations is
distinguishable from the melting point range of another crystalline
population by a temperature range of from 1.degree. C. to
16.degree. C. More preferably, one of the crystalline populations
has a melting point in the range from 140.degree. C. to 165.degree.
C. and the other crystalline population has a melting point in the
range from 142.degree. C. to 148.degree. C.
[0074] The copolymer may have a melt flow rate (MFR) in the range
of from 0.1 dg/min to 100 dg/min, preferably from 0.5 dg/min to 50
dg/min, even more preferably from 1.0 dg/min to 35 dg/min. MFR is
determined according to ASTM D-1238, condition L (2.16 kg,
230.degree. C.). The melting point of the copolymer may be less
than 165.degree. C., and preferably less than 160.degree. C. Upper
limits for melting point depend on the catalyst and polymerization
details but would typically not be higher than 165.degree. C. The
hexane extractable level (as measured by 21 CFR 177.1520(d)(3)(i))
of the copolymer may be less than 2.0 wt %, and is preferably less
than 1.0 wt %.
[0075] The copolymer may include blends, including reactor blends
with .alpha.-olefins, particularly homopolymers. A typical reactor
blend with linear polypropylene and particularly metallocene
catalyzed polypropylene is representative.
[0076] The copolymer may further be described as "branched". As
used herein, the term "branched" means one or more
.alpha.,.omega.-diene unit linkages, desirably at the
.alpha.,.omega. positions of the .alpha.,.omega.-diene unit,
between two or more polymer chains formed 15 by the polymerization
of one or more .alpha.-olefins.
[0077] Examples of suitable .alpha.,.omega.-dienes include
.alpha.,.omega.-dienes that contain at least 7 carbon atoms and
have up to about 30 carbon atoms, more suitably are
.alpha.,.omega.-dienes that contain from 8 to 12 carbon atoms.
Representative examples of such .alpha.,.omega.-dienes include
1,6-heptadiene, 1,7-octadiene, 1,8-nonadiene, 1,9-decadiene,
1,10-undecadiene, 1,11-dodecadiene, 1,12-tridecadiene,
1,13-tetradecadiene, and the like. Of these, 1,7-octadiene, and
1,9-decadiene are more desirable; particularly desirable is
1,9-decadiene. The diene content can be estimated, for example, by
measuring absorbence at 722 cm.sup.-1 using infrared spectroscopy.
Branched, substituted .alpha.,.omega.-dienes, for example
2-methyl-1,9-decadiene, 2-methyl-1,7-octadiene,
3,4-dimethyl-1,6-heptadie- ne, 4-ethyl-1,7-octadiene, or
3-ethyl-4-methyl-5-propyl-1,10-undecadiene are also envisioned.
[0078] Note that while .alpha.,.omega.-dienes are preferred, other
dienes can also be employed to make the copolymers useful in this
invention. These would include cyclic dienes, such as
vinylnorbornene, or aromatic types, such as divinyl benzene.
[0079] As with the polyolefins, metallocene produced
diene-propylene copolymers are particularly useful for the same
reasons described above.
[0080] The copolymer, which is the copolymerization reaction
product of .alpha.,.omega.-diene(s) and olefin(s), may be prepared
by slurry polymerization of the olefins and diene under conditions
in which the catalyst site remains relatively insoluble and/or
immobile so that the polymer chains are rapidly immobilized
following their formation. Such immobilization is affected, for
example, by (1) using a solid, insoluble catalyst, (2) conducting
the copolymerization in a medium in which the resulting copolymer
is generally insoluble, and (3) maintaining the polymerization
reactants and products below the crystalline melting point of the
copolymer.
[0081] Generally, the metallocene supported catalyst compositions
described above are useful for copolymerizing
.alpha.,.omega.-dienes and olefins. The polymerization processes
suitable for copolymerizing .alpha.,.omega.-dienes and olefins, and
particularly .alpha.-olefins, are well known by those skilled in
the art and include solution polymerization, slurry polymerization,
and low pressure gas phase polymerization. Metallocene supported
catalysts compositions are particularly useful in the known
operating modes employing fixed-bed, moving-bed, fluid-bed, or
slurry processes conducted in single, series or parallel
reactors.
[0082] Generally, any of the above polymerization process may be
used. When propylene is the selected olefin, a common propylene
polymerization process is one that is conducted using a slurry
process in which the polymerization medium can be either a liquid
monomer, like propylene, or a hydrocarbon solvent or diluent,
advantageously aliphatic paraffin such as propane, isobutane,
hexane, heptane, cyclohexane, etc. or an aromatic diluent such as
toluene. In this instance, the polymerization temperatures may be
those considered low, e.g., less than 50.degree. C., desirably
0.degree. C.-30.degree. C., or may be in a higher range, such as up
to about 150.degree. C., desirably from 50.degree. C. up to about
80.degree. C., or at any ranges between the end points indicated.
Pressures can vary from about 100 to about 700 psia (0.69-4.8 MPa).
Additional description is given in U.S. Pat. Nos. 5,274,056 and
4,182,810 and WO 94/21962 which are each fully incorporated by
reference.
[0083] More particularly, the polymerization method of forming a
propylene/.alpha.,.omega.-diene copolymer includes contacting a
catalyst, and desirably a metallocene catalyst, under suitable
polymerization conditions with polymerizable reactants, such as
propylene monomers, and .alpha.,.omega.-diene monomers and
recovering the propylene .alpha.,.omega.-diene copolymer. The
preferred metallocene catalyst is a zirconocene. Additionally, the
contacting step may include hydrogen and ethylene monomers. The
hydrogen, in ppm, may be present in the range of 100 to 50,000 and
desirably from 500 to 20,000 and most desirably from 1,000 to
10,000 measured as gas phase concentration in equilibrium with
liquid propylene at polymerization temperatures. The
.alpha.,.omega.-diene monomers, in wt % based upon the total weight
of the monomers introduced into the polymerization reactor, may be
present in the range of 0.001 to 2 and desirably from 0.003 to 2
and more desirably from 0.003 to 1.5. The ethylene monomer, in wt %
based upon the total weight of the monomers introduced into the
polymerization reactor, may be present in the range of 0 to 8 and
desirably from 1 to 7 and more desirably from 2 to 6. The
polymerizable reactants, in wt % based upon the total weight of the
monomer(s) and other chemicals introduced into the polymerization
reactor, may be present in the range of 90 to 99.999 and desirably
from 93 to 99.997 and more desirably from 95 to 99.995.
[0084] Generally it is thought best to use the minimum amount of
nucleating agent necessary, i.e., an effective amount, although the
diene-propylene copolymers described herein may well provide
additional advantages beyond nucleation which would warrant the use
of more than the minimum amount necessary for the desired Tc.
Preferred weight percentages of diene-propylene copolymer in the
blend generally have a lower limit of 0.01, or 0.02, or 0.10 or
0.15, or 0.20, or 0.25, or 0.30 weight percent, and an upper limit
of 30, or 25, or 20, or 15, or 10, or 8, or 6, or 5. weight percent
based on the total weight of the blend.
[0085] Conversely, the preferred weight percentages of
crystallizable polyolefin in the blend have an upper limit of 99.99
or 99.90, or 99.80, or 99.0 and a lower limit of 70.0, or 75.0, or
80.0, or 85.0, or 90.0 based on the total weight of the blend.
[0086] The polyolefin component or components preferably make up
essentially the rest of the composition, i.e., it is ideal to
minimize the use of additives although their use is certainly
contemplated. Non-polymeric additives include, for example, process
oil, flow improvers, fire retardants, antioxidants, plasticizers,
pigments, vulcanizing or curative agents, vulcanizing or curative
accelerators, cure retarders, processing aids, flame retardants,
tackifying resins, and the like. These compounds may include
fillers and/or reinforcing materials. These include carbon black,
clay, talc, calcium carbonate, mica, silica, silicate, combinations
thereof, and the like. Other additives, which may be employed to
enhance properties, include antiblocking agents, and a coloring
agent. Lubricants, mold release agents, nucleating agents,
reinforcements, and fillers (including granular, fibrous, or
powder-like) may also be employed. Nucleating agents and fillers
tend to improve rigidity of the article. The list described herein
is not intended to be inclusive of all types of additives, which
may be employed with the present invention. Effective additive
levels are known in the art and depend on the details of the base
polymer, the fabrication mode and the desired end application.
Particularly suitable additives include stabilizers and
neutralizers.
[0087] The components described above as well as additional
additives and components may be physically blended together using
techniques well known in the art. Alternatively, the polyolefin and
diene-propylene copolymer(s) may be polymerized and intimately
blended in a single, series or multiple stage polymerization
process and additives physically blended thereafter. This approach
has obvious advantages.
[0088] Ideally, the presence of diene-propylene nucleating agent as
described above improves the Tc by at least 3.degree. C., more
preferably at least 5.degree. C., even more preferably at least
7.degree. C., still more preferably 10.degree. C. or more.
[0089] The compositions of this invention are thermoplastic. When
softened or melted with heat, they can be formed or molded using
techniques such as compression molding, injection molding, gas
assisted injection molding, calendering, vacuum forming,
thermoforming, rotomolding, extrusion and/or blow molding. They can
be spun, drawn into films, fibers and laminates of single or
multiple layers. These compositions are particularly useful for
injection molding.
[0090] Examples of resulting articles include: automotive trims
both exterior and interior, electrical equipment, household and
personal articles, appliances, etc.
EXAMPLES
[0091] General
[0092] Polymerization was conducted in a series of two 150 gallon
stirred tanks, auto refrigerated boiling liquid reactor.
Polymerization grade propylene monomers were purified by passing
first through basic alumina activated at 600.degree. C., followed
by molecular sieves activated at 600.degree. C. 1,9-decadiene (96%)
was purchased from Aldrich-Sigma Bulk Chemicals and used as
received.
[0093] Catalyst Preparation
[0094] All catalyst preparations were performed in an inert
atmosphere with <1.5 ppm H.sub.2O content. The silica support,
available from Grace Davison, a subsidiary of W. R. Grace Co.-Conn.
as Sylopol.RTM.952 having N.sub.2 pore volume 1.63 cc/g and a
surface area of 312 m.sup.2/g was calcined at 600.degree. C. under
a dry nitrogen flow for 8-24 hours to achieve a hydroxyl content of
0.8 to 1.2 mmol/g silica.
[0095] In a nitrogen purged dry glove box, the calcined silica (500
g) was charged to vessel that was equipped with an overhead
stirrer. A solution of tris(perfluorophenyl)boron (30 g, 0.059
mole) in hexane (2 L), was added to silica followed by addition of
N.N-diethylaniline (9.6 ml, 0.061 mole). The mixture was stirred at
49.degree. C. for 1 hour. In a separate container,
dimethylsilylbis(2-methyl-4-phenyl indenyl)zirconium dimethyl (4.5
g, 0.0077 mole), hexane (820 mL), triethylaluminium (187 mL, 25 wt
% in heptane), and 1,9-decadiene (10 mL) were mixed to form a
slurry. The 1,9-decadiene is used in this instance as a Lewis base
to stabilize the catalyst, for instance by improving its shelf
life. Other Lewis bases, such as other dienes including those
described above and styrene, are known to be suitable for
stabilizing the catalyst and may also be used. The slurry was then
transferred to the silica-containing vessel, and the mixture was
stirred at 49.degree. C. for additional 1 hour. The solvent was
removed by purging with nitrogen for 14 hours, and a free flowing
solid catalyst was obtained. Metallocene loading was 0.015 mmol of
transition metal per gram of catalyst.
[0096] Synthesis of Diene-Modified Propylene Polymers
[0097] Propylene/diene copolymers were produced in a series of two
150 gallon stirred tanks, auto refrigerated boiling liquid
reactors. The conditions in the two reactors were as follows:
1 Reactor 1 Reactor 2 Reaction Temperature (.degree. F.) 165 155
Propylene flow rate (lb/hr) 175 65 Gas phase H.sub.2 conc. (ppm)
3500-2500 3500-2500 Solid Concentration (wt %) 25-30 25-30
[0098] All polymers were made with varying levels of 1,9-decadiene
(4.5-9.5% in hexane) charged to reactor 1. H.sub.2 concentration
was adjusted to obtain the polymers with desired MFR.
[0099] Polymer Characterization
[0100] Melt flow rate (MFR) of the polymers was measured using ASTM
D-1238 at 230.degree. C. and 2.16 kg load. Molecular weight of the
polymers was analyzed by GPC using Waters 150.degree. C. high
temperature system with a DRI detector and Showdex AT-806 MS
column. Melting and crystallization temperatures of the polymers
were measured on a TA Instrument DSC-912 using a heating and
cooling rate of 10.degree. C./min with a starting temperature of
0.degree. C. and a stopping temperature of 250.degree. C. The
melting temperatures reported were obtained from the second melt.
The mechanical properties were measured using ASTM-1708
microtensile testing procedure.
[0101] Ethylene Propylene Copolymers (m-EP)
[0102] The ethylene propylene copolymers were made in a 9 liter
Continuous Flow Stirred Tank Reactor using hexane as the solvent.
The liquid full reactor has a residence time of 9 minutes and the
pressure is maintained at 700 kPa. A mixed feed of hexane, ethylene
and propylene is pre-chilled to approximately -30.degree. C. to
remove the heat of polymerization, before entering the reactor.
Solutions of catalyst/activator in toluene and the scavenger in
hexane are separately and continuously admitted into the reactor to
initiate the polymerization. The reactor temperature is maintained
between 35 and 50.degree. C., depending on the target molecular
weight. The feed temperature is varied, depending on the
polymerization rate to maintain a constant reactor temperature. The
polymerization rate is varied from about 0.5 kg/hr to about 4
kg/hr. The propylene and ethylene feeds (at ratios adjusted for
target compositions) are mixed in hexane and fed to the reactor.
The polymerization catalyst, dimethylsilyl bridged bis-indenyl
hafnium dimethyl activated 1.1 molar ratio with N',N'-dimethyl
anilinium-tetrakis (pentafluorophenyl)borate is introduced at the
rate of at 0.0135 g/hr. A dilute solution of triisobutyl aluminum
is introduced into the reactor as a scavenger of catalyst
terminators; a rate of approximately 111 mol of scavenger per mole
of catalyst is adequate for this polymerization. After the
polymerization reaches steady state, a representative sample of the
polymer produced in this polymerization is collected, and then
steam-distilled to isolate the polymer.
[0103] Variations in the composition of the copolymer are obtained
principally by changing the ratio of ethylene to propylene.
Molecular weight or Mooney Viscosity of the copolymer is varied by
either changing the reactor temperature or by changing the ratio of
total monomer feed rate to the polymerization rate. The ethylene
propylene copolymer used in this invention has an ethylene content
of 11.4 wt %, and ML (1+4) 125.degree. C. (Mooney Viscosity) of
30.2.
[0104] Preparation of Blends
[0105] The mixing involved dry blending the ingredients of each
sample, followed by melt homogenization of the batches on a
Brabender mixer. The mixing temperature used was in the range 188
to 216.degree. C. The polymers were added first to the mixer and
fully fluxed, after which the other ingredients (rubber modifier,
extra stabilizers) were incorporated. Mixing was done for 5 minutes
at low rotor speed, followed by an additional 5 minutes at high
rotor speed. The compounded mix was then dumped and collected in
chunks. The molded part property data are shown in Table 1 and 2
below. The measurements involved DSC and tensile properties
(ASTM-1078). FIG. 1 shows the crystallization temperature of
metallocene ethylene/propylene copolymers with various nucleating
agents including diene-modified PP. Clearly, the diene-modified PP
shows distinctive nucleating effect when being used at same level
as other commercial nucleating agents. FIG. 2 further demonstrates
that the diene-modified PP has most profound effect on
crystallization temperature of the blends when the diene-modified
PP is used in certain concentration levels.
2TABLE 1 Nucleating Agent Efficiency of Diene-Modified PP - Blends
of Diene-Modified PP with Various Polyolefins Examples 1 2 3 4 5 6
7 8 M-EP* 100 100 100 100 100 100 100 100 Diene-Modified PP (MFR
5.5) 0.2 Diene-Modified PP (MFR 2.1) 0.2 M-iPP (Achieve 3825, MFR
32)** 0.2 ZN-PP (PP3445, MFR 36)*** 0.2 Millad 0.2 NA-11 0.2 Sodium
Benzoate 0.2 Stabilizer.sup..dagger. 0.1 0.1 0.1 0.1 0.1 0.1 0.1
0.1 DSC Tm(.degree. C.), 1st heat 72.1 72.4 72 73.7 73.1 73 74.7
75.6 .quadrature.Hm (j/g), 1st heat 39.5 37.8 37.8 37.4 36 38.8
37.3 34.2 Tc (.degree. C.) 39.9 43.1 41.9 41.9 42.6 38.9 34.9 33.6
.quadrature.Hc (j/g) 32.3 37.6 33.1 34.6 36.8 35.9 32.2 32.8 Tm
(.degree. C.), 2nd heat 77 72.6 73.3 72.4 74.8 76 76.6 74.8
.quadrature.Hm (j/g), 2nd heat 34.3 35 32.9 34.9 37 36.4 34.2 38.7
Tensile Test @23.degree. C., 2 in/min. Young Modulus (psi) 7530
7600 7260 6910 7230 7280 7620 7680 Yield Stress (psi) 1130 1070
1060 1030 1020 1010 1040 1030 Yield Strain (%) 44 40 40 39 39 40 39
39 Break Stress (psi) 3780 3400 3780 3390 3740 3420 3480 3490 Break
Strain (%) 1210 1050 1230 1190 1290 1220 1270 1220
*Metallocene-catalyzed ethylene propylene copolymer, ethylene
content 11.4 wt %; mooney 30.2 **Commercial metallocene-catalyzed
isotactic polypropylene. ***Commercial, conventional isotactic
polypropylene. .sup..dagger.Stabilizer was made by mixing Irgafoss
168, Ethanox 330, and Calcium Stearate in 1:1:1 ratio.
[0106]
3TABLE 2 Mechanical and Thermal Characteristic of
M-EP/Diene-Modified PP Blends Example 1 9 2 10 11 12 13 14 15 16 17
18 M-EP* 100 100 100 100 100 98.5 97 94 88 75 50 25 Diene-Modified
PP (MFR 5.5) 0 0.1 0.2 0.4 0.8 1.5 3 6 12 25 50 75
Stabilizer.sup..dagger. DSC Tm (.degree. C.), 1st heat 72.1 74.1
72.4 73.7 73.9 72.1 69 68.8 69.9 69.9 52.6 43.9 .quadrature.Hm
(j/g), 1st heat 39.5 34.1 37.8 36.1 35.9 35.9 36.8 30.4 30.5 23.8
14.2 1.4 Tc (.degree. C.) 39.9 42.3 43.1 42.9 44.5 49.6 46.1 45.4
46.5 46.4 45.8 -- .quadrature.Hc (j/g) 32.3 40.1 37.6 34.9 32.6
34.3 38.3 27.1 21.9 28.9 19.4 -- Tm (.degree. C.), 2nd heat 77 71.8
72.6 72.2 70.9 70.2 69.9 69.8 67.5 68.5 66 -- .quadrature.Hm (j/g),
2nd heat 34.3 35.3 35 34.7 31.7 32.2 27.6 26 24.3 20.6 13.1 --
Tensile Test @23.degree. C., 2 in/min. Young Modulus (psi) 7530
6800 7600 7300 6620 6710 7030 8010 8810 12190 19050 29060 Yield
Stress (psi) 1130 970 1070 1040 970 990 1010 1150 1210 1540 2200
3490 Yield Strain (%) 44 40 40 40 40 42 41 42 38 32 30 29 Break
Stress (psi) 3780 3420 3400 3720 3420 3570 3570 3950 4090 4620 5040
5620 Break Strain (%) 1210 1200 1050 1270 1220 1190 1260 1320 1270
1230 1110 1080 *Metallocene-catalyzed ethylene propylene copolymer,
ethylene content 11.4 wt %; mooney 30.2 .sup..dagger.Stabilizer was
made by mixing Irgafoss 168, Ethanox 330, and Calcium Stearate in
1:1:1 ratio.
[0107] While the illustrative embodiments of the invention have
been described with particularity, it will be understood that
various other modifications will be apparent to and can be readily
made by those skilled in the art without departing from the spirit
and scope of the invention. Accordingly, it is not intended that
the scope of the claims appended hereto be limited to the examples
and descriptions set forth herein but rather that the claims be
construed as encompassing all the features of patentable novelty
which reside in the present invention, including all features which
would be treated as equivalents thereof by those skilled in the art
to which the invention pertains.
[0108] All patents, test procedures, and other documents cited
herein, including priority documents, are fully incorporated by
reference to the extent such disclosure is not inconsistent with
this invention and for all jurisdictions in which such
incorporation is permitted.
[0109] When numerical lower limits and numerical upper limits are
listed herein, ranges from any lower limit to any upper limit are
contemplated.
* * * * *