U.S. patent application number 12/090206 was filed with the patent office on 2009-03-12 for multi-layer, elastic articles.
This patent application is currently assigned to Dow Global Technologies Inc.. Invention is credited to Andy C. Chang, Yunwa Wilson Cheung, Seema V. Karande, Rajen M. Patel, Hong Peng, Benjamin C. Poon.
Application Number | 20090068427 12/090206 |
Document ID | / |
Family ID | 37758677 |
Filed Date | 2009-03-12 |
United States Patent
Application |
20090068427 |
Kind Code |
A1 |
Patel; Rajen M. ; et
al. |
March 12, 2009 |
MULTI-LAYER, ELASTIC ARTICLES
Abstract
The invention is an article comprising at least two layers, a
low crystallinity layer and a high crystallinity layer. One or both
layers is capable of being elongated so that a pre-stretched
article is capable of being formed.
Inventors: |
Patel; Rajen M.; (Lake
Jackson, TX) ; Chang; Andy C.; (Houston, TX) ;
Peng; Hong; (Lake Jackson, TX) ; Karande; Seema
V.; (Pearland, TX) ; Poon; Benjamin C.;
(Pearland, TX) ; Cheung; Yunwa Wilson; (Pittsford,
NY) |
Correspondence
Address: |
THE DOW CHEMICAL COMPANY;JONES DAY
717 TEXAS, SUITE 3300
HOUSTON
TX
77002-2712
US
|
Assignee: |
Dow Global Technologies
Inc.
Midland
MI
|
Family ID: |
37758677 |
Appl. No.: |
12/090206 |
Filed: |
October 25, 2006 |
PCT Filed: |
October 25, 2006 |
PCT NO: |
PCT/US06/60209 |
371 Date: |
September 2, 2008 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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60730705 |
Oct 26, 2005 |
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60754087 |
Dec 27, 2005 |
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60824728 |
Sep 6, 2006 |
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Current U.S.
Class: |
428/212 ;
428/516; 428/523; 442/398; 525/123; 525/190 |
Current CPC
Class: |
B32B 5/26 20130101; B32B
2262/0253 20130101; Y10T 428/24942 20150115; B32B 2307/514
20130101; B32B 2323/043 20130101; B32B 27/32 20130101; B32B 5/022
20130101; Y10T 428/31587 20150401; Y10T 442/678 20150401; D01F 8/06
20130101; Y10T 428/31913 20150401; B32B 2437/00 20130101; C08L
23/0815 20130101; D04H 1/4291 20130101; B32B 7/02 20130101; C08L
23/06 20130101; Y10T 442/659 20150401; B32B 2323/046 20130101; B32B
2323/10 20130101; Y10T 442/674 20150401; D01F 6/46 20130101; Y10T
442/668 20150401; B32B 2305/72 20130101; B32B 27/12 20130101; D04H
1/4374 20130101; Y10T 428/31938 20150401; C08L 23/0815 20130101;
C08L 2666/06 20130101 |
Class at
Publication: |
428/212 ;
428/523; 428/516; 442/398; 525/123; 525/190 |
International
Class: |
B32B 7/02 20060101
B32B007/02; B32B 27/00 20060101 B32B027/00; B32B 27/12 20060101
B32B027/12; C08L 75/04 20060101 C08L075/04; C08L 31/06 20060101
C08L031/06; C08L 23/00 20060101 C08L023/00 |
Claims
1. An article having at least two layers, the article comprising
(a) a low crystallinity layer and (b) a high crystallinity layer,
wherein said article is capable of undergoing plastic deformation
upon elongation and wherein said article comprises at least one
ethylene/.alpha.-olefin interpolymer, wherein the
ethylene/.alpha.-olefin interpolymer is a block copolymer
comprising at least 50 mole percent ethylene and comprises one or
more of the following criteria: (a) has a Mw/Mn from 1.7 to 3.5, at
least one melting point, Tm, in degrees Celsius, and a density, d,
in grams/cubic centimeter, wherein the numerical values of Tm and d
correspond to the relationship: Tm>-2002.9+4538.5(d)-2422.2(d)2;
or (b) has a Mw/Mn from 1.7 to 3.5, and is characterized by a heat
of fusion, .DELTA.H in J/g, and a delta quantity, .DELTA.T, in
degrees Celsius defined as the temperature difference between the
tallest DSC peak and the tallest CRYSTAF peak, wherein the
numerical values of .DELTA.T and .DELTA.H have the following
relationships: .DELTA.T>-0.1299(.DELTA.H)+62.81 for .DELTA.H
greater than zero and up to 130 J/g, .DELTA.T.gtoreq.48.degree. C.
for .DELTA.H greater than 130 J/g, wherein the CRYSTAF peak is
determined using at least 5 percent of the cumulative polymer, and
if less than 5 percent of the polymer has an identifiable CRYSTAF
peak, then the CRYSTAF temperature is 30.degree. C.; or (c) is
characterized by an elastic recovery, Re, in percent at 300 percent
strain and 1 cycle measured with a compression-molded film of the
ethylene/.alpha.-olefin interpolymer, and has a density, d, in
grams/cubic centimeter, wherein the numerical values of Re and d
satisfy the following relationship when ethylene/.alpha.-olefin
interpolymer is substantially free of a cross-linked phase:
Re>1481-1629(d); or (d) has a molecular fraction which elutes
between 40.degree. C. and 130.degree. C. when fractionated using
TREF, characterized in that the fraction has a molar comonomer
content of at least 5 percent higher than that of a comparable
random ethylene interpolymer fraction eluting between the same
temperatures, wherein said comparable random ethylene interpolymer
has the same comonomer(s) and has a melt index, density, and molar,
comonomer content (based on the whole polymer) within 10 percent of
that of the ethylene/.alpha.-olefin interpolymer; (e) has a storage
modulus at 25.degree. C., G'(25.degree. C.), and a storage modulus
at 100.degree. C., G'(100.degree. C.), wherein the ratio of
G'(25.degree. C.) to G'(100.degree. C.) is in the range of 1:1 to
9:1; (f) an average block index greater than zero and up to 1.0 and
a molecular weight distribution, Mw/Mn, greater than 1.3; or (g) at
least one molecular fraction which elutes between 40.degree. C. and
130.degree. C. when fractionated using TREF, characterized in that
the fraction has a block index of at least 0.5 and up to 1.
2. The article of claim 1, wherein the low crystallinity layer
comprises a low crystallinity polymer and the high crystallinity
layer comprises a high crystallinity polymer.
3. The article of claim 1, wherein the high crystallinity layer
comprises a homopolymer or copolymer of propylene and one or more
comonomers selected from ethylene and C4-C20 alpha-olefins.
4. The article of claim 1, wherein at least one layer of the
article is capable of being elongated in at least one direction to
an elongation of at least 50% of said article's original
measurement at a temperature at or below the lowest melting point
of the polymers comprising the article.
5. The article of claim 1, wherein at least one layer of the
article has been elongated.
6. The article of claim 1 in which the low crystallinity polymer
and high crystallinity polymer have a difference in crystallinity
of at least 3 weight percent.
7. The article of claim 1 in which the low crystallinity polymer
has a melting point as determined by Differential Scanning
Calorimetry (DSC) that is greater than the melting point of the
high crystallinity polymer.
8. The article of claim 1 in which at least one high crystallinity
layer comprises a nonwoven layer.
9. The article of claim 1 in which at least one low crystallinity
layer comprises a nonwoven layer.
10. The article of claim 1 in which at least one high crystallinity
layer comprises a film layer.
11. The article of claim 1 in which at least one high crystallinity
layer comprises a film layer and at least one low crystallinity
layer comprises a film layer.
12. The article of claim 1 in which at least one high crystallinity
layer comprises a nonwoven layer and at least one low crystallinity
layer comprises a film layer.
13. An article comprising a multi-layer film comprising (a) a low
crystallinity film non-skin layer comprising a low crystallinity
polymer and (b) at least two high crystallinity film layers,
wherein said article is capable of undergoing plastic deformation
upon elongation and wherein said low crystallinity film layer
comprises at least one ethylene/.alpha.-olefin interpolymer,
wherein the ethylene/.alpha.-olefin interpolymer comprises one or
more of the following criteria: (a) has a Mw/Mn from 1.7 to 3.5, at
least one melting point, Tm, in degrees Celsius, and a density, d,
in grams/cubic centimeter, wherein the numerical values of Tm and d
correspond to the relationship: Tm>-2002.9+4538.5(d)-2422.2(d)2;
or (b) has a Mw/Mn from 1.7 to 3.5, and is characterized by a heat
of fusion, .DELTA.H in J/g, and a delta quantity, .DELTA.T, in
degrees Celsius defined as the temperature difference between the
tallest DSC peak and the tallest CRYSTAF peak, wherein the
numerical values of .DELTA.T and .DELTA.H have the following
relationships: .DELTA.T>-0.1299(.DELTA.H)+62.81 for .DELTA.H
greater than zero and up to 130 J/g, .DELTA.T.gtoreq.48.degree. C.
for .DELTA.H greater than 130 J/g, wherein the CRYSTAF peak is
determined using at least 5 percent of the cumulative polymer, and
if less than 5 percent of the polymer has an identifiable CRYSTAF
peak, then the CRYSTAF temperature is 30.degree. C.; or (c) is
characterized by an elastic recovery, Re, in percent at 300 percent
strain and 1 cycle measured with a compression-molded film of the
ethylene/.alpha.-olefin interpolymer, and has a density, d, in
grams/cubic centimeter, wherein the numerical values of Re and d
satisfy the following relationship when ethylene/.alpha.-olefin
interpolymer is substantially free of a cross-linked phase:
Re>1481-1629(d); or (d) has a molecular fraction which elutes
between 40.degree. C. and 130.degree. C. when fractionated using
TREF, characterized in that the fraction has a molar comonomer
content of at least 5 percent higher than that of a comparable
random ethylene interpolymer fraction eluting between the same
temperatures, wherein said comparable random ethylene interpolymer
has the same comonomer(s) and has a melt index, density, and molar
comonomer content (based on the whole polymer) within 10 percent of
that of the ethylene/.alpha.-olefin interpolymer; (e) has a storage
modulus at 25.degree. C., G'(25.degree. C.), and a storage modulus
at 100.degree. C., G'(100.degree. C.), wherein the ratio of
G'(25.degree. C.) to G'(100.degree. C.) is in the range of 1:1 to
9:1 and wherein at least one high crystallinity layer comprises a
polymer selected from the group consisting of a propylene
homopolymer, a copolymer of propylene and one or more comonomers
selected from ethylene and C4-C20 alpha-olefins, an ethylene
homopolymer, and a copolymer of ethylene and one or more comonomers
selected from ethylene and C3-C20 alpha-olefins; (f) an average
block index greater than zero and up to 1.0 and a molecular weight
distribution, Mw/Mn, greater than 1.3; or (g) at least one
molecular fraction which elutes between 40.degree. C. and
130.degree. C. when fractionated using TREF, characterized in that
the fraction has a block index of at least 0.5 and up to 1.
14. An article comprising a multi-layer laminate comprising (a) a
low crystallinity film or nonwoven non-skin layer comprising a low
crystallinity polymer and (b) at least two high crystallinity film
or nonwoven layers wherein said article is capable of undergoing
plastic deformation upon elongation and wherein said low
crystallinity film layer comprises at least one
ethylene/.alpha.-olefin interpolymer, wherein the
ethylene/.alpha.-olefin interpolymer comprises one or more of the
following criteria: (a) has a Mw/Mn from 1.7 to 3.5, at least one
melting point, Tm, in degrees Celsius, and a density, d, in
grams/cubic centimeter, wherein the numerical values of Tm and d
correspond to the relationship: Tm>-2002.9+4538.5(d)-2422.2(d)2;
or (b) has a Mw/Mn from 1.7 to 3.5, and is characterized by a heat
of fusion, .DELTA.H in J/g, and a delta quantity, .DELTA.T, in
degrees Celsius defined as the temperature difference between the
tallest DSC peak and the tallest CRYSTAF peak, wherein the
numerical values of .DELTA.T and .DELTA.H have the following
relationships: .DELTA.T>-0.1299(.DELTA.H)+62.81 for .DELTA.H
greater than zero and up to 130 J/g. .DELTA.T.gtoreq.48.degree. C.
for .DELTA.H greater than 130 J/g, wherein the CRYSTAF peak is
determined using at least 5 percent of the cumulative polymer, and
if less than 5 percent of the polymer has an identifiable CRYSTAF
peak, then the CRYSTAF temperature is 30.degree. C.; or (c) is
characterized by an elastic recovery, Re, in percent at 300 percent
strain and 1 cycle measured with a compression-molded film of the
ethylene/.alpha.-olefin interpolymer, and has a density, d, in
grams/cubic centimeter, wherein the numerical values of Re and d
satisfy the following relationship when ethylene/.alpha.-olefin
interpolymer is substantially free of a cross-linked phase:
Re>1481-1629(d); or (d) has a molecular fraction which elutes
between 40.degree. C. and 130.degree. C. when fractionated using
TREF, characterized in that the fraction has a molar comonomer
content of at least 5 percent higher than that of a comparable
random ethylene interpolymer fraction eluting between the same
temperatures, wherein said comparable random ethylene interpolymer
has the same comonomer(s) and has a melt index, density, and molar
comonomer content (based on the whole polymer) within 10 percent of
that of the ethylene/.alpha.-olefin interpolymer; (e) has a storage
modulus at 25.degree. C., G'(25.degree. C.), and a storage modulus
at 100.degree. C., G'(100.degree. C.), wherein the ratio of
G'(25.degree. C.) to G'(100.degree. C.) is in the range of 1:1 to
9', 1 and wherein said high crystallinity layer(s) comprises a
polymer selected from the group consisting of a propylene
homopolymer, a copolymer of propylene and one or more comonomers
selected from ethylene and C4-C20 alpha-olefins, an ethylene
homopolymer, and a copolymer of ethylene and one or more comonomers
selected from ethylene and C3-C20 alpha-olefins; (f) an average
block index greater than zero and up to 1.0 and a molecular weight
distribution, Mw/Mn, greater than 1.3; or (g) at least one
molecular fraction which elutes between 40.degree. C. and
130.degree. C. when fractionated using TREF, characterized in that
the fraction has a block index of at least 0.5 and up to 1.
15. The article of claim 14, wherein the high crystallinity film or
nonwoven layer(s) comprises a polymer selected from the group
consisting of homogeneously branched polymers, LLDPE, LDPE, HDPE,
SLEP, hPP, and PP plastomers and PP elastomers, and RCP.
16. The article of claim 14, wherein said low crystallinity film
layer is a blown film and wherein said ethylene/.alpha.-olefin
interpolymer has a melt index (ASTM D1238 condition 190 C/2.16 kg)
of from 0.5 to 5 g/10 minutes.
17. The article of claim 14 in which the multi-layer laminate
comprises a third layer located between the low crystallinity layer
and the high crystallinity layer.
18. The article of claim 14 in which the multi-layer laminate
comprises a third layer, wherein the low crystallinity layer is
located between the third layer and the high crystallinity
layer.
19. The article of claim 18, wherein the third layer comprises a
second high crystallinity polymer.
20. The article of claim 14, wherein the multi-layer laminate has a
haze value of greater than 70%.
21. The article of claim 14 wherein the multi-layer laminate has a
permanent set of less than 30% after a 50% hysteresis test.
22. A garment portion comprising an article of claim 14 adhered to
a garment substrate.
23. An article of claim 14, wherein the multi-layer film comprises
at least one elongated film layer.
24. The article of claim 14 in which at least one film layer is
cross-linked.
25. A fiber comprising (a) a low crystallinity polymer and (b) a
high crystallinity polymer, wherein said fiber is capable of
undergoing plastic deformation upon elongation and wherein said low
crystallinity polymer comprises at least one
ethylene/.alpha.-olefin interpolymer, wherein the
ethylene/.alpha.-olefin interpolymer is a block copolymer
comprising at least 50 mole percent ethylene and comprises at least
one criteria selected from the group consisting of: (a) has a Mw/Mn
from 1.7 to 3.5, at least one melting point, Tm, in degrees
Celsius, and a density, d, in grams/cubic centimeter, wherein the
numerical values of Tm and d correspond to the relationship:
Tm>-2002.9+4538.5(d)-2422.2(d)2; or (b) has a Mw/Mn from 1.7 to
3.5, and is characterized by a heat of fusion, .DELTA.H in J/g, and
a delta quantity, .DELTA.T, in degrees Celsius defined as the
temperature difference between the tallest DSC peak and the tallest
CRYSTAF peak, wherein the numerical values of .DELTA.T and .DELTA.H
have the following relationships:
.DELTA.T>-0.1299(.DELTA.H)+62.81 for .DELTA.H greater than zero
and up to 130 J/g, .DELTA.T.gtoreq.48.degree. C. for .DELTA.H
greater than 130 J/g, wherein the CRYSTAF peak is determined using
at least 5 percent of the cumulative polymer, and if less than 5
percent of the polymer has an identifiable CRYSTAF peak, then the
CRYSTAF temperature is 30.degree. C.; or (c) is characterized by an
elastic recovery, Re, in percent at 300 percent strain and 1 cycle
measured with a compression-molded film of the
ethylene/.alpha.-olefin interpolymer, and has a density, d, in
grams/cubic centimeter, wherein the numerical values of Re and d
satisfy the following relationship when ethylene/.alpha.-olefin
interpolymer is substantially free of a cross-linked phase:
Re>1481-1629(d); or (d) has a molecular fraction which elutes
between 40.degree. C. and 130.degree. C. when fractionated using
TREF, characterized in that the fraction has a molar comonomer
content of at least 5 percent higher than that of a comparable
random ethylene interpolymer fraction elating between the same
temperatures, wherein said comparable random ethylene interpolymer
has the same comonomer(s) and has a melt index, density, and molar
comonomer content (based on the whole polymer) within 10 percent of
that of the ethylene/.alpha.-olefin interpolymer; (e) has a storage
modulus at 25.degree. C., G'(25.degree. C.), and a storage modulus
at 100.degree. C., G'(100 C), wherein the ratio of G'(25.degree.
C.) to G'(100.degree. C.) is in the range of 1:1 to 9:1 and wherein
said high crystallinity polymer comprises a polymer selected from
the group consisting of a propylene homopolymer, a copolymer of
propylene and one or more comonomers selected from ethylene and
C4-C20 alpha-olefins, an ethylene homopolymer, and a copolymer of
ethylene and one or more comonomers selected from ethylene and
C3-C20 alpha-olefins; (f) an average block index greater than zero
and up to 1.0 and a molecular weight distribution, Mw/Mn, greater
than 1.3; or (g) at least one molecular fraction which elutes
between 40.degree. C. and 130.degree. C. when fractionated using
TREF, characterized in that the fraction has a block index of at
least 0.5 and up to 1.
26. The fiber of claim 25, wherein the high crystallinity polymer
comprises a polymer selected from the group consisting of LLDPE,
LDPE, HDPE, SLEP, hPP, and RCP.
27. The fiber of claim 25 in the form of a bicomponent fiber in
which the high crystallinity polymer comprises at least a portion
of the surface of the fiber.
28. The fiber of claim 25 in the form of a bicomponent fiber in
which the low crystallinity polymer comprises at least a portion of
the surface of the fiber.
29. A web comprising the fiber of claim 25.
30. The web of claim 29 in which at least a portion of the fibers
are bonded to each other.
31. The fiber of claim 25 in which the high crystallinity polymer,
low Crystallinity polymer, or both, further comprises succinic acid
or succinic anhydride functionality.
32. The fiber of claim 25 in which the high crystallinity layer
comprises at least one Ziegler-Natta, metallocene or single site
catalyzed polyolefin and the low crystallinity layer comprises a
propylene-based polymer.
33. An article comprising (a) a fiber comprising a low
crystallinity polymer and (b) a high crystallinity polymer, wherein
said article is capable of undergoing plastic deformation upon
elongation and wherein said low crystallinity polymer comprises at
least one ethylene/.alpha.-olefin interpolymer, wherein the
ethylene/.alpha.-olefin interpolymer comprises at least one
criteria selected from the group consisting of: (a) has a Mw/Mn
from 1.7 to 3.5, at least one melting point, Tm, in degrees
Celsius, and a density, d, in grams/cubic centimeter, wherein the
numerical values of Tm and d correspond to the relationship:
Tm>-2002.9+4538.5(d)-2422.2(d)2; or (b) has a Mw/Mn from 1.7 to
3.5, and is characterized by a heat of fusion, .DELTA.H in J/g, and
a delta quantity, .DELTA.T, in degrees Celsius defined as the
temperature difference between the tallest DSC peak and the tallest
CRYSTAF peak, wherein the numerical values of .DELTA.T and .DELTA.H
have the following relationships:
.DELTA.T>-0.1299(.DELTA.H)+62.81 for .DELTA.H greater than zero
and up to 130 J/g, .DELTA.T.gtoreq.48.degree. C. for .DELTA.H
greater than 130 J/g, wherein the CRYSTAF peak is determined using
at least 5 percent of the cumulative polymer, and if less than 5
percent of the polymer has an identifiable CRYSTAF peak, then the
CRYSTAF temperature is 30.degree. C.; or (c) is characterized by an
elastic recovery, Re, in percent at 300 percent strain and 1 cycle
measured with a compression-molded film of the
ethylene/.alpha.-olefin interpolymer, and has a density, d, in
grams/cubic centimeter, wherein the numerical values of Re and d
satisfy the following relationship when ethylene/.alpha.-olefin
interpolymer is substantially free of a cross-linked phase:
Re>1481-1629(d); or (d) has a molecular fraction which elutes
between 40.degree. C. and 130.degree. C. when fractionated using
TREF, characterized in that the fraction has a molar comonomer
content of at least 5 percent higher than that of a comparable
random ethylene interpolymer fraction eluting between the same
temperatures, wherein said comparable random ethylene interpolymer
has the same comonomer(s) and has a melt index, density, and molar
comonomer content (based on the whole polymer) within 10 percent of
that of the ethylene/.alpha.-olefin interpolymer; (e) has a storage
modulus at 25.degree. C., G'(25.degree. C.), and a storage modulus
at 100.degree. C., G'(100.degree. C.), wherein the ratio of
G'(25.degree. C.) to G'(100.degree. C.) is in the range of 1:1 to
9:1 and wherein said high crystallinity polymer comprises a polymer
selected from the group consisting of a propylene homopolymer, a
copolymer of propylene and one or more comonomers selected from
ethylene and C4-C20 alpha-olefins, an ethylene homopolymer, and a
copolymer of ethylene and one or more comonomers selected from
ethylene and C3-C20 alpha-olefins; (f) an average block index
greater than zero and up to 1.0 and a molecular weight
distribution, Mw/Mn, greater than 1.3, or (g) at least one
molecular fraction which elutes between 40.degree. C. and
130.degree. C. when fractionated using TREF, characterized in that
the fraction has a block index of at least 0.5 and up to 1.
34. The article of claim 33 further comprising at least one
nonwoven layer, wherein said layer comprises high crystallinity
polymer (b).
35. An article comprising: A) a first layer of filaments comprising
a low crystallinity polymer; B) a second layer of elastomeric
meltblown fibers, said meltblown fibers bonded to at least a
portion of the first layer filaments; C) a third layer of spunbond
fibers; and, D) a fourth layer of spunbond fibers; wherein said
first and second layers are disposed between said third and fourth
layers; wherein the low crystallinity polymer comprises at least
one criteria selected from the group consisting of: (a) has a Mw/Mn
from 0.7 to 3.5, at least one melting point, Tm, in degrees
Celsius, and a density, d, in grams/cubic centimeter, wherein the
numerical values of Tm and d correspond to the relationship:
Tm>-2002.9+4538.5(d)-2422.2(d)2; or (b) has a Mw/Mn from 1.7 to
3.5, and is characterized by a heat of fusion, .DELTA.H in J/g, and
a delta quantity, .DELTA.T, in degrees Celsius defined as the
temperature difference between the tallest DSC peak and the tallest
CRYSTAF peak, wherein the numerical values of .DELTA.T and .DELTA.H
have the following relationships:
.DELTA.T>-0.1299(.DELTA.H)+62.81 for .DELTA.H greater than zero
and up to 130 J/g, .DELTA.T.gtoreq.48.degree. C. for .DELTA.H
greater than 130 J/g, wherein the CRYSTAF peak is determined using
at least 5 percent of the cumulative polymer, and if less than 5
percent of the polymer has an identifiable CRYSTAF peak, then the
CRYSTAF temperature is 30.degree. C.; or (c) is characterized by an
elastic recovery, Re, in percent at 300 percent strain and 1 cycle
measured with a compression-molded film of the
ethylene/.alpha.-olefin interpolymer, and has a density, d, in
grams/cubic centimeter, wherein the numerical values of Re and d
satisfy the following relationship when ethylene/.alpha.-olefin
interpolymer is substantially free of a cross-linked phase:
Re>1481-1629(d); or (d) has a molecular fraction which elutes
between 40.degree. C. and 130.degree. C. when fractionated using
TREF, characterized in that the fraction has a molar comonomer
content of at least 5 percent higher than that of a comparable
random ethylene interpolymer fraction eluting between the same
temperatures, wherein said comparable random ethylene interpolymer
has the same comonomer(s) and has a melt index, density, and molar
comonomer content (based on the whole polymer) within 10 percent of
that of the ethylene/.alpha.-olefin interpolymer; (e) has a storage
modulus at 25.degree. C., G'(25.degree. C.), and a storage modulus
at 100.degree. C., G'(100.degree. C.), wherein the ratio of
G'(25.degree. C.) to G'(100.degree. C.) is in the range of 1:1 to
9:1; (f) an average block index greater than zero and up to 1.0 and
a molecular weight distribution, Mw/Mn, greater than 1.3; or (g) at
least one molecular fraction which elutes between 40.degree. C. and
130.degree. C. when fractionated using TREF, characterized in that
the fraction has a block index of at least 0.5 and up to 1.
36. The article of claim 35, wherein (C) and (D) are skin or
surface layers.
Description
FIELD OF THE INVENTION
[0001] This invention relates to polymer articles such as
laminates, films, fabrics and fibers comprising a low crystallinity
layer and a high crystallinity layer.
BACKGROUND AND SUMMARY OF THE INVENTION
[0002] Known co-extrusion processes involve melting of at least two
separate polymer compositions and their simultaneous extrusion and
immediate combination. The extrudate can be cooled, e.g., using a
chilled roll, until the polymers have solidified and can be
mechanically wound onto a roll. The extrudate may be oriented to a
controlled degree in the machine and/or transverse direction. This
drawing may be performed at temperatures below the melting point of
the co-extrudate. In this way, articles can be made combining the
desired properties of different polymer compositions.
[0003] Co-extruded films are generally made from polymer
compositions, which develop considerable mechanical strength upon
cooling by the forming of crystalline phases. Such polymer
compositions are also capable of developing increased strength upon
orientation of the compositions and better alignment of the
crystalline regions.
[0004] Elasticity in films and laminates is desired for a number of
applications. Examples of such applications are in personal care
products, such as diaper back sheets, diaper waistbands, and diaper
ears; medical applications, such as gowns and bags; and garment
applications, such as disposable wear. In use in the final
structure, elastic articles can provide desirable characteristics,
such as helping to achieve compliance of garments to an underlying
shape. In diaper waistbands, for example, a high elastic recovery
ensures good conformability throughout the use of the diaper.
[0005] Difficulty in processing elastic monolayer films arises from
the tackiness of the films on the roll, which causes "blocking",
i.e., sticking of the film to itself. This limits the storage of
the article after it has been produced. Elastic polymers can also
have poor aesthetics, including, for example, poor surface
appearance and a rubbery or tacky feel or touch.
[0006] Several approaches have been taken to alleviate these
problems. U.S. Pat. No. 6,649,548 discloses laminates of nonwoven
fabrics with films to impart a better feel. U.S. Pat. Nos.
4,629,643 and 5,814,413 and PCT Publications WO 99/47339 and WO
01/05574 disclose various mechanical and processing techniques used
to emboss or texture the film surface in order to increase the
surface area and improve the feel. U.S. Pat. Nos. 4,714,735 and
4,820,590 disclose films comprising an elastomer, ethylene vinyl
acetate (EVA), and process oil that are prepared by orienting the
film at elevated temperature and annealing the film to freeze in
the stresses. The film is subsequently heated, which shrinks and
forms an elastic film.
[0007] In one embodiment, these references also disclose films
having layers of ethylene polymers or copolymers on either side of
the elastic film to reduce tackiness. By heat-setting the film, it
can be stabilized in its extended condition. Upon application of
heat higher than the heat setting temperature, the heat set is
removed and the film returns to its original length and remains
elastic. Two heating steps are involved, adding cost and
complexity. U.S. Pat. No. 4,880,682 discloses a multilayer film
comprising an elastomer core layer and thermoplastic skin layer(s).
The elastomers are ethylene/propylene (EP) rubbers,
ethylene/propylene/diene monomer rubbers (EPDM), and butyl rubber,
in a laminated structure with EVA as the skin layers. After
casting, these films are oriented to yield films having a
micro-undulated surface providing a low gloss film.
[0008] Micro-textured elastomeric laminated films having at least
one adhesive layer are disclosed in U.S. Pat. Nos. 5,354,597 and
5,376,430. U.S. Pat. No. 4,476,180 describes blends of styrenic
block copolymer based elastomers with ethylene-vinyl acetate
copolymers to reduce the tackiness without excessively degrading
the mechanical properties.
[0009] WO 2004/063270 describes an article that includes a low
crystallinity layer and high crystallinity layer capable of
undergoing plastic deformation upon elongation. The crystallinity
layer includes a low crystallinity polymer and, optionally, an
additional polymer. The high crystallinity layer includes a high
crystallinity polymer having a melting point at least 25 C higher
that that of the low crystallinity polymer. The low crystallinity
polymer and the high crystallinity polymer can have compatible
crystallinity.
SUMMARY OF THE INVENTION
[0010] In one embodiment the present invention is an article
comprising at least two layers, a first or low crystallinity layer
often comprising a low crystallinity polymer and a second or high
crystallinity layer often comprising a high crystallinity polymer.
The high crystallinity polymer may have a melting point as
determined by differential scanning calorimetry (DSC) that is about
the same, greater than, or less than, or within about 25 C of the
melting point of the low crystallinity polymer. The article is
capable of being elongated at a temperature below the melting point
of the lowest melting component in at least one direction to an
elongation of at least about 50%, preferably at least about 100%
and more preferably at least about 150%, of its original length or
width, to form a pre-stretched, and optionally subsequently
relaxed, article. Preferably, the high crystallinity layer is
capable of undergoing plastic deformation upon the elongation.
[0011] In another embodiment, the invention is a pre-stretched,
multi-layer film or laminate comprising:
[0012] A. At least one core or non-skin layer comprising (i)
opposing first and second planar surfaces, and (ii) a low
crystalline, elastic polymer, and
[0013] B. At least one first and, optionally a second, outer or
skin layer(s) each comprising (i) opposing first and second planar
surfaces, and (ii) a high crystalline polymer, the second or bottom
planar surface of the first outer layer in intimate contact with
the first or top planar surface of the core layer and the first or
top planar surface of the second outer layer in intimate contact
with the bottom or second planar surface of the core layer. The
high crystalline polymer of one skin layer can be the same or
different than the high crystalline polymer of the other skin
layer. Preferably the at least one core layer polymer is an
ethylene/.alpha.-olefin multi-block interpolymer component that are
further defined and discussed in copending PCT Application No.
PCT/US2005/008917, filed on Mar. 17, 2005 and published on Sep. 29,
2005 as WO/2005/090427, and the at least one skin layer polymer is
typically a polyolefin. Typically, the skin layer polymer of the
first and second outer layers is often the same.
[0014] Upon preparation, the articles of the present invention may
be stretched or activated, typically at an elongation of at least
about 50%, preferably at least about 100% and more preferably at
least about 150%, more preferably at least 300%, more preferably at
least 400% of its original measurement (e.g. length or width) to an
approximate maximum of 500% to 1500%. The stretched article is
optionally subsequently relaxed to a very low tension to allow
substantial elastic recovery before winding up on a roll.
[0015] In another embodiment, the invention is a process for making
a pre-stretched, multi-layer film comprising at least two layers, a
first or low crystallinity layer comprising a low crystallinity
polymer and a second or high crystallinity layer comprising a high
crystallinity polymer. The process comprises the steps of: (1)
forming the film, and (2) elongating the film in at least one
direction to at least about 150%, preferably at least about 200%,
of its original length or width. Preferably, the film is elongated
at a temperature below the melting point of the high crystallinity
polymer, more preferably at a temperature below the melting point
of the low crystallinity polymer. The elongation step produces a
film with a haze value of greater than 0%, typically of at least
10%, more typically of at least 25%, and even more typically of at
least 50%.
[0016] In another embodiment, the invention is the article
described in the first and second embodiments in the form of a
fiber, preferably a bicomponent fiber. Preferably, the high
crystallinity polymer comprises at least a portion of the surface
of the fiber, especially in fibers with a configuration of
sheath/core, side-by-side, crescent moon, tri-lobal,
islands-in-the-sea, or flat, although there are some applications
where the low crystallinity polymer can comprise at least a portion
of the surface of the fiber, e.g., binder fiber applications.
Fibers in which the high crystallinity polymer has been plastically
deformed are particularly preferred.
[0017] Other embodiments of the invention include the article
described in the previous embodiments in the form of a woven,
nonwoven or woven/nonwoven blended fabric, films comprising four or
more layers, garments and other structures made from the articles,
e.g., diaper back-sheets and elastic tabs, hospital wear, etc.,
cross-linked articles, articles containing fillers and the like.
Another preferred embodiment is an article described in the
previous embodiments comprising a laminate comprising
nonwoven/film/nonwoven laminates, nonwoven/nonwoven/nonwoven
laminates, laminates comprising at least two nonwovens, and
woven/nonwoven laminates.
[0018] In many embodiments of this invention, preferably the weight
percent crystallinity difference between the high and low
crystallinity layers is at least about 3%, preferably at least
about 5% and more preferably at least about 10% and not in excess
of about 90%.
[0019] In many embodiments, the article may comprise at least one
ethylene/.alpha.-olefin interpolymer in the low crystallinity
layer, the high crystallinity layer, either, or both, wherein the
ethylene/.alpha.-olefin interpolymer is described in and discussed
in copending PCT Application No. PCT/US2005/008917, filed on Mar.
17, 2005 and published on Sep. 29, 2005 as WO/2005/090427 which is
incorporated herein by reference. The ethylene/.alpha.-olefin
interpolymer is characterized by one or more of the following:
[0020] (a) has a Mw/Mn from about 1.7 to about 3.5, at least one
melting point, Tm, in degrees Celsius, and a density, d, in
grams/cubic centimeter, wherein the numerical values of Tm and d
correspond to the relationship:
T.sub.m.gtoreq.858.91-1825.3(d)+1112.8(d).sup.2; or
[0021] (b) has a Mw/Mn from about 1.7 to about 3.5, and is
characterized by a heat of fusion, .DELTA.H in J/g, and a delta
quantity, .DELTA.T, in degrees Celsius defined as the temperature
difference between the tallest DSC peak and the tallest CRYSTAF
peak, wherein the numerical values of .DELTA.T and .DELTA.H have
the following relationships:
.DELTA.T>-0.1299(.DELTA.H)+62.81 for .DELTA.H greater than zero
and up to 130 J/g,
.DELTA.T.gtoreq.48.degree. C. for .DELTA.H greater than 130
J/g,
wherein the CRYSTAF peak is determined using at least 5 percent of
the cumulative polymer, and if less than 5 percent of the polymer
has an identifiable CRYSTAF peak, then the CRYSTAF temperature is
30.degree. C.; or
[0022] (c) is characterized by an elastic recovery, Re, in percent
at 300 percent strain and 1 cycle measured with a
compression-molded film of the ethylene/.alpha.-olefin
interpolymer, and has a density, d, in grams/cubic centimeter,
wherein the numerical values of Re and d satisfy the following
relationship when ethylene/.alpha.-olefin interpolymer is
substantially free of a cross-linked phase:
Re>1481-1629(d); or
[0023] (d) has a molecular fraction which elutes between 40.degree.
C. and 130.degree. C. when fractionated using TREF, characterized
in that the fraction has a molar comonomer content of at least 5
percent higher than that of a comparable random ethylene
interpolymer fraction eluting between the same temperatures,
wherein said comparable random ethylene interpolymer has the same
comonomer(s) and has a melt index, density, and molar comonomer
content (based on the whole polymer) within 10 percent of that of
the ethylene/.alpha.-olefin interpolymer; or
[0024] (e) has a storage modulus at 25.degree. C., G'(25.degree.
C.), and a storage modulus at 100.degree. C., G'(100.degree. C.),
wherein the ratio of G'(25.degree. C.) to G'(100.degree. C.) is in
the range of about 1:1 to about 9:1
wherein the ethylene/.alpha.-olefin interpolymer has a density of
from about 0.85 to about 0.89 g/cc and a melt index (12) of from
about 0.5 g/10 min. to about 20 g/10 min.
BRIEF DESCRIPTION OF THE DRAWINGS
[0025] FIG. 1 shows the melting point/density relationship for the
inventive polymers (represented by diamonds) as compared to
traditional random copolymers (represented by circles) and
Ziegler-Natta copolymers (represented by triangles).
[0026] FIG. 2 shows plots of delta DSC-CRYSTAF as a function of DSC
Melt Enthalpy for various polymers. The diamonds represent random
ethylene/octene copolymers; the squares represent polymer examples
1-4; the triangles represent polymer examples 5-9; and the circles
represent polymer examples 10-19. The "X" symbols represent polymer
examples A*-F*.
[0027] FIG. 3 shows the effect of density on elastic recovery for
unoriented films made from inventive interpolymers (represented by
the squares and circles) and traditional copolymers (represented by
the triangles which are various Dow AFFINITY.RTM. polymers). The
squares represent inventive ethylene/butene copolymers; and the
circles represent inventive ethylene/octene copolymers.
[0028] FIG. 4 is a plot of octene content of TREF fractionated
ethylene/1-octene copolymer fractions versus TREF elution
temperature of the fraction for the polymer of Example 5
(represented by the circles) and comparative polymers E and F
(represented by the "X" symbols). The diamonds represent
traditional random ethylene/octene copolymers.
[0029] FIG. 5 is a plot of octene content of TREF fractionated
ethylene/1-octene copolymer fractions versus TREF elution
temperature of the fraction for the polymer of Example 5 (curve 1)
and for comparative F (curve 2). The squares represent Example F*;
and the triangles represent Example 5.
[0030] FIG. 6 is a graph of the log of storage modulus as a
function of temperature for comparative ethylene/1-octene copolymer
(curve 2) and propylene/ethylene-copolymer (curve 3) and for two
ethylene/1-octene block copolymers of the invention made with
differing quantities of chain shuttling agent (curves 1).
[0031] FIG. 7 shows a plot of TMA (1 mm) versus flex modulus for
some inventive polymers (represented by the diamonds), as compared
to some known polymers. The triangles represent various Dow
VERSIFY.RTM. polymers; the circles represent various random
ethylene/styrene copolymers; and the squares represent various Dow
AFFINITY.RTM. polymers.
DETAILED DESCRIPTION OF THE INVENTION
[0032] "Low crystallinity", "high crystallinity" and like terms are
used in a relative sense, not in an absolute sense. However, low
crystallinity layers have crystallinity of from about 1 to about
25, preferably from about 1 to about 20, and more preferably from
about 1 to about 15 weight percent crystallinity.
[0033] Typical high crystalline polymers often include linear low
density polyethylene (LLDPE), low density polyethylene (LDPE),
LLDPE/LDPE blends, high density polyethylene (HDPE),
homopolypropylene (hPP), substantially linear ethylene polymer
(SLEP), random propylene based copolymer, polypropylene (PP)
plastomers and elastomers, random copolymer (RCP), and the like,
and various blends thereof. Low crystallinity polymers of
particular interest preferably include ethylene/.alpha.-olefin
multi-block interpolymers defined and discussed in copending PCT
Application No. PCT/US2005/008917, filed on Mar. 17, 2005 and
published on Sep. 29, 2005 as WO/2005/090427, which in turn claims
priority to U.S. Provisional Application No. 60/553,906, filed Mar.
17, 2004, both which are incorporated by reference. Low crystalline
polymers also include propylene/ethylene, propylene/1-butene,
propylene/1-hexene, propylene/4-methyl-1-pentene,
propylene/1-octene, propylene/ethylene/1-butene,
propylene/ethylene/ENB, propylene/ethylene/1-hexene,
propylene/ethylene/1-octene, propylene/styrene, and
propylene/ethylene/styrene. Representative of these copolymers are
the VERSIFY.RTM. elastic propylene copolymers manufactured and
marketed by The Dow Chemical Company and VISTAMAXX propylene
copolymers made by Exxon-Mobil.
[0034] The term "polymer" generally includes, but is not limited
to, homopolymers, copolymers, such as, for example, block, graft,
random and alternating copolymers, terpolymers, etc., and blends
and modifications of the same. Furthermore, unless otherwise
specifically limited, the term "polymer" shall include all possible
geometrical configurations of the material. These configurations
include, but are not limited to, isotactic, syndiotactic and random
symmetries.
[0035] All percentages specified herein are weight percentages
unless otherwise specified.
[0036] "Interpolymer" means a polymer prepared by the
polymerization of at least two different types of monomers. The
generic term "interpolymer" includes the term "copolymer" (which is
usually employed to refer to a polymer prepared from two different
monomers) as well as the term "terpolymer" (which is usually
employed to refer to a polymer prepared from three different types
of monomers). It also encompasses polymers made by polymerizing
four or more types of monomers.
[0037] The term "ethylene/.alpha.-olefin interpolymer" generally
refers to polymers comprising ethylene and an .alpha.-olefin having
3 or more carbon atoms. Preferably, ethylene comprises the majority
mole fraction of the whole polymer, i.e., ethylene comprises at
least about 50 mole percent of the whole polymer. More preferably
ethylene comprises at least about 60 mole percent, at least about
70 mole percent, or at least about 80 mole percent, with the
substantial remainder of the whole polymer comprising at least one
other comonomer that is preferably an .alpha.-olefin having 3 or
more carbon atoms. For many ethylene/octene copolymers, the
preferred composition comprises an ethylene content greater than
about 80 mole percent of the whole polymer and an octene content of
from about 10 to about 15, preferably from about 15 to about 20
mole percent of the whole polymer. In some embodiments, the
ethylene/.alpha.-olefin interpolymers do not include those produced
in low yields or in a minor amount or as a by-product of a chemical
process. While the ethylene/.alpha.-olefin interpolymers can be
blended with one or more polymers, the as-produced
ethylene/.alpha.-olefin interpolymers are substantially pure and
often comprise a major component of the reaction product of a
polymerization process.
[0038] The ethylene/.alpha.-olefin interpolymers comprise ethylene
and one or more copolymerizable .alpha.-olefin comonomers in
polymerized form, characterized by multiple blocks or segments of
two or more polymerized monomer units differing in chemical or
physical properties. That is, the ethylene/.alpha.-olefin
interpolymers are block interpolymers, preferably multi-block
interpolymers or copolymers. The terms "interpolymer" and
copolymer" are used interchangeably herein. In some embodiments,
the multi-block copolymer can be represented by the following
formula:
(AB)n
where n is at least 1, preferably an integer greater than 1, such
as 2, 3, 4, 5, 10, 15, 20, 30, 40, 50, 60, 70, 80, 90, 100, or
higher, "A" represents a hard block or segment and "B" represents a
soft block or segment. Preferably, As and Bs are linked in a
substantially linear fashion, as opposed to a substantially
branched or substantially star-shaped fashion. In other
embodiments, A blocks and B blocks are randomly distributed along
the polymer chain. In other words, the block copolymers usually do
not have a structure as follows.
AAA-AA-BBB-BB
[0039] In still other embodiments, the block copolymers do not
usually have a third type of block, which comprises different
comonomer(s). In yet other embodiments, each of block A and block B
has monomers or comonomers substantially randomly distributed
within the block. In other words, neither block A nor block B
comprises two or more sub-segments (or sub-blocks) of distinct
composition, such as a tip segment, which has a substantially
different composition than the rest of the block.
[0040] The multi-block polymers typically comprise various amounts
of "hard" and "soft" segments. "Hard" segments refer to blocks of
polymerized units in which ethylene is present in an amount greater
than about 95 weight percent, and preferably greater than about 98
weight percent based on the weight of the polymer. In other words,
the comonomer content (content of monomers other than ethylene) in
the hard segments is less than about 5 weight percent, and
preferably less than about 2 weight percent based on the weight of
the polymer. In some embodiments, the hard segments comprises all
or substantially all ethylene. "Soft" segments, on the other hand,
refer to blocks of polymerized units in which the comonomer content
(content of monomers other than ethylene) is greater than about 5
weight percent, preferably greater than about 8 weight percent,
greater than about 10 weight percent, or greater than about 15
weight percent based on the weight of the polymer. In some
embodiments, the comonomer content in the soft segments can be
greater than about 20 weight percent, greater than about 25 weight
percent, greater than about 30 weight percent, greater than about
35 weight percent, greater than about 40 weight percent, greater
than about 45 weight percent, greater than about 50 weight percent,
or greater than about 60 weight percent.
[0041] The soft segments can often be present in a block
interpolymer from about 1 weight percent to about 99 weight percent
of the total weight of the block interpolymer, preferably from
about 5 weight percent to about 95 weight percent, from about 10
weight percent to about 90 weight percent, from about 15 weight
percent to about 85 weight percent, from about 20 weight percent to
about 80 weight percent, from about 25 weight percent to about 75
weight percent, from about 30 weight percent to about 70 weight
percent, from about 35 weight percent to about 65 weight percent,
from about 40 weight percent to about 60 weight percent, or from
about 45 weight percent to about 55 weight percent of the total
weight of the block interpolymer. Conversely, the hard segments can
be present in similar ranges. The soft segment weight percentage
and the hard segment weight percentage can be calculated based on
data obtained from DSC or NMR. Such methods and calculations are
disclosed in a concurrently filed U.S. patent application Ser. No.
11/376,835, Attorney Docket No. 385063-999558, entitled
"Ethylene/.alpha.-Olefin Block Interpolymers", filed on Mar. 15,
2006, in the name of Colin L. P. Shan, Lonnie Hazlitt, et. al. and
assigned to Dow Global Technologies Inc., the disclosure of which
is incorporated by reference herein in its entirety.
Ethylene/.alpha.-Olefin Interpolymers
[0042] The ethylene/.alpha.-olefin interpolymers used in
embodiments of the invention (also referred to as "inventive
interpolymer" or "inventive polymer") comprise ethylene and one or
more copolymerizable .alpha.-olefin comonomers in polymerized form,
characterized by multiple blocks or segments of two or more
polymerized monomer units differing in chemical or physical
properties (block interpolymer), preferably a multi-block
copolymer. The ethylene/.alpha.-olefin interpolymers are
characterized by one or more of the aspects described as
follows.
[0043] In one aspect, the ethylene/.alpha.-olefin interpolymers
used in embodiments of the invention have a M.sub.w/M.sub.n from
about 1.7 to about 3.5 and at least one melting point, T.sub.m, in
degrees Celsius and density, d, in grams/cubic centimeter, wherein
the numerical values of the variables correspond to the
relationship:
T.sub.m>-2002.9+4538.5(d)-2422.2(d).sup.2, and preferably
T.sub.m.gtoreq.-6288.1+13141(d)-6720.3(d).sup.2, and more
preferably
T.sub.m.gtoreq.858.91-1825.3(d)+1112.8(d).sup.2.
[0044] Such melting point/density relationship is illustrated in
FIG. 1. Unlike the traditional random copolymers of
ethylene/.alpha.-olefins whose melting points decrease with
decreasing densities, the inventive interpolymers (represented by
diamonds) exhibit melting points substantially independent of the
density, particularly when density is between about 0.87 g/cc to
about 0.95 g/cc. For example, the melting point of such polymers
are in the range of about 110.degree. C. to about 130.degree. C.
when density ranges from 0.875 g/cc to about 0.945 g/cc. In some
embodiments, the melting point of such polymers are in the range of
about 115.degree. C. to about 125.degree. C. when density ranges
from 0.875 g/cc to about 0.945 g/cc.
[0045] In another aspect, the ethylene/.alpha.-olefin interpolymers
comprise, in polymerized form, ethylene and one or more
.alpha.-olefins and are characterized by a .DELTA.T, in degree
Celsius, defined as the temperature for the tallest Differential
Scanning Calorimetry ("DSC") peak minus the temperature for the
tallest Crystallization Analysis Fractionation ("CRYSTAF") peak and
a heat of fusion in J/g, .DELTA.H, and .DELTA.T and .DELTA.H
satisfy the following relationships:
.DELTA.T>-0.1299(.DELTA.H)+62.81, and preferably
.DELTA.T.gtoreq.-0.1299(.DELTA.H)+64.38, and more preferably
.DELTA.T.gtoreq.-0.1299(.DELTA.H)+65.95,
for .DELTA.H up to 130 J/g. Moreover, .DELTA.T is equal to or
greater than 48.degree. C. for .DELTA.H greater than 130 J/g. The
CRYSTAF peak is determined using at least 5 percent of the
cumulative polymer (that is, the peak must represent at least 5
percent of the cumulative polymer), and if less than 5 percent of
the polymer has an identifiable CRYSTAF peak, then the CRYSTAF
temperature is 30.degree. C., and .DELTA.H is the numerical value
of the heat of fusion in J/g. More preferably, the highest CRYSTAF
peak contains at least 10 percent of the cumulative polymer. FIG. 2
shows plotted data for inventive polymers as well as comparative
examples. Integrated peak areas and peak temperatures are
calculated by the computerized drawing program supplied by the
instrument maker. The diagonal line shown for the random ethylene
octene comparative polymers corresponds to the equation
.DELTA.T=-0.1299 (.DELTA.H)+62.81.
[0046] In yet another aspect, the ethylene/.alpha.-olefin
interpolymers have a molecular fraction which elutes between
40.degree. C. and 130.degree. C. when fractionated using
Temperature Rising Elution Fractionation ("TREF"), characterized in
that said fraction has a molar comonomer content higher, preferably
at least 5 percent higher, more preferably at least 10 percent
higher, than that of a comparable random ethylene interpolymer
fraction eluting between the same temperatures, wherein the
comparable random ethylene interpolymer contains the same
comonomer(s), and has a melt index, density, and molar comonomer
content (based on the whole polymer) within 10 percent of that of
the block interpolymer. Preferably, the Mw/Mn of the comparable
interpolymer is also within 10 percent of that of the block
interpolymer and/or the comparable interpolymer has a total
comonomer content within 10 weight percent of that of the block
interpolymer.
[0047] In still another aspect, the ethylene/.alpha.-olefin
interpolymers are characterized by an elastic recovery, Re, in
percent at 300 percent strain and 1 cycle measured on a
compression-molded film of an ethylene/.alpha.-olefin interpolymer,
and has a density, d, in grams/cubic centimeter, wherein the
numerical values of Re and d satisfy the following relationship
when ethylene/.alpha.-olefin interpolymer is substantially free of
a cross-linked phase:
Re>1481-1629(d); and preferably
Re.gtoreq.1491-1629(d); and more preferably
Re.gtoreq.1501-1629(d); and even more preferably
Re.gtoreq.1511-1629(d).
[0048] FIG. 3 shows the effect of density on elastic recovery for
unoriented films made from certain inventive interpolymers and
traditional random copolymers. For the same density, the inventive
interpolymers have substantially higher elastic recoveries.
[0049] In some embodiments, the ethylene/.alpha.-olefin
interpolymers have a tensile strength above 10 MPa, preferably a
tensile strength.gtoreq.11 MPa, more preferably a tensile
strength.gtoreq.13 MPa and/or an elongation at break of at least
600 percent, more preferably at least 700 percent, highly
preferably at least 800 percent, and most highly preferably at
least 900 percent at a crosshead separation rate of 11
cm/minute.
[0050] In other embodiments, the ethylene/.alpha.-olefin
interpolymers have (1) a storage modulus ratio, G'(25.degree.
C.)/G'(100.degree. C.), of from 1 to 50, preferably from 1 to 20,
more preferably from 1 to 10; and/or (2) a 70.degree. C.
compression set of less than 80 percent, preferably less than 70
percent, especially less than 60 percent, less than 50 percent, or
less than 40 percent, down to a compression set of 0 percent.
[0051] In still other embodiments, the ethylene/.alpha.-olefin
interpolymers have a 70.degree. C. compression set of less than 80
percent, less than 70 percent, less than 60 percent, or less than
50 percent. Preferably, the 70.degree. C. compression set of the
interpolymers is less than 40 percent, less than 30 percent, less
than 20 percent, and may go down to about 0 percent.
[0052] In some embodiments, the ethylene/.alpha.-olefin
interpolymers have a heat of fusion of less than 85 J/g and/or a
pellet blocking strength of equal to or less than 100
pounds/foot.sup.2 (4800 Pa), preferably equal to or less than 50
lbs/ft.sup.2 (2400 Pa), especially equal to or less than 5
lbs/ft.sup.2 (240 Pa), and as low as 0 lbs/ft.sup.2 (0 Pa).
[0053] In other embodiments, the ethylene/.alpha.-olefin
interpolymers comprise, in polymerized form, at least 50 mole
percent ethylene and have a 70.degree. C. compression set of less
than 80 percent, preferably less than 70 percent or less than 60
percent, most preferably less than 40 to 50 percent and down to
close zero percent.
[0054] In some embodiments, the multi-block copolymers possess a
PDI fitting a Schultz-Flory distribution rather than a Poisson
distribution. The copolymers are further characterized as having
both a polydisperse block distribution and a polydisperse
distribution of block sizes and possessing a most probable
distribution of block lengths. Preferred multi-block copolymers are
those containing 4 or more blocks or segments including terminal
blocks. More preferably, the copolymers include at least 5, 10 or
20 blocks or segments including terminal blocks.
[0055] Comonomer content may be measured using any suitable
technique, with techniques based on nuclear magnetic resonance
("NMR") spectroscopy preferred. Moreover, for polymers or blends of
polymers having relatively broad TREF curves, the polymer desirably
is first fractionated using TREF into fractions each having an
eluted temperature range of 10.degree. C. or less. That is, each
eluted fraction has a collection temperature window of 10.degree.
C. or less. Using this technique, said block interpolymers have at
least one such fraction having a higher molar comonomer content
than a corresponding fraction of the comparable interpolymer.
[0056] In another aspect, the inventive polymer is an olefin
interpolymer, preferably comprising ethylene and one or more
copolymerizable comonomers in polymerized form, characterized by
multiple blocks (i.e., at least two blocks) or segments of two or
more polymerized monomer units differing in chemical or physical
properties (blocked interpolymer), most preferably a multi-block
copolymer, said block interpolymer having a peak (but not just a
molecular fraction) which elutes between 40.degree. C. and
130.degree. C. (but without collecting and/or isolating individual
fractions), characterized in that said peak, has a comonomer
content estimated by infra-red spectroscopy when expanded using a
full width/half maximum (FWHM) area calculation, has an average
molar comonomer content higher, preferably at least 5 percent
higher, more preferably at least 10 percent higher, than that of a
comparable random ethylene interpolymer peak at the same elution
temperature and expanded using a full width/half maximum (FWHM)
area calculation, wherein said comparable random ethylene
interpolymer has the same comonomer(s) and has a melt index,
density, and molar comonomer content (based on the whole polymer)
within 10 percent of that of the blocked interpolymer. Preferably,
the Mw/Mn of the comparable interpolymer is also within 10 percent
of that of the blocked interpolymer and/or the comparable
interpolymer has a total comonomer content within 10 weight percent
of that of the blocked interpolymer. The full width/half maximum
(FWHM) calculation is based on the ratio of methyl to methylene
response area [CH.sub.3/CH.sub.2] from the ATREF infra-red
detector, wherein the tallest (highest) peak is identified from the
base line, and then the FWHM area is determined. For a distribution
measured using an ATREF peak, the FWHM area is defined as the area
under the curve between T.sub.1 and T.sub.2, where T.sub.1 and
T.sub.2 are points determined, to the left and right of the ATREF
peak, by dividing the peak height by two, and then drawing a line
horizontal to the base line, that intersects the left and right
portions of the ATREF curve. A calibration curve for comonomer
content is made using random ethylene/.alpha.-olefin copolymers,
plotting comonomer content from NMR versus FWHM area ratio of the
TREF peak. For this infra-red method, the calibration curve is
generated for the same comonomer type of interest. The comonomer
content of TREF peak of the inventive polymer can be determined by
referencing this calibration curve using its FWHM methyl:methylene
area ratio [CH.sub.3/CH.sub.2] of the TREF peak.
[0057] Comonomer content may be measured using any suitable
technique, with techniques based on nuclear magnetic resonance
(NMR) spectroscopy preferred. Using this technique, said blocked
interpolymers has higher molar comonomer content than a
corresponding comparable interpolymer.
[0058] Preferably, for interpolymers of ethylene and 1-octene, the
block interpolymer has a comonomer content of the TREF fraction
elating between 40 and 130.degree. C. greater than or equal to the
quantity (-0.2013) T+20.07, more preferably greater than or equal
to the quantity (-0.2013) T+21.07, where T is the numerical value
of the peak elution temperature of the TREF fraction being
compared, measured in .degree. C.
[0059] FIG. 4 graphically depicts an embodiment of the block
interpolymers of ethylene and 1-octene where a plot of the
comonomer content versus TREF elution temperature for several
comparable ethylene/1-octene interpolymers (random copolymers) are
fit to a line representing (-0.2013) T+20.07 (solid line). The line
for the equation (-0.2013) T+21.07 is depicted by a dotted line.
Also depicted are the comonomer contents for fractions of several
block ethylene/1-octene interpolymers of the invention (multi-block
copolymers). All of the block interpolymer fractions have
significantly higher 1-octene content than either line at
equivalent elution temperatures. This result is characteristic of
the inventive interpolymer and is believed to be due to the
presence of differentiated blocks within the polymer chains, having
both crystalline and amorphous nature.
[0060] FIG. 5 graphically displays the TREF curve and comonomer
contents of polymer fractions for Example 5 and comparative F to be
discussed below. The peak eluting from 40 to 130.degree. C.,
preferably from 60.degree. C. to 95.degree. C. for both polymers is
fractionated into three parts, each part eluting over a temperature
range of less than 10.degree. C. Actual data for Example 5 is
represented by triangles. The skilled artisan can appreciate that
an appropriate calibration curve may be constructed for
interpolymers containing different comonomers and a line used as a
comparison fitted to the TREF values obtained from comparative
interpolymers of the same monomers, preferably random copolymers
made using a metallocene or other homogeneous catalyst composition.
Inventive interpolymers are characterized by a molar comonomer
content greater than the value determined from the calibration
curve at the same TREF elution temperature, preferably at least 5
percent greater, more preferably at least 10 percent greater.
[0061] In addition to the above aspects and properties described
herein, the inventive polymers can be characterized by one or more
additional characteristics. In one aspect, the inventive polymer is
an olefin interpolymer, preferably comprising ethylene and one or
more copolymerizable comonomers in polymerized form, characterized
by multiple blocks or segments of two or more polymerized monomer
units differing in chemical or physical properties (blocked
interpolymer), most preferably a multi-block copolymer, said block
interpolymer having a molecular fraction which elutes between
40.degree. C. and 130.degree. C., when fractionated using TREF
increments, characterized in that said fraction has a molar
comonomer content higher, preferably at least 5 percent higher,
more preferably at least 10, 15, 20 or 25 percent higher, than that
of a comparable random ethylene interpolymer fraction eluting
between the same temperatures, wherein said comparable random
ethylene interpolymer comprises the same comonomer(s), preferably
it is the same comonomer(s), and a melt index, density, and molar
comonomer content (based on the whole polymer) within 10 percent of
that of the blocked interpolymer. Preferably, the Mw/Mn of the
comparable interpolymer is also within 10 percent of that of the
blocked interpolymer and/or the comparable interpolymer has a total
comonomer content within 10 weight percent of that of the blocked
interpolymer.
[0062] Preferably, the above interpolymers are interpolymers of
ethylene and at least one .alpha.-olefin, especially those
interpolymers having a whole polymer density from about 0.855 to
about 0.935 g/cm.sup.3, and more especially for polymers having
more than about 1 mole percent comonomer, the blocked interpolymer
has a comonomer content of the TREF fraction eluting between 40 and
130.degree. C. greater than or equal to the quantity (-0.1356)
T+13.89, more preferably greater than or equal to the quantity
(-0.1356) T+14.93, and most preferably greater than or equal to the
quantity (-0.2013)T+21.07, where T is the numerical value of the
peak ATREF elution temperature of the TREF fraction being compared,
measured in .degree. C.
[0063] Preferably, for the above interpolymers of ethylene and at
least one alpha-olefin especially those interpolymers having a
whole polymer density from about 0.855 to about 0.935 g/cm.sup.3,
and more especially for polymers having more than about 1 mole
percent comonomer, the blocked interpolymer has a comonomer content
of the TREF fraction eluting between 40 and 130.degree. C. greater
than or equal to the quantity (-0.2013) T+20.07, more preferably
greater than or equal to the quantity (-0.2013) T+21.07, where T is
the numerical value of the peak elution temperature of the TREF
fraction being compared, measured in .degree. C.
[0064] In still another aspect, the inventive polymer is an olefin
interpolymer, preferably comprising ethylene and one or more
copolymerizable comonomers in polymerized form, characterized by
multiple blocks or segments of two or more polymerized monomer
units differing in chemical or physical properties (blocked
interpolymer), most preferably a multi-block copolymer, said block
interpolymer having a molecular fraction which elutes between
40.degree. C. and 130.degree. C., when fractionated using TREF
increments, characterized in that every fraction having a comonomer
content of at least about 6 mole percent, has a melting point
greater than about 100.degree. C. For those fractions having a
comonomer content from about 3 mole percent to about 6 mole
percent, every fraction has a DSC melting point of about
110.degree. C. or higher. More preferably, said polymer fractions,
having at least 1 mol percent comonomer, has a DSC melting point
that corresponds to the equation:
Tm.gtoreq.(-5.5926)(mol percent comonomer in the
fraction)+135.90.
[0065] In yet another aspect, the inventive polymer is an olefin
interpolymer, preferably comprising ethylene and one or more
copolymerizable comonomers in polymerized form, characterized by
multiple blocks or segments of two or more polymerized monomer
units differing in chemical or physical properties (blocked
interpolymer), most preferably a multi-block copolymer, said block
interpolymer having a molecular fraction which elutes between
40.degree. C. and 130.degree. C., when fractionated using TREF
increments, characterized in that every fraction that has an ATREF
elution temperature greater than or equal to about 76.degree. C.,
has a melt enthalpy (heat of fusion) as measured by DSC,
corresponding to the equation:
Heat of fusion(J/gm).ltoreq.(3.1718)(ATREF elution temperature in
Celsius)-136.58,
[0066] The inventive block interpolymers have a molecular fraction
which elutes between 40.degree. C. and 130.degree. C., when
fractionated using TREF increments, characterized in that every
fraction that has an ATREF elution temperature between 40.degree.
C. and less than about 76.degree. C., has a melt enthalpy (heat of
fusion) as measured by DSC, corresponding to the equation:
Heat of fusion(J/gm).ltoreq.(1.1312)(ATREF elution temperature in
Celsius)+22.97.
ATREF Peak Comonomer Composition Measurement by Infra-Red
Detector
[0067] The comonomer composition of the TREF peak can be measured
using an IR4 infra-red detector available from Polymer Char,
Valencia, Spain (http://www.polymerchar.com/).
[0068] The "composition mode" of the detector is equipped with a
measurement sensor (CH.sub.2) and composition sensor (CH.sub.3)
that are fixed narrow band infra-red filters in the region of
2800-3000 cm.sup.-1. The measurement sensor detects the methylene
(CH.sub.2) carbons on the polymer (which directly relates to the
polymer concentration in solution) while the composition sensor
detects the methyl (CH.sub.3) groups of the polymer. The
mathematical ratio of the composition signal (CH.sub.3) divided by
the measurement signal (CH.sub.2) is sensitive to the comonomer
content of the measured polymer in solution and its response is
calibrated with known ethylene alpha-olefin copolymer
standards.
[0069] The detector when used with an ATREF instrument provides
both a concentration (CH.sub.2) and composition (CH.sub.3) signal
response of the eluted polymer during the TREF process. A polymer
specific calibration can be created by measuring the area ratio of
the CH.sub.3 to CH.sub.2 for polymers with known comonomer content
(preferably measured by NMR). The comonomer content of an ATREF
peak of a polymer can be estimated by applying a the reference
calibration of the ratio of the areas for the individual CH.sub.3
and CH.sub.2 response (i.e. area ratio CH.sub.3/CH.sub.2 versus
comonomer content).
[0070] The area of the peaks can be calculated using a full
width/half maximum (FWHM) calculation after applying the
appropriate baselines to integrate the individual signal responses
from the TREF chromatogram. The full width/half maximum calculation
is based on the ratio of methyl to methylene response area
[CH.sub.3/CH.sub.2] from the ATREF infra-red detector, wherein the
tallest (highest) peak is identified from the base line, and then
the FWHM area is determined. For a distribution measured using an
ATREF peak, the FWHM area is defined as the area under the curve
between T1 and T2, where T1 and T2 are points determined, to the
left and right of the ATREF peak, by dividing the peak height by
two, and then drawing a line horizontal to the base line, that
intersects the left and right portions of the ATREF curve.
[0071] The application of infra-red spectroscopy to measure the
comonomer content of polymers in this ATREF-infra-red method is, in
principle, similar to that of GPC/FTIR systems as described in the
following references: Markovich, Ronald P.; Hazlitt, Lonnie G.;
Smith, Linley; "Development of gel-permeation
chromatography-Fourier transform infrared spectroscopy for
characterization of ethylene-based polyolefin copolymers".
Polymeric Materials Science and Engineering (1991), 65, 98-100.;
and Deslauriers, P. J.; Rohlfing, D. C.; Shieh, E. T.; "Quantifying
short chain branching microstructures in ethylene-1-olefin
copolymers using size exclusion chromatography and Fourier
transform infrared spectroscopy (SEC-FTIR)", Polymer (2002), 43,
59-170., both of which are incorporated by reference herein in
their entirety.
[0072] In other embodiments, the inventive ethylene/.alpha.-olefin
interpolymer is characterized by an average block index, ABI, which
is greater than zero and up to about 1.0 and a molecular weight
distribution, M.sub.w/M.sub.n, greater than about 1.3. The average
block index, ABI, is the weight average of the block index ("BI")
for each of the polymer fractions obtained in preparative TREF from
20.degree. C. and 110.degree. C., with an increment of 5.degree.
C.:
ABI=.SIGMA.(w.sub.iBI.sub.i)
where BI.sub.i is the block index for the ith fraction of the
inventive ethylene/.alpha.-olefin interpolymer obtained in
preparative TREF, and w.sub.i is the weight percentage of the ith
fraction.
[0073] For each polymer fraction, BI is defined by one of the two
following equations (both of which give the same BI value):
BI = 1 / T X - 1 / T XO 1 / T A - 1 / T AB or BI = LnP X - LnP XO
LnP A - LnP AB ##EQU00001##
where T.sub.X is the preparative ATREF elution temperature for the
ith fraction (preferably expressed in Kelvin), P.sub.X is the
ethylene mole fraction for the ith fraction, which can be measured
by NMR or IR as described above. P.sub.AB is the ethylene mole
fraction of the whole ethylene/.alpha.-olefin interpolymer (before
fractionation), which also can be measured by NMR or IR. T.sub.A
and P.sub.A are the ATREF elution temperature and the ethylene mole
fraction for pure "hard segments" (which refer to the crystalline
segments of the interpolymer). As a first order approximation, the
T.sub.A and P.sub.A values are set to those for high density
polyethylene homopolymer, if the actual values for the "hard
segments" are not available. For calculations performed herein,
T.sub.A is 372.degree. K., P.sub.A is 1.
[0074] T.sub.AB is the ATREF temperature for a random copolymer of
the same composition and having an ethylene mole fraction of
P.sub.AB. T.sub.AB can be calculated from the following
equation:
Ln P.sub.AB=.alpha./T.sub.AB+.beta.
where .alpha. and .beta. are two constants which can be determined
by calibration using a number of known random ethylene copolymers.
It should be noted that .alpha. and .beta. may vary from instrument
to instrument. Moreover, one would need to create their own
calibration curve with the polymer composition of interest and also
in a similar molecular weight range as the fractions. There is a
slight molecular weight effect. If the calibration curve is
obtained from similar molecular weight ranges, such effect would be
essentially negligible. In some embodiments, random ethylene
copolymers satisfy the following relationship:
Ln P=-237.83/T.sub.ATREF+0.639
[0075] T.sub.XO is the ATREF temperature for a random copolymer of
the same composition and having an ethylene mole fraction of
P.sub.X. T.sub.XO can be calculated from Ln
P.sub.X=.alpha./T.sub.XO+.beta.. Conversely, P.sub.XO is the
ethylene mole fraction for a random copolymer of the same
composition and having an ATREF temperature of T.sub.X, which can
be calculated from Ln P.sub.XO=.alpha./T.sub.X+.beta..
[0076] Once the block index (BI) for each preparative TREF fraction
is obtained, the weight average block index, ABI, for the whole
polymer can be calculated. In some embodiments, ABI is greater than
zero but less than about 0.3 or from about 0.1 to about 0.3. In
other embodiments, ABI is greater than about 0.3 and up to about
1.0. Preferably, ABI should be in the range of from about 0.4 to
about 0.7, from about 0.5 to about 0.7, or from about 0.6 to about
0.9. In some embodiments, ABI is in the range of from about 0.3 to
about 0.9, from about 0.3 to about 0.8, or from about 0.3 to about
0.7, from about 0.3 to about 0.6, from about 0.3 to about 0.5, or
from about 0.3 to about 0.4. In other embodiments, ABI is in the
range of from about 0.4 to about 1.0, from about 0.5 to about 1.0,
or from about 0.6 to about 1.0, from about 0.7 to about 1.0, from
about 0.8 to about 1.0, or from about 0.9 to about 1.0.
[0077] Another characteristic of the inventive
ethylene/.alpha.-olefin interpolymer is that the inventive
ethylene/.alpha.-olefin interpolymer comprises at least one polymer
fraction which can be obtained by preparative TREF, wherein the
fraction has a block index greater than about 0.1 and up to about
1.0 and a molecular weight distribution, M.sub.w/M.sub.n, greater
than about 1.3. In some embodiments, the polymer fraction has a
block index greater than about 0.6 and up to about 1.0, greater
than about 0.7 and up to about 1.0, greater than about 0.8 and up
to about 1.0, or greater than about 0.9 and up to about 1.0. In
other embodiments, the polymer fraction has a block index greater
than about 0.1 and up to about 1.0, greater than about 0.2 and up
to about 1.0, greater than about 0.3 and up to about 1.0, greater
than about 0.4 and up to about 1.0, or greater than about 0.4 and
up to about 1.0. In still other embodiments, the polymer fraction
has a block index greater than about 0.1 and up to about 0.5,
greater than about 0.2 and up to about 0.5, greater than about 0.3
and up to about 0.5, or greater than about 0.4 and up to about 0.5.
In yet other embodiments, the polymer fraction has a block index
greater than about 0.2 and up to about 0.9, greater than about 0.3
and up to about 0.8, greater than about 0.4 and up to about 0.7, or
greater than about 0.5 and up to about 0.6.
[0078] For copolymers of ethylene and an .alpha.-olefin, the
inventive polymers preferably possess (1) a PDI of at least 1.3,
more preferably at least 1.5, at least 1.7, or at least 2.0, and
most preferably at least 2.6, up to a maximum value of 5.0, more
preferably up to a maximum of 3.5, and especially up to a maximum
of 2.7; (2) a heat of fusion of 80 J/g or less; (3) an ethylene
content of at least 50 weight percent; (4) a glass transition
temperature, T.sub.g, of less than -25.degree. C., more preferably
less than -30.degree. C., and/or (5) one and only one T.sub.m.
[0079] Further, the inventive polymers can have, alone or in
combination with any other properties disclosed herein, a storage
modulus, G', such that log(G') is greater than or equal to 400 kPa,
preferably greater than or equal to 1.0 MPa, at a temperature of
100.degree. C. Moreover, the inventive polymers possess a
relatively flat storage modulus as a function of temperature in the
range from 0 to 100.degree. C. (illustrated in FIG. 6) that is
characteristic of block copolymers, and heretofore unknown for an
olefin copolymer, especially a copolymer of ethylene and one or
more C.sub.3-8 aliphatic .alpha.-olefins. (By the term "relatively
flat" in this context is meant that log G' (in Pascals) decreases
by less than one order of magnitude between 50 and 100.degree. C.,
preferably between 0 and 100.degree. C.).
[0080] The inventive interpolymers may be further characterized by
a thermomechanical analysis penetration depth of 1 mm at a
temperature of at least 90.degree. C. as well as a flexural modulus
of from 3 kpsi (20 MPa) to 13 kpsi (90 MPa). Alternatively, the
inventive interpolymers can have a thermomechanical analysis
penetration depth of 1 mm at a temperature of at least 104.degree.
C. as well as a flexural modulus of at least 3 kpsi (20 MPa). They
may be characterized as having an abrasion resistance (or volume
loss) of less than 90 mm.sup.3. FIG. 7 shows the TMA (1 mm) versus
flex modulus for the inventive polymers, as compared to other known
polymers. The inventive polymers have significantly better
flexibility-heat resistance balance than the other polymers.
[0081] Additionally, the ethylene/.alpha.-olefin interpolymers can
have a melt index, 12, from 0.01 to 2000 g/10 minutes, preferably
from 0.01 to 1000 g/10 minutes, more preferably from 0.01 to 500
g/10 minutes, and especially from 0.01 to 100 g/10 minutes. In
certain embodiments, the ethylene/.alpha.-olefin interpolymers have
a melt index, 12, from 0.01 to 10 g/10 minutes, from 0.5 to 50 g/10
minutes, from 1 to 30 g/10 minutes, from 1 to 6 g/10 minutes or
from 0.3 to 10 g/10 minutes. In certain embodiments, the melt index
for the ethylene/.alpha.-olefin polymers is 1 g/10 minutes, 3 g/10
minutes or 5 g/10 minutes.
[0082] The polymers can have molecular weights, M.sub.w, from 1,000
g/mole to 5,000,000 g/mole, preferably from 1000 g/mole to
1,000,000, more preferably from 10,000 g/mole to 500,000 g/mole,
and especially from 10,000 g/mole to 300,000 g/mole. The density of
the inventive polymers can be from 0.80 to 0.99 g/cm.sup.3 and
preferably for ethylene containing polymers from 0.85 g/cm.sup.3 to
0.97 g/cm.sup.3. In certain embodiments, the density of the
ethylene/.alpha.-olefin polymers ranges from 0.860 to 0.925
g/cm.sup.3 or 0.867 to 0.910 g/cm.sup.3.
[0083] The process of making the polymers has been disclosed in the
following patent applications: U.S. Provisional Application No.
60/553,906, filed Mar. 17, 2004; U.S. Provisional Application No.
60/662,937, filed Mar. 17, 2005; U.S. Provisional Application No.
60/662,939, filed Mar. 17, 2005; U.S. Provisional Application No.
60/566,2938, filed Mar. 17, 2005; PCT Application No.
PCT/US2005/008916, filed Mar. 17, 2005; PCT Application No.
PCT/US2005/008915, filed Mar. 17, 2005; and PCT Application No.
PCT/US2005/008917, filed Mar. 17, 2005, all of which are
incorporated by reference herein in their entirety. For example,
one such method comprises contacting ethylene and optionally one or
more addition polymerizable monomers other than ethylene under
addition polymerization conditions with a catalyst composition
comprising: [0084] the admixture or reaction product resulting from
combining: [0085] (A) a first olefin polymerization catalyst having
a high comonomer incorporation index, [0086] (B) a second olefin
polymerization catalyst having a comonomer incorporation index less
than 90 percent, preferably less than 50 percent, most preferably
less than 5 percent of the comonomer incorporation index of
catalyst (A), and [0087] (C) a chain shuttling agent.
[0088] Representative catalysts and chain shuttling agent are as
follows.
[0089] Catalyst (A1) is
[N-(2,6-di(1-methylethyl)phenyl)amido)(2-isopropylphenyl)(.alpha.-naphtha-
len-2-diyl(6-pyridin-2-diyl)methane)]hafnium dimethyl, prepared
according to the teachings of WO 03/40195, 2003US0204017, U.S. Ser.
No. 10/429,024, filed May 2, 2003, and WO 04/24740.
##STR00001##
[0090] Catalyst (A2) is
[N-(2,6-di(1-methylethyl)phenyl)amido)(2-methylphenyl)(1,2-phenylene-(6-p-
yridin-2-diyl)methane)]hafnium dimethyl, prepared according to the
teachings of WO 03/40195, 2003US0204017, U.S. Ser. No. 10/429,024,
filed May 2, 2003, and WO 04/24740.
##STR00002##
[0091] Catalyst (A3) is
bis[N,N'''-(2,4,6-tri(methylphenyl)amido)ethylenediamine]hafnium
dibenzyl.
##STR00003##
[0092] Catalyst (A4) is
bis((2-oxoyl-3-(dibenzo-1H-pyrrole-1-yl)-5-(methyl)phenyl)-2-phenoxymethy-
l)cyclohexane-1,2-diyl zirconium (IV) dibenzyl, prepared
substantially according to the teachings of US-A-2004/0010103.
##STR00004##
[0093] Catalyst (B1) is
1,2-bis-(3,5-di-t-butylphenylene)(1-(N-(1-methylethyl)immino)methyl)(2-ox-
oyl) zirconium dibenzyl
##STR00005##
[0094] Catalyst (B2) is
1,2-bis-(3,5-di-t-butylphenylene)(1-(N-(2-methylcyclohexyl)-immino)methyl-
)(2-oxoyl) zirconium dibenzyl
##STR00006##
[0095] Catalyst (C1) is
(t-butylamido)dimethyl(3-N-pyrrolyl-1,2,3,3a,7a-.eta.-inden-1-yl)silaneti-
tanium dimethyl prepared substantially according to the techniques
of U.S. Pat. No. 6,268,444:
##STR00007##
[0096] Catalyst (C2) is
(t-butylamido)di(4-methylphenyl)(2-methyl-1,2,3,3a,7a-.eta.-inden-1-yl)si-
lanetitanium dimethyl prepared substantially according to the
teachings of US-A-2003/004286:
##STR00008##
[0097] Catalyst (C3) is
(t-butylamido)di(4-methylphenyl)(2-methyl-1,2,3,3a,8a-.eta.-s-indacen-1-y-
l)silanetitanium dimethyl prepared substantially according to the
teachings of US-A-2003/004286:
##STR00009##
[0098] Catalyst (D1) is
bis(dimethyldisiloxane)(indene-1-yl)zirconium dichloride available
from Sigma-Aldrich:
##STR00010##
[0099] Shuttling Agents The shuttling agents employed include
diethylzinc, di(1-butyl)zinc, di(n-hexyl)zinc, triethylaluminum,
trioctylaluminum, triethylgallium, i-butylaluminum
bis(dimethyl(t-butyl)siloxane), i-butylaluminum
bis(di(trimethylsilyl)amide), n-octylaluminum
di(pyridine-2-methoxide), bis(n-octadecyl)i-butylaluminum,
i-butylaluminum bis(di(n-pentyl)amide), n-octylaluminum
bis(2,6-di-t-butylphenoxide, n-octylaluminum
di(ethyl(1-naphthyl)amide), ethylaluminum
bis(t-butyldimethylsiloxide), ethylaluminum
di(bis(trimethylsilyl)amide), ethylaluminum
bis(2,3,6,7-dibenzo-1-azacycloheptaneamide), n-octylaluminum
bis(2,3,6,7-dibenzo-1-azacycloheptaneamide), n-octylaluminum
bis(dimethyl(t-butyl)siloxide, ethylzinc (2,6-diphenylphenoxide),
and ethylzinc (t-butoxide).
[0100] Preferably, the foregoing process takes the form of a
continuous solution process for forming block copolymers,
especially multi-block copolymers, preferably linear multi-block
copolymers of two or more monomers, more especially ethylene and a
C.sub.3-20 olefin or cycloolefin, and most especially ethylene and
a C.sub.4-20 .alpha.-olefin, using multiple catalysts that are
incapable of interconversion. That is, the catalysts are chemically
distinct. Under continuous solution polymerization conditions, the
process is ideally suited for polymerization of mixtures of
monomers at high monomer conversions. Under these polymerization
conditions, shuttling from the chain shuttling agent to the
catalyst becomes advantaged compared to chain growth, and
multi-block copolymers, especially linear multi-block copolymers
are formed in high efficiency.
[0101] The inventive interpolymers may be differentiated from
conventional, random copolymers, physical blends of polymers, and
block copolymers prepared via sequential monomer addition,
fluxional catalysts, anionic or cationic living polymerization
techniques. In particular, compared to a random copolymer of the
same monomers and monomer content at equivalent crystallinity or
modulus, the inventive interpolymers have better (higher) heat
resistance as measured by melting point, higher TMA penetration
temperature, higher high-temperature tensile strength, and/or
higher high-temperature torsion storage modulus as determined by
dynamic mechanical analysis. Compared to a random copolymer
containing the same monomers and monomer content, the inventive
interpolymers have lower compression set, particularly at elevated
temperatures such as body temperature or higher, lower stress
relaxation, lower stress relaxation particularly at body
temperature or higher, higher creep resistance, higher tear
strength, higher blocking resistance, faster setup due to higher
crystallization (solidification) temperature, higher recovery
(particularly at elevated temperatures), better abrasion
resistance, higher retractive force, and better oil and filler
acceptance.
[0102] The inventive interpolymers also exhibit a unique
crystallization and branching distribution relationship. That is,
the inventive interpolymers have a relatively large difference
between the tallest peak temperature measured using CRYSTAF and DSC
as a function of heat of fusion, especially as compared to random
copolymers containing the same monomers and monomer level or
physical blends of polymers, such as a blend of a high density
polymer and a lower density copolymer, at equivalent overall
density. It is believed that this unique feature of the inventive
interpolymers is due to the unique distribution of the comonomer in
blocks within the polymer backbone. In particular, the inventive
interpolymers may comprise alternating blocks of differing
comonomer content (including homopolymer blocks). The inventive
interpolymers may also comprise a distribution in number and/or
block size of polymer blocks of differing density or comonomer
content, which is a Schultz-Flory type of distribution. In
addition, the inventive interpolymers also have a unique peak
melting point and crystallization temperature profile that is
substantially independent of polymer density, modulus, and
morphology. In a preferred embodiment, the microcrystalline order
of the polymers demonstrates characteristic spherulites and
lamellae that are distinguishable from random or block copolymers,
even at PDI values that are less than 1.7, or even less than 1.5,
down to less than 1.3.
[0103] Moreover, the inventive interpolymers may be prepared using
techniques to influence the degree or level of blockiness. That is
the amount of comonomer and length of each polymer block or segment
can be altered by controlling the ratio and type of catalysts and
shuttling agent as well as the temperature of the polymerization,
and other polymerization variables. A surprising benefit of this
phenomenon is the discovery that as the degree of blockiness is
increased, the optical properties, tear strength, and high
temperature recovery properties of the resulting polymer are
improved. In particular, haze decreases while clarity, tear
strength, and high temperature recovery properties increase as the
average number of blocks in the polymer increases. By selecting
shuttling agents and catalyst combinations having the desired chain
transferring ability (high rates of shuttling with low levels of
chain termination) other forms of polymer termination are
effectively suppressed. Accordingly, little if any .beta.-hydride
elimination is observed in the polymerization of
ethylene/.alpha.-olefin comonomer mixtures according to embodiments
of the invention, and the resulting crystalline blocks are highly,
or substantially completely, linear, possessing little or no long
chain branching.
[0104] Polymers with highly crystalline chain ends can be
selectively prepared in accordance with embodiments of the
invention. In elastomer applications, reducing the relative
quantity of polymer that terminates with an amorphous block reduces
the intermolecular dilutive effect on crystalline regions. This
result can be obtained by choosing chain shuttling agents and
catalysts having an appropriate response to hydrogen or other chain
terminating agents. Specifically, if the catalyst which produces
highly crystalline polymer is more susceptible to chain termination
(such as by use of hydrogen) than the catalyst responsible for
producing the less crystalline polymer segment (such as through
higher comonomer incorporation, regio-error, or atactic polymer
formation), then the highly crystalline polymer segments will
preferentially populate the terminal portions of the polymer. Not
only are the resulting terminated groups crystalline, but upon
termination, the highly crystalline polymer forming catalyst site
is once again available for reinitiation of polymer formation. The
initially formed polymer is therefore another highly crystalline
polymer segment. Accordingly, both ends of the resulting
multi-block copolymer are preferentially highly crystalline.
[0105] The ethylene .alpha.-olefin interpolymers used in the
embodiments of the invention are preferably interpolymers of
ethylene with at least one C.sub.3-C.sub.20 .alpha.-olefin.
Copolymers of ethylene and a C.sub.3-C.sub.20 .alpha.-olefin are
especially preferred. The interpolymers may further comprise
C.sub.4-C.sub.11 diolefin and/or alkenylbenzene. Suitable
unsaturated comonomers useful for polymerizing with ethylene
include, for example, ethylenically unsaturated monomers,
conjugated or nonconjugated dienes, polyenes, alkenylbenzenes, etc.
Examples of such comonomers include C.sub.3-C.sub.20
.alpha.-olefins such as propylene, isobutylene, 1-butene, 1-hexene,
1-pentene, 4-methyl-1-pentene, 1-heptene, 1-octene, 1-nonene,
1-decene, and the like. 1 Butene and 1-octene are especially
preferred. Other suitable monomers include styrene, halo- or
alkyl-substituted styrenes, vinylbenzocyclobutane, 1,4-hexadiene,
1,7-octadiene, and naphthenics (e.g., cyclopentene, cyclohexene and
cyclooctene).
[0106] While ethylene/.alpha.-olefin interpolymers are preferred
polymers, other ethylene/olefin polymers may also be used. Olefins
as used herein refer to a family of unsaturated hydrocarbon-based
compounds with at least one carbon-carbon double bond. Depending on
the selection of catalysts, any olefin may be used in embodiments
of the invention. Preferably, suitable olefins are C.sub.3-C.sub.20
aliphatic and aromatic compounds containing vinylic unsaturation,
as well as cyclic compounds, such as cyclobutene, cyclopentene,
dicyclopentadiene, and norbornene, including but not limited to,
norbornene substituted in the 5 and 6 position with
C.sub.1-C.sub.20 hydrocarbyl or cyclohydrocarbyl groups. Also
included are mixtures of such olefins as well as mixtures of such
olefins with C.sub.4-C.sub.40 diolefin compounds.
[0107] Examples of olefin monomers include, but are not limited to
propylene, isobutylene, 1-butene, 1-pentene, 1-hexene, 1-heptene,
1-octene, 1-nonene, 1-decene, and 1-dodecene, 1-tetradecene,
1-hexadecene, 1-octadecene, 1-eicosene, 3-methyl-1-butene,
3-methyl-1-pentene, 4-methyl-1-pentene, 4,6-dimethyl-1-heptene,
4-vinylcyclohexene, vinylcyclohexane, norbornadiene, ethylidene
norbornene, cyclopentene, cyclohexene, dicyclopentadiene,
cyclooctene, C.sub.4-C.sub.40 dienes, including but not limited to
1,3-butadiene, 1,3-pentadiene, 1,4-hexadiene, 1,5-hexadiene,
1,7-octadiene, 1,9-decadiene, other C.sub.4-C.sub.40
.alpha.-olefins, and the like. In certain embodiments, the
.alpha.-olefin is propylene, 1-butene, 1-pentene, 1-hexene,
1-octene or a combination thereof. Although any hydrocarbon
containing a vinyl group potentially may be used in embodiments of
the invention, practical issues such as monomer availability, cost,
and the ability to conveniently remove unreacted monomer from the
resulting polymer may become more problematic as the molecular
weight of the monomer becomes too high.
[0108] The polymerization processes described herein are well
suited for the production of olefin polymers comprising
monovinylidene aromatic monomers including styrene, o-methyl
styrene, p-methyl styrene, t-butylstyrene, and the like. In
particular, interpolymers comprising ethylene and styrene can be
prepared by following the teachings herein. Optionally, copolymers
comprising ethylene, styrene and a C.sub.3-C.sub.20 alpha olefin,
optionally comprising a C.sub.4-C.sub.20 diene, having improved
properties can be prepared.
[0109] Suitable non-conjugated diene monomers can be a straight
chain, branched chain or cyclic hydrocarbon diene having from 6 to
15 carbon atoms. Examples of suitable non-conjugated dienes
include, but are not limited to, straight chain acyclic dienes,
such as 1,4-hexadiene, 1,6-octadiene, 1,7-octadiene, 1,9-decadiene,
branched chain acyclic dienes, such as 5-methyl-1,4-hexadiene;
3,7-dimethyl-1,6-octadiene; 3,7-dimethyl-1,7-octadiene and mixed
isomers of dihydromyricene and dihydroocinene, single ring
alicyclic dienes, such as 1,3-cyclopentadiene; 1,4-cyclohexadiene;
1,5-cyclooctadiene and 1,5-cyclododecadiene, and multi-ring
alicyclic fused and bridged ring dienes, such as tetrahydroindene,
methyl tetrahydroindene, dicyclopentadiene,
bicyclo-(2,2,1)-hepta-2,5-diene; alkenyl, alkylidene, cycloalkenyl
and cycloalkylidene norbornenes, such as 5-methylene-2-norbornene
(MNB); 5-propenyl-2-norbornene, 5-isopropylidene-2-norbornene,
5-(4-cyclopentenyl)-2-norbornene, 5-cyclohexylidene-2-norbornene,
5-vinyl-2-norbornene, and norbornadiene. Of the dienes typically
used to prepare EPDMs, the particularly preferred dienes are
1,4-hexadiene (HD), 5-ethylidene-2-norbornene (ENB),
5-vinylidene-2-norbornene (VNB), 5-methylene-2-norbornene (MNB),
and dicyclopentadiene (DCPD). The especially preferred dienes are
5-ethylidene-2-norbornene (ENB) and 1,4-hexadiene (HD).
[0110] One class of desirable polymers that can be made in
accordance with embodiments of the invention are elastomeric
interpolymers of ethylene, a C.sub.3-C.sub.20 .alpha.-olefin,
especially propylene, and optionally one or more diene monomers.
Preferred .alpha.-olefins for use in this embodiment of the present
invention are designated by the formula CH.sub.2.dbd.CHR*, where R*
is a linear or branched alkyl group of from 1 to 12 carbon atoms.
Examples of suitable .alpha.-olefins include, but are not limited
to, propylene, isobutylene, 1-butene, 1-pentene, 1-hexene,
4-methyl-1-pentene, and 1-octene. A particularly preferred
.alpha.-olefin is propylene. The propylene based polymers are
generally referred to in the art as EP or EPDM polymers. Suitable
dienes for use in preparing such polymers, especially multi-block
EPDM type polymers include conjugated or non-conjugated, straight
or branched chain-, cyclic- or polycyclic-dienes comprising from 4
to 20 carbons. Preferred dienes include 1,4-pentadiene,
1,4-hexadiene, 5-ethylidene-2-norbornene, dicyclopentadiene,
cyclohexadiene, and 5-butylidene-2-norbornene. A particularly
preferred diene is 5-ethylidene-2-norbornene.
[0111] Because the diene containing polymers comprise alternating
segments or blocks containing greater or lesser quantities of the
diene (including none) and .alpha.-olefin (including none), the
total quantity of diene and .alpha.-olefin may be reduced without
loss of subsequent polymer properties. That is, because the diene
and .alpha.-olefin monomers are preferentially incorporated into
one type of block of the polymer rather than uniformly or randomly
throughout the polymer, they are more efficiently utilized and
subsequently the crosslink density of the polymer can be better
controlled. Such crosslinkable elastomers and the cured products
have advantaged properties, including higher tensile strength and
better elastic recovery.
[0112] In some embodiments, the inventive interpolymers made with
two catalysts incorporating differing quantities of comonomer have
a weight ratio of blocks formed thereby from 95:5 to 5:95. The
elastomeric polymers desirably have an ethylene content of from 20
to 90 percent, a diene content of from 0.1 to 10 percent, and an
.alpha.-olefin content of from 10 to 80 percent, based on the total
weight of the polymer. Further preferably, the multi-block
elastomeric polymers have an ethylene content of from 60 to 90
percent, a diene content of from 0.1 to 10 percent, and an
.alpha.-olefin content of from 10 to 40 percent, based on the total
weight of the polymer. Preferred polymers are high molecular weight
polymers, having a weight average molecular weight (Mw) from 10,000
to about 2,500,000, preferably from 20,000 to 500,000, more
preferably from 20,000 to 350,000, and a polydispersity less than
3.5, more preferably less than 3.0, and a Mooney viscosity (ML
(1+4) 125.degree. C.) from 1 to 250. More preferably, such polymers
have an ethylene content from 65 to 75 percent, a diene content
from 0 to 6 percent, and an .alpha.-olefin content from 20 to 35
percent.
[0113] The ethylene/.alpha.-olefin interpolymers can be
functionalized by incorporating at least one functional group in
its polymer structure. Exemplary functional groups may include, for
example, ethylenically unsaturated mono- and di-functional
carboxylic acids, ethylenically unsaturated mono- and di-functional
carboxylic acid anhydrides, salts thereof and esters thereof. Such
functional groups may be grafted to an ethylene/.alpha.-olefin
interpolymer, or it may be copolymerized with ethylene and an
optional additional comonomer to form an interpolymer of ethylene,
the functional comonomer and optionally other comonomer(s). Means
for grafting functional groups onto polyethylene are described for
example in U.S. Pat. Nos. 4,762,890, 4,927,888, and 4,950,541, the
disclosures of these patents are incorporated herein by reference
in their entirety. One particularly useful functional group is
malic anhydride.
[0114] The amount of the functional group present in the functional
interpolymer can vary. The functional group can typically be
present in a copolymer-type functionalized interpolymer in an
amount of at least about 1.0 weight percent, preferably at least
about 5 weight percent, and more preferably at least about 7 weight
percent. The functional group will typically be present in a
copolymer-type functionalized interpolymer in an amount less than
about 40 weight percent, preferably less than about 30 weight
percent, and more preferably less than about 25 weight percent.
Testing Methods
[0115] In the examples that follow, the following analytical
techniques are employed:
GPC Method for Samples 1-4 and A-C
[0116] An automated liquid-handling robot equipped with a heated
needle set to 160.degree. C. is used to add enough
1,2,4-trichlorobenzene stabilized with 300 ppm Ionol to each dried
polymer sample to give a final concentration of 30 .mu.g/mL. A
small glass stir rod is placed into each tube and the samples are
heated to 160.degree. C. for 2 hours on a heated, orbital-shaker
rotating at 250 rpm. The concentrated polymer solution is then
diluted to 1 mg/ml using the automated liquid-handling robot and
the heated needle set to 160.degree. C.
[0117] A Symyx Rapid GPC system is used to determine the molecular
weight data for each sample. A Gilson 350 pump set at 2.0 ml/min
flow rate is used to pump helium-purged 1,2-dichlorobenzene
stabilized with 300 ppm Ionol as the mobile phase through three
Plgel 10 micrometer (.mu.m) Mixed B 300 mm.times.7.5 mm columns
placed in series and heated to 160.degree. C. A Polymer Labs
ELS1000 Detector is used with the Evaporator set to 250.degree. C.,
the Nebulizer set to 165.degree. C., and the nitrogen flow rate set
to 1.8 SLM at a pressure of 60-80 psi (400-600 kPa) N.sub.2. The
polymer samples are heated to 160.degree. C. and each sample
injected into a 250 .mu.l loop using the liquid-handling robot and
a heated needle. Serial analysis of the polymer samples using two
switched loops and overlapping injections are used. The sample data
is collected and analyzed using Symyx Epoch.TM. software. Peaks are
manually integrated and the molecular weight information reported
uncorrected against a polystyrene standard calibration curve.
Standard CRYSTAF Method
[0118] Branching distributions are determined by crystallization
analysis fractionation (CRYSTAF) using a CRYSTAF 200 unit
commercially available from PolymerChar, Valencia, Spain. The
samples are dissolved in 1,2,4 trichlorobenzene at 160.degree. C.
(0.66 mg/mL) for 1 hr and stabilized at 95.degree. C. for 45
minutes. The sampling temperatures range from 95 to 30.degree. C.
at a cooling rate of 0.2.degree. C./min. An infrared detector is
used to measure the polymer solution concentrations. The cumulative
soluble concentration is measured as the polymer crystallizes while
the temperature is decreased. The analytical derivative of the
cumulative profile reflects the short chain branching distribution
of the polymer.
[0119] The CRYSTAF peak temperature and area are identified by the
peak analysis module included in the CRYSTAF Software (Version
2001.b, PolymerChar, Valencia, Spain). The CRYSTAF peak finding
routine identifies a peak temperature as a maximum in the dW/dT
curve and the area between the largest positive inflections on
either side of the identified peak in the derivative curve. To
calculate the CRYSTAF curve, the preferred processing parameters
are with a temperature limit of 70.degree. C. and with smoothing
parameters above the temperature limit of 0.1, and below the
temperature limit of 0.3.
DSC Standard Method (Excluding Samples 1-4 and A-C)
[0120] Differential Scanning Calorimetry results are determined
using a TAI model Q1000 DSC equipped with an RCS cooling accessory
and an autosampler. A nitrogen purge gas flow of 50 ml/min is used.
The sample is pressed into a thin film and melted in the press at
about 175.degree. C. and then air-cooled to room temperature
(25.degree. C.). 3-10 mg of material is then cut into a 6 mm
diameter disk, accurately weighed, placed in a light aluminum pan
(ca 50 mg), and then crimped shut. The thermal behavior of the
sample is investigated with the following temperature profile. The
sample is rapidly heated to 180.degree. C. and held isothermal for
3 minutes in order to remove any previous thermal history. The
sample is then cooled to -40.degree. C. at 10.degree. C./min
cooling rate and held at -40.degree. C. for 3 minutes. The sample
is then heated to 150.degree. C. at 10.degree. C./min. heating
rate. The cooling and second heating curves are recorded.
[0121] The DSC melting peak is measured as the maximum in heat flow
rate (W/g) with respect to the linear baseline drawn between
-30.degree. C. and end of melting. The heat of fusion is measured
as the area under the melting curve between -30.degree. C. and the
end of melting using a linear baseline.
GPC Method (Excluding Samples 1-4 and A-C)
[0122] The gel permeation chromatographic system consists of either
a Polymer Laboratories Model PL-210 or a Polymer Laboratories Model
PL-220 instrument. The column and carousel compartments are
operated at 140.degree. C. Three Polymer Laboratories 10-micron
Mixed-B columns are used. The solvent is 1,2,4 trichlorobenzene.
The samples are prepared at a concentration of 0.1 grams of polymer
in 50 milliliters of solvent containing 200 ppm of butylated
hydroxytoluene (BHT). Samples are prepared by agitating lightly for
2 hours at 160.degree. C. The injection volume used is 100
microliters and the flow rate is 1.0 ml/minute.
[0123] Calibration of the GPC column set is performed with 21
narrow molecular weight distribution polystyrene standards with
molecular weights ranging from 580 to 8,400,000, arranged in 6
"cocktail" mixtures with at least a decade of separation between
individual molecular weights. The standards are purchased from
Polymer Laboratories (Shropshire, UK). The polystyrene standards
are prepared at 0.025 grams in 50 milliliters of solvent for
molecular weights equal to or greater than 1,000,000, and 0.05
grams in 50 milliliters of solvent for molecular weights less than
1,000,000. The polystyrene standards are dissolved at 80.degree. C.
with gentle agitation for 30 minutes. The narrow standards mixtures
are run first and in order of decreasing highest molecular weight
component to minimize degradation. The polystyrene standard peak
molecular weights are converted to polyethylene molecular weights
using the following equation (as described in Williams and Ward, J.
Polym. Sci., Polym. Let., 6, 621 (1968)):
M.sub.polyethylene=0.431(M.sub.polystyrene).
[0124] Polyethylene equivalent molecular weight calculations are
performed using Viscotek TriSEC software Version 3.0.
Compression Set
[0125] Compression set is measured according to ASTM D 395. The
sample is prepared by stacking 25.4 mm diameter round discs of 3.2
mm, 2.0 mm, and 0.25 mm thickness until a total thickness of 12.7
mm is reached. The discs are cut from 12.7 cm.times.12.7 cm
compression molded plaques molded with a hot press under the
following conditions: zero pressure for 3 min at 190.degree. C.,
followed by 86 MPa for 2 min at 190.degree. C., followed by cooling
inside the press with cold running water at 86 MPa.
Density
[0126] Samples for density measurement are prepared according to
ASTM D 1928. Measurements are made within one hour of sample
pressing using ASTM D792, Method B.
Flexural/Secant Modulus/Storage Modulus
[0127] Samples are compression molded using ASTM D 1928. Flexural
and 2 percent secant moduli are measured according to ASTM D-790.
Storage modulus is measured according to ASTM D 5026-01 or
equivalent technique.
Optical Properties
[0128] Films of 0.4 mm thickness are compression molded using a hot
press (Carver Model #4095-4PR1001R). The pellets are placed between
polytetrafluoroethylene sheets, heated at 190.degree. C. at 55 psi
(380 kPa) for 3 min, followed by 1.3 MPa for 3 min, and then 2.6
MPa for 3 min. The film is then cooled in the press with running
cold water at 1.3 MPa for 1 min. The compression molded films are
used for optical measurements, tensile behavior, recovery, and
stress relaxation.
[0129] Clarity is measured using BYK Gardner Haze-gard as specified
in ASTM D 1746.
[0130] 45.degree. gloss is measured using BYK Gardner Glossmeter
Microgloss 45.degree. as specified in ASTM D-2457.
[0131] Internal haze is measured using BYK Gardner Haze-gard based
on ASTM D 1003 Procedure A. Mineral oil is applied to the film
surface to remove surface scratches.
Mechanical Properties--Tensile, Hysteresis, and Tear
[0132] Stress-strain behavior in uniaxial tension is measured using
ASTM D 1708 microtensile specimens. Samples are stretched with an
Instron at 500% min.sup.-1 at 21.degree. C. Tensile strength and
elongation at break are reported from an average of 5
specimens.
[0133] 100% and 300% Hysteresis is determined from cyclic loading
to 100% and 300% strains using ASTM D 1708 microtensile specimens
with an Instron.TM. instrument. The sample is loaded and unloaded
at 267% min.sup.-1 for 3 cycles at 21.degree. C. Cyclic experiments
at 300% and 80.degree. C. are conducted using an environmental
chamber. In the 80.degree. C. experiment, the sample is allowed to
equilibrate for 45 minutes at the test temperature before testing.
In the 21.degree. C., 300% strain cyclic experiment, the retractive
stress at 150% strain from the first unloading cycle is recorded.
Percent recovery for all experiments are calculated from the first
unloading cycle using the strain at which the load returned to the
base line. The percent recovery is defined as:
% Recovery = f - s f .times. 100 ##EQU00002##
where .epsilon..sub.f is the strain taken for cyclic loading and
.epsilon..sub.s is the strain where the load returns to the
baseline during the 1.sup.st unloading cycle.
[0134] Stress relaxation is measured at 50 percent strain and
37.degree. C. for 12 hours using an Instron.TM. instrument equipped
with an environmental chamber. The gauge geometry was 76
mm.times.25 mm.times.0.4 mm. After equilibrating at 37.degree. C.
for 45 min in the environmental chamber, the sample was stretched
to 50% strain at 333% min.sup.-1. Stress was recorded as a function
of time for 12 hours. The percent stress relaxation after 12 hours
was calculated using the formula:
% Stress Relaxation = L 0 - L 12 L 0 .times. 100 ##EQU00003##
where L.sub.0 is the load at 50% strain at 0 time and L.sub.12 is
the load at 50 percent strain after 12 hours.
[0135] Tensile notched tear experiments are carried out on samples
having a density of 0.88 g/cc or less using an Instron.TM.
instrument. The geometry consists of a gauge section of 76
mm.times.13 mm.times.0.4 mm with a 2 mm notch cut into the sample
at half the specimen length. The sample is stretched at 508 mm
min-1 at 21.degree. C. until it breaks. The tear energy is
calculated as the area under the stress-elongation curve up to
strain at maximum load. An average of at least 3 specimens are
reported.
TMA
[0136] Thermal Mechanical Analysis (Penetration Temperature) is
conducted on 30 mm diameter.times.3.3 mm thick, compression molded
discs, formed at 180.degree. C. and 10 MPa molding pressure for 5
minutes and then air quenched. The instrument used is a TMA 7,
brand available from Perkin-Elmer. In the test, a probe with 1.5 mm
radius tip (P/N N519-0416) is applied to the surface of the sample
disc with 1N force. The temperature is raised at 5.degree. C./min
from 25.degree. C. The probe penetration distance is measured as a
function of temperature. The experiment ends when the probe has
penetrated 1 mm into the sample.
DMA
[0137] Dynamic Mechanical Analysis (DMA) is measured on compression
molded disks formed in a hot press at 180.degree. C. at 10 MPa
pressure for 5 minutes and then water cooled in the press at
90.degree. C./min. Testing is conducted using an ARES controlled
strain rheometer (TA instruments) equipped with dual cantilever
fixtures for torsion testing.
[0138] A 1.5 mm plaque is pressed and cut in a bar of dimensions
32.times.12 mm. The sample is clamped at both ends between fixtures
separated by 10 mm (grip separation .DELTA.L) and subjected to
successive temperature steps from -100.degree. C. to 200.degree. C.
(5.degree. C. per step). At each temperature the torsion modulus G'
is measured at an angular frequency of 10 rad/s, the strain
amplitude being maintained between 0.1 percent and 4 percent to
ensure that the torque is sufficient and that the measurement
remains in the linear regime.
[0139] An initial static force of 10 g is maintained (auto-tension
mode) to prevent slack in the sample when thermal expansion occurs.
As a consequence, the grip separation .DELTA.L increases with the
temperature, particularly above the melting or softening point of
the polymer sample. The test stops at the maximum temperature or
when the gap between the fixtures reaches 65 mm.
Melt Index
[0140] Melt index, or I.sub.2, is measured in accordance with ASTM
D 1238, Condition 190.degree. C./2.16 kg. Melt index, or I.sub.10
is also measured in accordance with ASTM D 1238, Condition
190.degree. C./10 kg.
ATREF
[0141] Analytical temperature rising elution fractionation (ATREF)
analysis is conducted according to the method described in U.S.
Pat. No. 4,798,081 and Wilde, L.; Ryle, T. R.; Knobeloch, D. C.;
Peat, I. R.; Determination of Branching Distributions in
Polyethylene and Ethylene Copolymers, J. Polym. Sci., 20, 441-455
(1982), which are incorporated by reference herein in their
entirety. The composition to be analyzed is dissolved in
trichlorobenzene and allowed to crystallize in a column containing
an inert support (stainless steel shot) by slowly reducing the
temperature to 20.degree. C. at a cooling rate of 0.1.degree.
C./min. The column is equipped with an infrared detector. An ATREF
chromatogram curve is then generated by eluting the crystallized
polymer sample from the column by slowly increasing the temperature
of the eluting solvent (trichlorobenzene) from 20 to 120.degree. C.
at a rate of 1.5.degree. C./min.
.sup.13C NMR Analysis
[0142] The samples are prepared by adding approximately 3 g of a
50/50 mixture of tetrachloroethane-d.sup.2/orthodichlorobenzene to
0.4 g sample in a 10 mm NMR tube. The samples are dissolved and
homogenized by heating the tube and its contents to 150.degree. C.
The data are collected using a JEOL Eclipse.TM. 400 MHz
spectrometer or a Varian Unity Plus.TM. 400 MHz spectrometer,
corresponding to a .sup.13C resonance frequency of 100.5 MHz. The
data are acquired using 4000 transients per data file with a 6
second pulse repetition delay. To achieve minimum signal-to-noise
for quantitative analysis, multiple data files are added together.
The spectral width is 25,000 Hz with a minimum file size of 32K
data points. The samples are analyzed at 130.degree. C. in a 10 mm
broad band probe. The comonomer incorporation is determined using
Randall's triad method (Randall, J. C.; JMS-Rev. Macromol. Chem.
Phys., C29, 201-317 (1989), which is incorporated by reference
herein in its entirety.
Polymer Fractionation by TREF
[0143] Large-scale TREF fractionation is carried by dissolving
15-20 g of polymer in 2 liters of 1,2,4-trichlorobenzene (TCB) by
stirring for 4 hours at 160.degree. C. The polymer solution is
forced by 15 psig (100 kPa) nitrogen onto a 3 inch by 4 foot (7.6
cm.times.12 cm) steel column packed with a 60:40 (v:v) mix of 30-40
mesh (600-425 .mu.m) spherical, technical quality glass beads
(available from Potters Industries, HC 30 Box 20, Brownwood, Tex.,
76801) and stainless steel, 0.028'' (0.7 mm) diameter cut wire shot
(available from Pellets, Inc. 63 Industrial Drive, North Tonawanda,
N.Y., 14120). The column is immersed in a thermally controlled oil
jacket, set initially to 160.degree. C. The column is first cooled
ballistically to 125.degree. C., then slow cooled to 20.degree. C.
at 0.04.degree. C. per minute and held for one hour. Fresh TCB is
introduced at about 65 ml/min while the temperature is increased at
0.167.degree. C. per minute.
[0144] Approximately 2000 ml portions of eluant from the
preparative TREF column are collected in a 16 station, heated
fraction collector. The polymer is concentrated in each fraction
using a rotary evaporator until about 50 to 100 ml of the polymer
solution remains. The concentrated solutions are allowed to stand
overnight before adding excess methanol, filtering, and rinsing
(approx. 300-500 ml of methanol including the final rinse). The
filtration step is performed on a 3 position vacuum assisted
filtering station using 5.0 .mu.m polytetrafluoroethylene coated
filter paper (available from Osmonics Inc., Cat# Z50WP04750). The
filtrated fractions are dried overnight in a vacuum oven at
60.degree. C. and weighed on an analytical balance before further
testing.
Melt Strength
[0145] Melt Strength (MS) is measured by using a capillary
rheometer fitted with a 2.1 mm diameter, 20:1 die with an entrance
angle of approximately 45 degrees. After equilibrating the samples
at 190.degree. C. for 10 minutes, the piston is mm at a speed of 1
inch/minute (2.54 cm/minute). The standard test temperature is
190.degree. C. The sample is drawn uniaxially to a set of
accelerating nips located 100 mm below the die with an acceleration
of 2.4 mm/sec.sup.2. The required tensile force is recorded as a
function of the take-up speed of the nip rolls. The maximum tensile
force attained during the test is defined as the melt strength. In
the case of polymer melt exhibiting draw resonance, the tensile
force before the onset of draw resonance was taken as melt
strength. The melt strength is recorded in centiNewtons ("cN").
Catalysts
[0146] The term "overnight", if used, refers to a time of
approximately 16-18 hours, the term "room temperature", refers to a
temperature of 20-25.degree. C., and the term "mixed alkanes"
refers to a commercially obtained mixture of C.sub.6-9 aliphatic
hydrocarbons available under the trade designation Isopar E.RTM.,
from ExxonMobil Chemical Company. In the event the name of a
compound herein does not conform to the structural representation
thereof, the structural representation shall control. The synthesis
of all metal complexes and the preparation of all screening
experiments were carried out in a dry nitrogen atmosphere using dry
box techniques. All solvents used were HPLC grade and were dried
before their use.
[0147] MMAO refers to modified methylalumoxane, a
triisobutylaluminum modified methylalumoxane available commercially
from Akzo-Noble Corporation.
[0148] The preparation of catalyst (B1) is conducted as
follows.
a) Preparation of
(1-methylethyl)(2-hydroxy-3,5-di(t-butyl)phenyl)methylimine
[0149] 3,5-Di-t-butylsalicylaldehyde (3.00 g) is added to 10 mL of
isopropylamine. The solution rapidly turns bright yellow. After
stirring at ambient temperature for 3 hours, volatiles are removed
under vacuum to yield a bright yellow, crystalline solid (97
percent yield).
b) Preparation of
1,2-bis-(3,5-di-t-butylphenylene)(1-(N-(1-methylethyl)immino)methyl)(2-ox-
oyl)zirconium dibenzyl
[0150] A solution of
(1-methylethyl)(2-hydroxy-3,5-di(t-butyl)phenyl)imine (605 mg, 2.2
mmol) in 5 mL toluene is slowly added to a solution of
Zr(CH.sub.2Ph).sub.4 (500 mg, 1.1 mmol) in 50 mL toluene. The
resulting dark yellow solution is stirred for 30 min. Solvent is
removed under reduced pressure to yield the desired product as a
reddish-brown solid.
[0151] The preparation of catalyst (B2) is conducted as
follows.
a) Preparation of
(1-(2-methylcyclohexyl)ethyl)(2-oxoyl-3,5-di(t-butyl)phenyl)imine
[0152] 2-Methylcyclohexylamine (8.44 mL, 64.0 mmol) is dissolved in
methanol (90 mL), and di-t-butylsalicaldehyde (10.00 g, 42.67 mmol)
is added. The reaction mixture is stirred for three hours and then
cooled to -25.degree. C. for 12 hrs. The resulting yellow solid
precipitate is collected by filtration and washed with cold
methanol (2.times.15 mL), and then dried under reduced pressure.
The yield is 11.17 g of a yellow solid. .sup.1H NMR is consistent
with the desired product as a mixture of isomers.
b) Preparation of
bis-(1-(2-methylcyclohexyl)ethyl)(2-oxoyl-3,5-di(t-butyl)phenyl)immino)zi-
rconium dibenzyl
[0153] A solution of
(1-(2-methylcyclohexyl)ethyl)(2-oxoyl-3,5-di(t-butyl)phenyl)imine
(7.63 g, 23.2 mmol) in 200 mL toluene is slowly added to a solution
of Zr(CH.sub.2Ph).sub.4 (5.28 g, 11.6 mmol) in 600 mL toluene. The
resulting dark yellow solution is stirred for 1 hour at 25.degree.
C. The solution is diluted further with 680 mL toluene to give a
solution having a concentration of 0.00783 M.
[0154] Cocatalyst 1 A mixture of methyldi(C.sub.14-18
alkyl)ammonium salts of tetrakis(pentafluorophenyl)borate
(here-in-after armeenium borate), prepared by reaction of a long
chain trialkylamine (Armeen.TM. M2HT, available from Akzo-Nobel,
Inc.), HCl and Li[B(C.sub.6F.sub.5).sub.4], substantially as
disclosed in U.S. Pat. No. 5,919,9883, Ex. 2.
[0155] Cocatalyst 2 Mixed C.sub.14-18 alkyldimethylammonium salt of
bis(tris(pentafluorophenyl)-alumane)-2-undecylimidazolide, prepared
according to U.S. Pat. No. 6,395,671, Ex. 16.
[0156] Shuttling Agents The shuttling agents employed include
diethylzinc (DEZ, SA1), di(1-butyl)zinc (SA2), di(n-hexyl)zinc
(SA3), triethylaluminum (TEA, SA4), trioctylaluminum (SA5),
triethylgallium (SA6), i-butylaluminum
bis(dimethyl(t-butyl)siloxane) (SA7), i-butylaluminum
bis(di(trimethylsilyl)amide) (SA8), n-octylaluminum
di(pyridine-2-methoxide) (SA9), bis(n-octadecyl)i-butylaluminum
(SA10), i-butylaluminum bis(di(n-pentyl)amide) (SA11),
n-octylaluminum bis(2,6-di-t-butylphenoxide) (SA12),
n-octylaluminum di(ethyl(1-naphthyl)amide) (SA13), ethylaluminum
bis(t-butyldimethylsiloxide) (SA14), ethylaluminum
di(bis(trimethylsilyl)amide) (SA15), ethylaluminum
bis(2,3,6,7-dibenzo-1-azacycloheptaneamide) (SA16), n-octylaluminum
bis(2,3,6,7-dibenzo-1-azacycloheptaneamide) (SA17), n-octylaluminum
bis(dimethyl(t-butyl)siloxide(SA18), ethylzinc
(2,6-diphenylphenoxide) (SA19), and ethylzinc (t-butoxide)
(SA20).
EXAMPLES 1-4, COMPARATIVE A-C
General High Throughput Parallel Polymerization Conditions
[0157] Polymerizations are conducted using a high throughput,
parallel polymerization reactor (PPR) available from Symyx
technologies, Inc. and operated substantially according to U.S.
Pat. Nos. 6,248,540, 6,030,917, 6,362,309, 6,306,658, and
6,316,663. Ethylene copolymerizations are conducted at 130.degree.
C. and 200 psi (1.4 MPa) with ethylene on demand using 1.2
equivalents of cocatalyst 1 based on total catalyst used (1.1
equivalents when MMAO is present). A series of polymerizations are
conducted in a parallel pressure reactor (PPR) contained of 48
individual reactor cells in a 6.times.8 array that are fitted with
a pre-weighed glass tube. The working volume in each reactor cell
is 6000 .mu.L. Each cell is temperature and pressure controlled
with stirring provided by individual stirring paddles. The monomer
gas and quench gas are plumbed directly into the PPR unit and
controlled by automatic valves. Liquid reagents are robotically
added to each reactor cell by syringes and the reservoir solvent is
mixed alkanes. The order of addition is mixed alkanes solvent (4
ml), ethylene, 1-octene comonomer (1 ml), cocatalyst 1 or
cocatalyst 1/MMAO mixture, shuttling agent, and catalyst or
catalyst mixture. When a mixture of cocatalyst 1 and MMAO or a
mixture of two catalysts is used, the reagents are premixed in a
small vial immediately prior to addition to the reactor. When a
reagent is omitted in an experiment, the above order of addition is
otherwise maintained. Polymerizations are conducted for
approximately 1-2 minutes, until predetermined ethylene
consumptions are reached. After quenching with CO, the reactors are
cooled and the glass tubes are unloaded. The tubes are transferred
to a centrifuge/vacuum drying unit, and dried for 12 hours at
60.degree. C. The tubes containing dried polymer are weighed and
the difference between this weight and the tare weight gives the
net yield of polymer. Results are contained in Table 1. In Table 1
and elsewhere in the application, comparative compounds are
indicated by an asterisk (*).
[0158] Examples 1-4 demonstrate the synthesis of linear block
copolymers by the present invention as evidenced by the formation
of a very narrow MWD, essentially monomodal copolymer when DEZ is
present and a bimodal, broad molecular weight distribution product
(a mixture of separately produced polymers) in the absence of DEZ.
Due to the fact that Catalyst (A1) is known to incorporate more
octene than Catalyst (B1), the different blocks or segments of the
resulting copolymers of the invention are distinguishable based on
branching or density.
TABLE-US-00001 TABLE 1 Cat. (A1) Cat (B1) Cocat MMAO shuttling Ex.
(.mu.mol) (.mu.mol) (.mu.mol) (.mu.mol) agent (.mu.mol) Yield (g)
Mn Mw/Mn hexyls.sup.1 A* 0.06 -- 0.066 0.3 -- 0.1363 300502 3.32 --
B* -- 0.1 0.110 0.5 -- 0.1581 36957 1.22 2.5 C* 0.06 0.1 0.176 0.8
-- 0.2038 45526 5.30.sup.2 5.5 1 0.06 0.1 0.192 -- DEZ (8.0) 0.1974
28715 1.19 4.8 2 0.06 0.1 0.192 -- DEZ (80.0) 0.1468 2161 1.12 14.4
3 0.06 0.1 0.192 -- TEA (8.0) 0.208 22675 1.71 4.6 4 0.06 0.1 0.192
-- TEA (80.0) 0.1879 3338 1.54 9.4 .sup.1C.sub.6 or higher chain
content per 1000 carbons .sup.2Bimodal molecular weight
distribution
[0159] It may be seen the polymers produced according to the
invention have a relatively narrow polydispersity (Mw/Mn) and
larger block-copolymer content (trimer, tetramer, or larger) than
polymers prepared in the absence of the shuttling agent.
[0160] Further characterizing data for the polymers of Table 1 are
determined by reference to the figures. More specifically DSC and
ATREF results show the following:
[0161] The DSC curve for the polymer of example 1 shows a
115.7.degree. C. melting point (Tm) with a heat of fusion of 158.1
J/g. The corresponding CRYSTAF curve shows the tallest peak at
34.5.degree. C. with a peak area of 52.9 percent. The difference
between the DSC Tm and the Tcrystaf is 81.2.degree. C.
[0162] The DSC curve for the polymer of example 2 shows a peak with
a 109.7.degree. C. melting point (Tm) with a heat of fusion of
214.0 J/g. The corresponding CRYSTAF curve shows the tallest peak
at 46.2.degree. C. with a peak area of 57.0 percent. The difference
between the DSC Tm and the Tcrystaf is 63.5.degree. C.
[0163] The DSC curve for the polymer of example 3 shows a peak with
a 120.7.degree. C. melting point (Tm) with a heat of fusion of
160.1 J/g. The corresponding CRYSTAF curve shows the tallest peak
at 66.1.degree. C. with a peak area of 71.8 percent. The difference
between the DSC Tm and the Tcrystaf is 54.6.degree. C.
[0164] The DSC curve for the polymer of example 4 shows a peak with
a 104.5.degree. C. melting point (Tm) with a heat of fusion of
170.7 J/g. The corresponding CRYSTAF curve shows the tallest peak
at 30.degree. C. with a peak area of 18.2 percent. The difference
between the DSC Tm and the Tcrystaf is 74.5.degree. C.
[0165] The DSC curve for comparative A shows a 90.0.degree. C.
melting point (Tm) with a heat of fusion of 86.7 J/g. The
corresponding CRYSTAF curve shows the tallest peak at 48.5.degree.
C. with a peak area of 29.4 percent. Both of these values are
consistent with a resin that is low in density. The difference
between the DSC Tm and the Tcrystaf is 41.8.degree. C.
[0166] The DSC curve for comparative B shows a 129.8.degree. C.
melting point (Tm) with a heat of fusion of 237.0 J/g. The
corresponding CRYSTAF curve shows the tallest peak at 82.4.degree.
C. with a peak area of 83.7 percent. Both of these values are
consistent with a resin that is high in density. The difference
between the DSC Tm and the Tcrystaf is 47.4.degree. C.
[0167] The DSC curve for comparative C shows a 125.3.degree. C.
melting point (Tm) with a heat of fusion of 143.0 J/g. The
corresponding CRYSTAF curve shows the tallest peak at 81.8.degree.
C. with a peak area of 34.7 percent as well as a lower crystalline
peak at 52.4.degree. C. The separation between the two peaks is
consistent with the presence of a high crystalline and a low
crystalline polymer. The difference between the DSC Tm and the
Tcrystaf is 43.5.degree. C.
EXAMPLES 5-19, COMPARATIVES D-F
Continuous Solution Polymerization, Catalyst A1/B2+DEZ
[0168] Continuous solution polymerizations are carried out in a
computer controlled autoclave reactor equipped with an internal
stirrer. Purified mixed alkanes solvent (Isopar.TM. E available
from ExxonMobil Chemical Company), ethylene at 2.70 lbs/hour (1.22
kg/hour), 1-octene, and hydrogen (where used) are supplied to a 3.8
L reactor equipped with a jacket for temperature control and an
internal thermocouple. The solvent feed to the reactor is measured
by a mass-flow controller. A variable speed diaphragm pump controls
the solvent flow rate and pressure to the reactor. At the discharge
of the pump, a side stream is taken to provide flush flows for the
catalyst and cocatalyst 1 injection lines and the reactor agitator.
These flows are measured by Micro-Motion mass flow meters and
controlled by control valves or by the manual adjustment of needle
valves. The remaining solvent is combined with 1-octene, ethylene,
and hydrogen (where used) and fed to the reactor. A mass flow
controller is used to deliver hydrogen to the reactor as needed.
The temperature of the solvent/monomer solution is controlled by
use of a heat exchanger before entering the reactor. This stream
enters the bottom of the reactor. The catalyst component solutions
are metered using pumps and mass flow meters and are combined with
the catalyst flush solvent and introduced into the bottom of the
reactor. The reactor is run liquid-full at 500 psig (3.45 MPa) with
vigorous stirring. Product is removed through exit lines at the top
of the reactor. All exit lines from the reactor are steam traced
and insulated. Polymerization is stopped by the addition of a small
amount of water into the exit line along with any stabilizers or
other additives and passing the mixture through a static mixer. The
product stream is then heated by passing through a heat exchanger
before devolatilization. The polymer product is recovered by
extrusion using a devolatilizing extruder and water cooled
pelletizer. Process details and results are contained in Table 2.
Selected polymer properties are provided in Table 3.
TABLE-US-00002 TABLE 2 Process details for preparation of exemplary
polymers Cat Cat A1 Cat B2 DEZ Cocat Cocat Poly C.sub.8H.sub.16
Solv. H.sub.2 T A1.sup.2 Flow B2.sup.3 Flow DEZ Flow Conc. Flow
[C.sub.2H.sub.4]/ Rate.sup.5 Ex. kg/hr kg/hr sccm.sup.1 .degree. C.
ppm kg/hr ppm kg/hr Conc % kg/hr ppm kg/hr [DEZ].sup.4 kg/hr Conv
%.sup.6 Solids % Eff..sup.7 D* 1.63 12.7 29.90 120 142.2 0.14 -- --
0.19 0.32 820 0.17 536 1.81 88.8 11.2 95.2 E* '' 9.5 5.00 '' -- --
109 0.10 0.19 '' 1743 0.40 485 1.47 89.9 11.3 126.8 F* '' 11.3
251.6 '' 71.7 0.06 30.8 0.06 -- -- '' 0.11 -- 1.55 88.5 10.3 257.7
5 '' '' -- '' '' 0.14 30.8 0.13 0.17 0.43 '' 0.26 419 1.64 89.6
11.1 118.3 6 '' '' 4.92 '' '' 0.10 30.4 0.08 0.17 0.32 '' 0.18 570
1.65 89.3 11.1 172.7 7 '' '' 21.70 '' '' 0.07 30.8 0.06 0.17 0.25
'' 0.13 718 1.60 89.2 10.6 244.1 8 '' '' 36.90 '' '' 0.06 '' '' ''
0.10 '' 0.12 1778 1.62 90.0 10.8 261.1 9 '' '' 78.43 '' '' '' '' ''
'' 0.04 '' '' 4596 1.63 90.2 10.8 267.9 10 '' '' 0.00 123 71.1 0.12
30.3 0.14 0.34 0.19 1743 0.08 415 1.67 90.31 11.1 131.1 11 '' '' ''
120 71.1 0.16 '' 0.17 0.80 0.15 1743 0.10 249 1.68 89.56 11.1 100.6
12 '' '' '' 121 71.1 0.15 '' 0.07 '' 0.09 1743 0.07 396 1.70 90.02
11.3 137.0 13 '' '' '' 122 71.1 0.12 '' 0.06 '' 0.05 1743 0.05 653
1.69 89.64 11.2 161.9 14 '' '' '' 120 71.1 0.05 '' 0.29 '' 0.10
1743 0.10 395 1.41 89.42 9.3 114.1 15 2.45 '' '' '' 71.1 0.14 ''
0.17 '' 0.14 1743 0.09 282 1.80 89.33 11.3 121.3 16 '' '' '' 122
71.1 0.10 '' 0.13 '' 0.07 1743 0.07 485 1.78 90.11 11.2 159.7 17 ''
'' '' 121 71.1 0.10 '' 0.14 '' 0.08 1743 '' 506 1.75 89.08 11.0
155.6 18 0.69 '' '' 121 71.1 '' '' 0.22 '' 0.11 1743 0.10 331 1.25
89.93 8.8 90.2 19 0.32 '' '' 122 71.1 0.06 '' '' '' 0.09 1743 0.08
367 1.16 90.74 8.4 106.0 *Comparative, not an example of the
invention .sup.1standard cm.sup.3/min
.sup.2[N-(2,6-di(1-methylethyl)phenyl)amido)(2-isopropylphenyl)(.alpha.-na-
phthalen-2-diyl(6-pyridin-2-diyl)methane)]hafnium dimethyl
.sup.3bis-(1-(2-methylcyclohexyl)ethyl)(2-oxoyl-3,5-di(t-butyl)phenyl)immi-
no) zirconium dibenzyl .sup.4molar ratio in reactor .sup.5polymer
production rate .sup.6percent ethylene conversion in reactor
.sup.7efficiency, kg polymer/g M where g M = g Hf + g Zr
TABLE-US-00003 TABLE 3 Properties of exemplary polymers Heat of
CRYSTAF Density Mw Mn Fusion T.sub.m T.sub.c T.sub.CRYSTAF Tm -
T.sub.CRYSTAF Peak Area Ex. (g/cm.sup.3) I.sub.2 I.sub.10
I.sub.10/I.sub.2 (g/mol) (g/mol) Mw/Mn (J/g) (.degree. C.)
(.degree. C.) (.degree. C.) (.degree. C.) (percent) D* 0.8627 1.5
10.0 6.5 110,000 55,800 2.0 32 37 45 30 7 99 E* 0.9378 7.0 39.0 5.6
65,000 33,300 2.0 183 124 113 79 45 95 F* 0.8895 0.9 12.5 13.4
137,300 9,980 13.8 90 125 111 78 47 20 5 0.8786 1.5 9.8 6.7 104,600
53,200 2.0 55 120 101 48 72 60 6 0.8785 1.1 7.5 6.5 109600 53300
2.1 55 115 94 44 71 63 7 0.8825 1.0 7.2 7.1 118,500 53,100 2.2 69
121 103 49 72 29 8 0.8828 0.9 6.8 7.7 129,000 40,100 3.2 68 124 106
80 43 13 9 0.8836 1.1 9.7 9.1 129600 28700 4.5 74 125 109 81 44 16
10 0.8784 1.2 7.5 6.5 113,100 58,200 1.9 54 116 92 41 75 52 11
0.8818 9.1 59.2 6.5 66,200 36,500 1.8 63 114 93 40 74 25 12 0.8700
2.1 13.2 6.4 101,500 55,100 1.8 40 113 80 30 83 91 13 0.8718 0.7
4.4 6.5 132,100 63,600 2.1 42 114 80 30 81 8 14 0.9116 2.6 15.6 6.0
81,900 43,600 1.9 123 121 106 73 48 92 15 0.8719 6.0 41.6 6.9
79,900 40,100 2.0 33 114 91 32 82 10 16 0.8758 0.5 3.4 7.1 148,500
74,900 2.0 43 117 96 48 69 65 17 0.8757 1.7 11.3 6.8 107,500 54,000
2.0 43 116 96 43 73 57 18 0.9192 4.1 24.9 6.1 72,000 37,900 1.9 136
120 106 70 50 94 19 0.9344 3.4 20.3 6.0 76,800 39,400 1.9 169 125
112 80 45 88
[0169] The resulting polymers are tested by DSC and ATREF as with
previous examples. Results are as follows:
[0170] The DSC curve for the polymer of example 5 shows a peak with
a 119.6.degree. C. melting point (Tm) with a heat of fusion of 60.0
J/g. The corresponding CRYSTAF curve shows the tallest peak at
47.6.degree. C. with a peak area of 59.5 percent. The delta between
the DSC Tm and the Tcrystaf is 72.0.degree. C.
[0171] The DSC curve for the polymer of example 6 shows a peak with
a 115.2.degree. C. melting point (Tm) with a heat of fusion of 60.4
J/g. The corresponding CRYSTAF curve shows the tallest peak at
44.2.degree. C. with a peak area of 62.7 percent. The delta between
the DSC Tm and the Tcrystaf is 71.0.degree. C.
[0172] The DSC curve for the polymer of example 7 shows a peak with
a 121.3.degree. C. melting point with a heat of fusion of 69.1
.mu.g. The corresponding CRYSTAF curve shows the tallest peak at
49.2.degree. C. with a peak area of 29.4 percent. The delta between
the DSC Tm and the Tcrystaf is 72.1.degree. C.
[0173] The DSC curve for the polymer of example 8 shows a peak with
a 123.5.degree. C. melting point (Tm) with a heat of fusion of 67.9
J/g. The corresponding CRYSTAF curve shows the tallest peak at
80.1.degree. C. with a peak area of 12.7 percent. The delta between
the DSC Tm and the Tcrystaf is 43.4.degree. C.
[0174] The DSC curve for the polymer of example 9 shows a peak with
a 124.6.degree. C. melting point (Tm) with a heat of fusion of 73.5
.mu.g. The corresponding CRYSTAF curve shows the tallest peak at
80.8.degree. C. with a peak area of 16.0 percent. The delta between
the DSC Tm and the Tcrystaf is 43.8.degree. C.
[0175] The DSC curve for the polymer of example 10 shows a peak
with a 115.6.degree. C. melting point (Tm) with a heat of fusion of
60.7 J/g. The corresponding CRYSTAF curve shows the tallest peak at
40.9.degree. C. with a peak area of 52.4 percent. The delta between
the DSC Tm and the Tcrystaf is 74.7.degree. C.
[0176] The DSC curve for the polymer of example 11 shows a peak
with a 113.6.degree. C. melting point (Tm) with a heat of fusion of
70.4 J/g. The corresponding CRYSTAF curve shows the tallest peak at
39.6.degree. C. with a peak area of 25.2 percent. The delta between
the DSC Tm and the Tcrystaf is 74.1.degree. C.
[0177] The DSC curve for the polymer of example 12 shows a peak
with a 113.2.degree. C. melting point (Tm) with a heat of fusion of
48.9 J/g. The corresponding CRYSTAF curve shows no peak equal to or
above 30.degree. C. (Tcrystaf for purposes of further calculation
is therefore set at 30.degree. C.). The delta between the DSC Tm
and the Tcrystaf is 83.2.degree. C.
[0178] The DSC curve for the polymer of example 13 shows a peak
with a 114.4.degree. C. melting point (Tm) with a heat of fusion of
49.4 J/g. The corresponding CRYSTAF curve shows the tallest peak at
33.8.degree. C. with a peak area of 7.7 percent. The delta between
the DSC Tm and the Tcrystaf is 84.4.degree. C.
[0179] The DSC for the polymer of example 14 shows a peak with a
120.8.degree. C. melting point (Tm) with a heat of fusion of 127.9
J/g. The corresponding CRYSTAF curve shows the tallest peak at
72.9.degree. C. with a peak area of 92.2 percent. The delta between
the DSC Tm and the Tcrystaf is 47.9.degree. C.
[0180] The DSC curve for the polymer of example 15 shows a peak
with a 114.3.degree. C. melting point (Tm) with a heat of fusion of
36.2 J/g. The corresponding CRYSTAF curve shows the tallest peak at
32.3.degree. C. with a peak area of 9.8 percent. The delta between
the DSC Tm and the Tcrystaf is 82.0.degree. C.
[0181] The DSC curve for the polymer of example 16 shows a peak
with a 116.6.degree. C. melting point (Tm) with a heat of fusion of
44.9 .mu.g. The corresponding CRYSTAF curve shows the tallest peak
at 48.0.degree. C. with a peak area of 65.0 percent. The delta
between the DSC Tm and the Tcrystaf is 68.6.degree. C.
[0182] The DSC curve for the polymer of example 17 shows a peak
with a 116.0.degree. C. melting point (Tm) with a heat of fusion of
47.0 J/g. The corresponding CRYSTAF curve shows the tallest peak at
43.1.degree. C. with a peak area of 56.8 percent. The delta between
the DSC Tm and the Tcrystaf is 72.9.degree. C.
[0183] The DSC curve for the polymer of example 18 shows a peak
with a 120.5.degree. C. melting point (Tm) with a heat of fusion of
141.8 J/g. The corresponding CRYSTAF curve shows the tallest peak
at 70.0.degree. C. with a peak area of 94.0 percent. The delta
between the DSC Tm and the Tcrystaf is 50.5.degree. C.
[0184] The DSC curve for the polymer of example 19 shows a peak
with a 124.8.degree. C. melting point (Tm) with a heat of fusion of
174.8 J/g. The corresponding CRYSTAF curve shows the tallest peak
at 79.9.degree. C. with a peak area of 87.9 percent. The delta
between the DSC Tm and the Tcrystaf is 45.0.degree. C.
[0185] The DSC curve for the polymer of comparative D shows a peak
with a 37.3.degree. C. melting point (Tm) with a heat of fusion of
31.6 J/g. The corresponding CRYSTAF curve shows no peak equal to
and above 30.degree. C. Both of these values are consistent with a
resin that is low in density. The delta between the DSC Tm and the
Tcrystaf is 7.3.degree. C.
[0186] The DSC curve for the polymer of comparative E shows a peak
with a 124.0.degree. C. melting point (Tm) with a heat of fusion of
179.3 J/g. The corresponding CRYSTAF curve shows the tallest peak
at 79.3.degree. C. with a peak area of 94.6 percent. Both of these
values are consistent with a resin that is high in density. The
delta between the DSC Tm and the Tcrystaf is 44.6.degree. C.
[0187] The DSC curve for the polymer of comparative F shows a peak
with a 124.8.degree. C. melting point (Tm) with a heat of fusion of
90.4 .mu.g. The corresponding CRYSTAF curve shows the tallest peak
at 77.6.degree. C. with a peak area of 19.5 percent. The separation
between the two peaks is consistent with the presence of both a
high crystalline and a low crystalline polymer. The delta between
the DSC Tm and the Tcrystaf is 47.2.degree. C.
Physical Property Testing
[0188] Polymer samples are evaluated for physical properties such
as high temperature resistance properties, as evidenced by TMA
temperature testing, pellet blocking strength, high temperature
recovery, high temperature compression set and storage modulus
ratio, G'(25.degree. C.)/G'(100.degree. C.). Several commercially
available polymers are included in the tests: Comparative G* is a
substantially linear ethylene/1-octene copolymer (AFFINITY.RTM.,
available from The Dow Chemical Company), Comparative H* is an
elastomeric, substantially linear ethylene/1-octene copolymer
(AFFINITY.RTM.EG8100, available from The Dow Chemical Company),
Comparative I is a substantially linear ethylene/1-octene copolymer
(AFFINITY.RTM. PL1840, available from The Dow Chemical Company),
Comparative J is a hydrogenated styrene/butadiene/styrene triblock
copolymer (KRATON.TM. G1652, available from KRATON Polymers),
Comparative K is a thermoplastic vulcanizate (TPV, a polyolefin
blend containing dispersed therein a crosslinked elastomer).
Results are presented in Table 4.
TABLE-US-00004 TABLE 4 High Temperature Mechanical Properties TMA-1
mm Pellet Blocking 300% Strain Compression penetration Strength
G'(25.degree. C.)/ Recovery (80.degree. C.) Set (70.degree. C.) Ex.
(.degree. C.) lb/ft.sup.2 (kPa) G'(100.degree. C.) (percent)
(percent) D* 51 -- 9 Failed -- E* 130 -- 18 -- -- F* 70 141 (6.8) 9
Failed 100 5 104 0 (0) 6 81 49 6 110 -- 5 -- 52 7 113 -- 4 84 43 8
111 -- 4 Failed 41 9 97 -- 4 -- 66 10 108 -- 5 81 55 11 100 -- 8 --
68 12 88 -- 8 -- 79 13 95 -- 6 84 71 14 125 -- 7 -- -- 15 96 -- 5
-- 58 16 113 -- 4 -- 42 17 108 0 (0) 4 82 47 18 125 -- 10 -- -- 19
133 -- 9 -- -- G* 75 463 (22.2) 89 Failed 100 H* 70 213 (10.2) 29
Failed 100 I* 111 -- 11 -- -- J* 107 -- 5 Failed 100 K* 152 -- 3 --
40
[0189] In Table 4, Comparative F (which is a physical blend of the
two polymers resulting from simultaneous polymerizations using
catalyst A1 and B1) has a 1 mm penetration temperature of about
70.degree. C., while Examples 5-9 have a 1 mm penetration
temperature of 100.degree. C. or greater. Further, examples 10-19
all have a 1 mm penetration temperature of greater than 85.degree.
C., with most having 1 mm TMA temperature of greater than
90.degree. C. or even greater than 100.degree. C. This shows that
the novel polymers have better dimensional stability at higher
temperatures compared to a physical blend. Comparative J (a
commercial SEBS) has a good 1 mm TMA temperature of about
107.degree. C., but it has very poor (high temperature 70.degree.
C.) compression set of about 100 percent and it also failed to
recover (sample broke) during a high temperature (80.degree. C.)
300 percent strain recovery. Thus the exemplified polymers have a
unique combination of properties unavailable even in some
commercially available, high performance thermoplastic
elastomers.
[0190] Similarly, Table 4 shows a low (good) storage modulus ratio,
G'(25.degree. C.)/G'(100.degree. C.), for the inventive polymers of
6 or less, whereas a physical blend (Comparative F) has a storage
modulus ratio of 9 and a random ethylene/octene copolymer
(Comparative G) of similar density has a storage modulus ratio an
order of magnitude greater (89). It is desirable that the storage
modulus ratio of a polymer be as close to 1 as possible. Such
polymers will be relatively unaffected by temperature, and
fabricated articles made from such polymers can be usefully
employed over a broad temperature range. This feature of low
storage modulus ratio and temperature independence is particularly
useful in elastomer applications such as in pressure sensitive
adhesive formulations.
[0191] The data in Table 4 also demonstrate that the polymers of
the invention possess improved pellet blocking strength. In
particular, Example 5 has a pellet blocking strength of 0 MPa,
meaning it is free flowing under the conditions tested, compared to
Comparatives F and G which show considerable blocking. Blocking
strength is important since bulk shipment of polymers having large
blocking strengths can result in product clumping or sticking
together upon storage or shipping, resulting in poor handling
properties.
[0192] High temperature (70.degree. C.) compression set for the
inventive polymers is generally good, meaning generally less than
about 80 percent, preferably less than about 70 percent and
especially less than about 60 percent. In contrast, Comparatives F,
G, H and J all have a 70.degree. C. compression set of 100 percent
(the maximum possible value, indicating no recovery). Good high
temperature compression set (low numerical values) is especially
needed for applications such as gaskets, window profiles, o-rings,
and the like.
TABLE-US-00005 TABLE 5 Ambient Temperature Mechanical Properties
Tensile 100% 300% Retractive Flex Tensile Abrasion: Notched Strain
Strain Stress Stress Modu- Modu- Tensile Elongation Tensile
Elongation Volume Tear Recovery Recovery at 150% Compression
Relaxation lus lus Strength at Break.sup.1 Strength at Break Loss
Strength 21.degree. C. 21.degree. C. Strain Set 21.degree. C. at
50% Ex. (MPa) (MPa) (MPa).sup.1 (%) (MPa) (%) (mm.sup.3) (mJ)
(percent) (percent) (kPa) (Percent) Strain.sup.2 D* 12 5 -- -- 10
1074 -- -- 91 83 760 -- -- E* 895 589 -- 31 1029 -- -- -- -- -- --
-- F* 57 46 -- -- 12 824 93 339 78 65 400 42 -- 5 30 24 14 951 16
1116 48 -- 87 74 790 14 33 6 33 29 -- -- 14 938 -- -- -- 75 861 13
-- 7 44 37 15 846 14 854 39 -- 82 73 810 20 -- 8 41 35 13 785 14
810 45 461 82 74 760 22 -- 9 43 38 -- -- 12 823 -- -- -- -- -- 25
-- 10 23 23 -- -- 14 902 -- -- 86 75 860 12 -- 11 30 26 -- -- 16
1090 -- 976 89 66 510 14 30 12 20 17 12 961 13 931 -- 1247 91 75
700 17 -- 13 16 14 -- -- 13 814 -- 691 91 -- -- 21 -- 14 212 160 --
-- 29 857 -- -- -- -- -- -- -- 15 18 14 12 1127 10 1573 -- 2074 89
83 770 14 -- 16 23 20 -- -- 12 968 -- -- 88 83 1040 13 -- 17 20 18
-- -- 13 1252 -- 1274 13 83 920 4 -- 18 323 239 -- -- 30 808 -- --
-- -- -- -- -- 19 706 483 -- -- 36 871 -- -- -- -- -- -- -- G* 15
15 -- -- 17 1000 -- 746 86 53 110 27 50 H* 16 15 -- -- 15 829 --
569 87 60 380 23 -- I* 210 147 -- -- 29 697 -- -- -- -- -- -- -- J*
-- -- -- -- 32 609 -- -- 93 96 1900 25 -- K* -- -- -- -- -- -- --
-- -- -- -- 30 -- .sup.1Tested at 51 cm/minute .sup.2measured at
38.degree. C. for 12 hours
[0193] Table 5 shows results for mechanical properties for the new
polymers as well as for various comparison polymers at ambient
temperatures. It may be seen that the inventive polymers have very
good abrasion resistance when tested according to ISO 4649,
generally showing a volume loss of less than about 90 mm.sup.3,
preferably less than about 80 mm.sup.3, and especially less than
about 50 mm.sup.3. In this test, higher numbers indicate higher
volume loss and consequently lower abrasion resistance.
[0194] Tear strength as measured by tensile notched tear strength
of the inventive polymers is generally 1000 mJ or higher, as shown
in Table 5. Tear strength for the inventive polymers can be as high
as 3000 mJ, or even as high as 5000 mJ. Comparative polymers
generally have tear strengths no higher than 750 mJ.
[0195] Table 5 also shows that the polymers of the invention have
better retractive stress at 150 percent strain (demonstrated by
higher retractive stress values) than some of the comparative
samples. Comparative Examples F, G and H have retractive stress
value at 150 percent strain of 400 kPa or less, while the inventive
polymers have retractive stress values at 150 percent strain of 500
kPa (Ex. 11) to as high as about 1100 kPa (Ex. 17). Polymers having
higher than 150 percent retractive stress values would be quite
useful for elastic applications, such as elastic fibers and
fabrics, especially nonwoven fabrics. Other applications include
diaper, hygiene, and medical garment waistband applications, such
as tabs and elastic bands.
[0196] Table 5 also shows that stress relaxation (at 50 percent
strain) is also improved (less) for the inventive polymers as
compared to, for example, Comparative G. Lower stress relaxation
means that the polymer retains its force better in applications
such as diapers and other garments where retention of elastic
properties over long time periods at body temperatures is
desired.
Optical Testing
TABLE-US-00006 [0197] TABLE 6 Polymer Optical Properties Ex.
Internal Haze (percent) Clarity (percent) 45.degree. Gloss
(percent) F* 84 22 49 G* 5 73 56 5 13 72 60 6 33 69 53 7 28 57 59 8
20 65 62 9 61 38 49 10 15 73 67 11 13 69 67 12 8 75 72 13 7 74 69
14 59 15 62 15 11 74 66 16 39 70 65 17 29 73 66 18 61 22 60 19 74
11 52 G* 5 73 56 H* 12 76 59 I* 20 75 59
[0198] The optical properties reported in Table 6 are based on
compression molded films substantially lacking in orientation.
Optical properties of the polymers may be varied over wide ranges,
due to variation in crystallite size, resulting from variation in
the quantity of chain shuttling agent employed in the
polymerization.
Extractions of Multi-Block Copolymers
[0199] Extraction studies of the polymers of examples 5, 7 and
Comparative E are conducted. In the experiments, the polymer sample
is weighed into a glass fritted extraction thimble and fitted into
a Kumagawa type extractor. The extractor with sample is purged with
nitrogen, and a 500 mL round bottom flask is charged with 350 mL of
diethyl ether. The flask is then fitted to the extractor. The ether
is heated while being stirred. Time is noted when the ether begins
to condense into the thimble, and the extraction is allowed to
proceed under nitrogen for 24 hours. At this time, heating is
stopped and the solution is allowed to cool. Any ether remaining in
the extractor is returned to the flask. The ether in the flask is
evaporated under vacuum at ambient temperature, and the resulting
solids are purged dry with nitrogen. Any residue is transferred to
a weighed bottle using successive washes of hexane. The combined
hexane washes are then evaporated with another nitrogen purge, and
the residue dried under vacuum overnight at 40.degree. C. Any
remaining ether in the extractor is purged dry with nitrogen.
[0200] A second clean round bottom flask charged with 350 mL of
hexane is then connected to the extractor. The hexane is heated to
reflux with stirring and maintained at reflux for 24 hours after
hexane is first noticed condensing into the thimble. Heating is
then stopped and the flask is allowed to cool. Any hexane remaining
in the extractor is transferred back to the flask. The hexane is
removed by evaporation under vacuum at ambient temperature, and any
residue remaining in the flask is transferred to a weighed bottle
using successive hexane washes. The hexane in the flask is
evaporated by a nitrogen purge, and the residue is vacuum dried
overnight at 40.degree. C.
[0201] The polymer sample remaining in the thimble after the
extractions is transferred from the thimble to a weighed bottle and
vacuum dried overnight at 40.degree. C. Results are contained in
Table 7.
TABLE-US-00007 TABLE 7 ether ether C.sub.8 hexane hexane C.sub.8
residue wt. soluble soluble mole soluble soluble mole C.sub.8 mole
Sample (g) (g) (percent) percent.sup.1 (g) (percent) percent.sup.1
percent.sup.1 Comp. 1.097 0.063 5.69 12.2 0.245 22.35 13.6 6.5 F*
Ex. 5 1.006 0.041 4.08 -- 0.040 3.98 14.2 11.6 Ex. 7 1.092 0.017
1.59 13.3 0.012 1.10 11.7 9.9 .sup.1Determined by .sup.13C NMR
Testing Methods
[0202] In the foregoing characterizing disclosure and the examples
that follow, the following analytical techniques are employed:
GPC Method for Samples 1-4 and A-C
[0203] An automated liquid-handling robot equipped with a heated
needle set to 160.degree. C. is used to add enough
1,2,4-trichlorobenzene stabilized with 300 ppm Ionol to each dried
polymer sample to give a final concentration of 30 mg/mL. A small
glass stir rod is placed into each tube and the samples are heated
to 160.degree. C. for 2 hours on a heated, orbital-shaker rotating
at 250 rpm. The concentrated polymer solution is then diluted to 1
mg/ml using the automated liquid-handling robot and the heated
needle set to 160.degree. C.
[0204] A Symyx Rapid GPC system is used to determine the molecular
weight data for each sample. A Gilson 350 pump set at 2.0 ml/min
flow rate is used to pump helium-purged 1,2-dichlorobenzene
stabilized with 300 ppm Ionol as the mobile phase through three
Plgel 10 micrometer (.mu.m) Mixed B 300 mm.times.7.5 mm columns
placed in series and heated to 160.degree. C. A Polymer Labs
ELS1000 Detector is used with the Evaporator set to 250.degree. C.,
the Nebulizer set to 165.degree. C., and the nitrogen flow rate set
to 1.8 SLM at a pressure of 60-80 psi (400-600 kPa) N2. The polymer
samples are heated to 160.degree. C. and each sample injected into
a 250 .mu.l loop using the liquid-handling robot and a heated
needle. Serial analysis of the polymer samples using two switched
loops and overlapping injections are used. The sample data is
collected and analyzed using Symyx Epoch.TM. software. Peaks are
manually integrated and the molecular weight information reported
uncorrected against a polystyrene standard calibration curve.
[0205] The DSC melting peak is measured as the maximum in heat flow
rate (W/g) with respect to the linear baseline drawn between
-30.degree. C. and end of melting. The heat of fusion is measured
as the area under the melting curve between -30.degree. C. and the
end of melting using a linear baseline.
Standard CRYSTAF Method
[0206] Branching distributions are determined by crystallization
analysis fractionation (CRYSTAF) using a CRYSTAF 200 unit
commercially available from PolymerChar, Valencia, Spain. The
samples are dissolved in 1,2,4 trichlorobenzene at 160.degree. C.
(0.66 mg/mL) for 1 hr and stabilized at 95.degree. C. for 45
minutes. The sampling temperatures range from 95 to 30.degree. C.
at a cooling rate of 0.2.degree. C./min. An infrared detector is
used to measure the polymer solution concentrations. The cumulative
soluble concentration is measured as the polymer crystallizes while
the temperature is decreased. The analytical derivative of the
cumulative profile reflects the short chain branching distribution
of the polymer.
[0207] The CRYSTAF peak temperature and area are identified by the
peak analysis module included in the CRYSTAF Software (Version
2001.b, PolymerChar, Valencia, Spain). The CRYSTAF peak finding
routine identifies a peak temperature as a maximum in the dW/dT and
the area between the largest positive inflections on either side of
the identified peak in the derivative curve. To calculate the
CRYSTAF curve, the preferred processing parameters are with a
temperature limit of 70.degree. C. and with smoothing parameters
above the temperature limit of 0.1, and below the temperature limit
of 0.3.
DSC Standard Method (Excluding Samples 1-4 and A-C)
[0208] Differential Scanning Calorimetry results are determined
using a TAI model Q1000 DSC equipped with an RCS cooling accessory
and an autosampler. A nitrogen purge gas flow of 50 ml/min is used.
The sample is pressed into a thin film and melted in the press at
about 175.degree. C. and then air-cooled to room temperature
(25.degree. C.). 3-10 mg Of material is then cut into a 6 mm
diameter disk, accurately weighed, placed in a light aluminum pan
(ca 50 mg), and then crimped shut. The thermal behavior of the
sample is investigated with the following temperature profile. The
sample is rapidly heated to 180.degree. C. and held isothermal for
3 minutes in order to remove any previous thermal history. The
sample is then cooled to -40.degree. C. at 10.degree. C./min
cooling rate and held at -40.degree. C. for 3 minutes. The sample
is then heated to 150.degree. C. at 10.degree. C./min. heating
rate. The cooling and second heating curves are recorded.
[0209] The DSC melting peak is measured as the maximum in heat flow
rate (W/g) with respect to the linear baseline drawn between
-30.degree. C. and end of melting. The heat of fusion is measured
as the area under the melting curve between -30.degree. C. and the
end of melting using a linear baseline.
Abrasion Resistance
[0210] Abrasion resistance is measured on compression molded
plaques according to ISO 4649. The average value of 3 measurements
is reported. Plaques for the test are 6.4 mm thick and compression
molded using a hot press (Carver Model #4095-4PR1001R). The pellets
are placed between polytetrafluoroethylene sheets, heated at
190.degree. C. at 55 psi (380 kPa) for 3 minutes, followed by 1.3
MPa for 3 minutes, and then 2.6 MPa for 3 minutes. Next the plaques
are cooled in the press with running cold water at 1.3 MPa for 1
minute and removed for testing.
GPC Method (For All Samples, Including AA-DD, but Excluding Samples
1-4 and A-C)
[0211] The gel permeation chromatographic system consists of either
a Polymer Laboratories Model PL-210 or a Polymer Laboratories Model
PL-220 instrument. The column and carousel compartments are
operated at 140.degree. C. Three Polymer Laboratories 10-micron
Mixed-B columns are used. The solvent is 1,2,4 trichlorobenzene.
The samples are prepared at a concentration of 0.1 grams of polymer
in 50 milliliters of solvent containing 200 ppm of butylated
hydroxytoluene (BHT). Samples are prepared by agitating lightly for
2 hours at 160.degree. C. The injection volume used is 100
microliters and the flow rate is 1.0 ml/minute.
[0212] Calibration of the GPC column set is performed with 21
narrow molecular weight distribution polystyrene standards with
molecular weights ranging from 580 to 8,400,000, arranged in 6
"cocktail" mixtures with at least a decade of separation between
individual molecular weights. The standards are purchased from
Polymer Laboratories (Shropshire, UK). The polystyrene standards
are prepared at 0.025 grams in 50 milliliters of solvent for
molecular weights equal to or greater than 1,000,000, and 0.05
grams in 50 milliliters of solvent for molecular weights less than
1,000,000. The polystyrene standards are dissolved at 80.degree. C.
with gentle agitation for 30 minutes. The narrow standards mixtures
are run first and in order of decreasing highest molecular weight
component to minimize degradation. The polystyrene standard peak
molecular weights are converted to polyethylene molecular weights
using the following equation (as described in Williams and Ward, J.
Polym. Sci., Polym Let., 6, 621 (1968)):
Mpolyethylene=0.431(Mpolystyrene).
[0213] Polyetheylene equivalent molecular weight calculations are
performed using Viscotek TriSEC software Version 3.0.
Compression Set
[0214] Compression set is measured according to ASTM D 395. The
sample is prepared by stacking 25.4 mm diameter round discs of 3.2
mm, 2.0 mm, and 0.25 mm thickness until a total thickness of 12.7
mm is reached. The discs are cut from 12.7 cm.times.12.7 cm
compression molded plaques molded with a hot press under the
following conditions: zero pressure for 3 min at 190.degree. C.,
followed by 86 MPa for 2 min at 190.degree. C., followed by cooling
inside the press with cold running water at 86 MPa.
Density
[0215] Samples for density measurement are prepared according to
ASTM D 1928. Measurements are made within one hour of sample
pressing using ASTM D792, Method B.
Flexural/Secant Modulus/Storage Modulus
[0216] Samples are compression molded using ASTM D 1928. Flexural
and 2 percent secant moduli are measured according to ASTM D-790.
Storage modulus is measured according to ASTM D 5026-01 or
equivalent technique.
Optical Properties
[0217] Films of 0.4 mm thickness are compression molded using a hot
press (Carver Model #4095-4PR1001R). The pellets are placed between
polytetrafluoroethylene sheets, heated at 190.degree. C. at 55 psi
(380 kPa) for 3 min, followed by 1.3 MPa for 3 min, and then 2.6
MPa for 3 min. The film is then cooled in the press with running
cold water at 1.3 MPa for 1 min. The compression molded films are
used for optical measurements, tensile behavior, recovery, and
stress relaxation.
[0218] Clarity is measured using BYK Gardner Haze-gard as specified
in ASTM D 1746.
[0219] 45.degree. gloss is measured using BYK Gardner Glossmeter
Microgloss 45.degree. as specified in ASTM D-2457.
[0220] Internal haze is measured using BYK Gardner Haze-gard based
on ASTM D 1003 Procedure A. Mineral oil is applied to the film
surface to remove surface scratches.
Mechanical Properties--Tensile, Hysteresis, and Tear
[0221] Stress-strain behavior in uniaxial tension is measured using
ASTM D 1708 microtensile specimens. Samples are stretched with an
Instron at 500% min-1 at 21.degree. C. Tensile strength and
elongation at break are reported from an average of 5
specimens.
[0222] 100%, 150%, and 300% Hysteresis are determined from cyclic
loading to 100%, 150%, and 300% strains using ASTM D 1708
microtensile specimens with an Instron.TM. instrument. The sample
is loaded and unloaded at 267% min-1 for 3 cycles at 21.degree. C.
Cyclic experiments at 300% and 80.degree. C. are conducted using an
environmental chamber. In the 80.degree. C. experiment, the sample
is allowed to equilibrate for 45 minutes at the test temperature
before testing. In the 21.degree. C., 300% strain cyclic
experiment, the retractive stress at 150% strain from the first
unloading cycle is recorded. Percent recovery for all experiments
are calculated from the first unloading cycle using the strain at
which the load returned to the base line. The percent recovery is
defined as:
% Recovery = f - s f .times. 100 ##EQU00004##
where .epsilon..sub.f is the strain taken for cyclic loading and
.epsilon..sub.s is the strain where the load returns to the
baseline during the 1st unloading cycle. Permanent set is defined
as .epsilon..sub.s.
[0223] Stress relaxation is measured at 50 percent strain and
37.degree. C. for 12 hours using an Instron.TM. instrument equipped
with an environmental chamber. The gauge geometry was 76
mm.times.25 mm.times.0.4 mm. After equilibrating at 37.degree. C.
for 45 min in the environmental chamber, the sample was stretched
to 50% strain at 333% min-1. Stress was recorded as a function of
time for 12 hours. The percent stress relaxation after 12 hours was
calculated using the formula:
% Stress Relaxation = L 0 - L 12 L 0 .times. 100 ##EQU00005##
where L0 is the load at 50% strain at 0 time and L12 is the load at
50 percent strain after 12 hours.
[0224] Tensile notched tear experiments are carried out on samples
having a density of 0.88 g/cc or less using an Instron.TM.
instrument. The geometry consists of a gauge section of 76
mm.times.13 mm.times.0.4 mm with a 2 mm notch cut into the sample
at half the specimen length. The sample is stretched at 508 mm
min-1 at 21.degree. C. until it breaks. The tear energy is
calculated as the area under the stress-elongation curve up to
strain at maximum load. An average of at least 3 specimens are
reported.
TMA
[0225] Thermal Mechanical Analysis (Penetration Temperature) is
conducted on 30 mm diameter.times.3.3 mm thick, compression molded
discs, formed at 180.degree. C. and 10 MPa molding pressure for 5
minutes and then air quenched. The instrument used is a TMA 7,
brand available from Perkin-Elmer. In the test, a probe with 1.5 mm
radius tip (P/N N519-0416) is applied to the surface of the sample
disc with 1N force. The temperature is raised at 5.degree. C./min
from 25.degree. C. The probe penetration distance is measured as a
function of temperature. The experiment ends when the probe has
penetrated 1 mm into the sample.
DMA
[0226] Dynamic Mechanical Analysis (DMA) is measured on compression
molded disks formed in a hot press at 180.degree. C. at 10 MPa
pressure for 5 minutes and then water cooled in the press at
90.degree. C./min. Testing is conducted using an ARES controlled
strain rheometer (TA instruments) equipped with dual cantilever
fixtures for torsion testing.
[0227] A 1.5 mm plaque is pressed and cut in a bar of dimensions
32.times.12 mm. The sample is clamped at both ends between fixtures
separated by 10 mm (grip separation .quadrature.L) and subjected to
successive temperature steps from -100.degree. C. to 200.degree. C.
(5.degree. C. per step). At each temperature the torsion modulus G'
is measured at an angular frequency of 10 rad/s, the strain
amplitude being maintained between 0.1 percent and 4 percent to
ensure that the torque is sufficient and that the measurement
remains in the linear regime.
[0228] An initial static force of 10 g is maintained (auto-tension
mode) to prevent slack in the sample when thermal expansion occurs.
As a consequence, the grip separation .quadrature.L increases with
the temperature, particularly above the melting or softening point
of the polymer sample. The test stops at the maximum temperature or
when the gap between the fixtures reaches 65 mm.
Pellet Blocking Strength
[0229] Pellets (150 g) are loaded into a 2'' (5 cm) diameter hollow
cylinder that is made of two halves held together by a hose clamp.
A 2.75 lb (1.25 kg) load is applied to the pellets in the cylinder
at 45.degree. C. for 3 days. After 3 days, the pellets loosely
consolidate into a cylindrical shaped plug. The plug is removed
from the form and the pellet blocking force measured by loading the
cylinder of blocked pellets in compression using an Instron.TM.
instrument to measure the compressive force needed to break the
cylinder into pellets.
Melt Index
[0230] Melt index, or 12, is measured in accordance with ASTM D
1238, Condition 190.degree. C./2.16 kg. Melt index, or 110 is also
measured in accordance with ASTM D 1238, Condition 190.degree.
C./10 kg.
ATREF
[0231] Analytical temperature rising elution fractionation (ATREF)
analysis is conducted according to the method described in U.S.
Pat. No. 4,798,081. The composition to be analyzed is dissolved in
trichlorobenzene and allowed to crystallize in a column containing
an inert support (stainless steel shot) by slowly reducing the
temperature to 20.degree. C. at a cooling rate of 0.1.degree.
C./min. The column is equipped with an infrared detector. An ATREF
chromatogram curve is then generated by eluting the crystallized
polymer sample from the column by slowly increasing the temperature
of the eluting solvent (trichlorobenzene) from 20 to 120.degree. C.
at a rate of 1.5.degree. C./min.
Polymer Fractionation by TREF
[0232] Large-scale TREF fractionation is carried by dissolving
15-20 g of polymer in 2 liters of 1,2,4-trichlorobenzene (TCB) by
stirring for 4 hours at 160.degree. C. The polymer solution is
forced by 15 psig (100 kPa) nitrogen onto a 3 inch by 4 foot (7.6
cm.times.12 cm) steel column packed with a 60:40 (v:v) mix of 30-40
mesh (600-425 .mu.m) spherical, technical quality glass beads
(available from Potters Industries, HC 30 Box 20, Brownwood, Tex.,
76801) and stainless steel, 0.028'' (0.7 mm) diameter cut wire shot
(available form Pellets, Inc. 63 Industrial Drive, North Tonawanda,
N.Y., 14120). The column is immersed in a thermally controlled oil
jacket, set initially to 160.degree. C. The column is first cooled
ballistically to 125.degree. C., then slow cooled to 20.degree. C.
at 0.04.degree. C. per minute and held for one hour. Fresh TCB is
introduced at about 65 ml/min while the temperature is increased at
0.167.degree. C. per minute.
[0233] Approximately 2000 ml portions of eluant from the
preparative TREF column are collected in a 16 station, heated
fraction collector. The polymer is concentrated in each fraction
using a rotary evaporator until about 50 to 100 ml of the polymer
solution remains. The concentrated solutions are allowed to stand
overnight before adding excess methanol, filtering, and rinsing
(approx. 300-500 ml of methanol including the final rinse). The
filtration step is performed on a 3 position vacuum assisted
filtering station using 5.0 .mu.m polytetrafluoroethylene coated
filter paper (available from Osmonics Inc., Cat# Z50WP04750). The
filtrated fractions are dried overnight in a vacuum oven at
60.degree. C. and weighed on an analytical balance before further
testing.
13C NMR Analysis
[0234] The samples are prepared by adding approximately 3 g of a
50/50 mixture of tetrachloroethane-d2/orthodichlorobenzene to 0.4 g
sample in a 10 mm NMR tube. The samples are dissolved and
homogenized by heating the tube and its contents to 150.degree. C.
The data is collected using a JEOL Eclipse.TM. 400 MHz spectrometer
or a Varian Unity Plus.TM. 400 MHz spectrometer, corresponding to a
13C resonance frequency of 100.5 MHz. The data is acquired using
4000 transients per data file with a 6 second pulse repetition
delay. To achieve minimum signal-to-noise for quantitative
analysis, multiple data files are added together. The spectral
width is 25,000 Hz with a minimum file size of 32K data points. The
samples are analyzed at 130.degree. C. in a 10 mm broad band probe.
The comonomer incorporation is determined using Randall's triad
method (Randall, J. C.; JMS-Rev. Macromol. Chem. Phys., C29,
201-317 (1989).
Atomic Force Microscopy (AFM)
[0235] Sections are collected from the sample material using a
Leica UCT.TM. microtome with a FC cryo-chamber operated at
-80.degree. C. A diamond knife is used to section all sample
material to a thickness of 120 nm. Sections are placed on freshly
cleaved mica surfaces, and mounted on standard AFM specimen metal
support disks with a double carbon tape. The sections are examined
with a DI NanoScope IV.TM. Multi-Mode AFM, in tapping mode with
phase detection. Nano-sensor tips are used in all experiments.
[0236] For nonwoven laminate structures, the following tensile test
is used:
[0237] For the tensile test, 6 inch by 1 inch specimens can be cut
from the samples. When appropriate, a direction such as machine
direction (MD) or cross direction (CD) may be specified for samples
which possess directionality due to the particular nature of the
manufacturing process. These specimens can be then loaded into an
Instron 5564 (Canton, Mass.) equipped with pneumatic grips and
fitted with a 20 pound capacity tension load cell or a higher
capacity load cell when loads exceed 20 pounds. After proper
calibration of the load cell according to the manufacturer's
instructions, the specimen is oriented parallel to the displacement
direction of the crosshead and then gripped with a separation of 3
inches. The sample is then stretched to break at a rate of 500% per
minute (111.25 mm/min). Strain or elongation is a quantity that is
commonly used. It is described according to the following
equation:
Elongation ( % ) = L - L 0 L 0 .times. 100 % ##EQU00006##
such that L.sub.o is defined as the original length of 3 inches, L
is the length of the sample at any point during the tensile test.
The length of the sample and the corresponding force at the point
just before complete breakage of the sample is noted. This point
may or may not correspond to a local maximum in force. This point
is also commonly described as elongation at break or strain at
break.
[0238] For cast film, preferably the melt index of at least one
layer, preferably the low crystallinity layer, is at least 1 g/10
min and more preferably from 2 to 20 g/10 min. For blown film,
preferably at least one layer, preferably the low crystallinity
layer, have melt indices of less than 5 g/10 min and more
preferably less than 2 g/10 min. and as low as about 0.1 g/10
min.
[0239] The Article
[0240] One embodiment of the invention includes an article
comprising a low crystallinity layer and a high crystallinity
layer, the high crystallinity layer is often capable of undergoing
plastic deformation upon elongation. "Elongation" is a uni-axial or
biaxial stretching of the article to a degree sufficient to cause
plastic deformation of the high crystallinity layer. Dimensional
profile (surface roughness or corrugated-like structure) and
increase in Haze value can be used by one of ordinary skill in the
art to determine whether an article is plastically deformed. Haze
is measured according to ASTM D1003 using a HazeGard PLUS Hazemeter
available from BYK Gardner of Melville, N.Y., with a light source
CIE Illuminant C. Plastically deformed articles according to the
invention can have a Haze value of greater than about 70%, or
greater than about 80%, or greater than about 90%. The plastically
deformed articles have an increased haze value compared to the
article prior to elongation. Though not limited by theory, the
change (increase) in haze is thought to originate from an increase
in surface roughness. Surface roughness is thought to originate
from differential recovery behavior after deformation. Upon
deformation, the high and low crystallinity layers are thought to
extend similarly but upon release, there is differential recovery
behavior between the higher and lower crystallinity layers. Lower
recovery (higher set) of the higher crystallinity layer and the
retractive force of the lower crystallinity layer is thought to
produce a mechanical instability and result in a structure that can
be described as corrugated, micro-undulated, micro-textured, or
crenulated.
[0241] The surface roughness of the article can be measured by a
number of instruments capable of precise surface roughness
measurements. One such instrument is Surfcom 110B manufactured by
Tokyo Seimitsu Company. The Surfcom instrument contains a diamond
stylus which moves across the surface of the sample. The sample can
range in hardness from metal to plastic to rubber. The instrument
records the surface irregularities over the length traveled by the
stylus. The surface roughness is quantified using a combination of
three factors Ra (pm)--the arithmetic mean representing the
departure of the extrudate surface profile from a mean line; Ry
(m)--the sum of the height of the highest peak from a mean line and
the depth of the deepest valley from a mean line; and Rz (um)--the
sum of two means which are the average height of the five highest
peaks from a mean line and the average depth of the five deepest
valleys from a mean line. The combination of the Ra, Ry and Rz
values characterize the surface profile of the film. By comparing
the values of the non-elongated film against the values of the
plastically deformed film, the increase in the roughness of the
film surface, and thus the effectiveness of the orientation
process, can be determined.
[0242] A pre-stretching or elongating step is optional, but
preferable, and may be done on the article, one or more individual
layers of the article such as the high crystallinity layer, the low
crystallinity layer, or both, or may not be done at all. If being
done to more than one layer, the pre-stretching may be done on each
layer separately or on the layers together. Similarly, the
stretching may be done in any direction.
[0243] In some embodiments, the article is elongated in at least
one direction to at least about 100%, or at least about 150%, of
its original length or width. Generally, the article is elongated
at a temperature below the melting temperature of either of the low
crystallinity polymer or high crystallinity polymer. This
"pre-stretching" step is accomplished by any means known to those
skilled in the art, especially however, they are particularly
suited for MD (machine direction) and/or CD (cross direction)
orientation activation methods including ring-rolling, MD
orientation (MDO) rolls, etc., and a stretch-bonded lamination
process. This stretching is a "pre-stretch" in the context that the
film will again be likely stretched in its ultimate use, e.g.,
packaging or shipping applications, and diapers. This step may be
performed on the articles of invention alone or on the articles of
invention in laminate form or on some other form such as elastic
nonwovens.
[0244] The article prior to being pre-stretched may have poor
elastic and hysteresis characteristics due to the influence of the
high crystallinity layer(s). However, upon elongating the article
beyond the plastic deformation point of the high crystallinity
layer(s), the elastic and hysteresis properties are improved, e.g.,
the effect of pre-stretching films above 50% strain results in
subsequent lower permanent set.
[0245] Typically the article is formed using any fabrication
process, such as an extrusion coated or cast film process,
lamination processes, melt blown, spunbond, fiber extrusion, fiber
spinning processes, separated or recovered from that process, and
then pre-stretched. Preferably the article is pre-stretched after
the article has solidified (more preferably, but not necessarily,
crystallized). Operating at or above the melting point of the lower
crystallinity layer is not favored for this invention as is
typical, for example, in the double bubble orientation (Pahlke)
process, and because generally it will not produce the desired
structures. Preferably, the lower crystallinity layer has
substantially achieved its maximum crystallinity before the
pre-stretch procedure.
[0246] This invention is especially useful for film converters who
must store the elastic film on rolls prior to assembly into
laminate structures. A particular challenge for conventional
elastic film is blocking. This invention serves to remedy this
problem. This invention is also useful during conversion to reduce
the coefficient of friction and to increase the bending stiffness
of the film during conveyance, cutting, assembly, and other steps.
Other applications include elastic diaper back-sheets, feminine
hygiene films, elastic strips, elastic laminates in gowns, sheets
and the like.
[0247] In one particular embodiment, the article is formed by
co-extruding the low crystallinity layer and high crystallinity
layer prior to elongation. The article can optionally be oriented
in the machine direction (MD) or the transverse direction (TD) or
both directions (biaxially) using conventional equipment and
processes. Orientation can be carried in a separate step prior to
the elongation step described below. Thus, an oriented article can
be prepared as an intermediate product, which is then later
elongated in a separate step. In this embodiment, the orientation
is preferably carried out such that minimal plastic deformation of
the high crystallinity layer occurs. Alternatively, orientation and
elongation to plastic deformation can be carried out in a single
step.
[0248] In some embodiments the low crystallinity layer is in
contact or intimate contact with the high crystallinity layer. The
term "in contact" means that there is sufficient interfacial
adhesion provided by, for example, compatible crystallinity, such
that adjacent polymeric layers do not delaminate, even after
orientation and/or elongation. The term "in intimate contact" means
that essentially one full planar surface of one layer is in an
adhering relationship with a planar surface of another layer.
Typically the two planar surfaces are co-terminus with one another.
In certain embodiments the low crystallinity layer adheres to the
high crystallinity layer through the use of conventional materials,
such as adhesives.
[0249] "Planar surface" is used in distinction to "edge surface".
If rectangular in shape or configuration, a film will comprise two
opposing planar surfaces joined by four edge surfaces (two opposing
pairs of edge surfaces, each pair intersecting the other pair at
right angles). The bottom planar surface of the first skin layer is
adapted to join or adhere to the top planar surface of the core
layer, and the top planar surface of the second skin layer is
adapted to join or adhere to the bottom planar surface of the core
layer. In practice, the first and second skin layers are typically
of the same composition and as such, are interchangeable. Likewise,
the top and bottom planar surfaces of both the skin and core layers
are functionally essentially the same and as such, each layer can
be "flipped", i.e., the top planar surface can serve as the bottom
planar surface, and vice versa. The films can be of any size and
shape and as such, so can the planar and edge surfaces, e.g., thin
or thick, polygonal or circular, etc. Typically, the film is in an
extended ribbon form.
[0250] The films of this invention can be prepared by any
conventional process, and often are formed by separately extruding
the individual layers using conventional extrusion equipment, and
then joining or laminating the respective planar surfaces of the
individual layers to one another using conventional techniques and
equipment, e.g., feeding the individual layers together in an
aligned fashion through a set of pinch rollers.
[0251] The skin layers typically comprise less than 30 weight
percent (wt %), preferably less than 20 wt % and more preferably
less than 10 wt %, of a three-layer film consisting of one core
layer and two skin layers. Each skin layer is typically the same as
the other skin layer in thickness and weight although one skin
layer can vary from the other in either or both measurements.
[0252] In another embodiment the article is a film wherein the high
crystallinity layer forms a skin layer. In a different embodiment,
the high crystallinity layer is intermediate to the low
crystallinity layer and another type of skin layer, such as any
conventional polymer layer. In yet another embodiment, high
crystallinity layers are present on both sides of the low
crystallinity layer. In this embodiment, the two high crystallinity
layers can be the same or different in composition and the same or
different in thickness. In yet another embodiment, the article
includes, in sequence, a high crystallinity layer, a low
crystallinity layer, and an additional low crystallinity layer. In
this embodiment, the two low crystallinity layers can be the same
or different in composition and the same or different in thickness.
The article can comprise as many layers as desired.
[0253] The high crystallinity layer or one or more low
crystallinity layers may also form a skin layer and be adapted to
adhere by melting onto a substrate. Skin layers other than the high
crystallinity and low crystallinity layer can also be adapted for
melt adhesion onto a substrate.
[0254] Non-polymeric additives that can be added to one or more
layers include, 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, and combinations of two or more of these
materials. Other additives, which may be employed to enhance
properties, include anti-blocking and coloring agents. 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 exemplary lists provided above are not exhaustive of
the various kinds and types of additives that can be employed with
the present invention.
[0255] The overall thickness of the article is not particularly
limited, but is typically less than 20 mil, often less than 10 mil.
The thickness of any of the individual layers can vary widely, and
are typically determined by process, use and economic
considerations.
Low Crystallinity Layer
[0256] The low crystallinity layer has a level of crystallinity
that can be detected by Differential Scanning Calorimetry (DSC),
but it has elastomeric properties. The low crystallinity layer does
not have substantial loss of its elastic properties, even after
extension of the high crystallinity layer to and beyond the point
of plastic deformation. The low crystallinity layer often comprises
a low crystallinity polymer and, optionally, at least one
additional polymer. Typically, the low crystallinity layer(s)
comprises at least about 40, preferably at least about 50, more
preferably at least about 60, preferably at least about 80 and up
to about 98 weight percent of the total weight of the high and low
crystallinity polymers.
Low Crystallinity Polymer
[0257] The low crystallinity polymer of the present invention is a
soft, elastic polymer that often has a low to moderate level of
crystallinity. In a particular embodiment, the low crystallinity
polymer is an ethylene/.alpha.-olefin multi-block interpolymers
employed in the present invention are a unique class of compounds
that are further defined and discussed in copending PCT Application
No. PCT/US2005/008917, filed on Mar. 17, 2005 and published on Sep.
29, 2005 as WO/2005/090427, which in turn claims priority to U.S.
Provisional Application No. 60/553,906, filed Mar. 17, 2004. The
low crystallinity polymer may also be a copolymer of propylene and
one or more comonomers selected from ethylene, C4-C12
alpha-olefins, and combinations of two or more such comonomers. In
a particular aspect of this embodiment, the low crystallinity
polymer includes units derived from the one or more comonomers in
an amount ranging from a lower limit of about 2%, 5%, 6%, 8%, or
10% by weight to an upper limit of about 60%, 50%, or 45% by
weight. These percentages by weight are based on the total weight
of the ethylene-derived and comonomer-derived units, i.e., based on
the sum of weight percent ethylene-derived units and weight percent
comonomer-derived units equaling 100%.
[0258] Embodiments of the invention include low crystallinity
polymers having a heat of fusion, as determined by DSC, ranging
from a lower limit of about 1 Joules/gram (J/g), or 3 J/g, or 5
J/g, or 10 J/g, or 15 J/g, to an upper limit of about 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. "Heat of fusion" is measured using DSC.
[0259] The crystallinity of the low crystallinity polymer may also
be expressed in terms of crystallinity percent. The thermal energy
for 100% crystalline polypropylene is taken to be 165 J/g., and for
100% crystalline polyethylene is 292 J/gm. That is, 100%
crystallinity is taken as being equal to 165 J/g for polypropylene
and 292 J/gm for polyethylene.
[0260] The level of crystallinity may be reflected in the melting
point. "Melting point" is determined by DSC as previously
discussed. The low crystallinity polymer, according to an
embodiment of the invention has one or more melting points. The
peak having the highest heat flow (i.e., tallest peak height) of
these peaks is considered the melting point. The low crystallinity
polymer can have a melting point determined by DSC ranging from an
upper limit of about 135 C, or 130 C, to a lower limit of about 20
C, or 25 C, or 30 C, or 35 C, or 40 C or 45 C. The low
crystallinity polymer can have a crystallization peak temperature
determined by DSC ranging from an upper limit of about 120 C, or
110 C, to a lower limit of about 0 C, 30 C, or 50 C, or 60 C.
[0261] The low crystallinity polymer can have a weight average
molecular weight (Mw) of from about 10,000 to about 5,000,000
g/mol, or from about 20,000 to about 1,000,000 g/mol, or from about
80,000 to about 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 about 1.5 or 1.8 to an upper
limit of about 40 or 20 or 10 or 5 or 3.
[0262] In some embodiments of the invention, the low crystallinity
polymer has a Mooney viscosity ML(1+4)125 C of about 100 or less,
or 75 or less, or less, or 30 or less. Mooney viscosity is measured
as ML(1+4)125.degree. C. according to ASTM D1646 unless otherwise
specified.
[0263] Additional Polymers
[0264] In some embodiments, the low crystallinity layer optionally
comprises one or more additional polymers. The optional additional
polymer can be the same or different from the high crystallinity
polymer of the high crystallinity layer. In a particular
embodiment, the additional polymer has a crystallinity between the
crystallinity of the low crystallinity polymer and the high
crystallinity polymer.
[0265] In a particular embodiment, the low crystallinity layer is a
blend comprising a continuous phase including the low crystallinity
polymer described above and a dispersed phase including a
relatively more crystalline additional polymer. Minor amounts of
the additional polymer may be present in the continuous phase. In a
particular aspect of this embodiment, the dispersed phase is
composed of individual domains less than 50 microns in diameter. In
some embodiments, these individual domains of the dispersed phase
can be maintained during processing even without cross-linking.
[0266] In one embodiment, the additional polymer is a propylene
copolymer of ethylene, a C4-C20 .alpha.-olefin, or combinations
thereof, wherein the amount of ethylene and/or C4-C20
.alpha.-olefin(s) present in the additional polymer is less than
the amount of ethylene and/or C4-C20 .alpha.-olefin(s) present in
the low crystallinity polymer.
[0267] In one embodiment, the low crystallinity layer is a blend
comprising from about 2% to about 95% by weight of an additional
polymer and from about 5% to about 98% by weight of the low
crystallinity polymer based on the total weight of the blend, in
which the additional polymer is more crystalline than the low
crystallinity polymer. In a particular aspect of this embodiment,
the additional polymer is present in the blend in an amount of from
a lower limit of about 2% or 5% to an upper limit of about 30% or
20% or 15% by weight based on the total weight of the blend.
[0268] High Crystallinity Layer
[0269] The high crystallinity layer has a level of crystallinity
sufficient to permit yield and plastic deformation during
elongation and/or to have non-tacky or non-blocky characteristics.
The high crystallinity layer can be oriented in the machine, cross
(transverse) or oblique direction only, or in two or more of these
directions as can be detected by microscopy. The orientation can
lead to subsequent frangibility of the high crystallinity layer.
Typically, the high crystallinity layer(s) comprises less than
about 60, preferably less than about 50, more preferably less than
about 40, and can be as low as about 2 weight percent of the total
weight of the high and low crystallinity layers.
[0270] High Crystallinity Polymer
[0271] The high crystallinity layer often includes a high
crystallinity polymer. The high crystallinity polymers of the
present invention are defined as polymeric components, including
blends, that include homopolymers or copolymers of ethylene or
propylene or an alpha-olefin having 12 carbon atoms or less with
minor olefinic monomers that include linear, branched, or
ring-containing C3 to C30 olefins, capable of insertion
polymerization, or combinations of such olefins. In one embodiment,
the amount of alpha-olefin in the copolymer has an upper range of
about 9 wt %, or 8 wt %, or 6 wt %, and a lower range of about 2 wt
%, based on the total weight of the high crystallinity polymer.
[0272] Examples of minor olefinic monomers include, but are not
limited to C2 to C20 linear or branched alpha-olefins, such as
ethylene, propylene, 1-butene, 1-hexene, 1-octene,
4-methyl-1-pentene, 3-methyl-1-pentene, and
3,5,5-trimethyl-1-hexene, and ring-containing olefinic monomers
containing up to 30 carbon atoms such as cyclopentene,
vinylcyclohexane, vinylcyclohexene, norbornene, and methyl
norbornene.
[0273] Suitable aromatic-group-containing monomers can contain up
to 30 carbon atoms and can comprise at least one aromatic
structure, such as a phenyl, indenyl, fluorenyl, or naphthyl
moiety. The aromatic-group-containing monomer further includes at
least one polymerizable double bond such that after polymerization,
the aromatic structure will be pendant from the polymer backbone.
The polymerizable olefinic moiety of the aromatic-group containing
monomer can be linear, branched, cyclic-containing, or a mixture of
these structures. When the polymerizable olefinic moiety contains a
cyclic structure, the cyclic structure and the aromatic structure
can share 0, 1, or 2 carbons. The polymerizable olefinic moiety
and/or the aromatic group can also have from one to all of the
hydrogen atoms substituted with linear or branched alkyl groups
containing from 1 to 4 carbon atoms. Examples of aromatic monomers
include, but are not limited to styrene, alpha-methylstyrene,
vinyltoluenes, vinylnaphthalene, allyl benzene, and indene,
especially styrene and allyl benzene.
[0274] In one embodiment, the high crystallinity polymer is a
homopolymer or copolymer of polypropylene with isotactic propylene
sequences or mixtures of such sequences. The polypropylene used can
vary widely in form. The propylene component may be a combination
of homopolymer polypropylene, and/or random, and/or block
copolymers. In a particular embodiment, the high crystallinity
polymer is copolymer of propylene and one or more comonomers
selected from ethylene and C4 to C12 .alpha.-olefins. In a
particular aspect of this embodiment, the comonomer is present in
the copolymer in an amount of up to about 9% by weight, or from
about 2% to about 8% by weight, or from about 2% to about 6% by
weight, based on the total weight of the copolymer.
[0275] In another embodiment, the high crystallinity polymer is a
homopolymer or copolymer of ethylene and one or more comonomers
selected from C3 to C20 .alpha.-olefins. In a particular aspect of
this embodiment, the comonomer is present in the copolymer in an
amount of from about 0.5 wt % to about 25 wt % based on the total
weight of the copolymer.
[0276] In certain embodiments of the invention, the high
crystallinity polymer has a weight average molecular weight (Mw) of
from about 10,000-5,000,000 g/mol, or from about 20,000-1,000,000
g/mol, or from about 80,000-500,000 g.mu.mol and a molecular weight
distribution Mw/Mn (sometimes referred to as a "polydispersity
index" (PDI)) ranging from a lower limit of about 1.5-1.8 to an
upper limit of about 40 or 20 or 10 or 5 or 3.
[0277] In one embodiment, the high crystallinity polymer is
produced with metallocene catalysis and displays narrow molecular
weight distribution, meaning that the ratio of the weight average
molecular weight to the number average molecular weight will be
equal to or below about 4, most typically in the range of from
about 1.7-4.0, preferably from about 1.8-2.8.
[0278] In another embodiment, the high crystallinity polymer is
produced with a single site catalysis, although non-metallocene,
and displays narrow molecular weight distribution, meaning that the
ratio of the weight average molecular weight to the number average
molecular weight will be equal to or below about 4, most typically
in the range of from about 1.7-4.0, preferably from about
1.8-2.8.
[0279] In another embodiment, the high crystallinity polymer is
produced with a Ziegler-Natta or chrome catalysis, and displays
medium to broad molecular weight distribution, meaning that the
ratio of the weight average molecular weight to the number average
molecular weight will be equal to or below about 60, most typically
in the range of from about 3.5-20, preferably from about 3.5-8.
[0280] The high crystallinity polymers of the present invention can
optionally contain long chain branches. These can optionally be
generated using one or more .quadrature.,.quadrature.-dienes.
Alternatively, the high crystallinity polymer may contain small
quantities of at least one diene, and preferably at least one of
the dienes is a non-conjugated diene to aid in the vulcanization or
other chemical modification. The amount of diene is preferably no
greater than about 10 wt %, more preferably no greater than about 5
wt %. Preferred dienes are those that are used for the
vulcanization of ethylene/propylene rubbers including, but not
limited to, ethylidene norbornene, vinyl norbornene,
dicyclopentadiene, and 1,4-hexadiene.
[0281] Embodiments of the invention include high crystallinity
polymers having a heat of fusion, as determined by DSC, with a
lower limit of about 60 J/g, or 80 J/g. In one embodiment, the high
crystallinity polymer has a heat of fusion higher than the heat of
fusion of the low crystallinity polymer.
[0282] Embodiments of the invention include high crystallinity
polymers having a melting point with a lower limit of about 70 C,
90 C, 100 C, or 110 C, or 115 C, or 120 C, or 130 C, and can be as
high as about 300 C.
[0283] In one embodiment, the high crystallinity polymer has a
higher crystallinity than the low crystallinity polymer. The degree
of crystallinity can be determined based on the heat of fusion or
density of the polymer components. In one embodiment, the low
crystallinity polymer has a lower melting point than the high
crystallinity polymer, and the additional polymer, if used, has a
melting point between that of the low crystallinity polymer and
that of the high crystallinity polymer. In another embodiment, the
low crystallinity polymer has a lower heat of fusion than that of
the high crystallinity polymer, and the additional polymer, if
used, has a heat of fusion intermediate of the low crystallinity
polymer and the high crystallinity polymer.
[0284] Compatible Crystallinity
[0285] In some embodiments the low crystallinity polymer and high
crystallinity polymer have compatible crystallinity. Compatible
crystallinity can be obtained by using polymers for the high
crystallinity and low crystallinity layers that have the same
crystallinity type, i.e., based on the same crystallizable
sequence, such as ethylene sequences or propylene sequences, or the
same stereo-regular sequences, i.e., isotactic or syndiotactic. For
example, compatible crystallinity can be achieved by providing both
layers with methylene sequences of sufficient length, as is
achieved by the incorporation of ethylene derived units.
[0286] Compatible crystallinity can also be obtained by using
polymers with stereo-regular alpha-olefin sequences. This may be
achieved, for example, by providing either syndiotactic sequences
or isotactic sequences in both layers.
[0287] For purposes of this invention, isotactic refers to a
polymer sequence in which greater than 50% of adjacent monomers
which have groups of atoms that are not part of the backbone
structure are located either all above or all below the atoms in
the backbone chain, when the latter are all in one plane.
[0288] For purposes of this invention, syndiotactic refers to a
polymer sequence in which greater than 50% of adjacent monomers
which have groups of atoms that are not part of the backbone
structure are located in a symmetrical fashion above and below the
atoms in the backbone chain, when the latter are all in one
plane.
Fiber Applications
[0289] The polymers, layers, and articles of this invention have
many useful applications. Representative examples in addition to
those that are described elsewhere include mono- and multifilament
fibers, staple fibers, binder fibers, spunbond fibers or melt blown
fibers (using, e.g., systems as disclosed in U.S. Pat. No.
4,430,563, 4,663,220, 4,668,566 or 4,322,027), both woven and
nonwoven fabrics, strapping, tape, monofilament, continuous
filament (e.g., for use in apparel, upholstery) and structures made
from such fibers (including, e.g., blends of these fibers with
other fibers such as PET or cotton. Staple and filament fibers can
be melt spun into the final fiber diameter directly without
additional drawing, or they can be melt spun into a higher diameter
and subsequently hot or cold drawn to the desired diameter using
conventional fiber drawing techniques.
Crosslinking
[0290] Any of the polymers used in any layer of these inventions
can be used in essentially the same manner as known polyolefins for
the making and using of elastic fibers. In this regard, the
polymers used this invention can include functional groups, such as
a carbonyl, sulfide, silane radicals, etc., and can be crosslinked
or uncrosslinked. If crosslinked, the polymers can be crosslinked
using known techniques and materials with the understanding that
not all crosslinking techniques and materials are effective on all
polyolefins, e.g., while peroxide, azo and electromagnetic
radiation (such as e-beam, UV, IR and visible light) techniques are
all effective to at least a limited extent with polyethylenes, only
some of these, e.g., e-beam, are effective with polypropylenes and
then not necessarily to the same extent as with polyethylenes. The
use of additives, promoters, etc., can be employed as desired.
[0291] "Substantially crosslinked" and similar terms generally mean
that the polymer, shaped or in the form of an article, has xylene
extractables of less than or equal to 70 weight percent (i.e.,
greater than or equal to 30 weight percent gel content), preferably
less than or equal to 40 weight percent (i.e., greater than or
equal to 60 weight percent gel content). Xylene extractables (and
gel content) are determined in accordance with ASTM D-2765.
[0292] The elastic fibers, layers or polymers used in this
invention can be cross-linked by any means known in the art,
including, but not limited to, electron-beam irradiation, beta
irradiation, gamma irradiation, corona irradiation, silanes,
peroxides, allyl compounds and UV radiation with or without
crosslinking catalyst. U.S. patent application Ser. No. 10/086,057
(published as US2002/0132923 A1) and U.S. Pat. No. 6,803,014
disclose electron-beam irradiation methods that can be used in
embodiments of the invention. If crosslinking is to be employed on
an article. the article is usually shaped before it is
cross-linked.
[0293] Irradiation may be accomplished by the use of high energy,
ionizing electrons, ultra violet rays, X-rays, gamma rays, beta
particles and the like and combination thereof. Preferably,
electrons are employed up to 70 megarads dosages. The irradiation
source can be any electron beam generator operating in a range of
about 150 kilovolts to about 6 megavolts with a power output
capable of supplying the desired dosage. The voltage can be
adjusted to appropriate levels which may be, for example, 100,000,
300,000, 1,000,000 or 2,000,000 or 3,000,000 or 6,000,000 or higher
or lower. Many other apparati for irradiating polymeric materials
are known in the art. The irradiation is usually carried out at a
dosage between about 3 megarads to about 35 megarads, preferably
between about 8 to about 20 megarads. Further, the irradiation can
be carried out conveniently at room temperature, although higher
and lower temperatures, for example 0.degree. C. to about
60.degree. C., may also be employed. Preferably, the irradiation is
carried out after shaping or fabrication of the article. Also, in a
preferred embodiment, the ethylene interpolymer which has been
incorporated with a pro-rad additive is irradiated with electron
beam radiation at about 8 to about 20 megarads.
[0294] Crosslinking can be promoted with a crosslinking catalyst,
and any catalyst that will provide this function can be used.
Suitable catalysts generally include organic bases, carboxylic
acids, and organometallic compounds including organic titanates and
complexes or carboxylates of lead, cobalt, iron, nickel, zinc and
tin. Dibutyltindilaurate, dioctyltinmaleate, dibutyltindiacetate,
dibutyltindioctoate, stannous acetate, stannous octoate, lead
naphthenate, zinc caprylate, cobalt naphthenate; and the like. Tin
carboxylate, especially dibutyltindilaurate and dioctyltinmaleate,
are particularly effective for this invention. The catalyst (or
mixture of catalysts) is present in a catalytic amount, typically
between about 0.015 and about 0.035 phr.
[0295] Representative pro-rad additives include, but are not
limited to, azo compounds, organic peroxides and polyfunctional
vinyl or allyl compounds such as, for example, triallyl cyanurate,
triallyl isocyanurate, pentaerthritol tetramethacrylate,
glutaraldehyde, ethylene glycol dimethacrylate, diallyl maleate,
dipropargyl maleate, dipropargyl monoallyl cyanurate, dicumyl
peroxide, di-tert-butyl peroxide, t-butyl perbenzoate, benzoyl
peroxide, cumene hydroperoxide, t-butyl peroctoate, methyl ethyl
ketone peroxide, 2,5-dimethyl-2,5-di(t-butyl peroxy)hexane, lauryl
peroxide, tert-butyl peracetate, azobisisobutyl nitrite and the
like and combination thereof. Preferred pro-rad additives for use
in the present invention are compounds which have poly-functional
(i.e. at least two) moieties such as C.dbd.C, C.dbd.N or
C.dbd.O.
[0296] At least one pro-rad additive can be introduced to the
ethylene interpolymer by any method known in the art. However,
preferably the pro-rad additive(s) is introduced via a masterbatch
concentrate comprising the same or different base resin as the
ethylene interpolymer. Preferably, the pro-rad additive
concentration for the masterbatch is relatively high e.g., about 25
weight percent (based on the total weight of the concentrate).
[0297] The at least one pro-rad additive is introduced to the
ethylene polymer in any effective amount. Preferably, the at least
one pro-rad additive introduction amount is from about 0.001 to
about 5 weight percent, more preferably from about 0.005 to about
2.5 weight percent and most preferably from about 0.015 to about 1
weight percent (based on the total weight of the ethylene
interpolymer.
[0298] In addition to electron-beam irradiation, crosslinking can
also be effected by UV irradiation. U.S. Pat. No. 6,709,742
discloses a cross-linking method by UV irradiation which can be
used in embodiments of the invention. The method comprises mixing a
photoinitiator, with or without a photocrosslinker, with a polymer
before, during, or after a fiber is formed and then exposing the
fiber with the photoinitiator to sufficient UV radiation to
crosslink the polymer to the desired level. The photoinitiators
used in the practice of the invention are aromatic ketones, e.g.,
benzophenones or monoacetals of 1,2-diketones. The primary
photoreaction of the monacetals is the homolytic cleavage of the
.alpha.-bond to give acyl and dialkoxyalkyl radicals. This type of
.alpha.-cleavage is known as a Norrish Type I reaction which is
more fully described in W. Horspool and D. Armesto, Organic
Photochemistry: A Comprehensive Treatment, Ellis Horwood Limited,
Chichester, England, 1992; J. Kopecky, Organic Photochemistry: A
Visual Approach, VCH Publishers, Inc., New York, N.Y. 1992; N. J.
Turro, et al., Acc. Chem. Res., 1972, 5, 92; and J. T. Banks, et
al., J. Am. Chem. Soc., 1993, 115, 2473. The synthesis of
monoacetals of aromatic 1,2 diketones, Ar--CO--C(OR).sub.2--Ar' is
described in U.S. Pat. Nos. 4,190,602 and Ger. Offen. 2,337,813.
The preferred compound from this class is
2,2-dimethoxy-2-phenylacetophenone,
C.sub.6H.sub.5--CO--C(OCH.sub.3).sub.2--C.sub.6H.sub.5, which is
commercially available from Ciba-Geigy as Irgacure 651. Examples of
other aromatic ketones useful in the practice of this invention as
photoinitiators are Irgacure 184, 369, 819, 907 and 2959, all
available from Ciba-Geigy.
[0299] In one embodiment, the photoinitiator is used in combination
with a photocrosslinker. Any photocrosslinker that will upon the
generation of free radicals, link two or more polyolefin backbones
together through the formation of covalent bonds with the backbones
can be used in this invention. Preferably these photocrosslinkers
are polyfunctional, i.e., they complise two or more sites that upon
activation will form a covalent bond with a site on the backbone of
the polymer. Representative photocrosslinkers include, but are not
limited to polyfunctional vinyl or allyl compounds such as, for
example, triallyl cyanurate, triallyl isocyanurate, pentaerthritol
tetramethacrylate, ethylene glycol dimethacrylate, diallyl maleate,
dipropargyl maleate, dipropargyl monoallyl cyanurate and the like.
Preferred photocrosslinkers for use in the present invention are
compounds which have polyfunctional (i.e. at least two) moieties.
Particularly preferred photocrosslinkers are triallycyanurate (TAC)
and triallylisocyanurate (TAIC).
[0300] Certain compounds act as both a photoinitiator and a
photocrosslinker in the practice of this invention. These compounds
are characterized by the ability to generate two or more reactive
species (e.g., free radicals, carbenes, nitrenes, etc.) upon
exposure to UV-light and to subsequently covalently bond with two
polymer chains. Any compound that can preform these two functions
can be used in the practice of this invention, and representative
compounds include the sulfonyl azides described in U.S. Pat. Nos.
6,211,302 and 6,284,842.
[0301] In another embodiment, the polymer, layer, or article is
subjected to secondary crosslinking, i.e., crosslinking other than
and in addition to photocrosslinking. In this embodiment, the
photoinitiator is used either in combination with a
nonphotocrosslinker, e.g., a silane, or the polymer is subjected to
a secondary crosslinking procedure, e.g, exposure to E-beam
radiation. Representative examples of silane crosslinkers are
described in U.S. Pat. No. 5,824,718, and crosslinking through
exposure to E-beam radiation is described in U.S. Pat. Nos.
5,525,257 and 5,324,576. The use of a photocrosslinker in this
embodiment is optional.
[0302] At least one photoadditive, i.e., photoinitiator and
optional photocrosslinker, can be introduced to the polymer by any
method known in the alt. However, preferably the photoadditive(s)
is (are) introduced via a masterbatch concentrate comprising the
same or different base resin as the polymer. Preferably, the
photoadditive concentration for the masterbatch is relatively high
e.g., about 25 weight percent (based on the total weight of the
concentrate).
[0303] The at least one photoadditive is introduced to the polymer
in any effective amount. Preferably, the at least one photoadditive
introduction amount is from about 0.001 to about 5, more preferably
from about 0.005 to about 2.5 and most preferably from about 0.015
to about 1, wt % (based on the total weight of the polymer).
[0304] The photoinitiator(s) and optional photocrosslinker(s) can
be added during different stages of the manufacturing process. If
photoadditives can withstand the extrusion temperature, a
polyolefin resin can be mixed with additives before being fed into
the extruder, e.g., via a masterbatch addition. Alternatively,
additives can be introduced into the extruder just prior the slot
die, but in this case the efficient mixing of components before
extrusion is important. In another approach, polyolefin fibers can
be drawn without photoadditives, and a photoinitiator and/or
photocrosslinker can be applied to the extruded fiber via a
kiss-roll, spray, dipping into a solution with additives, or by
using other industrial methods for post-treatment. The resulting
fiber with photoadditive(s) is then cured via electromagnetic
radiation in a continuous or batch process. The photo additives can
be blended with the polyolefin using conventional compounding
equipment, including single and twin-screw extruders.
[0305] The power of the electromagnetic radiation and the
irradiation time are chosen so as to allow efficient crosslinking
without polymer degradation and/or dimensional defects. The
preferred process is described in EP 0 490 854 B1. Photoadditive(s)
with sufficient thermal stability is (are) premixed with a
polyolefin resin, extruded into a fiber, and irradiated in a
continuous process using one energy source or several units linked
in a series. There are several advantages to using a continuous
process compared with a batch process to cure a fiber or sheet of a
knitted fabric which are collected onto a spool.
[0306] Irradiation may be accomplished by the use of UV-radiation.
Preferably, UV-radiation is employed up to the intensity of 100
J/cm.sup.2. The irradiation source can be any UV-light generator
operating in a range of about 50 watts to about 25000 watts with a
power output capable of supplying the desired dosage. The wattage
can be adjusted to appropriate levels which may be, for example,
1000 watts or 4800 watts or 6000 watts or higher or lower. Many
other apparati for UV-irradiating polymeric materials are known in
the art. The irradiation is usually carried out at a dosage between
about 3 J/cm.sup.2 to about 500 J/scm.sup.2, preferably between
about 5 J/cm.sup.2 to about 100 J/cm.sup.2. Further, the
irradiation can be carried out conveniently at room temperature,
although higher and lower temperatures, for example 0.degree. C. to
about 60.degree. C., may also be employed. The photocrosslinking
process is faster at higher temperatures. Preferably, the
irradiation is carried out after shaping or fabrication of the
article. In a preferred embodiment, the polymer which has been
incorporated with a photoadditive is irradiated with UV-radiation
at about 10 J/cm.sup.2 to about 50 j/cm.sup.2.
[0307] Applications of the Article
[0308] The articles of the present invention may be used in a
variety of applications. These include those applications and
manufacturing techniques described in U.S. Pat. No. 5,514,470 and
U.S. Pat. No. 5,336,545. In one embodiment, the article is a film
having at least two layers, which can be used in diaper back-sheets
and similar absorbent garments such as incontinent garments. In
other embodiments, the article is in the form of a woven or
nonwoven fabric, film/fabric laminate or fiber. The fabric may be
woven or non-woven. The fiber can be of any size or shape, and it
can be homogeneous or heterogeneous. If heterogeneous, then it can
be either conjugate, bicomponent or biconstituent.
[0309] The core layer or layers of the film of this invention
comprise a low crystalline ethylene/alpha-olefin multi-block
copolymer. If the film of this invention comprises two or more core
layers, then the composition of each core layer can be the same or
different from the composition of the other core layer(s).
[0310] The skin layers of the film of this invention comprise a
high crystalline, preferably non-tacky polyolefin homo- or
copolymer. The composition of each skin layer can be the same or
different from the composition of the other skin layer(s).
[0311] Preferably, the particular combination of core and skin
layers is chosen to insure that the melting point of the skin
polymer is not more than about 24 C greater, preferably not more
than about 20 C greater, than the melting point of the core polymer
with the lowest melting point.
Ethylene/.alpha.-Olefin Multi-Block Interpolymer Component(s)
[0312] The articles of the present invention comprise an
ethylene/.alpha.-olefin multi-block interpolymer. The
ethylene/.alpha.-olefin multi-block interpolymer may be contained
in the low crystallinity layer, the high crystallinity layer, or
some other part of the article. The ethylene/.alpha.-olefin
multi-block interpolymer may be present alone or in a blend with
any other polymer.
[0313] The ethylene/.alpha.-olefin multi-block interpolymers
employed in the present invention are a unique class of compounds
that are further defined and discussed in copending PCT Application
No. PCT/US2005/008917, filed on Mar. 17, 2005 and published on Sep.
29, 2005 as WO/2005/090427, which in turn claims priority to U.S.
Provisional Application No. 60/553,906, filed Mar. 17, 2004. For
purposes of United States patent practice, the contents of the
provisional application and the PCT application are herein
incorporated by reference in their entirety.
SPECIFIC EMBODIMENTS
[0314] Melt Flow Rate (MFR) and Melt Index (MI), as used herein,
were measured by ASTM D-1238 at 23.degree. C. and 190 C,
respectively, and both measurements used weight of 2.16 kg.
[0315] Blends of low crystallinity polymer and high crystallinity
polymer and other components may be prepared by any procedure that
guarantees an intimate mixture of the components. For example, the
components can be combined by melt pressing the components together
on a Carver press to a thickness of about 0.5 millimeter (20 mils)
and a temperature of about 180 C, rolling up the resulting slab,
folding the ends together, and repeating the pressing, rolling, and
folding operation about 10 times. Internal mixers are particularly
useful for solution or melt blending. Blending at a temperature of
about 180-240 C in a Brabender Plastograph for about 1-20 minutes
has been found satisfactory.
[0316] Still another method that may be used for admixing the
components involves blending the polymers in a Banbury internal
mixer above the flux temperature of all of the components, e.g.,
about 180 C for about 5 minutes. A complete mixture of the
polymeric components is indicated by the uniformity of the
morphology of the dispersion of low crystallinity polymer and high
crystallinity polymer. Continuous mixing may also be used. These
processes are well known in the art and include single and twin
screw mixing extruders, static mixers for mixing molten polymer
streams of low viscosity, impingement mixers, as well as other
machines and processes, designed to disperse the low crystallinity
polymer and the high crystallinity polymer in intimate contact.
Those skilled in the art will be able to determine the appropriate
procedure for blending of the polymers to balance the need for
intimate mixing of the component ingredients with the desire for
process economy. Still another method for admixing the components
of blends using a Haake mixer above the flux temperature of all of
the components, (e.g. 180.degree. C. and set at 40 rpm rotor speed
for about 3-5 minutes until torque reaches steady state). The
sample can then be removed and allowed to cool.
[0317] Blend components are selected based on the morphology
desired for a given application. The high crystallinity polymer can
be co-continuous with the low crystallinity polymer in the film
formed from the blend, however, a dispersed high crystallinity
polymer phase in a continuous low crystallinity polymer phase is
preferred. Those skilled in the art can select the volume fractions
of the two components to produce a dispersed high crystallinity
polymer morphology in a continuous low crystallinity polymer matrix
based on the viscosity ratio of the components (see S. Wu, Polymer
Engineering and Science, Vol. 27, Page 335, 1987).
Other Examples of the Invention
[0318] The below examples show how the present invention may be
implemented. The ratios described in the following examples are in
weight percentages, unless otherwise specified.
Example AA
Multi-Layer Pre-Stretched Elastic Films
[0319] Layer A--80/20 DOWLEX* 2045 (ethylene/1-octene
heterogeneously branched copolymer having a melt index of about 1
g/10 min (MI), density of about 0.92 g/cc, Tm of about 122.degree.
C.)/LDPE 132 (high pressure ethylene homopolymer having melt index
of about 0.22 g/10 min (MI), 0.922 g/cc, Tm of about 108.degree.
C.), a blended composition melting peak temperature of about
122.degree. C. (DOWLEX* is a trademark of The Dow Chemical
Company).
[0320] Layer B--Ethylene/1-octene Multi-block copolymer, Overall
density of about 0.87 g/cc, melt index of about 1 g/10 min., zinc
content of about 250 ppm (diethyl zinc is used as the chain
shuttling agent), melting peak temperature of about 115.degree. C.
to 125.degree. C., typically about 119-120.degree. C.
[0321] Layer C--Same as layer (A).
[0322] Layer ratios--5/90/5 or 10/90/10.
[0323] The film is made using co-extrusion using a blown film
process at a blow up ratio of about 3:1 and a melt temperature of
about 450.degree. F., die gap of about 90 mils, to a thickness of
about 5 mil. The film is pre-stretched to 400% elongation using set
of MDO draw rolls and relaxed to a very low tension to allow
substantial elastic recovery before winding up on a roll. This
pre-stretched elastic film is the inventive example. The lower wt %
of skin layers are preferred for enhanced elasticity performance of
the film.
Example BB
Multi-Layer Pre-Stretched Elastic Laminate
[0324] Layer A--80/20 DOWLEX 2247 (an ethylene/1-octene copolymer
(heterogeneously branched LLDPE) having melt index of about 2.3
g/10 min. (MI), density of about 0.917 g/cc, a Tm of about
122.degree. C.)/LDPE 501 (high pressure ethylene homopolymer having
melt index of about 2 g/10 min. (MI), density of about 0.922 g/cc,
Tm of about 108.degree. C.), the blended composition having a
melting peak temperature of about 122.degree. C.
[0325] Layer B--Ethylene/1-octene Multi-block copolymer, Overall
density=0.87 g/cc, melt index of about 2.5 g/10 min., zinc content
of about 250 ppm (diethyl zinc is used as the chain shuttling
agent), Melting peak temperature of about 115.degree. C. to
125.degree. C., typically about 119-120.degree. C.
[0326] Layer C--Same as layer (A).
[0327] Layer ratios--5/90/5 or 10/90/10.
[0328] The film is made using co-extrusion by casting a melt
curtain onto a perforated drum and drawing vacuum inside the drum
to create holes in the film. A polypropylene spunbond fabric of
about 20 grams/square meter basis weight point bonded with about
20% of the area bonded. made from either Ziegler-Natta or
metallocene polypropylene homopolymer or copolymer, is nipped in to
the melt curtain from the other side. Another polypropylene
spunbond fabric is adhesively laminated to the film side to make
spunbond/multi-layer film/spunbond laminate. This laminate is then
processed through a ring-rolling process (set of gears) to stretch
the laminate either in machine direction (MD) or cross direction
(CD) or both to a strain necessary for achieving the desired
elastic property (typically above about 100% strain). This
ring-rolled elastic laminate is then wound up on a roll and is
useful as an elastic component for hygiene articles such as
diapers.
Example CC
Multi-Layer Elastic Laminate
[0329] Two polypropylene based spunbond fabric having about 20
grams/square meter basis weight, made from either Ziegler-Natta or
metallocene polypropylene homopolymer or copolymer, is
pre-stretched in MD to about 100 to 150% elongation after
pre-heating the spunbond fabric to about 90 to 130.degree. C. This
results in a "necked" spunbond fabric, being necked in the CD. An
ethylene multi-block copolymer having overall density of about 0.87
g/cc, a melt index of about 5 g/10 min., and a zinc level of about
250 ppm (diethyl zinc is used as the chain shuttling agent), and
melting peak temperature of about 115.degree. C. to about
125.degree. C. is extrusion coated at about 2 mil thickness on to
this necked spunbond with other necked spunbond brought into light
contact from the other side using a nip-roll. This elastic laminate
is then cooled and wound up on a roll. This laminate exhibits
elastic recovery upon stretching in the CD, and is useful as
elastic component of a hygiene article such as a diaper.
Example DD
Multi-Layer Elastic Laminate
[0330] A row of fibers having a diameter of about 500-1000 denier
comprising an ethylene multi-block ethylene/1-octene copolymer
having overall density of 0.87 g/cc, melt index of about 10 g/10
min., a zinc level of about 250 ppm (diethyl zinc is used as the
chain shuttling agent), and melting peak temperature of about
115-125.degree. C. is extruded onto a moving belt. A small layer
(5-10% by weight of the final fibrous composite) of melt blown
fabric (nominal fiber diameter of about 10 microns), made from
elastic styrenic block copolymer formulation such as
Styrene-ethylene/butene-styrene (SEBS) formulation, is applied to
these fibers on-line. The resultant elastic composite fibrous
structure is stretched on-line to about 500% elongation.
Polypropylene based spunbond layers having about 20 grams/square
meter basis weight, made from either Ziegler-Natta or metallocene
polypropylene homopolymer or copolymer, are point bonded with about
20% of the area bonded on either side of this stretched fibrous
structure using ultrasonic bonding. This stretched elastic laminate
is relaxed to a very low tension to allow substantial recovery
before winding up on a roll. Any suitable thermoplastic elastomer
having desired high melt flow rate or melt index could be used for
the melt blown layer. Such laminates are useful for elastic
components of hygiene or medical articles such as side panels of
training pants.
[0331] While the illustrative embodiments of the invention have
been described with particularity, 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, the scope of the following claims are not limited to
the examples and descriptions. Rather the claims are to be
construed as encompassing all the features of patentable novelty
that reside in the present invention, including all features which
would be treated as equivalents of these features by those skilled
in the art to which the invention pertains.
[0332] When numerical lower limits and numerical upper limits are
listed above, ranges from any lower limit to any upper limit are
contemplated. All issued U.S. patents and allowed U.S. patent
applications cited above are incorporated herein by reference.
* * * * *
References