U.S. patent application number 09/828779 was filed with the patent office on 2001-10-04 for polymer blend.
This patent application is currently assigned to Sentinel Products, Corp.. Invention is credited to Bambara, John D., Cagwin, Todd, Hurley, Robert F., Kozma, Matthew L..
Application Number | 20010027221 09/828779 |
Document ID | / |
Family ID | 24688536 |
Filed Date | 2001-10-04 |
United States Patent
Application |
20010027221 |
Kind Code |
A1 |
Bambara, John D. ; et
al. |
October 4, 2001 |
Polymer blend
Abstract
The invention relates to polymer blends which can be used both
in foamed and unfoamed states as a replacement for conventional
EPDM and other elastomers. The composition of the blend includes a
single-site catalyzed polyolefin resin having a density of below
0.878 g cm.sup.-3 and up to 40 weight percent a polyolefin
including ethylene and propylene. The polymer blend is
cross-linked. The polymer blends are formable and foamable. The use
of sulfur to vulcanize the polymer blend is not necessary. The
polymer blends can be used to make foam for floatation or for
making gaskets.
Inventors: |
Bambara, John D.;
(Osterville, MA) ; Kozma, Matthew L.; (Osterville,
MA) ; Cagwin, Todd; (St. Johnsville, NY) ;
Hurley, Robert F.; (Centerville, MA) |
Correspondence
Address: |
JOHN W. FREEMAN
Fish & Richardson P.C.
225 Franklin Street
Boston
MA
02110
US
|
Assignee: |
Sentinel Products, Corp.
|
Family ID: |
24688536 |
Appl. No.: |
09/828779 |
Filed: |
April 10, 2001 |
Related U.S. Patent Documents
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09828779 |
Apr 10, 2001 |
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09468037 |
Dec 21, 1999 |
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6214894 |
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09468037 |
Dec 21, 1999 |
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08888431 |
Jul 7, 1997 |
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6004647 |
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08888431 |
Jul 7, 1997 |
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08669987 |
Jun 21, 1996 |
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5932659 |
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Current U.S.
Class: |
521/50 ; 521/134;
525/196; 525/197; 525/213 |
Current CPC
Class: |
C08L 23/16 20130101;
C08L 2205/035 20130101; C08L 23/0815 20130101; C08L 23/0869
20130101; C08L 2312/00 20130101; C08L 23/06 20130101; C08J 2425/00
20130101; C08J 2201/03 20130101; C08J 9/103 20130101; C08L 23/04
20130101; C08L 91/00 20130101; C08J 2323/02 20130101; C08L 2203/14
20130101; C08L 83/04 20130101; C08L 23/0853 20130101; C08F 255/00
20130101; C08L 2314/06 20130101; C08L 23/10 20130101; C08L 51/085
20130101; C08F 255/026 20130101; C08L 23/08 20130101; C08J 2323/16
20130101; C08J 9/0061 20130101; C08F 8/00 20130101; Y10T 428/215
20150115; C08J 9/04 20130101; C08F 255/02 20130101; C08J 2423/00
20130101; C08L 51/06 20130101; C08L 2205/02 20130101; C08L 23/08
20130101; C08L 2666/04 20130101; C08L 23/0815 20130101; C08L
2666/04 20130101; C08L 23/0815 20130101; C08L 2666/02 20130101;
C08F 8/00 20130101; C08F 210/02 20130101; C08L 23/04 20130101; C08L
83/00 20130101; C08L 23/06 20130101; C08L 2666/02 20130101; C08L
23/0815 20130101; C08L 2666/06 20130101; C08L 23/0815 20130101;
C08L 2666/24 20130101; C08L 23/0853 20130101; C08L 2666/02
20130101; C08L 23/10 20130101; C08L 83/00 20130101; C08L 23/10
20130101; C08L 2666/24 20130101; C08L 51/06 20130101; C08L 2666/02
20130101; C08L 51/085 20130101; C08L 2666/04 20130101; C08F 255/026
20130101; C08F 230/085 20200201 |
Class at
Publication: |
521/50 ; 521/134;
525/196; 525/197; 525/213 |
International
Class: |
C08L 023/18; C08L
023/26 |
Claims
What is claimed is:
1. A polymer blend comprising a single-site initiated polyolefin
resin having a density below 0.870 g cm.sup.-3 and up to 40 weight
percent of a polyolefin including ethylene and propylene, wherein a
portion of the polymer blend is cross-linked and the polymer blend
is formable.
2. The polymer blend of claim 1, wherein the polymer blend
comprises at least 5 percent of the single-site initiated
polyolefin resin and at least 5 percent of the polyolefin including
ethylene and propylene.
3. The polymer blend of claim 2, wherein the polyolefin including
ethylene and propylene is an ethylene-propylene-diene monomer
terpolymer.
4. The polymer blend of claim 3, further comprising less than about
70 weight percent of a second polyolefin resin.
5. The polymer blend of claim 4, wherein the second polyolefin
resin includes a polypropylene, a polyethylene, or a copolymer
containing ethylene or propylene.
6. The polymer blend of claim 5, wherein the polyethylene includes
a low density polyethylene, a linear low density polyethylene, a
medium density polyethylene, or a high density polyethylene.
7. The polymer blend of claim 6, wherein the copolymer includes an
ethylene-vinyl acetate copolymer, an ethylene-maleic anhydride
copolymer, or an ethylene-ethyl acetate copolymer.
8. The polymer blend of claim 1, wherein the polymer blend
comprises between about 5 and 95 weight percent of the single-site
initiated polyolefin resin and about 5 and 40.weight percent of the
polyolefin including ethylene and propylene.
9. The polymer blend of claim 8, wherein the polyolefin including
ethylene and propylene is an ethylene-propylene-diene monomer
terpolymer.
10. The polymer blend of claim 9, further comprising up to about 65
weight percent of a filler.
11. The polymer blend of claim 9, further comprising up to about 30
weight percent of an oil.
12. The polymer blend of claim 1, wherein the polymer blend is
foamed.
13. The polymer blend of claim 12, wherein the foamed polymer blend
has an average foam density between 1.5 and 25 pounds per cubic
foot.
14. A method of making a cross-linked polymer blend comprising the
steps of: providing a polymer mixture including a single-site
initiated polyolefin resin and up to 40 weight percent of a
polyolefin including ethylene and propylene; and cross-linking the
polymer mixture.
15. The method of claim 14, wherein the polymer mixture includes at
least 5 weight percent of the single-site initiated polyolefin
resin and at least 5 weight percent of the polyolefin including
ethylene and propylene.
16. The method of claim 15, wherein the polyolefin including
ethylene and propylene is an ethylene-propylene-diene monomer
terpolymer.
17. The method of claim 16, wherein the step of cross-linking the
polymer blend includes reacting the polymer blend with a
peroxide.
18. The method of claim 17, wherein the polymer mixture further
includes less than about 70 weight percent of a second polyolefin
resin.
19. The method of claim 18, wherein the second polyolefin resin
includes a polypropylene, a polyethylene, or a copolymer containing
ethylene or propylene.
20. The method of claim 19, wherein the polyethylene includes a low
density polyethylene, a linear low density polyethylene, a medium
density polyethylene, or a high density polyethylene.
21. The method of claim 19, wherein the copolymer includes an
ethylene-vinyl acetate copolymer, an ethylene-maleic anhydride
copolymer, or an ethylene-ethyl acetate copolymer.
22. The method of claim 17, wherein the polymer mixture includes
between about 5 and 95 weight percent of the single-site initiated
polyolefin resin and about 5 and 40 weight percent of the
ethylene-propylene-diene monomer terpolymer.
23. The method of claim 22, wherein the polymer mixture further
includes up to about 65 weight percent of a filler.
24. The method of claim 23, wherein the polymer mixture further
includes up to about 30 weight percent of an oil.
25. The method of claim 17, further comprising the step of
expanding the polymer mixture to form a foam.
26. The method of claim 25, wherein the foam has an average foam
density between 1.5 and 25 pounds per cubic foot.
27. The method of claim 25, wherein the step of expanding the
polymer mixture comprises compression molding the polymer mixture
at increased temperature and pressure.
28. The method of claim 27, wherein the compression molding
comprises the steps of pressing the polymer mixture using a high
tonnage press at a temperature of between 275 and 320.degree. F.
and a pressure of between 250 and 2500 psi for between 20 and 90
minutes followed by heating the polymer mixture at a temperature
between 300 and 380.degree. F.
29. The method of claim 28, wherein the step of heating the polymer
mixture further includes pressing the blend using a medium tonnage
press at a pressure of between 250 and 1500 psi.
30. A gasket comprising a polymer blend including a single-site
initiated polyolefin resin having a density below 0.870 g cm.sup.-3
and up to 40 weight percent of a polyolefin including ethylene and
propylene, wherein a portion of the polymer blend is cross-linked
and the gasket is thermally stable at 120.degree. F.
31. The gasket of claim 30, wherein the polymer blend comprises at
least 5 percent of the single-site initiated polyolefin resin and
at least 5 percent of the polyolefin including ethylene and
propylene.
32. The gasket of claim 31, wherein the polyolefin including
ethylene and propylene is an ethylene-propylene-diene monomer
terpolymer.
33. The gasket of claim 32, further comprising less than about 70
weight percent of a second polyolefin resin.
34. The gasket of claim 33, wherein the second polyolefin resin
includes a polypropylene, a polyethylene, or a copolymer containing
ethylene or propylene.
35. The gasket of claim 31, wherein the polymer blend comprises
between about 5 and 95 weight percent of the single-site initiated
polyolefin resin and about 5 and 40 weight percent of the
ethylene-propylene-diene monomer terpolymer.
36. The gasket of claim 35, further comprising up to about 65
weight percent of a filler.
37. The gasket of claim 35, further comprising up to about 30
weight percent of an oil.
38. The gasket of claim 30, wherein the polymer blend is
foamed.
39. The gasket of claim 38, wherein the foamed polymer blend has an
average foam density between 1.5 and 25 pounds per cubic foot.
40. A method of making a gasket comprising the steps of: providing
a polymer blend including a single-site initiated polyolefin resin
having a density below 0.870 g cm.sup.-3 and up to 40 weight
percent of a polyolefin including ethylene and propylene; and
forming the polymer blend in a mold in the shape of a gasket,
wherein a portion of the polymer blend is cross-linked and the
gasket is thermally stable at 120.degree. F.
41. The method of claim 40, wherein the step of forming includes
pressing the polymer blend in the mold.
42. The method of claim 41, wherein the step of forming includes
heating the polymer blend in the mold.
43. The method of claim 42, wherein the polymer blend is foamed.
Description
BACKGROUND OF THE INVENTION
[0001] The invention relates to cross-linked polymer blends
including single-site initiated polyolefin resins and polyolefins
including ethylene and propylene.
[0002] Polymer blends that can be formed (i.e., thermoformed or
pressure-formed) are useful in a number of applications,
particularly, when the polymer blends have good flexibility
properties, high thermal stability, and are foamable. For example,
these materials can be used as components in floatation devices for
water sports or as sealing or gasket components in, e.g., the
automotive industry. Traditionally, the physical properties
required by these types of applications suggest the use of high
density foams.
[0003] In general, polymer blends with these properties are based,
in part, on cross-linked ethylene-propylene-diene monomer (EPDM)
terpolymers or ethylene-vinyl acetate (EVA) copolymers. These
materials generally contain other additives, such as plasticizers,
to add to their flexibility. Thermal stability is typically
achieved by sulfur vulcanization of the compositions. However,
plasticizers can leach out of the materials over time which can
make the materials less flexible and the sulfur additives can make
the material less desirable for environmental reasons.
SUMMARY OF THE INVENTION
[0004] The invention features polymer blends which can be used both
in foamed and unfoamed states as a replacement for conventional
EPDM and other elastomers. The composition of the polymer blend
includes a single-site catalyzed polyolefin resin having a density
of below 0.878 g cm.sup.-3 and up to 40 weight percent of a
polyolefin including ethylene and propylene. The polymer blend is
cross-linked. The use of sulfur to vulcanize the polymer blend is
not necessary.
[0005] In one aspect, the invention features a polymer blend
including a single-site initiated polyolefin resin having a density
below 0.870 g cm.sup.-3 and up to 40 weight percent of a polyolefin
that includes ethylene and propylene. A portion of the polymer
blend is cross-linked. In addition, the polymer blend is formable.
In preferred embodiments, the polymer blend is foamed.
[0006] In another aspect, the invention features a method of making
a cross-linked polymer blend including the steps of providing a
polymer mixture including a single-site initiated polyolefin resin
and up to 40 weight percent of a polyolefin including ethylene and
propylene, and cross-linking the polymer mixture.
[0007] In preferred embodiments, the step of cross-linking the
polymer blend includes reacting the polymer blend with a peroxide.
In other preferred embodiments, the method further includes the
step of expanding the polymer mixture to form a foam. It is
preferred that the step of expanding the polymer mixture include
compression molding the polymer mixture at increased temperature
and pressure. Preferably, compression molding comprises the steps
of pressing the polymer mixture using a high tonnage press at a
temperature of between 275 and 320.degree. F. and a pressure of
between 250 and 2500 psi for between 20 and 90 minutes followed by
heating the polymer mixture at a temperature between 300 and
380.degree. F. The step of heating the polymer mixture further
preferably includes pressing the blend using a medium tonnage press
at a pressure of between 250 and 1500 psi.
[0008] In yet another aspect, the invention features a gasket
including a polymer blend including a single-site initiated
polyolefin resin having a density below 0.870 g. cm.sup.-3 and up
to 40 weight percent of a polyolefin including ethylene and
propylene. A portion of the polymer blend is cross-linked. The
gasket is thermally stable at 120.degree. F.
[0009] In another aspect, the invention features a method of making
a gasket including the steps of providing a polymer blend including
a single-site initiated polyolefin resin having a density below
0.870 g cm.sup.-3 and up to 40 weight percent of a polyolefin
including ethylene and propylene, and forming the polymer blend in
a mold in the shape of a gasket. A portion of the polymer blend is
cross-linked and the gasket is thermally stable at 120.degree. F.
In preferred embodiments, the step of forming includes pressing the
polymer blend in the mold. Preferably, the step of forming includes
heating the polymer blend in the mold.
[0010] In preferred embodiments, the polymer blend includes at
least 5 percent of the single-site initiated polyolefin resin and
at least 5 percent of the polyolefin that includes ethylene and
propylene. It is preferred that the polyolefin that includes
ethylene and propylene is an ethylene-propylene-diene monomer
(EPDM) terpolymer or an ethylene propylene rubber (EPR), most
preferably EPDM.
[0011] In preferred embodiments, the polymer blend further includes
less than about 70 weight percent of a second polyolefin resin. It
is preferred that the second polyolefin resin include a
polypropylene, a polyethylene, or a copolymer containing ethylene
or propylene. The second polyolefin resin can be a blend or mixture
of polymer resins. The polyethylene preferably includes a low
density polyethylene, a linear low density polyethylene, a medium
density polyethylene, or a high density polyethylene. The copolymer
preferably includes an ethylene-vinyl acetate copolymer, an
ethylene-maleic anhydride copolymer, or an ethylene-ethyl acetate
copolymer.
[0012] In other preferred embodiments, the polymer blend includes
between about 5 and 95 weight percent of the single-site initiated
polyolefin resin and about 5 and 40 weight percent of the
polyolefin including ethylene and propylene, preferably an
ethylene-propylene-diene monomer terpolymer. It is preferred that
the polymer blend further include up to about 65 weight percent of
a filler. It is preferred that the polymer blend further include up
to about 30 weight percent of an oil.
[0013] Preferably, the foamed polymer blend has an average foam
density between 1.5 and 25 pounds per cubic foot.
[0014] Copolymers include polymers resulting from the
polymerization of two or more monomeric species, for example,
polyolefins including ethylene and propylene. Copolymers including
ethylene and propylene can be ethylene-propylene rubbers (EPR).
Copolymers include terpolymers resulting from the polymerization of
three monomeric species (e.g., as in EPDM), sesquipolymers, and
greater combinations of monomeric species.
[0015] A polyolefin including ethylene and propylene can be an
ethylene-propylene-diene monomer (EPDM) terpolymer. EPDM can be a
polyolefin including ethylene, propylene, and a non-conjugated
diene that have been polymerized together to afford a copolymer (in
this case a terpolymer). The polymerization initiator can be any
known initiator, including a single-site initiator. For examples of
polyolefins including ethylene and propylene (i.e., EPR or EPDM
resins), see Borg, "Ethylene/Propylene Rubber," in Rubber
Technology, M. Morton, Ed., Van Nostrand Reinhold Company, New
York, 1973, pp. 220-248.
[0016] Single-site initiated polyolefin resins can be polyolefins
prepared from a single-site initiated polyolefin that has
controlled molecular weights and molecular weight distributions.
The single-site initiated polyolefin resin can be, for example,
polyethylene, polypropylene, or a copolymer of ethylene and
alpha-unsaturated olefin monomers.
[0017] The specific gravities of the polymer resins can be measured
using ASTM D-792 methods.
[0018] The foams are generally closed-cell foams in which greater
than approximately 70% of the form cell volumes have cell walls
isolating them from the external atmosphere. One way to determine
this is by measuring the amount of water that is absorbed into the
foam when the foam is immersed in water.
[0019] The invention can have one or more of the following
advantages. The polymer blends can have improved flexibility and
thermal stability over blends that do not include single-site
initiated polyolefin resins. Flexibility can be measured, for
example, by compressing the material by 25 percent and measuring
the force it takes to compress the foam. Other advantages of the
materials include thermoformability, and the ability to laminate to
other materials or to itself without adhesives.
[0020] The polymer blends, and foamed polymer blends, that include
single-site initiated polyolefin resins and a polyolefin including
ethylene and propylene have good flexibility without the addition
of other components such as plasticizers, for example. Plasticizers
can leach out of the polymer blends and foamed polymer blends over
time, leading to degradation of the physical properties of the
polymer blends. The polymer blends based on single-site initiated
polyolefin resins do not require plasticizer components to enhance
their physical properties. Since the polymer blends are
cross-linked, they do not contain sulfur or chlorine-containing
materials.
[0021] The foamed polymer blends generally have other advantages
over conventional EPDM and EVA foams as well as foams produced with
single-site initiated polyolefin resins without a polyolefin
including ethylene and propylene. The densities of the foamed
polymer blends can be lower than foams that do not contain a
polyolefin including ethylene and propylene and a single-site
initiated polyolefin resin. At equivalent densities, the foamed
polymer blends tend to have better tensile and tear strength than
foams that do not contain a polyolefin including ethylene and
propylene and a single-site initiated polyolefin. The polymer
blends and foamed polymer blends also can be formed (e.g.,
thermoformed or pressure-formed) into a shaped article. In other
preferred embodiments, the polymer blends and foamed polymer blends
can be thermoset or die-cut.
[0022] The foamed polymer blends tend to be flexible and have
superior weather resistance. Increased cross-linking gives the foam
good compression set resistance, creep and stress relaxation
resistance, and good thermal stability. The amount of cross-linking
in the polymer blends can range from about 24 to 100 percent. When
the polymer blend can be thermoformed, the amount of cross-linking
preferably can range from about 40 to 60 percent. When the polymer
blend can be thermoset, the amount of cross-linking can range from
about 95 to 100 percent.
[0023] The useable temperature range of the polymer blends is
extended. The polymer blends can be exposed to temperatures up to
160.degree. F. on a continuous basis and up to about 410.degree. F.
for brief periods of time under some circumstances. This quality
makes the polymer blends useful in foam applications for
floatation, automotive applications (e.g., gaskets, and door and
window seals), and athletics, where flexibility at low temperatures
can be important. When compared to EVA foams of equivalent
compression deflection, the foam generally has superior physical
properties and thermal stability. Increased thermal stability is an
important factor in automotive applications such as gasketing.
[0024] The thermal stability of the polymer blends can be related
to the dimensional stability of the polymer blends at elevated
temperatures. The dimensional changes are preferably less than 8
percent and more preferably less than 5 percent.
[0025] The tensile strength, elongation, compression resistance
(compression deflection), compression set, and tear resistance of
the foamed polymer blends can be measured according to ASTM
D-3575.
[0026] Other features and advantages of the invention will be
apparent from the following detailed description thereof, and from
the claims.
DETAILED DESCRIPTION
[0027] The polymer blends include at least one single-site
initiated polyolefin resin and a polyolefin including ethylene and
propylene. The polyolefin including ethylene and propylene can be
an EPR or EPDM resin. Some EPR or EPDM resins are available
commercially from Exxon Chemical Company, Houston, Tex., under the
tradename Vistalon.TM., and include Vistalon.TM. 5800, Vistalon.TM.
6205, Vistalon.TM. 7000, Vistalon.TM. 7500, Vistalon.TM. 8000,
Vistalon.TM. 2200, Vistalon.TM. 2504, Vistalon.TM. 2555,
Vistalon.TM. 2727, Vistalon.TM. 4608, Vistalon.TM. 719,
Vistalon.TM. 3708, Vistalon.TM. 404, Vistalon.TM. 457, Vistalon.TM.
503, Vistalon.TM. 707, and Vistalon.TM. 878. Other EPDM resins are
available commercially from DuPont, Wilmington, Del., under the
tradename Nordel.TM. and include Nordel.TM. 2522, Nordel.TM. 2722,
Nordel.TM. 1440, Nordel.TM. 1470, Nordel.TM. 1145, Nordel.TM. 1040,
and Nordel.TM. 1070. Preferred resins are EPDM resins, including
Nordel.TM. 1440 and Vistalon.TM. 2504.
[0028] Single-site initiated polyolefin resins can be prepared
using single-site initiators to polymerize a variety of olefins.
One class of a single-site initiators of particular interest are
the metallocene initiators which are described, for example, in J.
M. Canich, U.S. Pat. No. 5,026,798, in J. Ewen, et al., U.S. Pat.
No. 4,937,299, in J. Stevens, et al., U.S. Pat. No. 5,064,802, and
in J. Stevens, et al., U.S. Pat. No. 5,132,380, each of which are
incorporated herein by reference. These initiators, particularly
those based on group 4 transition metals, such as zirconium,
titanium and hafnium, are extremely high activity ethylene
polymerization initiators.
[0029] The single-site initiators are versatile. The polymerization
conditions such as a initiator composition and reactor conditions
can be modified to provide polyolefins with controlled molecular
weights (e.g., in a range from 200 g mol.sup.-1 to about 1 million
or higher g mol.sup.-1) and controlled molecular weight
distributions (e.g., M.sub.w/M.sub.n in a range from nearly 1 to
greater than 8, where M.sub.w is the weight average molecular
weight and M.sub.n is the number average molecular weight).
Molecular weights and molecular weight distributions of polymers
can be determined, for example, by gel permeation
chromatography.
[0030] The polyolefins provided by single-site initiators are
essentially linear, meaning that the polymers can contain uniformly
distributed, highly controlled short chain branching sites. As used
herein, the term "essentially linear" means that the polymers have
less than about one long-chain branch for every ten thousand carbon
atoms in the backbone of the polymer. As described above, one
method of determining branching is .sup.13C NMR spectroscopy. The
term "short-chain branching," as used herein, means a branch of a
polymer backbone of 6 carbon atoms or less which can be
distinguished by .sup.13C NMR spectroscopic methods.
[0031] When the single-site initiated polyolefins are copolymers,
the composition distribution breadth index (CDBI) is generally
greater than 50% and most preferably above 70%. The CDBI is a
measurement of the uniformity of distribution of comonomers among
the individual polymer chains having a comonomer content within 50%
of the median bulk molar comonomer content. Copolymers are
generally polymers of ethylene with C.sub.3-C.sub.20 alpha-olefins,
and/or diolefins, or with other unsaturated monomers such as
acrylates and styrenes.
[0032] The "melt index" (MI) of a polymer resin is a measurement of
processability under low shear rate conditions. The MI can be
determined by ASTM D-1238 Condition E (190.degree. C./2.16 kg). The
MI of the single-site initiated polyolefin resins is generally
between about 0.2 dg/min and about 100 dg/min, preferably, between
about 1 dg/min and about 10 dg/min, and most preferably between
about 2 dg/min and about 8 dg/min. The melt index of the polymer
resins can be measured using ASTM D-1238.
[0033] The single-site initiated polyolefin resins are derived from
ethylene polymerized with at least one comonomer selected from the
group consisting of at least one alpha-unsaturated C.sub.3-C.sub.20
olefin comonomers. Preferably, the alpha-unsaturated olefins
contain between 3 and 16 carbon atoms, most preferably between 3
and 8 carbon atoms. Examples of such alpha-unsaturated olefin
comonomers used as copolymers with ethylene include, but are not
limited to, propylene, isobutylene, 1-butene, 1-hexene,
3-methyl-1-pentene, 4-methyl-1-pentene, 1-octene, 1-decene,
1-dodecene, styrene, halo- or alkyl-substituted styrene,
tetrafluoroethylene, vinylcyclohexene, and
vinylbenzocyclobutane.
[0034] The-comonomer content of the polyolefin resins is generally
between about 1 mole percent and about 32 mole percent, preferably
between about 2 mole percent and about 26 mole percent, and most
preferably between about 6 mole percent and about 25 mole
percent.
[0035] The copolymer can include one or more C.sub.4-C.sub.20
polyene monomers. Preferably, the polyene is a straight-chain,
branched chain or cyclic hydrocarbon diene, most preferably having
between 6 and 15 carbon atoms. It is also preferred that the diene
be non-conjugated. Examples of dienes include, but are not limited
to, 1,3-butadiene, 1,4-hexadiene, 1,6-octadiene,
5-methyl-1,4-hexadiene, 3,7-dimethyl-1,6-octadiene,
3,7-dimethyl-1,7-octadiene, 5-ethylidene-2-norbornene, and
dicyclopentadiene. Especially preferred is 1,4-hexadiene.
[0036] Preferred single-site initiated polyolefin resins are
described, for example, in S. -Y. Lai, et al., U.S. Pat. Nos.
5,272,236, 5,278,272, and 5,380,810, in L. Spenadel, et al., U.S.
Pat. No. 5,246,783, in C. R. Davey, et al., U.S. Pat. No.
5,322,728, in W. J. Hodgson, Jr., U.S. Pat. No. 5,206,075, and in
F. C. Stehling, et al., WO 90/03414, each of which is incorporated
herein by reference. The resins contain varying amounts of
short-chain and long-chain branching, which depend, in part, on the
processing conditions.
[0037] Some single-site initiated polyolefin resins are available
commercially from Exxon Chemical Company, Houston, Tex., under the
tradename Exact.TM., and include Exact.TM. 3022, Exact.TM. 3024,
Exact.TM. 3025, Exact.TM. 3027, Exact.TM. 3028, Exact.TM. 3031,
Exact.TM. 3034, Exact.TM. 3035, Exact.TM. 3037, Exact.TM. 4003,
Exact.TM. 4024, Exact.TM. 4041, Exact.TM. 4049, Exact.TM. 4050,
Exact.TM. 4051, Exact.TM. 5008, and Exact.TM. 8002. Other
single-site initiated resins are available commercially from Dow
Plastics, Midland, Mich. (or DuPont/Dow), under the tradenames
Engage.TM. and Affinity.TM., and include CL8001, CL8002, EG8100,
EG8150, PL1840, PL1845 (or DuPont/Dow 8445), EG8200, EG8180,
GF1550, KC8852, FW1650, PL1880, HF1030, PT1409, CL8003, and D8130
(or XU583-00-01). Most preferably, the single-site initiated
polyolefin resins are selected from the group consisting of EG8100,
EG8180, and EG8200.
[0038] Additionally, the polymer blend can contain up to 70 weight
percent of other polymer resins other than the single-site
initiated polyolefin resin and the polyolefin including ethylene
and propylene. The other polymer resins can be-mixed or blended.
Other polymer resins include, for example, other single-site
initiated polyolefins, low density polyethylene (LDPE), high
density polyethylene (HDPE), linear low density polyethylene
(LLDPE), ethylene-propylene rubber, polystyrene, polyvinylchloride
(PVC), polyamides, polyacrylates, celluloses, polyesters,
polyhalocarbons, and copolymers of ethylene with propylene,
isobutene, butene, hexene, octene, vinyl acetate, vinyl chloride,
vinyl propionate, vinyl isobutyrate, vinyl alcohol, allyl alcohol,
allyl acetate, allyl acetone, allyl benzene, allyl ether, ethyl
acrylate, methyl acrylate, acrylic acid, or methacrylic acid. The
polymer blends can also include rubber materials such as
polychloroprene, polybutadiene, polyisoprene, polyisobutylene,
nitrile-butadiene rubber, styrene-butadiene rubber, chlorinated
polyethylene, chlorosulfonated polyethylene, epichlorohydrin
rubber, polyacrylates, butyl rubber, or halobutyl rubber. The
rubber material can be peroxide-cured. Preferred polymer resins
included in the polymer blend include other single-site initiated
polyolefins, LDPE, LLDPE, polypropylene, polystyrene, or ethylene
copolymers such as ethylene-vinyl acetate copolymer (EVA), or
ethylene-ethyl acrylate copolymer (EEA).
[0039] The polymer blends of the invention are cross-linked.
Cross-linking is generally introduced by reaction of the polymers
with a cross-linking agent. Cross-linking can take place partially
during blending of the polymer components. Alternatively, the
cross-linking can take place predominantly during expansion of the
foam. Cross-linking can be achieved by a number of methods,
including treatment of the polymers with a peroxide, such as an
organic peroxide, treatment of the polymers with high energy
irradiation, or by grafting the polymers, for example, with a
cross-linkable silane such as vinyl trimethoxysilane. Cross-linking
polyolefins by exposing them to high energy irradiation is
described, for example, in Mukherjee, et al. "Radiation-Induced
Changes is Polyolefins," Rev. Macromol. Chem. Phys. (1986)
C26:415-439, incorporated herein by reference.
[0040] The preferred method of cross-linking employs an organic
peroxide. Examples of organic peroxides include dicumylperoxide,
2,5-dimethyl-2,5-di(t-butylperoxy)-hexane,
1,1-bis(t-butylperoxy)-3,3,5-t- rimethylcyclohexane,
1,1-di-(t-butylperoxy)cyclohexane,
2,2'-bis(t-butylperoxy)-diisopropylbenzene,
4,4'-bis(t-butylperoxy)butylv- alerate, t-butylperbenzoate,
t-butylperterephthalate, and t-butyl peroxide. Most preferably, the
peroxide cross-linking agent is dicumylperoxide or
2,2'-bis(t-butylperoxy)-diisopropylbenzene.
[0041] The cross-linked polymer blend can be grafted. Grafting
involves attaching one or more monomer or polymer to the original
polymer resin chains. The grafting is generally accomplished by
forming active grafting sites on the original polymer chains in the
presence of monomers that can further polymerize as branches from
the original polymer chains. Active grafting sites can be
generated, for example, by free radicals or anions. A graft can
include other monomers, such as di- and tri-allyl cyanurates and
isocyanurates, alkyl di- and tri-acrylates and methacrylates, zinc
dimethacrylates and diacrylates, styrenes, divinylbenzene, vinyl
silanes with at least two hydrolyzable groups, and butadiene.
Silane-grafted polymer blends can be cross-linked by reaction with
moisture.
[0042] The polymer blends-can be foamed to make predominantly
closed-cell foams. The polymer blends can also be-formed under
elevated temperature (thermoformed or thermoset) or elevated
pressure (pressure-formed). The expanding medium, or foaming
agents, useful in the practice of the present invention, are
physical foaming agents or chemical foaming agents. Physical
foaming agents include medium expanding compositions that are gases
at temperatures and pressures encountered during the foaming step.
Typically, a physical foaming agent is introduced to the polymer
blend in the gaseous or liquid state and expands, for example, upon
a rapid decrease in pressure. Chemical foaming agents include
medium expanding compositions that are solid or liquid under
ordinary processing conditions until the composition is decomposed
to release gas. Chemical foaming agents can be decomposed, for
example, at elevated temperatures.
[0043] Physical foaming agents include low molecular weight organic
compounds including C.sub.1-C.sub.6 hydrocarbons such as acetylene,
propane, propene, butane, butene, butadiene, isobutane,
isobutylene, cyclobutane, cyclopropane, ethane, methane, ethene,
pentane, pentene, cyclopentane, pentene, pentadiene, hexane,
cyclohexane, hexene, and hexadiene, C.sub.1-C.sub.5 organohalogens,
C.sub.1-C.sub.6 alcohols, C.sub.1-C.sub.6 ethers, C.sub.1-C.sub.5
esters, C.sub.1-C.sub.5 amines, ammonia, nitrogen, carbon dioxide,
neon, or helium.
[0044] Chemical foaming agents include, for example,
azodicarbonamide, p-p'-oxybis(benzene)sulfonyl hydrazide,
p-toluenesulfonyl hydrazide, p-toluenesulfonyl semicarbazide,
5-phenyltetrazole, ethyl-5-phenyltetrazole,
dinitrosopentamethylenetetramine, and other azo, N-nitroso,
semicarbazide, sulfonyl hydrazides, carbonate, and bicarbonate
compounds that decompose when heated. The preferred foaming agents
are chemical foaming agents, such as azodicarbonamide. Combinations
of various physical and/or chemical foaming agents can be used to
foam the polymer blends.
[0045] Regardless of the method of cross-linking used, acceptably
flexible articles, particularly foamed articles, can only be
obtained in certain ranges of cross-linking density or level. Too
much cross-linking can render the material inelastic. In a foam,
this can result in less than optimal expansion and greater than
optimal density for a given level of foaming agent. Too little
cross-linking can be detrimental to physical properties such as
compression set properties or thermal stability, for example. It is
important to choose cross-linking levels that afford materials with
particular desired properties. The silane-grafting and resulting
cross-links can increase the melt strength of the composition. The
cross-linking levels can be determined by establishing the gel
content of the of the composition, for example, by extraction with
a solvent such as xylenes. The polymer blends can have cross-link
densities between about 24 to 100 percent, most preferably between
40 to 60 percent for thermoformable polymer blends and between
about 95 to 100 percent for thermoset polymer blends.
[0046] The polymer blend can include foam activating agents, which
decrease the decomposition temperature of the chemical foaming
agent when foaming is desired. Activating agents include metal
salts such as zinc salts, for example, zinc stearate or zinc
oxide.
[0047] The foamed polymer blends have densities between about 1.5
and about 25 pounds per cubic foot.
[0048] Other additives, alone or in combination, can be added to
the polymer blends, including particulate and fibrous fillers to
reinforce, strengthen or modify the Theological properties of the
material, antioxidants (e.g., hindered phenolics such as Irganox
1010, phosphites such as Irgafos 168, or polymerized
trimethyl-dihydroquinoline such as Agerite AK, Resin D or Flectol
H), oils, ultra-violet stabilizers, thermal stabilizers, antistatic
components, flame retardants, pigments or colorants, and other
processing aids. In particular, oils, such as hydrocarbon oils
(e.g., mineral oil), and fillers, such as talc, silica, or calcium
carbonate, are added to the polymer blends. Polymer modifiers such
as oils can serve as processing aids. The oils are generally
cross-linked into the polymer blend matrix by reaction with the
cross-linking agent and, therefore, do not leach out of the final
product.
[0049] The polymer blends preferably include between 5 and 40
weight percent EPDM and between 5 and 95 weight percent of a
single-site initiated polyolefin resin having a density below 0.878
g cm.sup.-3. The polymer blends can also include between 0 and 70
weight percent of another polyolefin resin which can be one or a
blend of more than one polyolefin resin including polypropylene,
high density polypropylene, linear low density polyethylene, or
other polymer or copolymer of ethylene or propylene. In addition,
the polymer blends can include between 0 and 30 weight percent of a
hydrocarbon oil, and between 0 and 65 weight percent of a filler,
such as mineral or fibrous fillers such as calcium carbonate or
talc. The blend can be cross-linked during processing by reaction
with an organic peroxide, such as dicumyl peroxide. The use of
sulfur to vulcanize the composition is not necessary.
[0050] The cross-linking level in the blend is relatively high as
evidenced by low compression set and high thermal stability. True
rubber-like properties are obtained with levels as low as 20 weight
percent EPDM. The blend does not maintain good properties
especially in foamed applications when levels above 40 weight
percent EPDM are used.
[0051] In general, the polymer blend can be prepared by mixing the
polyolefin including ethylene and propylene, single-site initiated
polyolefin resin, other polymer resins, and other additives are
heated and mixed, for example, in an internal mixer, such as a
Banbury-type mixer, or an extruder to provide a homogeneous blend.
The temperature and pressure of the mixing are selected to avoid
foaming. Preferred mixing conditions are at pressures between 20
and 200 psi and temperatures between 150 and 280.degree. F. using
an internal mixer. Alternatively, when an extruder is used to mix
the blend, the temperature is maintained below about 275.degree. F.
and the pressure is generally between 500 and 5000 psi depending on
the die (i.e., a pressure of between 2000 and 3000 psi is used to
extrude a flat sheet). In general, the treatment temperature is
selected to avoid substantial decomposition of the foaming agent
and the cross-linking agent. The polymer blend can be pre-formed
for pressing, for example, as a sheet, by roll milling or
extrusion. Alternatively, the blend can be pelletized.
[0052] The polymer blend foams can be produced by compression
molding, injection molding, or can be foamed as a sheet. In
particular, the polymer blends are foamed by compression molding in
a first pressing operation using a high tonnage hydraulic press at
a temperature between 275 and 320.degree. F. and a pressure of
between 250 and 2500 psi for between 20 and 90 minutes. The foam
can be further expanded in a subsequent heating stage in an oven at
a temperature between 300 and 380.degree. F. for between 20 and 320
minutes or a second pressing operation in a medium tonnage
hydraulic press at a temperature between 300 and 380.degree. F. and
a pressure of between 250 and 1500 psi for between 20 and 320
minutes. It has been observed that pre-forming step helps degas the
blend, the first pressing operation helps decrease the cell size
and improve cell quality, and the second pressing operation helps
prevent surface degradation and loss of material. The foams
generally have average densities of between 1.5 and 25 pcf.
[0053] The polymer blend can be formed by pre-heating a section of
a sheet to soften the blend and pressing the softened polymer blend
in a mold. The polymer blend can be foamed if it contains a foaming
agent and it is heated to induce foaming. The mold can be a single
piece or a matching mold and can be vented. Forming and/or foaming
a sheet in a mold in this way is one method of forming a gasket
from the polymer blend.
[0054] The polymer blend can be laminated to other materials or to
itself by heat treatment of the laminate interface. Although
adhesives can be applied, it is not necessary to use an adhesive to
laminate the polymer blend.
[0055] It is desired that the polymer blend, or foamed blend, have
good tensile strength, shear strength, and cleavage strength. The
tensile strength, elongation, compression resistance (compression
deflection), compression set, and tear strength can be determined,
for example, according to the procedure of ASTM D-3575. The
flexibility of the polymer blend is an important component of these
properties.
[0056] It is also desired that the foams be suitable for use in
floatation devices. Floatation performance tests can be conducted
according to the guidelines set forth by Underwriters Laboratories,
Inc. in UL 1191, incorporated herein by reference. It is
recommended that floatation materials generally have densities
greater than 1 pound per cubic foot (pcf), a specific buoyancy of
at least 58 pounds (lbs), a buoyancy retention factor of 98% for
certain wearable devices (V factor) and 95% for cushions (C
factor), a tensile strength of at least 20 pounds per square inch
(psi), good flexibility (no cracking), and a compression deflection
(25%) of at least 1 psi. The testing of the buoyancy retention
further includes heat conditioning that involves treating the
samples at 60.degree. C. for 120 hours. The heat conditioning
aspect of the test is essentially an elevated temperature creep
test that probes the thermal stability of the material.
[0057] The thermal stability of the polymer blend can be measured
from the floatation performance test, specifically the buoyancy
retention factor, albeit indirectly. The thermal stability of the
polymer blends relates to other applications. In particular, the
polymer blends and foamed polymer blends are useful in automotive
applications, particularly for making gaskets. The thermal
stability of the materials in combination with the flexibility and
formability make the polymer blends particularly suitable to
automotive gasket applications.
[0058] The thermal stability of the polymer blends in gasket
applications can be determined by monitoring their dimensional
stability at elevated temperatures. For automotive applications,
thermal stability can be tested by exposing a piece of the polymer
blend to an elevated temperature for a particular amount of time
and measuring the percent change in the dimensions of the piece.
For example, a piece of a polymer blend (i.e., a 12 inch.times.12
inch.times.1/4 inch piece of foam) can be heated to 158.degree. F.
for 24 hours. In other tests, for example, the pieces can be heated
to 158.degree. F. for 50 hours, 180.degree. F. for 7 days,
257.degree. F. for 30 minutes, 350.degree. F. for 4 minutes,
130.degree. F. for 66 hours, or 410.degree. F. for 11 minutes.
After cooling, the dimensions of the piece are calculated and the
percent change in each dimension is calculated. Percent changes in
dimensions that are less than about 8 percent, most preferably less
than 5 percent, indicate polymer blends with adequate thermal
stability for automotive gasket applications. Typical foam gaskets
for automotive applications have foam densities between 2 and 14
pounds per cubic foot.
[0059] The following specific examples are to be construed as
merely illustrative, and not limitive, of the remainder of the
disclosure.
EXAMPLES
[0060] The polymer blends were prepared according to the procedures
outlined above. Compositions for five examples are given below in
Tables 1-13 for Examples 1-13. Examples 1-4 are comparative
examples that do not contain a polyolefin including ethylene and
propylene.
[0061] The polymer blends are generally prepared by mixing the
components in a batch operation. The batch is weighed and segmented
into sequential additions in the proportions show in Table 1. A
high-shear internal mixer (i.e., a Banbury mixer) was used for
mixing in the Examples provided here. The mixing is accomplished
with counter rotating rotors contained within a closed chamber. A
port on top of the chamber can be opened for addition of the
components. The opening is sealed for-mixing with a pressurized
hydraulic ram. The resultant pressure holds the material inside the
chamber. The pressure further assists the rotors in softening,
melting, plasticating, fusing, and blending the components which is
accomplished by the heat that is provided to the chamber and the
rotors and shear heat that is generated by the working of the
material in the mixer. Various operations, such as scrape down or
addition of other components, are carried out at different
pre-designated temperatures. For example, the first melt and fusion
check was carried out at about 225.degree. F. in Example 1. At the
conclusion of the addition and mixing of all components, the
completed polymer blend is removed from the mixer.
[0062] Once the polymer blend is mixed, it is generally pre-formed
before foaming. A calendar heated to approximately 165.degree. F.
was used to prepare a pre-form for the pressing operation in
Example 1. In Example 1, the pre-form was roll milled in a two roll
mill to form a sheet. Once the polymer blend was pre-formed, it was
transported to a high tonnage press for expansion to a foam.
[0063] The pre-formed polymer blend is inserted into picture frame
type of mold in a high tonnage hydraulic press. In Example 1, the
mold was one of many daylights of a multiple cavity high tonnage
hydraulic press. Once all pre-forms have been inserted into the
molds, the press was closed. The pre-formed polymer blend was put
under approximately 2000 psi of pressure and heated for
approximately 50 minutes at 305.degree. F. Upon release at the end
of the heating period, the material was partially cross-linked and
partially expanded. The partially expanded polymer blend was then
transported to a low tonnage hydraulic press for final expansion of
the foam.
[0064] The partially cross-linked and expanded pre-formed polymer
blend was placed into a large mold cavity of a low tonnage
hydraulic press and was further heated for approximately 40 minutes
at 320.degree. F. under approximately 900 psi. Following the
completion of the heating period, the material was cooled and
allowed to normalize to room temperature. Following pressing
operations, the resulting foamed polymer blend was washed to remove
unwanted in-process material from the surface of the blend. Once
foamed, the polymer blend is ready for further fabrication or
skiving.
[0065] The compositions of comparative examples 1-4 are shown in
Tables 1-4, respectively. Examples 1-4 do not contain polyolefins
including ethylene and propylene (i.e., EPR or EPDM).
1TABLE 1 EXAMPLE 1 (no EPDM or EPR) Material Parts per Hundred of
Resin EXXON LD 740 35 DUPONT/DOW ENGAGE 8100 20 DUPONT/DOW ENGAGE
8180 45 KADOX 911C 0.25 IRGANOX 1010 0.5 LUPERCO 500-40KE 3 DONG
JIN D900B/A 20 CELOGEN CT 0.1 CAMELWITE ST 20 DRAKEOL #24 OIL
20
[0066]
2TABLE 2 EXAMPLE 2 (no EPDM or EPR) Material Parts per Hundred of
Resin EXXON LD 740 35 DUPONT/DOW ENGAGE 8100 20 DUPONT/DOW ENGAGE
8180 45 IRGANOX 1010 0.5 DONG JIN D900 B/A 20 KADOX 911C 0.25
CELOGEN OT/UNICELL OH 0.1 LUPERCO 500-40KE 3.5 CAMELWITE ST 20
DRAXEOL #24 OIL 20
[0067]
3TABLE 3 EXAMPLE 3 (no EPDM or EPR) Material Parts per Hundred of
Resin EXXON LD 740 35 DUPONT/DOW ENGAGE 8180 65 ZINC OXIDE 0.25
IRGANOX 1010 0.5 LUPERCO 500-40KE 3 DONG JIN D900B/A 20 CAMELWITE
ST 20 HYDROCARBON OIL 20
[0068]
4TABLE 4 EXAMPLE 4 (no EPDM or EPR) Material Parts per Hundred of
Resin EXXON LD 740 35 DUPONT/DOW ENGAGE 8180 65 IRGANOX 1010 0.5
DONG JIN D900B/A 20 ZINC OXIDE 0.25 LUPERCO 500-40KE 3.5 CAMELWITE
ST 20 HYDROCARBON OIL 20
[0069] The compositions of Examples 5-13 are listed in Tables 5-13,
respectively.
5TABLE 5 EXAMPLE 5 Material Parts per Hundred of Resin DOW 510 50
DUPONT/DOW ENGAGE 8180 30 EXXON VISTALON 2504 RUBBER 20 KADOX 911C
0.2 IRGANOX 1010 0.5 LUPERCO 500-40KE 1.85 DONG JIN D900 B/A 16
CELOGEN OT 0.1 CAMELWITE ST 20 DRAKEOL #34 OIL 10 TECHNER WHITE PM
1787E4 3.5
[0070]
6TABLE 6 EXAMPLE 6 Material Parts per Hundred of Resin DOW 510 50
DUPONT/DOW ENGAGE 8100 30 EXXON VISTALON 2504 RUBBER 20 BENNOX 1010
0.5 DONG JIN D900 B/A 16 CELOGEN OT 0.1 KADOX 911C 0.2 LUPERCO
500-40KE 1.85 TECHNER WHITE PM 1787E4 3.5 CAMELWITE ST 20 DRAKEOL
#34 OIL 15
[0071]
7TABLE 7 EXAMPLE 7 Material Parts per Hundred of Resin DUPONT/DOW
ENGAGE 8200 22.5 DUPONT/DOW ENGAGE 8100 22.5 DOW 510 30.0 NORDEL
1440 20.0 TECHNER BK PM9101 12.5 IRGANOX 1010 0.5 DONG JIN D900 B/A
9.0 CELOGEN OT/UNICELL OH 0.1 KADOX 911C 0.2 LUPERCO 500-40KE 2.0
CAMELWITE ST 20.0 DRAKEOL #34 OIL 10.0
[0072]
8TABLE 8 EXAMPLE 8 Material Parts per Hundred of Resin EXXON 117 50
DUPONT/DOW ENGAGE 8180 30 NORDEL 1440 RUBBER 20 ZINC OXIDE 0.2
IRGANOX 1010 0.5 LUPERCO 500-40KE 1.85 DONG JIN D900 B/A 16
CAMELWITE ST 20 HYDROCARBON OIL 10 TECHMER WHITE PM 1787E4 3.5
[0073]
9TABLE 9 EXAMPLE 9 Material Parts per Hundred of Resin EXXON 117 50
DUPONT/DOW ENGAGE 8180 30 NORDEL 1440 RUBBER 20 BENNOX 1010 0.5
DONG JIN D900 B/A 16 ZINC OXIDE 0.2 LUPERCO 500-40KE 1.85 TECHMER
WHITE PM 1787E4 3.5 CAMELWITE ST 20 OIL 15
[0074]
10TABLE 10 EXAMPLE 10 Material Parts per Hundred of Resin
DUPONT/DOW ENGAGE 8100 45 EXXON 117 30.0 NORDEL 1440 RUBBER 20.0
TECHMER BK P149101 12.5 IRGANOX 1010 0.5 DONG JIN D900 B/A 9.0 ZINC
OXIDE 0.2 LUPERCO 500-40KE 2.0 CAMELWITE ST 20.0 OIL 10
[0075]
11TABLE 11 EXAMPLE 11 Material Parts per Hundred of Resin
DUPONT/DOW ENGAGE 8180 45 EXXON 117.08 30 NORDEL 1440 RUBBER 20
HARWICK BK MC 19884 10 IRGANOX 1010 0.5 DONG JIN D900 B/A 9.0 KODAX
911C 0.2 LUPERCO 500-40KE 2 CAMELWITE ST 20
[0076]
12TABLE 12 EXAMPLE 12 Material Parts per Hundred of Resin EXXON
117.08 45 DUPONT/DOW ENGAGE 8180 30 NORDEL 1440 20 TECHMER BLACK
PM9101 12.5 KADOX 911C 0.2 IRGANOX 1010 0.5 LUPERCO 500-40KE 2.25
DONG JIN D900 B/A 10 CAMELWHITE ST 20 DRAXEOL #34 OIL 1
[0077]
13TABLE 13 EXAMPLE 13 Material Parts per Hundred of Resin EXXON LD
740 35 NORDEL 1440 RUBBER 20 DUPONT/DOW ENGAGE 8180 45 KADOX 911C
0.25 IRGANOX 1010 0.5 LUPERCO 500-40KE 3 DONG JIN D900 B/A 20
CELOGEN OT 0.1 CAMELWITE ST 20 DRAKDOL #34 OIL 20
[0078] In the Tables and Examples, EXXON LD 740 is an EVA copolymer
that contains 24.5% vinyl acetate, DUPONT/DOW ENGAGE 8100 and
DUPONT/DOW ENGAGE 8180 are single-site initiated polyethylene
resins (very low density polyethylene; VLDPE), DOW 510 is an LDPE
resin, EXXON VISTALON 2504 RUBBER is an EPDM rubber, DUPONT/DOW
ENGAGE 8200 is a single-site initiated polyethylene resin, NORDEL
1440 is a DuPont EPDM resin, Exxon 117.08 is a polyethylene resin,
KADOX 911C is zinc oxide, IRGANOX 1010 is a phenolic antioxidant,
BENNOX 1010 is an antioxidant, LUPERCO 500-40KE is dicumylperoxide
in a clay support, DONG JIN D900 B/A is azodicarbonamide, CELOGEN
OT is p,p'-oxybis(benzene)sulfonyl hydrazide (OBSH), CAMELWITE ST
is stearic acid coated calcium carbonate, TECHMER WHITE PM 1787E4
is a TiO.sub.2 coloring agent, TECHMER BK PM9101 is a black
coloring agent, and DRAKEOL #24 OIL is a mineral oil. DUPONT/DOW
ENGAGE 8180 has a melt index of 0.5 dg/min and a density of 0.863 g
mol.sup.-1. DUPONT/DOW ENGAGE 8100 has a melt index of 0.75-1.25
dg/min and a density of 0.865-0.871 g mol.sup.-1. DUPONT/DOW ENGAGE
8200 has a melt index of 5 dg/min and a density of 0.870 g
mol.sup.-1. Exxon LD 740 has a melt index of 5.5 dg/min and a
density of 0.948 g mol.sup.-1. Exxon 117.08 has a melt index of 1.6
dg/min and a density of 0.930 g mol.sup.-1. DOW 510 has a melt
index of 2 dg/min and a density of 0.919 g mol.sup.-1. EXXON
VISTALON 2504 RUBBER has a Mooney viscosity of about 26
ML(1+4).times.(125C) and a density of 0.86 g mol.sup.-1. NORDEL
1440 is a DuPont EPDM resin having a Mooney viscosity of about 40
ML(1+4).times.(121C) and a density of 0.86 g mol.sup.-1.
[0079] The properties of foams prepared by compression foaming the
polymer blends described in Examples 1, 2, 5, 6, and 7 are shown in
Table 14. Examples 5, 6, and 7, which include a polyolefin
including ethylene and propylene retain all of the good foam
properties of Examples 1 and 2, and have improved floatation
properties. As described above, the buoyancy retention is
determined after a long period exposure to elevated temperatures
and is a measure of the thermal stability of the foam. The polymer
blends that include a polyolefin including ethylene and propylene
(e.g., EPDM) in the formulation (i.e., Example 5 and Example 6)
performed better in the floatation test (and, therefore, had better
thermal stability) than the compositions that do not contain a
polyolefin including ethylene and propylene (i.e., Example 2).
[0080] Examples 7-13 are a higher density foam and are examples of
polymer blends and foams that are suitable for automotive
applications (e.g., making gaskets). For example, the formability
and thermal stability of the polymer blends and foamed polymer
blends make them suitable for forming gaskets.
14TABLE 14 Properties ASTM Ref. Example 1 Example 2 Example 5
Example 6 Example 7 Density (pcf) 3575 2.22 2.87 2.33 2.58 4.23
Tensile (psi) 3575 33 51 39 37 78 Elongation 3575 268 307 274 306
305 (%) Compression 3575 1.8 3.6 3.7 3.7 6.5 Deflection 25% (psi)
Compression 3575 6.3 10.8 10.7 10.6 14.8 Deflection 50% (psi)
Compression 3575 29 28 27 30.7 14.6 Set 50% (%) Compression 1056 57
59 58.3 61.8 27.8 Set 50% (%) Tear Die C 3575 3.9 6.5 5.7 6.2 12.3
(Pli) Split Tear 2.6 4.3 3.9 5 9.4 Durometer Shore A 0 3 2.7 3.3
9.7 Durometer Shore C 0 0 0 0 1.7 Durometer Shore OO 30 43 44 45 57
Cell Size Occular 0.25 0.20 0.20 0.20 0.18 Mode (mm) Cell Size
Occular 0.05 0.05 0.05 0.05 0.05 Range (mm) (max) Occular 0.63 0.43
0.41 0.38 0.34 Initial 59.3 59 62 Buoyancy @ 24 hrs (lbs) UL 1191
Buoyancy 91 102 99 Retention: V-Factor (%) C-Factor (%) 88 99
99
[0081] Other embodiments are within the claims.
* * * * *