U.S. patent application number 12/402211 was filed with the patent office on 2009-08-06 for tire innerliners having improved cold temperature properties.
Invention is credited to Bryan R. Chapman, David B. Dunaway, Bruce A. Harrington, Donald S. Tracey, Andy H. Tsou.
Application Number | 20090197995 12/402211 |
Document ID | / |
Family ID | 40932334 |
Filed Date | 2009-08-06 |
United States Patent
Application |
20090197995 |
Kind Code |
A1 |
Tracey; Donald S. ; et
al. |
August 6, 2009 |
Tire Innerliners Having Improved Cold Temperature Properties
Abstract
Provided are elastomeric compositions, such as a tire
innerliner, comprising at least one isobutylene based elastomer and
at least one hydrocarbon fluid additive ("HFA"). The compositions
have improved cold temperature properties and are particularly
useful as tire innerliners for an aircraft tire. The use of a HFA
in the elastomeric composition may allow for the use of reduced
amounts of secondary elastomers, such as natural rubber, while
allowing for an improved balance in the composition's brittleness
and permeability properties. Examples of useful HFAs include
polyalphaolefins, high purity hydrocarbon fluids, and water white
group III mineral oils.
Inventors: |
Tracey; Donald S.;
(Kingwood, TX) ; Tsou; Andy H.; (Allentown,
PA) ; Chapman; Bryan R.; (Annandale, NJ) ;
Harrington; Bruce A.; (Houston, TX) ; Dunaway; David
B.; (Houston, TX) |
Correspondence
Address: |
EXXONMOBIL CHEMICAL COMPANY
5200 BAYWAY DRIVE, P.O. BOX 2149
BAYTOWN
TX
77522-2149
US
|
Family ID: |
40932334 |
Appl. No.: |
12/402211 |
Filed: |
March 11, 2009 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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11323747 |
Dec 30, 2005 |
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12402211 |
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10518886 |
Dec 21, 2004 |
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PCT/US2003/016947 |
May 30, 2003 |
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11323747 |
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10398255 |
Apr 3, 2003 |
7425591 |
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PCT/US01/42767 |
Oct 16, 2001 |
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11323747 |
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09691764 |
Oct 18, 2000 |
6710116 |
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11323747 |
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60396497 |
Jul 17, 2002 |
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60294808 |
May 31, 2001 |
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61087461 |
Aug 8, 2008 |
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Current U.S.
Class: |
524/52 ; 524/425;
524/449; 524/451; 524/525 |
Current CPC
Class: |
C08L 23/22 20130101;
C08L 61/00 20130101; C08K 5/01 20130101; C08L 23/20 20130101; C08K
3/013 20180101; C08L 2312/04 20130101; C08L 7/00 20130101; C08L
23/283 20130101; C08K 5/01 20130101; C08L 23/283 20130101; C08K
5/01 20130101; C08L 23/22 20130101; C08L 23/22 20130101; C08L
2666/08 20130101; C08L 23/283 20130101; C08L 2666/08 20130101; C08L
23/283 20130101; C08L 2666/06 20130101 |
Class at
Publication: |
524/52 ; 524/525;
524/425; 524/449; 524/451 |
International
Class: |
C08L 7/00 20060101
C08L007/00; C08K 3/26 20060101 C08K003/26; C08K 3/34 20060101
C08K003/34; C08K 3/36 20060101 C08K003/36; C08L 3/00 20060101
C08L003/00 |
Claims
1. A cured elastomeric composition for use in a tire innerliner,
comprising: a. from 50 to 100 phr of at least one isobutylene-based
elastomer; b. less than or equal to 50 phr of natural rubber; and
c. from 1 to 30 phr of at least one hydrocarbon fluid additive,
wherein the hydrocarbon fluid additive has a flash point of at
least 200.degree. C., a pour point of less than or equal to
-15.degree. C., and specific gravity at 15.6.degree. C. of less
than or equal to 0.880; wherein the cured elastomeric composition
has a MOCON permeability coefficient of less than or equal to T,
where T=-0.1147Y+0.54 where Y is the change in brittleness
determined by subtracting the brittleness in .degree. C. of the
cured elastomeric composition containing the hydrocarbon fluid
additive from the brittleness in .degree. C. of a cured composition
having the same components except that it contains a naphthenic oil
having a flash point in the range of 160 to 170.degree. C., a pour
point of about -40.degree. C..+-.5%, and a specific gravity at
15.6.degree. C. of about 0.91.+-.0.01 instead of the hydrocarbon
fluid additive.
2. The cured elastomeric composition of claim 1, wherein the
isobutylene-based elastomer is selected from the group consisting
of butyl rubber, halogenated butyl rubber, star-branched butyl
rubber, halogenated star-branched butyl rubber,
poly(isobutylene-co-p-methylstyrene), halogenated
poly(isobutylene-co-p-methylstyrene), and mixtures thereof.
3. The cured elastomeric composition of claim 1, wherein the
composition comprises less than or equal to 10 phr of natural
rubber.
4. The cured composition of claim 1, wherein the hydrocarbon fluid
additive is selected from a group consisting of polyalphaolefins,
high purity hydrocarbon fluids, water white group III mineral oils,
and blends thereof.
5. The cured elastomeric composition of claim 1, wherein the
hydrocarbon fluid additive is a polyalphaolefin having a Kinematic
viscosity at 100.degree. C. of at least 4 cSt.
6. The cured elastomeric composition of claim 1, wherein the
hydrocarbon fluid additive is a polyalphaolefin having a Kinematic
viscosity at 100.degree. C. in the range of 6 to 40 cSt.
7. The cured elastomeric composition of claim 1, wherein the
hydrocarbon fluid additive is a polyalphaolefin having a viscosity
index of at least 120.
8. The cured elastomeric composition of claim 1, wherein the
composition is substantially free of naphthenic oil and/or is
substantially free of aromatic oil.
9. The cured elastomeric composition of claim 1, wherein the
composition further comprises one or more filler components
selected from calcium carbonate, mica, silica, silicates, talc,
titanium dioxide, starch, wood flour, carbon black, and mixtures
thereof.
10. The cured elastomeric composition of claim 1, wherein the
composition is a tire innerliner suitable for use in an aircraft
tire.
11. A cured elastomeric composition for use in a tire innerliner,
comprising: a. from 50 to 90 phr of at least one isobutylene-based
elastomer; b. from 1 to 50 phr of natural rubber; and c. from 1 to
30 phr of at least one hydrocarbon fluid additive, wherein the
hydrocarbon fluid additive has a flash point of at least
200.degree. C., a pour point of less than or equal to -15.degree.
C., and specific gravity at 15.6.degree. C. of less than or equal
to 0.880; wherein the cured elastomeric composition has a MOCON
permeability coefficient of less than or equal to Z, where
Z=0.282X+0.4817 where X is the amount of natural rubber in phr, and
wherein the cured elastomeric composition has a brittleness of less
than or equal to A, where A=-0.13X-51 where X is the amount of
natural rubber in phr.
12. The cured elastomeric composition of claim 11, wherein the
composition comprises from 70 to 90 phr of the isobutylene-based
elastomer.
13. The cured elastomeric composition of claim 11, wherein the
isobutylene-based elastomer is selected from the group consisting
of butyl rubber, halogenated butyl rubber, star-branched butyl
rubber, halogenated star-branched butyl rubber,
poly(isobutylene-co-p-methylstyrene), halogenated
poly(isobutylene-co-p-methylstyrene), and mixtures thereof.
14. The cured elastomeric composition of claim 11, wherein the
composition comprises from 10 to 30 phr of natural rubber.
15. The cured composition of claim 11, wherein the hydrocarbon
fluid additive is selected from a group consisting of
polyalphaolefins, high purity hydrocarbon fluids, water white group
III mineral oils, and blends thereof.
16. The cured elastomeric composition of claim 11, wherein the
hydrocarbon fluid additive is a polyalphaolefin having a Kinematic
viscosity at 100.degree. C. of at least 4 cSt.
17. The cured elastomeric composition of claim 11, wherein the
hydrocarbon fluid additive is a polyalphaolefin having a Kinematic
viscosity at 100.degree. C. in the range of 6 to 40 cSt.
18. The cured elastomeric composition of claim 11, wherein the
hydrocarbon fluid additive is a polyalphaolefin having a viscosity
index of at least 120.
19. The cured elastomeric composition of claim 11, wherein the
composition is substantially free of naphthenic oil and/or is
substantially free of aromatic oil.
20. The cured elastomeric composition of claim 11, wherein the
composition further comprises one or more filler components
selected from calcium carbonate, mica, silica, silicates, talc,
titanium dioxide, starch, wood flour, carbon black, and mixtures
thereof.
21. The cured elastomeric composition of claim 11, wherein the
composition is a tire innerliner suitable for use in an aircraft
tire.
22. A process for producing an air barrier comprising the steps of:
a. combining from 50 to 90 phr of at least one isobutylene-based
elastomer, from 1 to 50 phr of natural rubber, and from 1 to 30 phr
of at least one hydrocarbon fluid additive, wherein the hydrocarbon
fluid additive has a flash point of at least 200.degree. C., a pour
point of less than or equal to -15.degree. C., and specific gravity
at 15.6.degree. C. of less than or equal to 0.880; b. curing the
combined components to form a cured elastomeric composition wherein
the cured elastomeric composition has a MOCON permeability
coefficient of less than or equal to Z, where Z=0.282X+0.4817 where
X is the amount of natural rubber in phr, and wherein the cured
elastomeric composition has a brittleness of less than or equal to
A, where A=-0.13X-51 where X is the amount of natural rubber in
phr; and c. shaping the cured elastomeric composition to form the
air barrier.
23. The process of claim 22, wherein the air barrier is an
innerliner suitable for use in an aircraft tire.
24. An aircraft tire comprising an innerliner which comprises: a.
from 50 to 90 phr of at least one isobutylene-based elastomer; b.
from 1 to 50 phr of natural rubber; and c. from 1 to 30 phr of at
least one hydrocarbon fluid additive, wherein the hydrocarbon fluid
additive has a flash point of at least 200.degree. C., a pour point
of less than or equal to -15.degree. C., and specific gravity at
15.6.degree. C. of less than or equal to 0.880; wherein the
aircraft tire has a MOCON permeability coefficient of less than or
equal to Z, where Z=0.282X+0.4817 where X is the amount of natural
rubber in phr, and wherein the cured elastomeric composition has a
brittleness of less than or equal to A, where A=-0.13X-51 where X
is the amount of natural rubber in phr.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation-in-part and claims the
benefit of priority from U.S. patent application Ser. No.
11/323,747, filed on Dec. 30, 2005 the disclosure of which is
herein incorporated by reference. U.S. patent application Ser. No.
11/323,747 is (a) a continuation-in-part of U.S. patent application
Ser. No. 10/518,886, filed Dec. 21, 2004, which is a National Stage
Application of International Application No. PCT/US2003/016947,
filed May 30, 2003, which claims the benefit of Provisional
Application No. 60/396,497, filed Jul. 17, 2002; and (b) a
continuation-in-part of Ser. No. 10/398,255, filed Apr. 3, 2003,
which is a National Stage Application of International Application
No. PCT/US2001/42767, filed Oct. 16, 2001, which claims the benefit
of Provisional Application No. 60/294,808, filed May 31, 2001, and
is a continuation-in-part of Ser. No. 09/691,764, filed Oct. 18,
2000, now U.S. Pat. No. 6,710,116; the disclosures of which are all
incorporated herein by reference.
[0002] This application is also related to U.S. Application Ser.
No. 61/087,461, filed Aug. 8, 2008, herein incorporated by
reference.
FIELD OF THE INVENTION
[0003] This invention relates to tire innerliners having improved
cold temperature properties. More particularly, this invention
relates to cured elastomeric compositions for use as tire
innerliners that have improved cold temperature properties and
comprise a hydrocarbon fluid additive.
BACKGROUND OF THE INVENTION
[0004] Elastomeric compositions are used in a wide variety of
applications, including hoses, belts, footwear components,
vibration isolation devices, tires, and tire components such as
treads, sidewalls, and innerliners. The selection of ingredients
for the commercial formulation of an elastomeric composition
depends upon the balance of properties desired, the application,
and the application's end use. For example, in the tire industry
the balance between processing properties of the green (uncured)
composition in the tire plant and in-service performance of the
cured rubber tire composite is of particular importance. An
additional consideration to be balanced is the nature of the tire,
e.g., bias versus radial tire or passenger car tire versus truck
tire versus aircraft tire. The ability to improve a tire's air
impermeability properties and flex fatigue properties without
affecting the processability of the uncured elastomeric composition
or while maintaining or improving the physical property performance
of the cured elastomeric composition is a goal that still
remains.
[0005] Generally, the raw ingredients and materials used in tire
compounding impact tire performance variables. Thus, any
alternative to conventional ingredients must be compatible with the
rubbers, not interfere with the vulcanization rate, be easily
dispersed in all tire compounds, be cost effective, and not
adversely impact tire performance. This is of particular concern
for tire innerliners and tire innertubes where performance
properties must be maintained within specified tolerance levels.
For example, small increases in a tire innerliner compound's 300%
modulus can lead to reduction in fatigue resistance and cracks with
consequential loss in tire durability. Furthermore, for an
elastomeric composition that acts as an air barrier it is of
particular importance that any benefits in compound processability
are not to the detriment of the composition's air retention
capabilities.
[0006] Conventionally, halobutyl rubbers have been used to obtain
better air-retention in tires. While halobutyl rubber has allowed
for improvement in a composition's air-retention qualities, it can
negatively effect the composition's flex fatigue and brittleness
properties. This is of particular concern for certain tire
applications which require improved heat resistance and improved
cold temperature properties, such as is required for race-car
tires, snow tires, and aircraft tires. In order to improve flex
fatigue and brittleness properties, secondary elastomers, such as
ethylene-propylene rubber ("EP"), ethylene-propylene-diene rubber
("EPDM"), or natural rubber, have been blended with butyl rubbers
in tire innerliner/innertube compounds. While these secondary
elastomers may help improve flex fatigue and brittleness
temperatures, the blending of EP, EPDM, or natural rubbers often
increases the air permeability of the elastomeric composition.
[0007] Thus, there is still a need for an elastomeric composition
that is suitable for a tire innerliner or tire innertube that will
have enhanced thermal stability and physical properties under
severe temperature and operating conditions such as required for
race car tires and aircraft tires. It would be advantageous to have
an elastomeric composition that possesses improved low-temperature
toughness without sacrificing other advantageous traits such as
improved processability and air-impermeability.
SUMMARY OF THE INVENTION
[0008] The present disclosure provides an elastomeric composition,
such as a tire innerliner, comprising at least one isobutylene
based elastomer and at least one hydrocarbon fluid additive
("HFA"). The compositions are useful in a variety of applications
and are particularly suitable for an air barrier such as a tire
innertube or innerliner. In some embodiments, the composition
provides improved cold temperature properties and is particularly
useful as a tire innerliner for an aircraft tire.
[0009] In one aspect this disclosure relates to a cured elastomeric
composition for use in a tire innerliner, comprising (i) from 50 to
100 phr of at least one isobutylene-based elastomer; (ii) less than
or equal to 50 phr, or less than or equal to 10 phr, of natural
rubber; and (iii) from 1 to 30 phr of at least one HFA. The cured
elastomeric composition preferably has a MOCON permeability
coefficient of less than or equal to T, where T=-0.1147Y+0.54 where
Y is the change in brittleness determined by subtracting the
brittleness in .degree. C. of the cured elastomeric composition
containing HFA from the brittleness in .degree. C. of a cured
composition having the same components except that it contains a
naphthenic oil having a flash point in the range of 160 to
170.degree. C., a pour point of about -40.degree. C..+-.5%, and a
specific gravity at 15.6.degree. C. of about 0.91.+-.0.01 instead
of the HFA.
[0010] In another aspect this disclosure relates to a cured
elastomeric composition for use in a tire innerliner, comprising
(i) from 50 to 90 phr, or from 70 to 90 phr, of at least one
isobutylene-based elastomer; (ii) from 1 to 50 phr, or from 10 to
30 phr, or from 15 to 30 phr, of natural rubber; and (iii) from 1
to 30 phr, or from 4 to 30 phr, of at least one HFA. The cured
elastomeric composition preferably has a MOCON permeability
coefficient of less than or equal to Z, where Z=0.282X+0.4817 where
X is the amount of natural rubber in phr. The cured elastomeric
composition preferably has a brittleness of less than or equal to
A, where A=-0.13X-51 where X is the amount of natural rubber in
phr.
[0011] In yet another aspect this disclosure relates to a process
for producing an air barrier comprising the steps of (i) combining
from 50 to 90 phr of at least one isobutylene-based elastomer, from
1 to 50 phr (or from 10 to 50 phr) of natural rubber, and from 1 to
30 phr (or from 4 to 30 phr) of at least one HFA; (ii) curing the
combined components to form a cured elastomeric composition wherein
the cured elastomeric composition has a MOCON permeability
coefficient of less than or equal to Z, where Z=0.282X+0.4817 where
X is the amount of natural rubber in phr and a brittleness of less
than or equal to A, where A=-0.13X-51 where X is the amount of
natural rubber in phr; and (iii) shaping the cured elastomeric
composition to form the air barrier.
[0012] In one embodiment, and in combination with any of the above
disclosed aspects or embodiments, the isobutylene-based elastomer
is selected from the group consisting of butyl rubber, halogenated
butyl rubber, star-branched butyl rubber, halogenated star-branched
butyl rubber, poly(isobutylene-co-p-methylstyrene), halogenated
poly(isobutylene-co-p-methylstyrene), and mixtures thereof.
[0013] In another embodiment, and in combination with any of the
above disclosed aspects or embodiments, the HFA has a flash point
of at least 200.degree. C., a pour point of less than or equal to
-15.degree. C., and a specific gravity at 15.6.degree. C. of less
than or equal to 0.880.
[0014] In one embodiment and in combination with any of the above
disclosed aspects or embodiments, the hydrocarbon fluid additive is
selected from a group consisting of polyalphaolefins, high purity
hydrocarbon fluids, water white group III mineral oils, and blends
thereof.
[0015] In one embodiment and in combination with any of the above
disclosed aspects or embodiments, the HFA is a polyalphaolefin and
has a Kinematic viscosity at 100.degree. C. of at least 4 cSt, or
in the range of 6 to 40 cSt. The polyalphaolefin may also have a
viscosity index of at least 120.
[0016] In some embodiments, and in combination with any of the
above disclosed aspects or embodiments, the elastomeric composition
is substantially free of naphthenic oil and/or is substantially
free of aromatic oil.
[0017] In other embodiments, and in combination with any of the
above disclosed aspects or embodiments, the elastomeric composition
further comprises one or more filler components selected from
calcium carbonate, mica, silica, silicates, talc, titanium dioxide,
starch, wood flour, carbon black, and mixtures thereof.
[0018] These and other objects, features, and advantages will
become apparent as reference is made to the following detailed
description, preferred embodiments, examples, and appended
claims.
BRIEF DESCRIPTION OF THE FIGURE
[0019] FIG. 1 is a graph illustrating the impact on an elastomeric
composition's brittleness when the composition contains
polyalphaolefin ("PAO") and varying amounts of natural rubber.
[0020] FIG. 2 is a graph illustrating the impact on an elastomeric
composition's permeability when the composition contains PAO and
varying amounts of natural rubber.
[0021] FIG. 3 is a graph illustrating the improvement in an
elastomeric composition's brittleness/permeability balance that is
obtained when the composition comprises PAO.
DETAILED DESCRIPTION OF THE INVENTION
[0022] Various specific embodiments, versions, and examples are
described herein, including exemplary embodiments and definitions
that are adopted for purposes of understanding the claimed
invention. While the following detailed description gives specific
preferred embodiments, those skilled in the art will appreciate
that these embodiments are exemplary only, and that the invention
can be practiced in other ways. For purposes of determining
infringement, the scope of the invention will refer to any one or
more of the appended claims, including their equivalents, and
elements or limitations that are equivalent to those that are
recited. Any reference to the "invention" may refer to one or more,
but not necessarily all, of the inventions defined by the
claims.
[0023] The term "phr" means parts per hundred parts of rubber, and
is a measure common in the art wherein components of a composition
are measured relative to the total of all of the elastomer (rubber)
components. The total phr or parts for all rubber components,
whether one, two, three, or more different rubber components is
present in a given recipe is defined as 100 phr. All other
non-rubber components are ratioed against the 100 parts of rubber
and are expressed in phr.
[0024] The term "elastomer," as used herein, refers to any polymer
or combination of polymers consistent with the ASTM D1566
definition of "a material that is capable of recovering from large
deformations, and can be, or already is, modified to a state in
which it is essentially insoluble (but can swell) in boiling
solvent." As used herein, the term "elastomer" may be used
interchangeably with the term "rubber." Preferred elastomers have a
melting point that cannot be measured by DSC or if it can be
measured by DSC is less than 40.degree. C., or preferably less than
20.degree. C., or less than 0.degree. C. Preferred elastomers have
a Tg of -50.degree. C. or less as measured by DSC.
[0025] As used herein, the term "isobutylene based elastomer,"
refers to an elastomer or polymer comprising at least 70 mol %
repeat units from isobutylene.
[0026] The elastomeric compositions of the invention comprise
isobutylene based elastomers, hydrocarbon fluid additives ("HFA"),
and may further comprise various other fillers and additives. In
one embodiment, the HFA is used in addition to other conventional
processing aids or oils. However, in other embodiments, the HFA may
be able to partially or fully replace conventional processing aids
and/or oil, while maintaining current tire performance parameters
within an acceptable range. For example, the use of HFA in place of
aromatic process oils may allow for optimization of the tire
innerliners impermeability and brittleness properties.
Alternatively, the HFA may be blended with a naphthenic or
paraffinic process oil to maintain tire performance parameters
equivalent to those compositions containing only aromatic oil.
[0027] A thermal gravimetric analyzer with headspace gas
chromatography may be used to analyze the content and composition
of oil additives in the elastomeric composition. The amount of HFA
in the elastomeric composition may be determined as described in
Paragraphs [0623] to [0630] in U.S. Patent Application Publication
No. 2008/0045638, herein incorporated by reference.
[0028] In one embodiment, the elastomeric composition is
substantially free of naphthenic oil. Substantially free of
naphthenic oils is defined to mean that naphthenic oil has not
deliberately been added to the elastomeric composition, or, in the
alternative, if present the elastomeric composition comprises less
than 2 phr of naphthenic oil, or less than 0.5 phr, or more
preferably less than 0.25 phr, or most preferably less than 0.1 phr
of naphthenic oil. In one embodiment, naphthenic oil is present at
0 phr. Naphthenic oils are typically heavy hydrogenated oils having
greater than 40% of the carbons in naphthenic structures (i.e.,
saturated rings) and less than 20% of the carbons in aromatic
structures (i.e., unsaturated rings). Some naphthenic oils have
about 40-55% of the carbons in paraffinic chain-like structures
(i.e., isoparaffinic and normal paraffinic), 40-55% of the carbons
in naphthenic structures, and 6-15% of the carbons in aromatic
structures. As used herein, for the purpose of comparing an
elastomeric structure containing HFA to another composition having
the same components except that it contains a naphthenic oil
instead of the HFA, the naphthenic oil has a flash point in the
range of 160 to 170.degree. C., a pour point of about -40.degree.
C..+-.5%, and a specific gravity at 15.6.degree. C. of about
0.91.+-.0.01.
[0029] In another embodiment, the elastomeric composition is
substantially free of aromatic oil. Substantially free of aromatic
oil is defined to mean that aromatic oil has not deliberately been
added to the elastomeric composition, or, in the alternative, if
present the elastomeric composition comprises less than 2 phr of
aromatic oil, or less than 0.5 phr, or more preferably less than
0.25 phr, or most preferably less than 0.1 phr. In one embodiment,
aromatic oil is present at 0 phr. Generally, aromatic oils are
compounds containing at least 35% by mass of single- and
multiple-ring components. Generally, aromatic oils contain
unsaturated polycyclic components. Some aromatic oils have about
35-55% of the carbons in paraffinic chain-like structures (i.e.,
isoparaffinic and normal paraffinic), 10-35% of the carbons in
naphthenic structures (i.e., saturated rings), and 30-40% of the
carbons in aromatic structures (i.e., unsaturated rings).
[0030] In yet another embodiment, the elastomeric composition is
substantially free of paraffinic oil. Substantially free of
paraffinic oil is defined to mean that paraffinic oil has not
deliberately been added to the elastomeric composition, or, in the
alternative, if present the elastomeric composition comprises less
than 2 phr of paraffinic oil, or less than 0.5 phr, or more
preferably less than 0.25 phr, or most preferably less than 0.1
phr. In one embodiment, paraffinic oil is present at 0 phr.
Generally, paraffinic oils have greater than 60% of the carbons in
paraffinic chain-like structures (i.e., isoparaffinic and normal
paraffinic), and less than 40% of the carbons in naphthenic
structures (i.e., saturated rings), and less than 20% of the
carbons in aromatic structures (i.e., unsaturated rings). Some
paraffinic oils have about 60-80% of the carbons in paraffinic
chain-like structures, 20-40% of the carbons in naphthenic
structures, and 0-10% of the carbons in aromatic structures.
[0031] In a further embodiment, the elastomeric composition is
substantially free of polybutene processing oil. Substantially free
of polybutene processing oil is defined to mean that polybutene
processing oil has not deliberately been added to the elastomeric
composition, or, in the alternative, if present the elastomeric
composition comprises less than 2 phr of polybutene processing oil,
or less than 0.5 phr, or more preferably less than 0.25 phr, or
most preferably less than 0.1 phr. A polybutene processing oil
comprises 50 mole % or more of butene polymers, and is a copolymer
of at least isobutylene derived units, 1-butene derived units, and
2-butene derived units. The polybutene processing oil is preferably
low molecular weight and has a number average molecular weight of
15,000 g/mol or less.
Elastomer
[0032] The elastomeric compositions described herein comprise at
least one isobutylene-based elastomer. Typical isobutylene-based
elastomers that may be included in the compositions are C.sub.4
monoolefin based rubbers, such as butyl rubber
(isoprene-isobutylene rubber, "IIR"), branched ("star-branched")
butyl rubber, star-branched polyisobutylene rubber, bromobutyl
("BIIR"), chlorobutyl ("CIIR"), random copolymers of isobutylene
and para-methylstyrene (poly(isobutylene-co-p-methylstyrene)),
halogenated poly(isobutylene-co-p-methylstyrene) ("BIMSM"), any
halogenated versions of these elastomers, and mixtures thereof.
Useful elastomers can be made by any suitable means known in the
art, and the invention is not herein limited by the method of
producing the elastomer.
[0033] In some embodiments, the elastomeric composition comprises a
blend of two or more elastomers. Blends of elastomers may be
reactor blends and/or melt mixes. The individual elastomer
components may be present in various conventional amounts, with the
total elastomer content in the elastomeric composition being
expressed in the formulation as 100 phr.
[0034] Useful elastomers include isobutylene-based homopolymers or
copolymers. An isobutylene based elastomer refers to an elastomer
or polymer comprising at least 70 mol % repeat units from
isobutylene. These polymers can be described as random copolymers
of a C.sub.4 isomonoolefin derived unit, such as an isobutylene
derived unit, and at least one other polymerizable unit. The
isobutylene-based elastomer may or may not be halogenated.
[0035] The elastomer may also be a butyl-type rubber or branched
butyl-type rubber, including halogenated versions of these
elastomers. Useful elastomers are unsaturated butyl rubbers such as
homopolymers and copolymers of olefins, isoolefins, and
multiolefins. Non-limiting examples of other useful unsaturated
elastomers are poly(isobutylene-co-isoprene), polyisobutylene,
star-branched butyl rubber, halogenated and non-halogenated random
copolymers of isobutylene and para-methylstyrene, and mixtures
thereof.
[0036] The elastomer may or may not be halogenated. Preferred
halogenated elastomers may be selected from the group consisting of
halogenated butyl rubber, bromobutyl rubber, chlorobutyl rubber,
halogenated branched ("star-branched") butyl rubbers, and
halogenated random copolymers of isobutylene and
para-methylstyrene. Halogenation can be carried out by any means,
and the invention is not herein limited by the halogenation
process.
[0037] Examples of suitable commercially available halogenated
butyl rubbers include Bromobutyl 2222 and Bromobutyl 2225, both
available from ExxonMobil Chemical Company. Bromobutyl 2222 has a
Mooney viscosity from 27 to 37 (ML 1+8 at 125.degree. C., ASTM
D1646), and the bromine content is from 1.8 to 2.2 wt %. Further,
cure characteristics of Bromobutyl 2222 are as follows: MH is from
28 to 40 dNm, ML is from 7 to 18 dNm (ASTM D2084).
[0038] In one embodiment, the elastomer may be a branched or
"star-branched" butyl rubber ("SBB`). SBB is typically a
composition of a butyl rubber, either halogenated or not, and a
polydiene or block copolymer, either halogenated or not. In one
embodiment, the SBB or halogenated-SBB is a composition of a butyl
or halogenated butyl rubber and a copolymer of a polydiene and a
partially hydrogenated polydiene selected from the group including
styrene, polybutadiene, polyisoprene, polypiperylene, natural
rubber, styrene-butadiene rubber, ethylene-propylene diene rubber
(EPDM), ethylene-propylene rubber (EPR), styrene-butadiene-styrene,
and styrene-isoprene-styrene block copolymers. These polydienes are
present in one embodiment, based on the monomer wt %, greater than
0.3 wt %, or in another embodiment in the range of 0.3 to 3 wt %,
or in the range of 0.4 to 2.7 wt %.
[0039] In one embodiment, the elastomer may be a random copolymer
comprising a C.sub.4 isomonoolefin, such as isobutylene, and an
alkystyrene comonomer, such as para-methylstyrene, containing at
least 80%, alternatively at least 90%, by weight of the
para-isomer.
[0040] The copolymers may optionally include functionalized
interpolymers wherein at least one or more of the alkyl substituent
groups present in the styrene monomer units contain a halogen or
some other functional group. In one embodiment, up to 60 mol % of
the para-substituted styrene present in the random polymer
structure may be functionalized. In another embodiment, the amount
of functionalized para-methylstyrene is in the range of 0.1 to 5
mol %, or in the range of 0.2 to 3 mol %. The functional group may
be halogen or some other functional group which may be incorporated
by nucleophilic substitution of benzylic halogen with other groups
such as carboxylic acids, carboxy salts, carboxy esters, amides and
imides, hydroxyl, alkoxide, phenoxide, thiolate, thioether,
xanthate, cyanide, cyanate, amino, and mixtures thereof. These
functionalized isomonoolefin copolymers, their method of
preparation, methods of functionalization, and cure are more
particularly disclosed in U.S. Pat. No. 5,162,445, incorporated
herein by reference.
[0041] In a further embodiment, the elastomer comprises random
copolymers of isobutylene and para-methylstyrene containing from
0.5 to 20 mol % para-methylstyrene wherein up to 60 mol % of the
methyl substituent groups present on the benzyl ring contain a
bromine or chlorine atom, as well as acid or ester functionalized
versions thereof. In certain embodiments, the random copolymers
have a substantially homogeneous compositional distribution such
that at least 95% by weight of the polymer has para-alkylstyrene
content within 10% of the average para-alkylstyrene content of the
polymer. Exemplary polymers are characterized by a narrow molecular
weight distribution (Mw/Mn) of less than 5, alternatively less than
2.5, an exemplary viscosity average molecular weight in the range
of 200,000 up to 2,000,000 and an exemplary number average
molecular weight in the range of 25,000 to 750,000 as determined by
gel permeation chromatography.
[0042] The elastomer may be a brominated
poly(isobutylene-co-p-methylstyrene) ("BIMSM"). BIMSM polymers
generally contain from 0.1 to 5% mole of bromomethylstyrene groups
relative to the total amount of monomer derived units in the
copolymer. In one embodiment, the amount of bromomethyl groups is
in the range of 0.2 to 3.0 mol %, or in the range of 0.3 to 2.8 mol
%, or in the range of 0.4 to 2.5 mol %, or in the range of 0.3 to
2.0 mol %, wherein a desirable range may be any combination of any
upper limit with any lower limit. Expressed another way, exemplary
copolymers may contain 0.2 to 10 wt % of bromine, based on the
weight of the polymer, or 0.4 to 6 wt % bromine, or 0.6 to 5.6 wt
%, in another embodiment they are substantially free of ring
halogen or halogen in the polymer backbone chain. In one
embodiment, the random polymer is a copolymer of C.sub.4 to C.sub.7
isoolefin derived units (or isomonoolefin), para-methylstyrene
derived units, and para-(halomethylstyrene) derived units, wherein
the para-(halomethylstyrene) units are present in the polymer in
the range of 0.4 to 3.0 mol % based on the total number of
para-methylstyrene, and wherein the para-methylstyrene derived
units are present in the range of 3 to 15 wt %, or in the range of
4 to 10 wt %, based on the total weight of the polymer. In a
preferred embodiment, the para-(halomethylstyrene) is
para-(bromomethylstyrene).
[0043] Commercial embodiments of useful halogenated
isobutylene-p-methylstyrene rubbers include EXXPRO.TM. elastomers,
available from ExxonMobil Chemical Company, Houston, Tex., having a
Mooney viscosity (ML 1+8 at 125.degree. C., ASTM D1646) in the
range of 30 to 50, a p-methylstyrene content in the range of 4 to
8.5 wt %, and a bromine content in the range of 0.7 to 2.2 wt %
relative to the halogenated isobutylene-p-methylstyrene rubber.
[0044] In a preferred embodiment the elastomer is selected from
poly(isobutylene-co-alkylstyrene), preferably
poly(isobutylene-co-p-methylstyrene), halogenated
poly(isobutylene-co-alkylstyrene), preferably halogenated
poly(isobutylene-co-p-methylstyrene), star branched butyl rubber,
halogenated star-branched butyl rubber, butyl rubber, halogenated
butyl rubber, and mixtures thereof. In another preferred embodiment
the elastomer comprises bromobutyl rubber or chlorobutyl
rubber.
[0045] In another embodiment, the isobutylene-based elastomer in
the composition may be a blend of two or more different
isobutylene-based elastomers, alternately three or more,
alternately four or more. By "different isobutylene based
elastomer" is meant the isobutylene based elastomers differ in at
least one of the following: a) comonomer type (e.g. isoprene vs.
para-alkylstyrene); b) molecular weight (Mn as determined by GPC)
by at least 10%; c) Mooney Viscosity (ML 1+8 at 125.degree. C.,
ASTM D1646) by at least 10%; d) in comonomer content (by at least
10%; as determined by C.sup.13 nuclear magnetic resonance or
infrared spectroscopy); e) in halogen content by at least 1%;
and/or f) in halogen type (e.g. Cl vs. Br). Alternately the b)
and/or c) and/or d) differ by at least 20%, alternately by at least
30%. In another embodiment the halogen content varies by at least
2%, alternately by at least 3% alternately by at least 5%.
[0046] In other embodiments, the isobutylene based elastomer
portion of the elastomeric composition comprises from 50 to 90 phr,
or from 70 to 90 phr, of a first isobutylene-based elastomer and
from 10 to 50 phr, or from 15 to 30 phr, of different isobutylene
based elastomer(s).
Secondary Elastomer
[0047] The elastomeric composition may further include a secondary
elastomer. A secondary elastomer may be used in combination with
the at least one isobutylene-based elastomer to provide a balance
of properties. For example, the elastomeric composition may
comprise differing amounts of at least one isobutylene-based
elastomer and a secondary elastomer to provide beneficial compound
Mooney viscosity, Mooney scorch, curing characteristics, air
impermeability, flex fatigue retention, and adhesion to adjacent
components in a cured tire.
[0048] The secondary elastomer is generally a non isobutylene based
rubber of types conventionally used in tire rubber compounding,
herein referred to as "general purpose rubbers." A general purpose
rubber may be any rubber that usually provides high strength and
good abrasion along with low hysteresis and high resilience.
[0049] Examples of general purpose rubbers include natural rubbers
("NR"), polyisoprene rubber ("IR"), poly(styrene-co-butadiene)
rubber ("SBR"), solution-styrene-butadiene rubber ("sSBR"),
emulsion-styrene-butadiene rubber, nitrile rubber, polybutadiene
rubber ("BR"), high cis-polybutadiene, polyisoprene rubber,
poly(isoprene-co-butadiene) rubber ("IBR"),
styrene-isoprene-butadiene rubber ("SIBR"), and mixtures thereof.
Ethylene-propylene rubber ("EP") and ethylene-propylene-diene
rubber ("EPDM"), and their mixtures, are also referred to as
general purpose rubbers.
[0050] In one embodiment, the secondary elastomer is a general
purpose rubber such as polybutadiene rubber ("BR"). Another useful
general purpose rubber is high cis-polybutadiene ("cis-BR"). By
"cis-polybutadiene" or "high cis-polybutadiene", it is meant that
1,4-cis polybutadiene is used, wherein the amount of cis component
is at least 95%.
[0051] In yet another embodiment, the secondary elastomer may
comprise rubbers of ethylene and propylene derived units such as EP
and EPDM. Examples of suitable comonomers in making EPDM are
ethylidene norbornene, 1,4-hexadiene, dicyclopentadiene, as well as
others. In one embodiment, the secondary elastomer may comprise an
ethylene/alpha-olefin/diene terpolymer. The alpha-olefin may be
selected from the group consisting of C.sub.3 to C.sub.20
alpha-olefin with propylene, butene and octene being preferred and
propylene most preferred. The diene component may be selected from
the group consisting of C.sub.4 to C.sub.20 dienes.
[0052] In a preferred embodiment, the secondary elastomer is a
natural rubber. Desirable natural rubbers may be selected from
technically specified rubbers ("TSR"), such as Malaysian rubbers
which include, but are not limited to, SMR CV, SMR 5, SMR 10, SMR
20, SMR 50, and mixtures thereof. Preferred natural rubbers have a
Mooney viscosity at 100.degree. C. (ML 1+4, ASTM D1646) in the
range of 30 to 120, or in the range of 40 to 80.
[0053] In one embodiment, the elastomeric composition comprises 100
phr of an isobutylene-based elastomer. In another embodiment, the
elastomeric composition comprises a blend of at least one
isobutylene-based elastomer and a secondary elastomer which is a
non-isobutylene based elastomer.
[0054] In some embodiments, the elastomeric composition comprises
from 50 to 100 phr, or from 70 to 100 phr, or from 75 to 95 phr, of
isobutylene-based elastomers, and less than or equal to 50 phr, or
less than or equal to 30 phr, or less than or equal to 15 phr, or
less than or equal to 10 phr of a secondary elastomer. In one
embodiment, the elastomeric composition comprises from 90 to 100
phr of isobutylene based elastomers and less than or equal to 10
phr of a secondary elastomer. The secondary elastomer may be
natural rubber.
[0055] In one embodiment, a secondary elastomer other than natural
rubber is present; however no natural rubber is added to the
elastomeric composition. In some embodiments the elastomeric
composition comprises 0 phr of natural rubber.
[0056] In other embodiments, the elastomeric composition comprises
from 50 to 90 phr or from 70 to 90 phr of isobutylene-based
elastomers and from 10 to 50 phr or from 15 to 30 phr of a
secondary elastomer. The secondary elastomer may be natural
rubber.
[0057] The elastomers and/or secondary elastomers may be blended
with various other rubbers or plastics, in particular thermoplastic
resins such as nylons or polyolefins such as polypropylene or
copolymers of polypropylene. These compositions are useful in air
barriers such as bladders, tire innertubes, tire innerliners, air
sleeves (such as in air shocks), diaphragms, as well as other
applications where high air or oxygen retention is desirable.
Hydrocarbon Fluid Additive
[0058] The elastomeric compositions described herein include at
least one hydrocarbon fluid additive ("HFA"). The classes of
materials described herein that are useful as HFAs can be utilized
alone or admixed with other HFAs described herein to obtain desired
properties. Any HFA useful in the present invention may also be
described by any number of, or any combination of, parameters
described herein.
[0059] In one embodiment, the HFA is defined to be a hydrocarbon
liquid compound comprising carbon and hydrogen, having functional
groups selected from hydroxide, aryls, substituted aryls, halogens,
alkoxys, carboxylates, esters, carbon unsaturation, acrylates,
oxygen, nitrogen, and carboxyl present to an unappreciable extent.
By "unappreciable extent", it is meant that these groups and
compounds comprising these groups are not deliberately added to the
HFA, and if present at all for any reason, are present at less than
5 wt %, or less than 3 wt %, or preferably less than 1 wt %, or
less than 0.5 wt %, or less than 0.1 wt %, or less than 0.05 wt %,
or less than 0.01 wt %, or less than 0.001 wt %, based upon the
weight of the HFA.
[0060] In some embodiment, aromatic moieties (including compounds
whose molecules have the ring structure characteristic of benzene,
naphthalene, phenanthrene, anthracene, etc.) are substantially
absent from the HFA. In yet another embodiment, naphthenic moieties
(including compounds whose molecules have a saturated ring
structure such as would be produced by hydrogenating benzene,
naphthalene, phenanthrene, anthracene, etc.) are substantially
absent from the HFA. By "substantially absent", it is meant that
the aromatic moieties or the naphthenic moieties are not
deliberately added to the HFA, and if present at all for any
reason, are present at less than 5 wt %. Preferably, these groups
and compounds are present at less than 4 wt %, or less than 3 wt %,
or less than 2 wt %, or less than 1 wt %, or less than 0.7 wt %, or
less than 0.5 wt %, or less than 0.3 wt %, or less than 0.1 wt %,
or less than 0.05 wt %, or less than 0.01 wt %, or less than 0.001
wt %, based upon the weight of the HFA.
[0061] In some embodiments, the HFA is a hydrocarbon that contains
olefinic unsaturation to an unappreciable extent. By "unappreciable
extent of olefinic unsaturation", it is meant that the carbons
involved in olefinic bonds account for less than 10%, or less than
6%, or less than 2%, or preferably less than 1%, or less than 0.5%,
or less than 0.1%, or less than 0.05%, or less than 0.01%, or less
than 0.001%, of the total number of carbons. In some embodiments,
the percent of carbons of the HFA involved in olefinic bonds is in
the range of 0.001 to 10%, or in the range of 0.01 to 5%, or in the
range of 0.1 to 2%, of the total number of carbon atoms in the
HFA.
[0062] Particularly preferred HFAs include a) polyalphaolefins, b)
high purity hydrocarbon fluids derived from a so-called
Gas-To-Liquids processes, and c) Group III Mineral Oils; with a
viscosity index greater than 100 (preferably greater than 120), a
pour point less than -15.degree. C. (preferably less than
-20.degree. C.), a specific gravity less than 0.88 (preferably less
than 0.86), and a flash point greater than 200.degree. C.
(preferably greater than 230.degree. C.).
[0063] In preferred embodiments, the HFA has a kinematic viscosity
at 100.degree. C. (KV.sub.100) of 3 cSt or more, preferably 4 cSt
or more, preferably 5 cSt or more, preferably 6 cSt or more,
preferably 8 cSt or more, preferably 10 cSt or more, preferably 20
cSt or more, preferably 40 cSt or more, preferably 6 to 5000 cSt,
preferably 8 to 3000 cSt, preferably 10 to 1000 cSt, preferably 12
to 500 cSt, preferably 15 to 400 cSt, preferably 20 to 350 cSt,
preferably 35 to 300 cSt, preferably 40 to 200 cSt, preferably 8 to
300 cSt, preferably 6 to 150 cSt, preferably 10 to 100 cSt,
preferably less than 50 cSt, wherein a desirable range may be any
combination of any lower KV.sub.100 limit with any upper KV.sub.100
limit described herein.
[0064] In preferred embodiments, the HFA has a pour point of
-10.degree. C. or less, preferably -20.degree. C. or less,
preferably -30.degree. C. or less, preferably -40.degree. C. or
less, preferably -45.degree. C. or less, preferably -50.degree. C.
or less, preferably -10 to -100.degree. C., preferably -15 to
-80.degree. C., preferably -15 to -75.degree. C., preferably -20 to
-70.degree. C., preferably -25 to -65.degree. C., preferably
greater than -120.degree. C., wherein a desirable range may be any
combination of any lower pour point limit with any upper pour point
limit described herein.
[0065] In another embodiment, the HFA has a pour point of less than
-30.degree. C. when the kinematic viscosity at 40.degree. C. is
from 20 to 600 cSt (preferably 30 to 400 cSt, preferably 40 to 300
cSt). Most mineral oils, which typically include aromatic moieties
and other functional groups, have a pour point of from 10 to
-20.degree. C. in the same kinematic viscosity range.
[0066] In a preferred embodiment, the HFA has a glass transition
temperature (T.sub.g) of -40.degree. C. or less, preferably
-50.degree. C. or less, preferably -60.degree. C. or less,
preferably -70.degree. C. or less, preferably -80.degree. C. or
less, preferably -45 to -120.degree. C., preferably -65 to
-90.degree. C., wherein a desirable range may be any combination of
any lower T.sub.g limit with any upper T.sub.g limit described
herein.
[0067] In preferred embodiments, the HFA has a Viscosity Index (VI)
of 100 or more, preferably 110 or more, preferably 120 or more,
preferably 130 or more, preferably 115 to 350, preferably 135 to
300, preferably 140 to 250, preferably 150 to 200, preferably 125
to 180, wherein a desirable range may be any combination of any
lower VI limit with any upper VI limit described herein.
[0068] In preferred embodiments, the HFA has a flash point of
200.degree. C. or greater, preferably 210.degree. or greater,
preferably 230.degree. C. or greater, preferably 200 to 320.degree.
C., preferably 210 to 300.degree. C., preferably 215 to 290.degree.
C., preferably 220 to 280.degree. C., preferably 240 to 280.degree.
C., wherein a desirable range may be any combination of any lower
flash point limit with any upper flash point limit described
herein.
[0069] In preferred embodiments, the HFA has a specific gravity of
0.88 or less, or 0.86 or less, preferably 0.855 or less, preferably
0.84 or less, preferably 0.78 to 0.86, preferably 0.79 to 0.855,
preferably 0.80 to 0.85, preferably 0.81 to 0.845, preferably 0.82
to 0.84, wherein a desirable range may be any combination of any
lower specific gravity limit with any upper specific gravity limit
described herein.
[0070] In preferred embodiments, the HFA has a low degree of color,
such as typically identified as "water white", "prime white",
"standard white", or "bright and clear," preferably an APHA color
of 100 or less (preferably 80 or less, preferably 60 or less,
preferably 40 or less, preferably 20 or less).
[0071] In other embodiments, any HFA may have an initial boiling
point of from 300 to 600.degree. C. (preferably 350 to 500.degree.
C., preferably greater than 400.degree. C.).
[0072] Any of the HFAs for use in the present invention may be
described by any embodiment described herein or any combination of
the embodiments described herein.
[0073] In some embodiments, the HFA described herein has a flash
point of 200.degree. C. or more (preferably 210.degree. C. or more,
or 220.degree. C. or more, or 230.degree. C. or more) and a pour
point of -15.degree. C. or less (or -20.degree. C. or less, or
preferably -25.degree. C. or less, preferably -30.degree. C. or
less, preferably -35.degree. C. or less, preferably -45.degree. C.
or less, preferably -50.degree. C. or less).
[0074] In certain embodiments, the HFA has a) a specific gravity of
0.86 or less (preferably 0.855 or less, preferably 0.85 or less);
b) a VI of 120 or more (preferably 135 or more, preferably 140 or
more); and c) a flash point of 200.degree. C. or more (preferably
220.degree. C. or more, preferably 240.degree. C. or more).
[0075] In certain embodiments, the HFA has a) a flash point of
200.degree. C. or more; b) a specific gravity of 0.88, or 0.86 or
less; c) a pour point of -15.degree. C. or less; and d) a viscosity
index of 120 or more.
[0076] In another embodiment, the HFA has a pour point of
-20.degree. C. or less, preferably -30.degree. C. or less, and one
or more of the following properties: [0077] i. a kinematic
viscosity at 100.degree. C. of 3 cSt or greater (preferably 6 cSt
or greater, preferably 8 cSt or greater, preferably 10 cSt or
more); and/or, [0078] ii. a Viscosity Index of 120 or greater
(preferably 130 or greater); and/or, [0079] iii. a low degree of
color, such as typically identified as "water white", "prime
white", "standard white", or "bright and clear," preferably APHA
color of 100 or less (preferably 80 or less, preferably 60 or less,
preferably 40 or less, preferably 20 or less, preferably 15 or
less); and/or [0080] iv. a flash point of 200.degree. C. or more
(preferably 220.degree. C. or more, preferably 240.degree. C. or
more); and/or [0081] v. a specific gravity (15.6.degree. C.) of
less than 0.86.
[0082] Most mineral oils have a kinematic viscosity at 100.degree.
C. of less than 6 cSt, or an APHA color of greater than 20, or a
flash point less than 200.degree. C. when their pour point is less
than -20.degree. C.
[0083] In certain embodiments, the HFA has a pour point of
-15.degree. C. or less (preferably -15.degree. C. or less,
preferably -20.degree. C. or less, preferably -25.degree. C. or
less), a VI of 120 or more (preferably 135 or more, preferably 140
or more), and optionally a flash point of 200.degree. C. or more
(preferably 220.degree. C. or more, preferably 240.degree. C. or
more).
[0084] In certain embodiments, the HFA has a pour point of
-20.degree. C. or less (preferably -25.degree. C. or less,
preferably -30.degree. C. or less, preferably -40.degree. C. or
less) and one or more of the following: [0085] i. a flash point of
200.degree. C. or more (preferably 220.degree. C. or more,
preferably 240.degree. C. or more), and/or [0086] ii. a VI of 120
or more (preferably 135 or more, preferably 140 or more), and/or
[0087] iii. a KV100 of 4 cSt or more (preferably 6 cSt or more,
preferably 8 cSt or more, preferably 10 cSt or more), and/or [0088]
iv. a specific gravity of 0.86 or less (preferably 0.855 or less,
preferably 0.85 or less).
[0089] In certain embodiments, the HFA has a KV100 of 4 cSt or more
(preferably 5 cSt or more, preferably 6 cSt or more, preferably 8
cSt or more, preferably 10 cSt or more), a specific gravity of 0.86
or less (preferably 0.855 or less, preferably 0.85 or less), and a
flash point of 200.degree. C. or more (preferably 220.degree. C. or
more, preferably 240.degree. C. or more).
[0090] In a embodiment, the HFA has a flash point of 200.degree. C.
or more (preferably 220.degree. C. or more, preferably 240.degree.
C. or more), a pour point of -10.degree. C. or less (preferably
-15.degree. C. or less, preferably -20.degree. C. or less,
preferably -25.degree. C. or less), a specific gravity of 0.86 or
less (preferably 0.855 or less, preferably 0.85 or less), a KV100
of 4 cSt or more (preferably 5 cSt or more, preferably 6 cSt or
more, preferably 8 cSt or more, preferably 10 cSt or more), and
optionally a VI of 100 or more (preferably 120 or more, preferably
135 or more).
[0091] In a embodiment, the HFA has a flash point of 200.degree. C.
or more (preferably 210.degree. C. or more, preferably 220.degree.
C. or more), a pour point of -10.degree. C. or less (preferably
-20.degree. C. or less, preferably -30.degree. C. or less), and a
KV100 of 6 cSt or more (preferably 8 cSt or more, preferably 10 cSt
or more, preferably 15 cSt or more).
[0092] In certain embodiments, the HFA has a pour point of
-20.degree. C. or less (preferably -25.degree. C. or less,
preferably -30.degree. C. or less, preferably -40.degree. C. or
less) and one or more of the following: [0093] i. a flash point of
200.degree. C. or more (preferably 220.degree. C. or more,
preferably 240.degree. C. or more), and/or [0094] ii. a VI of 120
or more (preferably 135 or more, preferably 140 or more), and/or
[0095] iii. a KV100 of 4 cSt or more (preferably 6 cSt or more,
preferably 8 cSt or more, preferably 10 cSt or more), and/or [0096]
iv. a specific gravity of 0.86 or less (preferably 0.855 or less,
preferably 0.85 or less).
[0097] In a embodiment, the HFA has a KV100 of 35 cSt or more
(preferably 40 or more) and a specific gravity of 0.86 or less
(preferably 0.855 or less), and optionally one or more of the
following: [0098] a) a flash point of 200.degree. C. or more
(preferably 220.degree. C. or more, preferably 240.degree. C. or
more), and/or [0099] b) a pour point of -10.degree. C. or less
(preferably -15.degree. C. or less, preferably -20.degree. C. or
less, preferably -25.degree. C. or less).
[0100] In a preferred embodiment, the percentage of carbons in
chain-type paraffins (C.sub.P) for any HFA is at least 80%
(preferably at least 85%, preferably at least 90%, even preferably
at least 95%, even preferably at least 98%, most preferably at
least 99%). Chain-type paraffins (C.sub.P) are determined as
described in US 2008/0045638.
Polyalphaolefin
[0101] In preferred embodiments, the HFA is a polyalphaolefin
("PAO"). In general, PAOs are oligomers of .alpha.-olefins (also
known as 1-olefins) having a VI of 120 or more and are often used
as the base stock for synthetic lubricants. PAOs are typically
produced by the polymerization of alpha-olefins typically ranging
from 1-octene to 1-dodecene, with 1-decene being a preferred
material, although polymers of lower olefins such as ethylene and
propylene may also be used, including copolymers of ethylene with
higher olefins. The various grades of PAOs are mainly distinguished
by their molecular weight or by their kinematic viscosity measured
in centistokes (cSt) at 100.degree. C. PAOs are Group 4 compounds,
as defined by the American Petroleum Institute (API). Useful PAOs
are described in, for example, U.S. Pat. No. 3,149,178; U.S. Pat.
No. 4,827,064; U.S. Pat. No. 4,827,073; U.S. Pat. No. 5,171,908;
and U.S. Pat. No. 5,783,531 and in SYNTHETIC LUBRICANTS AND
HIGH-PERFORMANCE FUNCTIONAL FLUIDS, Leslie R. Rudnick & Ronald
L. Shubkin, eds. (Marcel Dekker, 1999), p. 3-62.
[0102] A PAO is not a polymer. (A polymer is defined to be 75 mer
units or more).
[0103] Useful PAOs may be made by any suitable means known in the
art, and the invention is not herein limited by the method of
producing the PAO. In one embodiment, the PAOs may be produced by
the oligomerization or polymerization of alpha-olefins in the
presence of a Friedel-Crafts (Lewis acid) catalyst, such as, for
example, AlCl.sub.3, BF.sub.3, or a coordination complex such as
ethylaluminum sesquichloride+TiCl.sub.4. Alternatively, the PAO may
be produced using a single-site coordination catalyst, such as a
metallocene catalyst or a constrained geometry catalyst.
[0104] Subsequent to the polymerization, the PAO may be
hydrogenated in order to reduce any residual unsaturation.
Preferred PAOs are hydrogenated to yield substantially (>99 wt
%) paraffinic materials. The PAOs may also be functionalized to
comprise, for example, esters, polyethers, polyalkylene glycols,
and the like.
[0105] The PAOs are preferably oligomers (e.g., are dimers,
trimers, tetramers, pentamers, etc.) of C.sub.4 to C.sub.24
.alpha.-olefins, C.sub.6 to C.sub.12 .alpha.-olefins, and/or
C.sub.8 to C.sub.12 .alpha.-olefins. Suitable olefins include
1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene,
1-decene, 1-undecene, 1-dodecene, 1-tetradecene, and
1-hexadecene.
[0106] In one embodiment, the PAO comprises oligomers of a single
alpha-olefin species having a carbon number of 5 to 24 (preferably
6 to 18, preferably 8 to 12, most preferably 10). In another
embodiment, the PAO comprises oligomers of mixed alpha-olefins
(i.e., involving two or more alpha-olefin species), each
alpha-olefin having a carbon number of 3 to 24 (preferably 5 to 24,
preferably 6 to 18, most preferably 8 to 12, or 8 to 14, or 8 to
16), provided that alpha-olefins having a carbon number of 3 or 4
are present at 10 wt % or less. In a preferred embodiment, the PAO
comprises oligomers of mixed alpha-olefins (i.e., involving two or
more alpha-olefin species) where the weighted average carbon number
for the alpha-olefin mixture is 6 to 14 (preferably 8 to 12,
preferably 9 to 11).
[0107] In one embodiment, at least one of the alpha-olefins is a
linear alpha-olefin (LAO); more preferably, all the alpha-olefins
are LAOs. Preferred PAO's comprise linear alpha olefins having 5 to
18 carbon atoms, preferably 6 to 12 carbon atoms, more preferably 8
to 12 carbon atoms, still more preferably an average of about 10
carbon atoms. Suitable LAOs include ethylene, propylene, 1-butene,
1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene, 1-decene,
1-undecene, 1-dodecene, 1-tridecene, 1-tetradecene, 1-pentadecene,
1-hexadecene, and blends thereof. Preferably, C.sub.2, C.sub.3, and
C.sub.4 alpha-olefins (i.e., ethylene, propylene and 1-butene
and/or isobutylene) are present in the PAO oligomers at an average
concentration of 30 wt % or less, or 20 wt % or less, or 10 wt % or
less, or 5 wt % or less; more preferably, C.sub.2, C.sub.3, and
C.sub.4 alpha-olefins are not present in the PAO oligomers.
[0108] In one or more embodiments, the PAO comprises oligomers of
two or more C.sub.2 to C.sub.24, or C.sub.3 to C.sub.20 LAOs, to
make `bipolymer` or `terpolymer` or higher-order copolymer
combinations. Other embodiments involve oligomerization of a
mixture of LAOs selected from C.sub.6 to C.sub.18 LAOs with even
carbon numbers, preferably a mixture of two or three LAOs selected
from 1-hexene, 1-octene, 1-decene, 1-dodecene, 1-tetradecene, and
1-hexadecene.
[0109] In general, PAOs are high purity hydrocarbons with a fully
paraffinic structure and a high-degree of side-chain branching. The
PAO may have irregular branching or regular branching. The PAO may
comprise oligomers or low molecular weight polymers of branched
and/or linear alpha olefins. Preferred PAOs have a "branching
ratio," as defined in U.S. Pat. No. 4,827,064 and measured
according to the method described therein, of 0.20 or less, or 0.18
or less, or 0.15 or less, or 0.10 or less.
[0110] The PAO may be a blend or mixture of one or more distinct
PAOs with different compositions and/or different physical
properties (e.g., kinematic viscosity, pour point, and/or viscosity
index).
[0111] The PAO or blend of PAOs may have a kinematic viscosity
("KV") at 100.degree. C. (as measured by ASTM D445 at 100.degree.
C.) (1 cSt=1 mm.sup.2/s) of 3 cSt or more, or 4 cSt or more, or 5
cSt or more, or 6 cSt or more, or 8 cSt or more, or 10 cSt or more,
or 20 cSt or more, or 30 cSt or more, or 40 cSt or more, or 80 cSt
or more, or 100 cSt or more, or 150 cSt or more, or 200 cSt or
more, or 300 cSt or more, or 500 cSt or more, or 750 or more, or
1000 cSt or more. In some embodiments, the PAO has a KV at
100.degree. C. in the range of 3 to 3,000 cSt, or 4 to 1,000 cSt,
preferably 4 to 300 cSt, or 5 to 150 cSt, or 6 to 100 cSt, or 6 to
40 cSt. In other embodiments, the PAO or blend of PAOs has a
KV100.degree. C. in the range of 3 cSt to 20 cSt, or in the range
of 5 cSt to 15 cSt, or preferably in the range of 6 cSt to 10 cSt.
In further embodiments, the PAO or blend of PAOs has a
KV100.degree. C. in the range of 40 to 200 cSt, or in the range of
60 to 150 cSt, or preferably 80 cSt to 120 cSt.
[0112] The PAO or blend of PAO may have a viscosity index ("VI"),
as determined by ASTM D-2270, of 100 or more, or 110 or more, or
120 or more, or 130 or more, or 140 or more, or 150 or more, or 170
or more, or 200 or more, or 250 or more, or 300 or more. Preferred
PAOs have a VI in the range of 90 to 400, or in the range of 100 to
350, or 120 to 250, or 130 to 180, or in other embodiments in the
range of 110 to 150 or 120 to 140.
[0113] PAOs with KV at 100.degree. C. of 10 cSt or less generally
have a VI of less than 150. A PAO with a high VI can be
advantageous as a higher VI may indicate that the PAO has a higher
viscosity at higher temperatures where polymer processing takes
place such as, 200.degree. C. or more; therefore, blending the PAO
into the polymer may be facilitated (it is well known that
homogeneous mixing of materials with severely mismatched
viscosities such as a high viscosity polymer and a low viscosity
fluid is difficult). On the other hand, for a given viscosity at
high temperature (e.g., 200.degree. C.), a higher VI means the PAO
has a lower viscosity at room temperature, so the PAO is easier to
pump. In certain embodiments, the PAO or blend of PAOs has a
KV100.degree. C. of 10 cSt or less and a VI of 150 or more. In
other embodiments, the PAO or blend of PAOs has a KV100.degree. C.
of 150 cSt or less, preferably between 10 and 150 cSt, and a VI of
greater than 105(KV100.degree. C.).sup.0.13 where KV100.degree. C.
is measured in cSt.
[0114] Useful PAOs typically possess a number average molecular
weight (Mn) in the range of 100 to 21,000 g/mole, or 300 to 15,000,
or 200 to 10,000, or 200 to 7,000, or 600 to 3,000, or in other
embodiments in the range of 200 to 2,000 g/mole or 200 to 500
g/mole.
[0115] Useful PAOs have a weight average molecular weight (Mw) of
less than 20,000 g/mole, or less than 10,000 g/mole, or less than
5,000 g/mole, or more preferably less than 4,000 g/mole, or less
than 2,000 g/mole, or less than 500 g/mole. In some embodiments,
the PAO may have an Mw of 1000 g/mole or more, or 2000 g/mole or
more, or 2500 g/mole or more, or 3000 g/mole or more, or 3500
g/mole or more. In other embodiments the PAO may have an Mw in the
range of 100 to 20,000 g/mole, or 200 to 10,000 g/mole, or 200 to
7,000 g/mole, or in the range of 2000 g/mole to 4000 g/mole, or in
the range of 2500 g/mole to 3500 g/mole.
[0116] In one or more embodiments, the PAO or blend of PAOs has a
molecular weight distribution as characterized by the ratio of the
weight- and number-averaged molecular weights (M.sub.w/M.sub.n) of
4 or less, or 3 or less, or 2.5 or less, or 2.3 or less, or 2.1 or
less, or 2.0 or less, or 1.9 or less, or 1.8 or less. In other
embodiments, the PAO or blend of PAOs has an M.sub.w/M.sub.n in the
range of 1 to 2.5, preferably 1.1 to 2.3, or 1.1 to 2.1, or 1.1 to
1.9.
[0117] Preferably the PAO has a pour point, as determined by ASTM
D97, of less than -15.degree. C. or less, more preferably
-20.degree. C. or less, or -30.degree. C. or less, or -40.degree.
C. or less, or -50.degree. C. or less; or in some embodiments in
the range of -20 to -80.degree. C., or -30 to -70.degree. C., or
-15 to -70.degree. C., or -25 to -60.degree. C.
[0118] The PAO may have a dielectric constant, as measured by ASTM
D 924, at 20.degree. C. of less than 3.0, or less than 2.8, or less
than 2.5, or less than 2.3, or less than 2.1.
[0119] Useful PAOs may have a specific gravity (ASTM D 4052,
15.6.degree. C.) of less than 0.880, or less than 0.86, or less
than 0.855, or less than 0.85, or more preferably in the range of
0.650 to 0.880, or 0.700 to 0.860, or 0.750 to 0.855, or 0.790 to
0.850, or 0.800 to 0.840.
[0120] Particularly preferred PAO's for use herein are those having
a flash point as measured by the open cup method (ASTM-D92) of
200.degree. C. or more, or 220.degree. C. or more, or 230.degree.
C. or more, or 250.degree. C. or more. In some embodiments, the PAO
may have a flash point in the range of about 200 to 300.degree. C.,
or in the range of about 210 to 275.degree. C., or in the range of
about 220 to 250.degree. C.
[0121] In one or more embodiments, the PAO or blend of PAOs has a
glass transition temperature (T.sub.g) of -40.degree. C. or less,
or -50.degree. C. or less, or -60.degree. C. or less, or
-70.degree. C. or less, or -80.degree. C. or less, preferably in
the range of -50 to -120.degree. C., or in some embodiments in the
range of 60 to -100.degree. C. or -70 to -90.degree. C.
[0122] Useful PAOs or blends of PAOs may have one or more of the
above described properties. For example, in one embodiment, the PAO
comprises C.sub.6 to C.sub.14 olefins having a kinematic viscosity
of 10 cSt or more at 100.degree. C., and a viscosity index of 120
or more, or 130 or more.
[0123] In another embodiment, a useful PAO is one having a flash
point of 200.degree. C. or more (preferably 220.degree. C. or more,
or 230.degree. C. or more, or 250.degree. C. or more) and a pour
point less than -25.degree. C. (preferably less than -30.degree.
C., or less than -35.degree. C., or less than -40.degree. C.).
[0124] In a further embodiment, an advantageous PAO or blend of
PAOs are those having i) a flash point of 200.degree. C. or more,
preferably 210.degree. C. or more, or 220.degree. C. or more, or
230.degree. C. or more; ii) a pour point less than -20.degree. C.,
preferably less than -25.degree. C., or less than -30.degree. C.,
or less than -35.degree. C., or less than -40.degree. C.; and iii)
a KV100.degree. C. of 10 cSt or more, preferably 35 cSt or more, or
40 cSt or more, or 60 cSt or more.
[0125] In yet another embodiment, the PAO or blends of PAOs have i)
a KV100.degree. C. of at least 3 cSt, preferably at least 4 cSt, or
at least 6 cSt, or at least 8 cSt, or at least 10 cSt; ii) a VI of
at least 120, preferably at least 130, or at least 140, or at least
150; iii) a pour point of -15.degree. C. or less, preferably
-20.degree. C. or less, or -30.degree. C. or less, or -40.degree.
C. or less; and iv) a specific gravity (15.6.degree. C.) of 0.86 or
less preferably 0.855 or less, or 0.85 or less, or 0.84 or
less.
[0126] Advantageous blends of PAOs include blends of two or more
PAOs where the ratio of the highest KV100.degree. C. to the lowest
KV100.degree. C. is at least 1.5, preferably at least 2, or at
least 3, or at least 5. Other blends of PAO also include two or
more PAOs where at least one PAO has a KV100.degree. C. of 300 cSt
or more and at least one other PAO has a KV100.degree. C. of less
than 300 cSt; or a blend where at least one PAO has a KV100.degree.
C. of 150 cSt or more and at least one other PAO has a
KV100.degree. C. of less than 150 cSt; or a blend where at least
one PAO has a KV100.degree. C. of 100 cSt or more and at least one
other PAO has a KV100.degree. C. of less than 100 cSt; or a blend
where at least one PAO has a KV100.degree. C. of 40 cSt or more and
at least one PAO has a KV100.degree. C. of less than 40 cSt; or at
least one PAO has a KV100.degree. C. of 10 cSt or more and at least
one PAO has a KV100.degree. C. of less than 10 cSt.
[0127] When a PAO or combination of more than one PAOs is employed,
it is preferred that the PAO or combination of PAOs have a pour
point less than or equal to -38.degree. C. and/or a Kinematic
viscosity less than or equal to 10.5 cSt at 100.degree. C. Such
formulations may include a PAO having one or more of the properties
described herein and another PAO with properties that may or may
not have one or more of the properties described herein as long as
the combination of PAOs have a pour point less than or equal to
-38.degree. C. and/or a Kinematic viscosity less than or equal to
10.5 cSt at 100.degree. C.
[0128] Desirable PAOs are available as SpectraSyn.TM. and
SpectraSyn Ultra.TM. from ExxonMobil Chemical in Houston, Tex.
(previously sold under the SHF and SuperSyn.TM. tradenames by
ExxonMobil Chemical Company). Other useful PAOs include
Synfluid.TM. available from ChevronPhillips Chemical Company
(Pasadena, Tex.), Durasyn.TM. available from Innovene (Chicago,
Ill.), Nexbase.TM. available from Neste Oil (Keilaniemi, Finland),
and Synton.TM. available from Chemtura Corporation (Middlebury,
Conn.). The percentage of carbons in chain-type paraffinic
structures (C.sub.P) is close to 100% (typically greater than 98%
or even 99%) for PAOs.
[0129] In a preferred embodiment of the present invention, the PAO
is not an oligomer of C.sub.4 olefins (i.e., 1-butene, 2-butene,
isobutylene, butadiene, and mixtures thereof), including
polybutenes and/or PIB and/or PNB. In another embodiment, the PAO
contains less than 90 wt % (preferably less than 80 wt %,
preferably less than 70 wt %, preferably less than 60 wt %,
preferably less than 50 wt %, preferably less than 40 wt %,
preferably less than 30 wt %, preferably less than 20 wt %,
preferably less than 10 wt %, preferably less than 5 wt %,
preferably less than 2 wt %, preferably less than 1 wt %,
preferably 0 wt %) of C.sub.4 olefins, in particular 1-butene and
isobutylene.
[0130] Preferably, the PAO is not a naphthenic mineral oil (also
called a naphthenic process oil or a naphthenic extender oil), nor
is it an aromatic mineral oil (also called an aromatic process oil
or an aromatic extender oil). More preferably, naphthenic and
aromatic mineral oils are substantially absent from the
compositions of the present invention. In certain embodiments,
paraffinic mineral oils with a kinematic viscosity at 40.degree. C.
of less than 80 cSt and a pour point of greater than -15.degree. C.
are substantially absent from the compositions of the present
invention.
High Purity Hydrocarbon Fluids
[0131] In an alternate embodiment, the HFA may be high purity
hydrocarbon fluid as described at paragraph [0275] on page 16 to
paragraph [0303] on page 18 of US 2008/0045638. Preferably the high
purity hydrocarbon fluid has a flash point of 200.degree. C. or
more and a pour point of -15.degree. C. or less.
[0132] In one embodiment, the HFA is a high purity hydrocarbon
fluid of lubricating viscosity comprising a mixture of C.sub.20 to
C.sub.120 paraffins, 50 wt % or more being isoparaffinic
hydrocarbons and less than 50 wt % being hydrocarbons that contain
naphthenic and/or aromatic structures. Preferably, the mixture of
paraffins comprises a wax isomerate lubricant basestock or oil,
which includes: [0133] i. hydroisomerized natural and refined
waxes, such as slack waxes, deoiled waxes, normal alpha-olefin
waxes, microcrystalline waxes, and waxy stocks derived from gas
oils, fuels hydrocracker bottoms, hydrocarbon raffinates,
hydrocracked hydrocarbons, lubricating oils, mineral oils,
polyalphaolefins, or other linear or branched hydrocarbon compounds
with carbon number of about 20 or more; and [0134] ii.
hydroisomerized synthetic waxes, such as Fischer-Tropsch waxes
(i.e., the high boiling point residues of Fischer-Tropsch
synthesis, including waxy hydrocarbons) or mixtures thereof. Most
preferred are lubricant basestocks or oils derived from
hydrocarbons synthesized in a Fischer-Tropsch process as part of an
overall Gas-to-Liquids (GTL) process.
[0135] In one embodiment, the mixture of paraffins has two or more
of the following properties: [0136] 1. a naphthenic content of less
than 40 wt % (preferably less than 30 wt %, preferably less than 20
wt %, preferably less than 15 wt %, preferably less than 10 wt %,
preferably less than 5 wt %, preferably less than 2 wt %,
preferably less than 1 wt %) based on the total weight of the
hydrocarbon mixture; and/or [0137] 2. a normal paraffins content of
less than 5 wt % (preferably less than 4 wt %, preferably less than
3 wt %, preferably less than 1 wt %) based on the total weight of
the hydrocarbon mixture; and/or [0138] 3. an aromatic content of 1
wt % or less (preferably 0.5 wt % or less); and/or [0139] 4. a
saturates level of 90 wt % or higher (preferably 95 wt % or higher,
preferably 98 wt % or higher, preferably 99 wt % or higher); and/or
[0140] 5. the percentage of carbons in chain-type paraffinic
structures (C.sub.P) of 80% or more (preferably 90% or more,
preferably 95% or more, preferably 98% or more); and/or [0141] 6. a
branched paraffin:normal paraffin ratio greater than about 10:1
(preferably greater than 20:1, preferably greater than 50:1,
preferably greater than 100:1, preferably greater than 500:1,
preferably greater than 1000:1); and/or [0142] 7. sidechains with 4
or more carbons making up less than 10% of all sidechains
(preferably less than 5%, preferably less than 1%); and/or [0143]
8. sidechains with 1 or 2 carbons making up at least 50% of all
sidechains (preferably at least 60%, preferably at least 70%,
preferably at least 80%, preferably at least 90%, preferably at
least 95%, preferably at least 98%); and/or [0144] 9. a sulfur
content of 300 ppm or less (preferably 100 ppm or less, preferably
50 ppm or less, preferably 10 ppm or less) where ppm is on a weight
basis; and/or [0145] 10. a nitrogen content of 300 ppm or less
(preferably 100 ppm or less, preferably 50 ppm or less, preferably
10 ppm or less) where ppm is on a weight basis; and/or [0146] 11. a
number-average molecular weight of 300 to 1800 g/mol (preferably
400 to 1500 g/mol, preferably 500 to 1200 g/mol, preferably 600 to
900 g/mol); and/or [0147] 12. a kinematic viscosity at 40.degree.
C. of 10 cSt or more (preferably 25 cSt or more, preferably between
about 50 and 400 cSt); and/or [0148] 13. a kinematic viscosity at
100.degree. C. ranging from 2 to 50 cSt (preferably 3 to 30 cSt,
preferably 5 to 25 cSt, preferably 6 to 20 cSt, preferably 8 to 16
cSt); and/or [0149] 14. a viscosity index (VI) of 80 or greater
(preferably 100 or greater, preferably 120 or greater, preferably
130 or greater, preferably 140 or greater, preferably 150 or
greater, preferably 160 or greater, preferably 180 or greater);
and/or [0150] 15. a pour point of -5.degree. C. or lower
(preferably -10.degree. C. or lower, preferably -15.degree. C. or
lower, preferably -20.degree. C. or lower, preferably -25.degree.
C. or lower, preferably -30.degree. C. or lower); and/or [0151] 16.
a flash point of 200.degree. C. or more (preferably 220.degree. C.
or more, preferably 240.degree. C. or more, preferably 260.degree.
C. or more); and/or [0152] 17. a specific gravity (15.6.degree.
C./15.6.degree. C.) of 0.86 or less (preferably 0.85 or less,
preferably 0.84 or less); and/or [0153] 18. an aniline point of
120.degree. C. or more; and/or [0154] 19. a bromine number of 1 or
less.
[0155] In a preferred embodiment, the mixture of paraffins
comprises a GTL basestock or oil. GTL basestocks and oils are
fluids of lubricating viscosity that are generally derived from
waxy synthesized hydrocarbons, that are themselves derived via one
or more synthesis, combination, transformation, and/or
rearrangement processes from gaseous carbon-containing compounds
and hydrogen-containing compounds as feedstocks, such as: hydrogen,
carbon dioxide, carbon monoxide, water, methane, ethane, ethylene,
acetylene, propane, propylene, propyne, butane, butylenes, and
butynes. Preferably, the feedstock is "syngas" (synthesis gas,
essentially CO and H.sub.2) derived from a suitable source, such as
natural gas and/or coal. GTL basestocks and oils include wax
isomerates, comprising, for example, hydroisomerized synthesized
waxes, hydroisomerized Fischer-Tropsch (F-T) waxes (including waxy
hydrocarbons and possible analogous oxygenates), or mixtures
thereof. GTL basestocks and oils may further comprise other
hydroisomerized basestocks and base oils. Particularly preferred
GTL basestocks or oils are those comprising mostly hydroisomerized
F-T waxes and/or other liquid hydrocarbons obtained by an F-T
synthesis process.
[0156] The synthesis of hydrocarbons, including waxy hydrocarbons,
by F-T may involve any suitable process known in the art, including
those involving a slurry, a fixed-bed, or a fluidized-bed of
catalyst particles in a hydrocarbon liquid. The catalyst may be an
amorphous catalyst, for example based on a Group VIII metal such as
Fe, Ni, Co, Ru, and Re on a suitable inorganic support material, or
a crystalline catalyst, for example a zeolitic catalyst. The
process of making a lubricant basestock or oil from a waxy stock is
characterized as a hydrodewaxing process. A hydrotreating step,
while typically not required for F-T waxes, can be performed prior
to hydrodewaxing if desired. Some F-T waxes may benefit from
removal of oxygenates while others may benefit from oxygenates
treatment prior to hydrodewaxing. The hydrodewaxing process is
typically conducted over a catalyst or combination of catalysts at
high temperatures and pressures in the presence of hydrogen. The
catalyst may be an amorphous catalyst, for example based on Co, Mo,
W, etc. on a suitable oxide support material, or a crystalline
catalyst, for example a zeolitic catalyst such as ZSM-23 and ZSM-48
and others disclosed in U.S. Pat. No. 4,906,350, often used in
conjunction with a Group VIII metal such as Pd or Pt. This process
may be followed by a solvent and/or catalytic dewaxing step to
lower the pour point of the hydroisomerate. Solvent dewaxing
involves the physical fractionation of waxy components from the
hydroisomerate. Catalytic dewaxing converts a portion of the
hydroisomerate to lower boiling hydrocarbons; it often involves a
shape-selective molecular sieve, such as a zeolite or
silicoaluminophosphate material, in combination with a catalytic
metal component, such as Pt, in a fixed-bed, fluidized-bed, or
slurry type process at high temperatures and pressures in the
presence of hydrogen.
[0157] Useful catalysts, processes, and compositions for GTL
basestocks and oils, Fischer-Tropsch hydrocarbon derived basestocks
and oils, and wax isomerate hydroisomerized basestocks and oils are
described in, for example, U.S. Pat. Nos. 2,817,693; 4,542,122;
5,545,674; 4,568,663; 4,621,072; 4,663,305; 4,897,178; 4,900,407;
4,921,594; 4,923,588; 4,937,399; 4,975,177; 5,059,299; 5,158,671;
5,182,248; 5,200,382; 5,290,426; 5,516,740; 5,580,442; 5,885,438;
5,935,416; 5,935,417; 5,965,475; 5,976,351; 5,977,425; 6,025,305;
6,080,301; 6,090,989; 6,096,940; 6,103,099; 6,165,949; 6,190,532;
6,332,974; 6,375,830; 6,383,366; 6,475,960; 6,620,312; and
6,676,827; European Patents EP 324 528, EP 532 116, EP 532 118, EP
537 815, EP 583 836, EP 666 894, EP 668 342, EP 776 959; WPO patent
applications WO 97/31693, WO 99/20720, WO 99/45085, WO 02/64710, WO
02/64711, WO 02/70627, WO 02/70629, WO 03/33320; and British
Patents 1350257; 1390359; 1429494; and 1440230. Particularly
favorable processes are described in European Patent Applications
EP 464 546 and EP 464 547. Processes using Fischer-Tropsch wax
feeds are described in U.S. Pat. Nos. 4,594,172; 4,943,672;
6,046,940; 6,103,099; 6,332,974; 6,375,830; and 6,475,960.
[0158] Desirable GTL-derived fluids are expected to become broadly
available from several sources, including Chevron, ConocoPhillips,
ExxonMobil, Sasol, SasolChevron, Shell, Statoil, and
Syntroleum.
[0159] In one embodiment, the HFA is a high purity hydrocarbon
fluid derived from a GTL process comprising a mixture of paraffins
of carbon number ranging from about C.sub.20 to C.sub.100, a molar
ratio of isoparaffins:n-paraffins greater than about 50:1, the
percentage of carbons in paraffinic structures (C.sub.P) of 98% or
more, a pour point ranging from about -20 to -60.degree. C., and a
kinematic viscosity at 100.degree. C. ranging from about 6 to 20
cSt.
[0160] As used herein, the following terms have the indicated
meanings: "hydroisomerized" describes a catalytic process in which
normal paraffins and/or slightly branched isoparaffins are
converted by rearrangement into more branched isoparaffins (also
known as "isodewaxing"); "wax" is a hydrocarbonaceous material
existing as a solid at or near room temperature, with a melting
point of 0.degree. C. or above, and consisting predominantly of
paraffinic molecules, most of which are normal paraffins; "slack
wax" is the wax recovered from petroleum oils such as by solvent
dewaxing, and may be further hydrotreated to remove
heteroatoms.
Group III Mineral Oils
[0161] In an alternate embodiment, the HFA may be a Group III
Mineral Oil (as described in US 2008/0045638) having a flash point
of 200.degree. C. or more and a pour point of -15.degree. C. or
less. Preferably the Group III Mineral Oil has a saturates level of
90% or more (preferably 92% or more, preferably 94% or more,
preferably 95% or more, preferably 98% or more); a sulfur content
of less than 0.03% (preferably between 0.001 and 0.01%); and a VI
of 120 or more (preferably 130 or more, preferably 140 or more).
Preferably the Group III Mineral Oil has a kinematic viscosity at
100.degree. C. of 3 to 50, preferably 4 to 40 cSt, preferably 6 to
30 cSt, preferably 8 to 20; and/or a number average molecular
weight of 300 to 5,000 g/mol, preferably 400 to 2,000 g/mol,
preferably 500 to 1,000 g/mol. Preferably the Group III Mineral Oil
has a pour point of -10.degree. C. or less, a flash point of
200.degree. C. or more, and a specific gravity (15.6.degree.
C./15.6.degree. C.) of 0.86 or less.
[0162] Preferably, the Group III Mineral Oil is a Group III
basestock. Desirable Group III basestocks are commercially
available from a number of sources and include those described in
the table below. The percentage of carbons in chain-type paraffinic
structures (C.sub.P) in such liquids is greater than 80%.
Chain-type paraffins (C.sub.P) are determined as described in US
2008/0045638.
TABLE-US-00001 Commercially available Group III Basestocks KV @
Pour Flash 100.degree. C., Point, Specific Point, cSt VI .degree.
C. gravity .degree. C. UCBO 4R .sup.1 4.1 127 -18 0.826 216 UCBO 7R
.sup.1 7.0 135 -18 0.839 250 Nexbase 3043 .sup.2 4.3 124 -18 0.831
224 Nexbase 3050 .sup.2 5.1 126 -15 0.835 240 Nexbase 3060 .sup.2
6.0 128 -15 0.838 240 Nexbase 3080 .sup.2 8.0 128 -15 0.843 260
Yubase YU-4 .sup.3 4.2 122 -15 0.843 230 Yubase YU-6 .sup.3 6.5 131
-15 0.842 240 Yubase YU-8 .sup.3 7.6 128 -12 0.850 260 Ultra-S 4
.sup.4 4.3 123 -20 0.836 220 Ultra-S 6 .sup.4 5.6 128 -20 0.839 234
Ultra-S 8 .sup.4 7.2 127 -15 0.847 256 VHVI 4 .sup.5 4.6 128 -21
0.826 VHVI 8 .sup.5 8.0 127 -12 0.850 248 Visom 4 .sup.6 4.0 210
Visom 6 .sup.6 6.6 148 -18 0.836 250 .sup.1 Available from
ChevronTexaco (USA). .sup.2 Available from Neste Oil (Finland).
.sup.3 Available from SK Corp (South Korea). .sup.4 Available from
ConocoPhillips (USA)/S-Oil (South Korea). .sup.5 Available from
PetroCanada (Canada). .sup.6 Available from ExxonMobil (USA).
Fillers and Additives
[0163] The elastomeric compositions may also contain other
components and additives customarily used in rubber compounds, such
as, for example, effective amounts of other processing aids,
pigments, accelerators, cross-linking and curing materials,
antioxidants, antiozonants, fillers, and/or clays.
[0164] The elastomeric composition may also optionally comprise at
least one filler, for example, calcium carbonate, clay, mica,
silica, silicates, talc, titanium dioxide, aluminum oxide, zinc
oxide, starch, wood flour, carbon black, or mixtures thereof. The
fillers may be any size and typically are in the range of about
0.0001 .mu.m to about 100 .mu.m, for example in the tire
industry.
[0165] As used herein, silica is meant to refer to any type or
particle size silica or another silicic acid derivative, or silicic
acid, processed by solution, pyrogenic, or the like methods,
including untreated, precipitated silica, crystalline silica,
colloidal silica, aluminum or calcium silicates, fumed silica, and
the like. Precipitated silica can be conventional silica,
semi-highly dispersible silica, or highly dispersible silica.
[0166] The elastomeric composition may also include clay. The clay
may be, for example, montmorillonite, nontronite, beidellite,
bentonite, vokoskoite, laponite, hectorite, saponite, sauconite,
magadite, kenyaite, stevensite, vermiculite, halloysite, aluminate
oxides, hydrotalcite, or mixtures thereof. The clay may contain at
least one silicate. Alternatively, the filler may be layered clay,
optionally, treated or pre-treated with a modifying agent such as
organic molecules; the layered clay may comprise at least one
silicate.
[0167] In one embodiment, the layered filler such as layered clay
may comprise at least one silicate. The silicate may comprise at
least one "smectite" or "smectite-type clay" referring to the
general class of clay minerals with expanding crystal lattices. For
example, this may include the dioctahedral smectites which consist
of montmorillonite, beidellite, and nontronite, and the
trioctahedral smectites, which includes saponite, hectorite, and
sauconite. Also encompassed are synthetically prepared
smectite-clays, for example those produced by hydrothermal
processes.
[0168] The layered filler such as the layered clays described above
may be modified such as intercalated or exfoliated by treatment
with at least one modifying agent. Modifying agents are also known
as swelling or exfoliating agents. Generally, they are additives
capable of undergoing ion exchange reactions with the cations
present at the interlayer surfaces of the layered filler. The
modifying agent may be present in the composition in an amount to
achieve optimal air retention as measured by the permeability
testing. For example, the additive may be employed in the range of
0.1 to 40 phr in one embodiment, or in the range of 0.2 to 20 phr,
or in the range of 0.3 to 10 phr in another embodiment.
[0169] Examples of suitable exfoliating additives include, but are
not limited to, cationic surfactants such as ammonium, alkylamines
or alkylammonium (primary, secondary, tertiary and quaternary),
phosphonium or sulfonium derivatives of aliphatic, aromatic or
arylaliphatic amines, phosphines and sulfides.
[0170] The elastomeric compositions may incorporate a clay treated
or pre-treated with a modifying agent to form a nanocomposite or
nanocomposite composition. Nanocomposites may include at least one
elastomer as described above and at least one modified layered
filler. The modified layered filler may be produced by the process
comprising contacting at least one layered filler such as at least
one layered clay with at least one modifying agent.
[0171] The amount of clay or exfoliated clay incorporated in the
nanocomposite is generally that which is sufficient to develop an
improvement in the mechanical properties or barrier properties of
the nanocomposite, for example, tensile strength or oxygen
permeability. Amounts generally will be in the range of 0.5 to 10
wt % in one embodiment, or in the range of 1 to 5 wt %, based on
the polymer content of the nanocomposite. Expressed in parts per
hundred parts of rubber, the clay or exfoliated clay may be present
in the range of 1 to 30 phr, or in the range of 5 to 20 phr.
[0172] In one embodiment, one or more, silane coupling agents are
used in the elastomeric compositions. Coupling agents are
particularly desirable when silica is the primary filler, or is
present in combination with another filler, as they help bind the
silica to the elastomer. The coupling agent may be a bifunctional
organosilane crosslinking agent. An "organosilane crosslinking
agent" is any silane coupled filler and/or crosslinking activator
and/or silane reinforcing agent known to those skilled in the art
including, but not limited to, vinyl triethoxysilane,
vinyl-tris-(beta-methoxyethoxy)silane,
methacryloylpropyltrimethoxysilane, gamma-amino-propyl,
triethoxysilane, gammamercaptopropyltrimethoxysilane, and the like,
and mixtures thereof.
[0173] The filler may be carbon black or modified carbon black. The
filler may also be a blend of carbon black and silica. In one
embodiment, the elastomeric composition comprises reinforcing grade
carbon black at a level in the range of 10 to 100 phr of the blend,
more preferably in the range of 30 to 80 phr in another embodiment,
and in yet another embodiment in the range of 50 to 80 phr. Useful
grades of carbon black include the ranges of from N110 to N990,
preferably N660.
Crosslinking Agents, Curatives, Cure Packages, and Curing
Processes
[0174] The elastomeric compositions and the articles made from
those compositions are generally manufactured with the aid of at
least one cure package, at least one curative, at least one
crosslinking agent, and/or undergo a process to cure the
elastomeric composition. As used herein, at least one curative
package refers to any material or method capable of imparting cured
properties to a rubber as is commonly understood in the
industry.
[0175] Generally, polymer blends are crosslinked to improve the
polymer's mechanical properties. Physical properties, performance
characteristics, and durability of vulcanized rubber compounds are
known to be related to the number (crosslink density) and type of
crosslinks formed during the vulcanization reaction. Polymer blends
may be crosslinked by adding curative agents, for example sulfur,
metals, metal oxides such as zinc oxide, peroxides, organometallic
compounds, radical initiators, fatty acids, and other agents common
in the art. Other known methods of curing that may be used include,
peroxide cure systems, resin cure systems, and heat or
radiation-induced crosslinking of polymers. Accelerators,
activators, and retarders may also be used in the curing
process.
[0176] The compositions may be vulcanized (cured) by any suitable
means, such as subjecting them to heat or radiation according to
any conventional vulcanization process. The amount of heat or
radiation needed is that which is required to affect a cure in the
composition, and the invention is not herein limited by the method
and amount of heat required to cure the composition. Typically, the
vulcanization is conducted at a temperature in the range of about
100.degree. C. to about 250.degree. C., or in the range of about
150.degree. C. to about 190.degree. C., for about 1 to 150
minutes.
[0177] Halogen-containing elastomers may be crosslinked by their
reaction with metal oxides. The metal oxide is thought to react
with halogen groups in the polymer to produce an active
intermediate which then reacts further to produce carbon-carbon
bonds. Zinc halide is liberated as a by-product and it serves as an
autocatalyst for this reaction. The metal oxide can be used alone
or in conjunction with its corresponding metal fatty acid complex
(e.g., zinc stearate, calcium stearate, etc.), or with the organic
and fatty acids added alone, such as stearic acid, and optionally
other curatives such as sulfur or a sulfur compound, an
alkylperoxide compound, diamines or derivatives thereof.
[0178] Sulfur is the most common chemical vulcanizing agent for
diene-containing elastomers. It exists as a rhombic 8-member ring
or in amorphous polymeric forms. The sulfur vulcanization system
may consist of an activator to activate the sulfur, an accelerator,
and a retarder to help control the rate of vulcanization.
Activators are chemicals that increase the rate of vulcanization by
reacting first with the accelerators to form rubber-soluble
complexes which then react with the sulfur to form sulfurating
agents. General classes of accelerators include amines, diamines,
guanidines, thioureas, thiazoles, thiurams, sulfenamides,
sulfenimides, thiocarbamates, xanthates, and the like.
[0179] Accelerators help control the onset of and rate of
vulcanization, and the number and type of crosslinks that are
formed. Retarders may be used to delay the initial onset of cure in
order to allow sufficient time to process the unvulcanized
rubber.
[0180] The acceleration of the vulcanization process may be
controlled by regulating the amount of the acceleration accelerant,
often an organic compound. The mechanism for accelerated
vulcanization of natural rubber, BR, and SBR involves complex
interactions between the curative, accelerator, activators, and
polymers. Ideally, all of the available curative is consumed in the
formation of effective crosslinks which join together two polymer
chains and enhance the overall strength of the polymer matrix.
Numerous accelerators are known in the art and include, but are not
limited to, the following: stearic acid, diphenyl guanidine (DPG),
tetramethylthiuram disulfide (TMTD), benzothiazyl disulfide (MBTS),
N-tertiarybutyl-2-benzothiazole sulfenamide (TBBS),
N-cyclohexyl-2-benzothiazole-sulfenamide (CBS), and thioureas.
[0181] In one embodiment, at least one curing agent(s) is present
in the range of 0.2 to 10 phr, or 0.5 to 5 phr, or in another
embodiment in the range of 0.75 phr to 2 phr.
Processing
[0182] The elastomeric composition may be compounded (mixed) by any
conventional means known to those skilled in the art. The mixing
may occur in a single step or in multiple stages. For example, the
ingredients are typically mixed in at least two stages, namely at
least one non-productive stage followed by a productive mixing
stage. The final curatives are typically mixed in the final stage
which is conventionally called the "productive" mix stage. In the
productive mix stage the mixing typically occurs at a temperature,
or ultimate temperature, lower than the mix temperature(s) of the
preceding non-productive mix stage(s). The elastomers, polymer
additives, silica and silica coupler, and carbon black, if used,
are generally mixed in one or more non-productive mix stages. The
terms "non-productive" and "productive" mix stages are well known
to those having skill in the rubber mixing art.
[0183] In one embodiment, the carbon black is added in a different
stage from zinc oxide and other cure activators and accelerators.
In another embodiment, antioxidants, antiozonants, and processing
materials are added in a stage after the carbon black has been
processed with the elastomers, and zinc oxide is added at a final
stage to maximize the compound modulus. In other embodiments,
additional stages may involve incremental additions of one or more
fillers.
[0184] In another embodiment, mixing of the components may be
carried out by combining the elastomer components, filler and clay
in any suitable mixing device such as a two-roll open mill,
Brabender.TM. internal mixer, Banbury.TM. internal mixer with
tangential rotors, Krupp internal mixer with intermeshing rotors,
or preferably a mixer/extruder, by techniques known in the art.
Mixing may be performed at temperatures up to the melting point of
the elastomer(s) used in the composition in one embodiment, or in
the range of 40.degree. C. to 250.degree. C. in another embodiment,
or in the range of 100.degree. C. to 200.degree. C. Mixing should
generally be conducted under conditions of shear sufficient to
allow the clay to exfoliate and become uniformly dispersed within
the elastomer(s) to form the nanocomposite.
[0185] Typically, from 70% to 100% of the elastomer or elastomers
is first mixed for 20 to 90 seconds, or until the temperature
reaches from 40.degree. C. to 75.degree. C. Then, approximately 75%
of the filler, and the remaining amount of elastomer, if any, is
typically added to the mixer, and mixing continues until the
temperature reaches from 90.degree. C. to 150.degree. C. Next, the
remaining filler is added, as well as the processing aids, and
mixing continues until the temperature reaches from 140.degree. C.
to 190.degree. C. The masterbatch mixture is then finished by
sheeting on an open mill and allowed to cool, for example, to from
60.degree. C. to 100.degree. C. when curatives may be added.
[0186] Mixing with the clays is performed by techniques known to
those skilled in the art, wherein the clay is added to the polymer
at the same time as the carbon black in one embodiment. The HFA
processing aid is typically added later in the mixing cycle after
the carbon black and clay have achieved adequate dispersion in the
elastomeric matrix.
[0187] The cured compositions can include various elastomers and
fillers with the HFA processing aid. The elastomeric compositions
typically include C.sub.4 to C.sub.7 monoolefin elastomers, such as
isobutylene-based elastomers, preferably halogenated
poly(isobutylene-co-p-methylstyrene), butyl rubber, with the HFA(s)
being present in the range of 2 to 40 phr in one embodiment, or 4
to 30 phr, or 4 to 15 phr, or 8 to 12 phr in another
embodiment.
[0188] In one embodiment, an air barrier can be made by the method
of combining at least one random copolymer comprising a C.sub.4 to
C.sub.7 isomonoolefin derived unit, at least one filler, and at
least one HFA, and at least one cure agent; and curing the combined
components.
[0189] In another embodiment, an air barrier can be made by the
method of combining at least one random copolymer comprising a
C.sub.4 to C.sub.7 isomonoolefin derived unit, at least one filler,
and HFA having a number average molecular weight greater than 400,
and at least one cure agent; and curing the combined components as
described above.
[0190] The elastomeric compositions as described above may be used
in the manufacture of air membranes such as innerliners and
innertubes used in the production of tires. Methods and equipment
used to manufacture the innerliners and tires are well known in the
art. The invention is not limited to any particular method of
manufacture for articles such as innerliners or tires.
[0191] In one embodiment, a tire innerliner stock may be prepared
by calendering the compounded rubber composition into sheet
material having a thickness of roughly 40 to 80 mil gauge and
cutting the sheet material into strips of appropriate width and
length for innerliner applications. The innerliner stock at this
stage of the manufacturing process is typically a sticky, uncured
mass and is therefore subject to deformation and tearing as a
consequence of handling and cutting operations associated with tire
construction.
[0192] The innerliner stock may then be used as an element in the
construction of a pneumatic tire. The pneumatic tire may be
composed of a layered laminate comprising an outer surface which
includes the tread and sidewall elements, an intermediate carcass
layer which comprises a number of plies containing tire reinforcing
fibers, (e.g., rayon, polyester, nylon or metal fibers) embedded in
a rubbery matrix, and an innerliner layer which is laminated to the
inner surface of the carcass layer. The tire may be built on a tire
forming drum using the layers described above. After the uncured
tire has been built on the drum, the uncured tire may be placed in
a heated mold having an inflatable tire shaping bladder to shape it
and heat it to vulcanization temperatures by methods well known in
the art. Vulcanization temperatures are generally in the range of
about 100.degree. C. to about 250.degree. C., or preferably in the
range of 125.degree. C. to 200.degree. C., and the vulcanization
time may be in them range of about one minute to several hours, or
more generally in the range of about 5 to 30 minutes. Vulcanization
of the assembled tire results in vulcanization of all elements of
the tire assembly, for example, the innerliner, the carcass and the
outer tread/sidewall layers and enhances the adhesion between these
elements, resulting in a cured, unitary tire from the
multi-layers.
INDUSTRIAL APPLICABILITY
[0193] The elastomeric compositions of the invention may be
extruded, compression molded, blow molded, injection molded, and
laminated into various shaped articles including fibers, films,
laminates, layers, industrial parts such as automotive parts,
appliance housings, consumer products, packaging, and the like. The
elastomeric compositions are particularly useful in air barriers,
such as in pneumatic tire components, hoses, air cushions,
pneumatic springs, air bellows, accumulator bags, and bladders for
fluid retention and curing processes.
[0194] In particular, the elastomeric compositions are useful in
articles for a variety of tire applications. Such tires can be
built, shaped, molded, and cured by various methods which are known
and will be readily apparent to those having skill in the art. The
elastomeric compositions may either be fabricated into a finished
article or a component of a finished article such as an innerliner
for a tire.
[0195] The elastomeric compositions of this invention are
particularly suitable for tire innerliners and innertubes and other
materials requiring good air retention. The elastomeric
compositions are especially useful for tire innerliners requiring
good air impermeability and good cold temperature properties, such
as required for aircraft tires.
[0196] In preferred embodiments, the elastomeric compositions of
this invention are particularly suitable for use as tire
innerliners or tire innertubes, as they have enhanced thermal
stability and physical properties suitable for operation under
severe temperature such as required for race car tires and aircraft
tires. The elastomeric compositions possess improved
low-temperature toughness without sacrificing other advantageous
traits such as improved processability and air-impermeability.
[0197] In particular the elastomeric compositions are useful for
aircraft tires. Aircraft tires must withstand extreme conditions
during service, in particular in terms of applied load and speed,
taking into account the tire's low weight and size. Aircraft tires
are subject to extreme loads and deflections and are subject to
extreme accelerations and very high speeds particularly during
landings, takeoffs and after prolonged taxiing the tires can build
up high heat all of which contribute to rapid wear. During takeoff,
very high speeds, of the order of 350 km/hr or even 450 km/hr, are
achieved, and hence heating conditions exist which are also very
severe.
[0198] Aircraft tires distinguished from other tires in that they
generally require an inflation pressure greater than 9 bar (0.9
MPa) and a relative deflection greater than 30%. The deflection of
a tire is defined by the radial deformation of the tire, or
variation in the radial height of the tire, when it changes from a
non-loaded state to a statically loaded state, under rated load and
pressure conditions. It is expressed in the form of relative
deflection, which is defined by the ratio of this variation in the
radial height of the tire to half the difference between the
external diameter of the tire and the maximum diameter of the rim
measured on the hook. The external diameter of the tire is measured
statically in an non-loaded state at the rated pressure. Despite an
aircraft tire's very high inflation pressures, greater than 9 bar,
their loading or deflection during operation may commonly reach
values double those observed for heavy-vehicle tires or passenger
cars.
[0199] The elastomeric compositions provided herein have improved
brittleness and impermeability properties, making them especially
suitable for use in aircraft tires. In some embodiments, there is a
synergistic effect when HFA is used allowing for the use of
secondary elastomers, such as natural rubber, at lower loading
levels where the brittleness is improved while maintaining the
permeability with an acceptable range.
[0200] In one embodiment the cured elastomeric composition has a
MOCON permeability coefficient of less than or equal to T, where
T=-0.1147Y+0.54 where Y is the change in brittleness determined by
subtracting the brittleness in .degree. C. of the cured elastomeric
composition containing HFA from the brittleness in .degree. C. of a
cured composition having the same components except that it
contains a naphthenic oil having a flash point in the range of 160
to 170.degree. C., a pour point of about -40.degree. C..+-.5%, and
a specific gravity at 15.6.degree. C. of about 0.91.+-.0.01 instead
of the HFA. In some embodiments, the cured elastomeric composition
has a MOCON permeability coefficient of less than or equal to T,
where T=-0.1147Y+0.50, or where T=-0.1147Y+0.45. In such
embodiments, the HFA is preferably a PAO.
[0201] In another embodiment, the cured elastomeric composition has
a MOCON permeability coefficient of less than or equal to Z, where
Z=0.282X+0.4817 where X is the amount of natural rubber in phr, and
has a brittleness of less than or equal to A, where A=-0.13X-51
where X is the amount of natural rubber in phr. In some
embodiments, the cured elastomeric composition has a MOCON
permeability coefficient of less than or equal to Z, where
Z=0.0155Y+0.6187. In some embodiments, the cured elastomeric
composition has a brittleness of less than or equal to A, where
A=-0.13X-50.5, or where A=-0.13X-51.5, or where A=-0.13X-52. In
such embodiments, the cured elastomeric composition preferably
comprises a PAO.
[0202] In yet another embodiment, the cured elastomeric composition
comprises 1 to 30 phr of HFA and has a permeability that is at
least 10% less, or 15% less, or 25% less, or 30% less, or 35% less
than the permeability of a cured composition having the same
components except that it contains a naphthenic oil having a flash
point in the range of 160 to 170.degree. C., a pour point of about
-40.degree. C., and a specific gravity at 15.6.degree. C. of about
0.91 instead of the HFA. In such embodiments, the HFA is preferably
a PAO.
[0203] In a further embodiment, the cured elastomeric composition
comprises 1 to 30 phr of HFA and has a brittleness temperature that
is at least 1.degree. C. less, or 1.5.degree. C. less, or 2.degree.
C. less, or 3.degree. C. less, than the brittleness temperature of
a cured composition having the same components except that it
contains a naphthenic oil having a flash point in the range of 160
to 170.degree. C., a pour point of about -40.degree. C., and a
specific gravity at 15.6.degree. C. of about 0.91 instead of the
HFA. In such embodiments, the HFA is preferably a PAO.
[0204] In still another embodiment, the cured elastomeric
composition comprises 1 to 30 phr of HFA and has a brittleness
temperature that is at least 2.degree. C. less, or 3.degree. C.
less, or 4.degree. C. less, or 5.degree. C. less, than the
brittleness temperature of a cured composition comprising 100 phr
of BIIR, 0 phr of NR, and a naphthenic oil having a flash point in
the range of 160 to 170.degree. C., a pour point of about
-40.degree. C., and a specific gravity at 15.6.degree. C. of about
0.91 instead of the HFA. In such embodiments, the HFA is preferably
a PAO.
[0205] In some embodiments, the use of HFA instead of a naphthenic
oil reduces the Tg of the elastomeric composition. This is
particularly advantageous as a high Tg makes the materials brittle,
especially at low temperatures. The elastomeric composition
comprising PAO may have a Tg less than or equal to -45.degree. C.,
or less than or equal to -50.degree. C., or less than or equal to
-55.degree. C.
[0206] In alternate embodiments, this invention relates to: [0207]
1. A cured elastomeric composition for use in a tire innerliner,
comprising: (a) from 50 to 100 phr of at least one
isobutylene-based elastomer; (b) less than or equal to 50 phr of
natural rubber; and (c) from 1 to 30 phr of at least one
hydrocarbon fluid additive, wherein the hydrocarbon fluid additive
has a flash point of at least 200.degree. C., a pour point of less
than or equal to -15.degree. C., and specific gravity at
15.6.degree. C. of less than or equal to 0.880; wherein the cured
elastomeric composition has a MOCON permeability coefficient of
less than or equal to T, where T=-0.1147Y+0.54 where Y is the
change in brittleness determined by subtracting the brittleness in
.degree. C. of the cured elastomeric composition containing the
hydrocarbon fluid additive from the brittleness in .degree. C. of a
cured composition having the same components except that it
contains a naphthenic oil having a flash point in the range of 160
to 170.degree. C., a pour point of about -40.degree. C..+-.5%, and
a specific gravity at 15.6.degree. C. of about 0.91.+-.0.01 instead
of the hydrocarbon fluid additive. [0208] 2. The composition of
paragraph 1, wherein the isobutylene-based elastomer is selected
from the group consisting of butyl rubber, halogenated butyl
rubber, star-branched butyl rubber, halogenated star-branched butyl
rubber, poly(isobutylene-co-p-methylstyrene), halogenated
poly(isobutylene-co-p-methylstyrene), and mixtures thereof. [0209]
3. The composition of paragraph 1 or 2, wherein the composition
comprises less than or equal to 10 phr of natural rubber. [0210] 4.
The composition of any one of paragraphs 1 to 3, wherein the
hydrocarbon fluid additive is selected from a group consisting of
polyalphaolefins, high purity hydrocarbon fluids, water white group
III mineral oils, and blends thereof. [0211] 5. The composition of
any one of paragraphs 1 to 3, wherein the hydrocarbon fluid
additive is a polyalphaolefin having a Kinematic viscosity at
100.degree. C. of at least 4 cSt. [0212] 6. The composition of any
one of paragraphs 1 to 3 or 5, wherein the hydrocarbon fluid
additive is a polyalphaolefin having a Kinematic viscosity at
100.degree. C. in the range of 6 to 40 cSt. [0213] 7. The
composition of any one of paragraphs 1 to 3, 5, or 6, wherein the
hydrocarbon fluid additive is a polyalphaolefin having a viscosity
index of at least 120. [0214] 8. The composition of any one of
paragraphs 1 to 7, wherein the composition is substantially free of
naphthenic oil and/or is substantially free of aromatic oil. [0215]
9. The composition of any one of paragraphs 1 to 8, wherein the
composition further comprises one or more filler components
selected from calcium carbonate, mica, silica, silicates, talc,
titanium dioxide, starch, wood flour, carbon black, and mixtures
thereof. [0216] 10. The composition of any one of paragraphs 1 to
9, wherein the composition is a tire innerliner suitable for use in
an aircraft tire. [0217] 11. A cured elastomeric composition for
use in a tire innerliner, comprising: (a) from 50 to 90 phr of at
least one isobutylene-based elastomer; (b) from 1 to 50 phr of
natural rubber; and (c) from 1 to 30 phr of at least one
hydrocarbon fluid additive, wherein the hydrocarbon fluid additive
has a flash point of at least 200.degree. C., a pour point of less
than or equal to -15.degree. C., and specific gravity at
15.6.degree. C. of less than or equal to 0.880; wherein the cured
elastomeric composition has a MOCON permeability coefficient of
less than or equal to Z, where Z=0.282X+0.4817 where X is the
amount of natural rubber in phr, and wherein the cured elastomeric
composition has a brittleness of less than or equal to A, where
A=-0.13X-51 where X is the amount of natural rubber in phr. [0218]
12. An aircraft tire comprising an innerliner which comprises: (a)
from 50 to 90 phr of at least one isobutylene-based elastomer; (b)
from 1 to 50 phr of natural rubber; and (c) from 1 to 30 phr of at
least one hydrocarbon fluid additive, wherein the hydrocarbon fluid
additive has a flash point of at least 200.degree. C., a pour point
of less than or equal to -15.degree. C., and specific gravity at
15.6.degree. C. of less than or equal to 0.880; wherein the
aircraft tire has a MOCON permeability coefficient of less than or
equal to Z, where Z=0.282X+0.4817 where X is the amount of natural
rubber in phr, and wherein the cured elastomeric composition has a
brittleness of less than or equal to A, where A=-0.13X-51 where X
is the amount of natural rubber in phr. [0219] 13. The composition
of paragraph 11 or 12, wherein the composition comprises from 70 to
90 phr of the isobutylene-based elastomer. [0220] 14. The
composition of any one of paragraphs 11 to 13, wherein the
isobutylene-based elastomer is selected from the group consisting
of butyl rubber, halogenated butyl rubber, star-branched butyl
rubber, halogenated star-branched butyl rubber,
poly(isobutylene-co-p-methylstyrene), halogenated
poly(isobutylene-co-p-methylstyrene), and mixtures thereof. [0221]
15. The composition of any one of paragraphs 11 to 14, wherein the
composition comprises from 10 to 30 phr of natural rubber. [0222]
16. The composition of any one of paragraphs 11 to 15, wherein the
hydrocarbon fluid additive is selected from a group consisting of
polyalphaolefins, high purity hydrocarbon fluids, water white group
III mineral oils, and blends thereof. [0223] 17. The composition of
any one of paragraphs 11 to 15, wherein the hydrocarbon fluid
additive is a polyalphaolefin having a Kinematic viscosity at
100.degree. C. of at least 4 cSt. [0224] 18. The composition of any
one of paragraphs 11 to 15, or 17, wherein the hydrocarbon fluid
additive is a polyalphaolefin having a Kinematic viscosity at
100.degree. C. in the range of 6 to 40 cSt. [0225] 19. The
composition of any one of paragraphs 11 to 15, 17, or 18, wherein
the hydrocarbon fluid additive is a polyalphaolefin having a
viscosity index of at least 120. [0226] 20. The composition of any
one of paragraphs 11 to 19, wherein the composition is
substantially free of naphthenic oil and/or is substantially free
of aromatic oil. [0227] 21. The composition of any one of
paragraphs 11 to 20, wherein the composition further comprises one
or more filler components selected from calcium carbonate, mica,
silica, silicates, talc, titanium dioxide, starch, wood flour,
carbon black, and mixtures thereof. [0228] 22. The composition of
any one of paragraphs 11 or 13 to 20, wherein the composition is a
tire innerliner suitable for use in an aircraft tire. [0229] 23. A
process for producing an air barrier comprising the steps of: (a)
combining from 50 to 90 phr of at least one isobutylene-based
elastomer, from 1 to 50 phr of natural rubber, and from 1 to 30 phr
of at least one hydrocarbon fluid additive, wherein the hydrocarbon
fluid additive has a flash point of at least 200.degree. C., a pour
point of less than or equal to -15.degree. C., and specific gravity
at 15.6.degree. C. of less than or equal to 0.880; (b) curing the
combined components to form a cured elastomeric composition wherein
the cured elastomeric composition has a MOCON permeability
coefficient of less than or equal to Z, where Z=0.282X+0.4817 where
X is the amount of natural rubber in phr, and wherein the cured
elastomeric composition has a brittleness of less than or equal to
A, where A=-0.13X-51 where X is the amount of natural rubber in
phr; and (c) shaping the cured elastomeric composition to form the
air barrier. [0230] 24. The process of paragraph 23, wherein the
air barrier is an innerliner suitable for use in an aircraft tire.
[0231] 25. The composition of paragraph 23 or 24, wherein the
composition comprises from 70 to 90 phr of the isobutylene-based
elastomer. [0232] 26. The composition of any one of paragraphs 23
to 25, wherein the isobutylene-based elastomer is selected from the
group consisting of butyl rubber, halogenated butyl rubber,
star-branched butyl rubber, halogenated star-branched butyl rubber,
poly(isobutylene-co-p-methylstyrene), halogenated
poly(isobutylene-co-p-methylstyrene), and mixtures thereof. [0233]
27. The composition of any one of paragraphs 23 to 26, wherein the
composition comprises from 10 to 30 phr of natural rubber. [0234]
28. The composition of any one of paragraphs 23 to 27, wherein the
hydrocarbon fluid additive is selected from a group consisting of
polyalphaolefins, high purity hydrocarbon fluids, water white group
III mineral oils, and blends thereof. [0235] 29. The composition of
any one of paragraphs 23 to 27, wherein the hydrocarbon fluid
additive is a polyalphaolefin having a Kinematic viscosity at
100.degree. C. of at least 4 cSt. [0236] 30. The composition of any
one of paragraphs 23 to 27, or 29, wherein the hydrocarbon fluid
additive is a polyalphaolefin having a Kinematic viscosity at
100.degree. C. in the range of 6 to 40 cSt. [0237] 31. The
composition of any one of paragraphs 23 to 27, 29, or 30, wherein
the hydrocarbon fluid additive is a polyalphaolefin having a
viscosity index of at least 120. [0238] 32. The composition of any
one of paragraphs 23 to 31, wherein the composition is
substantially free of naphthenic oil and/or is substantially free
of aromatic oil. [0239] 33. The composition of any one of
paragraphs 23 to 32, wherein the composition further comprises one
or more filler components selected from calcium carbonate, mica,
silica, silicates, talc, titanium dioxide, starch, wood flour,
carbon black, and mixtures thereof.
Testing Procedures
[0240] When possible, standard ASTM tests were used to determine
the cured compound physical properties. Stress/strain properties
(e.g., tensile strength, elongation at break, modulus values,
energy to break) were measured according to ASTM D412 Die C at room
temperature using an Instron 4202. Tensile strength measurements
were made at ambient temperature; the specimens (dog-bone shaped)
had a restricted width of 6 mm and a restricted length of 33 mm
between two tabs. Though the thickness of the test specimen was a
nominal 2.00 mm, the thickness of the specimens varied and was
measured manually by a Mitutoyo Digimatic Indicator connected to
the system computer. The specimens were pulled at a crosshead speed
of 500 mm/min and the stress/strain data was recorded. The average
stress/strain value of at least three specimens is reported. The
error (2.sigma.) in Tensile measurements is .+-.0.47 MPa. The error
(2.sigma.) in measuring 100% Modulus is .+-.0.11 MPa; the error
(2.sigma.) in measuring elongation is .+-.13%.
[0241] Cure properties were measured using an MDR 2000 from Alpha
Technologies, Inc. at the indicated temperature and 0.5 degree arc,
based on ASTM D 5289. The values "MH" and "ML" used herein refer to
"maximum torque" and "minimum torque," respectively. The "MS" value
is the Mooney scorch value, the "ML(1+8)" value is the Mooney
viscosity value of the polymer, and the "ML(1+4)" value is the
Mooney viscosity value of the composition. The error (2.sigma.) in
the Mooney viscosity measurement is .+-.0.65. The values of "Tc"
are cure times in minutes, and "Ts" is scorch time in minutes.
[0242] Permeability was measured using a Mocon OxTran Model 2/61
oxygen transmission rate test apparatus. The oxygen transmission
rate is measured under the principle of dynamic measurement of
oxygen transport through a thin film. Compound samples are clamped
into a diffusion cell. The samples are approximately 5.0 cm in
diameter and about 0.5 mm thick. The cell is then purged of
residual oxygen using a high purity nitrogen carrier gas. The
nitrogen gas is routed to a sensor until a stable zero value is
established. The measurement is typically conducted at 60.degree.
C. Pure oxygen air is then introduced into the outside of the
chamber of the diffusion cell. The oxygen diffusing through the
sample to the inside chamber is conveyed to a chamber which
measures the oxygen diffusion rate. The oxygen diffusion rate is
expressed as a transmission rate coefficient. The permeation
coefficient is a measure of the transmission rate normalized for
sample thickness (e.g., m) and is expressed as a volume of gas
(e.g., cc) per unit area (e.g., m.sup.2) of the sample in a
discrete unit of time (e.g., 24 hours), and has the units of
cc*mm/(m.sup.2-day). The permeability coefficient considers
atmospheric pressure and is expressed as cc*mm/(m.sup.2-day-mmHg).
A relative rating for the compound may then be obtained by
comparing the compound's permeation coefficient to that of the
control compound.
[0243] Techniques for determining the molecular weight (Mn, Mw, and
Mz) and Mw/Mn (molecular weight distribution, "MWD") of the PAO are
generally described in U.S. Pat. No. 2008/0045638, which is
incorporated herein by reference.
[0244] Color is determined on the APHA scale by ASTM D 1209. Note
that an APHA color of 100 corresponds to a Saybolt color (ASTM D
156) of about +10; an APHA color of 20 corresponds to a Saybolt
color of about +25; and an APHA color of 0 corresponds to a Saybolt
color of about +30.
[0245] Carbon type composition is determined by ASTM D 2140, and
gives the percentage of aromatic carbons (C.sub.A), naphthenic
carbons (C.sub.N), and paraffinic carbons (C.sub.P) in the fluid.
Specifically, C.sub.A is the wt % of total carbon atoms in the
fluid that are in aromatic ring-type structures; C.sub.N is the wt
% of total carbon atoms in the fluid that are in saturated
ring-type structures; and C.sub.P is the wt % of total carbon atoms
in the fluid that are in paraffinic chain-type structures. ASTM D
2140 involves calculating a "Viscosity Gravity Constant" (VGC) and
"Refractivity Intercept" (RI) for the fluid, and determining the
carbon type composition from a correlation based on these two
values. However, this method is known to fail for highly paraffinic
oils, because the VGC and RI values fall outside the correlation
range. Therefore, for purposes of this invention, the following
protocol is used: If the calculated VGC (ASTM D 2140) for a fluid
is 0.800 or greater, the carbon type composition including C.sub.P
is determined by ASTM D 2140. If the calculated VGC (ASTM D 2140)
is less than 0.800, the fluid is considered to have C.sub.P of at
least 80%. If the calculated VGC (ASTM D 2140) is less than 0.800
but greater than 0.765, then ASTM D 3238 is used to determine the
carbon type composition including C.sub.P. If application of ASTM D
3238 yields unphysical quantities (e.g., a negative C.sub.A value),
then C.sub.P is defined to be 100%. If the calculated VGC (ASTM D
2140) for a fluid is 0.765 or less, then C.sub.P is defined to be
100%.
[0246] Other test methods are listed in Table 1.
TABLE-US-00002 TABLE 1 Test Methods Parameter Units Test Mooney
Viscosity (composition) MU ASTM D 1646 ML 1 + 4, 100.degree. C.
Hardness Shore A ASTM D 2240 Mooney Scorch Time 135.degree. C. for
60 min, 1 min preheat t5 minutes ASTM D 1646 t10 minutes Moving Die
Rheometer (MDR) 160.degree. C. for 60 min, .+-.0.5.degree. arc ML
deciNewton.meter ASTM D 5289 MH dNewton.m t25 minutes t90 minutes
Tensile Test 100% Modulus MPa ASTM D 412 300% Modulus MPa die C
Tensile Strength MPa % Elongation at Break % Mocon Oxygen
Permeability Test 60.degree. C., 20% oxygen concentration See text.
Permeability Coefficient cc*mm(m.sup.2- day-mmHg) Cold Brittleness
.degree. C. ASTM D746 Tg of Elastomeric Composition .degree. C.
DSC* *According to the differential scanning calorimetry procedure
described in Paragraph [0597] of US 2008/004,5638.
[0247] Testing procedures not described herein are described in US
2008/0045638, which is incorporated by reference herein.
EXAMPLES
[0248] Elastomeric compositions comprising at least one
isobutylene-based elastomer and at least one PAO will now be
further described with reference to the following non-limiting
examples. The test methods used in the Examples are as described
above. The PAOs used in the examples were prepared with either
BF.sub.3 or AlCl.sub.3 catalyst systems. Table 2 lists typical
physical and chemical properties of the various PAOs used in the
examples. A listing of the various other components used in the
elastomeric compositions of the examples is in Table 3.
TABLE-US-00003 TABLE 2 PAO Properties Specific Kinematic Pour
Gravity @ Flash Viscosity @ Viscosity PAO Point 15.6.degree. C.
Point 100.degree. C. Index A -57.degree. C. 0.827 246.degree. C. 6
cSt 138 B -36.degree. C. 0.850 281.degree. C. 40 cSt 170
TABLE-US-00004 TABLE 3 Various Components in the Elastomeric
Compositions Material Brief Description Source BIIR 2222 Brominated
butyl rubber, Bromobutyl-2222, 27-37 Mooney Viscosity ExxonMobil
Chemical Company N660 Carbon black. Calsol .TM. 810 Naphthenic Oil,
ASTM R. E. Carroll, Inc. Type 103 (Trenton, NJ) Struktol 40MS
Composition of aliphatic- Strucktol Co. of aromatic-napthenic
resins. America (Stow, OH) SP-1068 Alkyl phenol formaldehyde
Schenectady Int. resin. (Schnectady, NY) Stearic Acid Activator ACI
5106NF, Witco Manufacturing SMR 20 Natural rubber. Kadox .TM. 911
Zinc Oxide Zinc Corp. of America (Monaca, PA) MBTS
2-Mercaptobenzothiazole Altax MBTS disulfide Sulfur Rubbermakers
Sulfur R E Carrol
Example 1
[0249] Various PAOs were evaluated as process aids in model tire
innerliner compounds. Naphthenic oil is typically used in such
compounds at 8 phr. In the compounds of Example 1, PAO was either
mixed with naphthenic oil or replaced the naphthenic oil. The
compound formulations are listed in Table 4, all amounts listed are
in phr. The compounds were mixed in a 1 L Banbury mixer using a
2-stage mixing procedure. The vulcanization system (Kadoz 911,
MBTS, and Sulfur) were added in the second stage. The compounds
were tested for a range of processing, curing, and physical
properties. The data is presented in Table 5.
TABLE-US-00005 TABLE 4 Model Tire Innerliner Compound Formulations
Compound 1 2 3 4 5 6 BIIR 100.00 100.00 100.00 100.00 100.00 100.00
2222 N660 60.00 60.00 60.00 60.00 60.00 60.00 Calsol 8.00 4.00 4.00
810 PAO-A 4.00 8.00 4.00 PAO-B 4.00 8.00 4.00 Struktol 7.00 7.00
7.00 7.00 7.00 7.00 40MS SP- 4.00 4.00 4.00 4.00 4.00 4.00 1068
Stearic 1.00 1.00 1.00 1.00 1.00 1.00 Acid Kadox 1.00 1.00 1.00
1.00 1.00 1.00 911 MBTS 1.25 1.25 1.25 1.25 1.25 1.25 Sulfur 0.50
0.50 0.50 0.50 0.50 0.50
TABLE-US-00006 TABLE 5 Properties of Model Tire Innerliner
Compounds with PAO Compound 1 2 3 4 5 6 Mooney Viscosity
100.degree. C., 4 min, 1 min preheat ML 1 + 4 [MU] 55.4 56.1 54.3
57.7 58.5 56.6 Mooney Scorch 135.degree. C., 1 min preheat t5 16.0
16.3 16.4 16.7 17.1 15.6 t10 18.4 18.9 19.3 19.5 20.1 18.2 MDR
160.degree. C., 0.5.degree. arc, 60 min ML [dNm] 1.31 1.32 1.27
1.37 1.42 1.35 MH [dNm] 3.92 4.47 4.47 4.31 4.72 4.66 ts1 [min]
4.05 3.95 3.92 4.17 4.05 3.75 t25 [min] 3.19 3.45 3.49 3.47 3.62
3.38 t50 [min] 4.84 5.22 5.32 5.38 5.53 5.19 t90 [min] 11.00 12.38
13.10 12.62 12.61 14.00 t95 [min] 14.06 18.60 19.02 17.18 18.00
21.12 Hardness 3 sec delay, 23.degree. C. [Shore A]0 39.8 40.6 40.7
40.1 40.9 40.2 (Median Values Reported) Tensile 1000 100% Modulus
[MPa] 0.88 0.94 0.98 1.02 1.08 0.99 300% Modulus [MPa] 2.64 2.91
3.03 3.16 3.42 3.05 Tensile Strength [MPa] 8.97 9.11 9.50 9.40 9.77
9.39 % Elongation at Break [%] 833.72 802.84 774.45 758.76 754.96
806.14 (Median Values Reported) MOCON Permeability Test Air @
60.degree. C. Permeability [cc*mm/(m.sup.2-day- 0.51685 0.5385
0.62075 0.5372 0.7524 0.7891 Coefficient mmHg)] (Avg of 2 Specimens
Reported) Cold Brittleness [.degree. C.] -50.2 -51 -52.6 -51 -51.4
-52.2
[0250] Typically, a compound viscosity in the range of 50 to 60 MU,
a tensile strength in the range of 9 to 11 MPa, an elongation at
break of greater than 700%, and a 300% modulus of 4 MPa or less are
desirable to ensure adequate processing qualities in a factory and
adequate performance in a tire. As seen in Table 5, the compounds
of Example 1 where the PAOs have been mixed with naphthenic oil or
have replaced the naphthenic oil had comparable compound properties
to Compound 1, which contained only naphthenic oil.
Example 2
[0251] In Example 2, model tire innerliner compounds were made
which contained varying amounts of halogenated butyl rubber and
natural rubber. PAO-A and PAO-B were used to replace the naphthenic
oil which would typically be used in the compounds. The compound
formulations are listed in Table 6, all amounts listed are in phr.
The compounds were tested for a range of processing, curing, and
physical properties, with the results listed in Table 7.
TABLE-US-00007 TABLE 6 Model Tire Innerliner Compound Formulations
Compound 7 8 9 10 11 12 13 14 13 BIIR 80.00 80.00 80.00 80.00 80.00
80.00 60.00 60.00 60.00 2222 SMR 20 20.00 20.00 20.00 20.00 20.00
20.00 40.00 40.00 40.00 N660 60.00 60.00 60.00 60.00 60.00 60.00
60.00 60.00 60.00 Calsol 8.00 8.00 810 PAO-A 8.00 4.00 12.00 8.00
PAO-B 8.00 4.00 12.00 8.00 Struktol 7.00 7.00 7.00 7.00 7.00 7.00
7.00 7.00 7.00 40MS SP- 4.00 4.00 4.00 4.00 4.00 4.00 4.00 4.00
4.00 1068 Stearic 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 Acid
Kadox 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 911 MBTS 1.25
1.25 1.25 1.25 1.25 1.25 1.25 1.25 1.25 Sulfur 0.50 0.50 0.50 0.50
0.50 0.50 0.50 0.50 0.50
TABLE-US-00008 TABLE 7 Properties of Model Tire Innerliner
Compounds with PAO & Natural Rubber Compound 7 8 9 10 11 12 13
14 15 Mooney Viscosity, 100.degree. C., 4 min, 1 min preheat ML 1 +
4 [MU] 52.7 51.7 54 51.4 43.9 46.2 49.3 46.6 48.1 Mooney Scorch,
135.degree. C., 1 min preheat t5 8.1 7.5 7.4 7.7 8.4 8.1 7.4 7.0
6.8 t10 10.3 9.3 9.0 9.6 10.7 10.2 8.9 8.6 8.2 MDR, 160.degree. C.,
0.5.degree. arc, 60 min ML [dNm] 1.34 1.30 1.41 1.32 1.10 1.17 1.34
1.27 1.33 MH [dNm] 4.79 5.32 4.99 4.34 4.42 4.56 5.87 5.68 5.79 ts1
[min] 4.14 3.92 4.04 4.26 4.42 4.44 3.51 3.48 3.42 t25 [min] 3.81
3.94 3.77 3.56 4.02 4.08 3.82 3.74 3.69 t50 [min] 5.59 5.68 5.76
5.48 5.84 6.03 5.41 5.35 5.35 t90 [min] 10.51 11.16 10.81 10.22
11.02 11.44 10.49 10.33 10.54 t95 [min] 12.59 13.55 13.03 12.05
13.32 14.00 12.70 12.52 12.74 Shore A Hardness, 39.9 42.9 42.4 42.6
39.5 40.5 43.1 42.9 43.1 3 sec delay, 23.degree. C. (Median Value
Reported) Tensile 1000 100% Modulus [MPa] 1.02 1.11 1.05 1.08 0.82
0.95 1.13 0.92 1.17 300% Modulus [MPa] 3.27 3.48 3.27 3.31 2.48
3.11 3.79 2.97 4.09 Tensile Strength [MPa] 9.15 9.45 9.71 9.36 8.60
9.39 11.82 10.24 11.65 % Elongation at Break [%] 749.11 713.95
753.99 754.88 800.33 772.19 704.03 711.88 678.47 (Median Value
Reported) MOCON Permeability Test Air @ 60.degree. C. Permeability
[cc*mm/(m.sup.2-day- 1.14345 1.04265 0.92205 0.9405 1.2851 1.0746
1.70825 1.97995 1.8112 Coefficient mmHg)] (Avg of 2 Specimens
Reported) Cold Brittleness [.degree. C.] -52.2 -52.6 -52.2 -53.8
-57.4 -57 -55.4 -58.6 -57.4
Example 3
[0252] In Example 3, model tire innerliner compounds were made
which contained varying amounts of halogenated butyl rubber and
natural rubber. PAO-A and PAO-B were used to replace the naphthenic
oil which would typically be used in the compounds. The compound
formulations are listed in Table 8, all amounts listed are in phr.
The compounds were tested for a range of processing, curing, and
physical properties, with the results listed in Table 9.
TABLE-US-00009 TABLE 8 Model Tire Innerliner Compound Formulations
Compound 1 2 3 4 5 6 7 8 9 10 11 12 BIIR 100 100 100 100 100 80 80
80 80 80 80 80 2222 SMR20 20 20 20 20 20 20 20 N660 60 60 60 60 60
60 60 60 60 60 60 60 Struktol 7 7 7 7 7 7 7 7 7 7 7 7 40MS SP- 4 4
4 4 4 4 4 4 4 4 4 4 1068 Stearic 1 1 1 1 1 1 1 1 1 1 1 1 Acid
Calsol 8 8 810 PAO-A 12 16 12 16 20 PAO-B 12 16 12 16 20 Kadox 1 1
1 1 1 1 1 1 1 1 1 1 911 MBTS 1.25 1.25 1.25 1.25 1.25 1.25 1.25
1.25 1.25 1.25 1.25 1.25 Sulfur 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5
0.5 0.5 0.5
TABLE-US-00010 TABLE 9 Properties of Model Tire Innerliner
Compounds with PAO Compound 1 2 3 4 5 6 Mooney Viscosity,
100.degree. C. 4 min, 1 min preheat ML 1 + 4 [MU] 55.1 46.7 49.4
41.2 42.9 52 Mooney Scorch @ 135.degree. C. t5 16.01 17.26 16.54
19.04 18.25 9.65 t10 18.51 19.92 19.04 21.83 20.94 13.56 MDR @
160.degree. C. ML [dNm] 1.29 1.06 1.22 0.94 1.01 1.33 MH [dNm] 4.51
4.01 4.22 3.68 3.67 4.83 ts2 [min] 6.18 7.13 6.84 8.12 8.4 5.94
tc50 [min] 5.11 5.26 5.14 5.54 5.43 5.46 tc90 [min] 12.42 13.56
13.37 13.12 13.61 12.58 Cold Brittleness -41 -44.6 -42.2 -46.2
-44.2 -45.4 [.degree. C.] Tensile [Mpa] 8.69 8 8.81 8.37 8.72 9.38
100% Modulus [Mpa] 0.88 0.73 0.85 0.72 0.75 0.99 300% Modulus [Mpa]
2.47 2.02 2.5 2.12 2.14 2.92 % Elongation [%] 843 855 874 864 860
818 MOCON @ 60.degree. C. cc*mm/(m.sup.2-day-mmHg) 0.5669 0.8214
0.6396 1.2916 1.0995 1.2581 Compound 7 8 9 10 11 12 Mooney
Viscosity, 100.degree. C. 4 min, 1 min preheat ML 1 + 4 [MU] 42.1
46.5 37.1 38.9 31.5 33.4 Mooney Scorch @ 135.degree. C. t5 11.28
11.49 12 12.95 14.17 15.74 t10 15.95 15.91 17.08 17.69 19.35 20.58
MDR @ 160.degree. C. ML [dNm] 1.07 1.21 0.92 0.99 0.75 0.82 MH
[dNm] 4.14 4.57 3.93 3.83 3.39 3.37 ts2 [min] 6.74 6.62 7.15 7.28
8.24 8.75 tc50 [min] 5.67 5.93 5.91 5.68 6.04 6.04 tc90 [min] 10.58
11.21 10.98 10.72 11.1 11.21 Cold Brittleness [.degree. C.] -48.2
-47 -47 -47.8 -50.2 -48.2 Tensile [Mpa] 8.84 9.22 7.93 8.28 7.2
7.72 100% Modulus [Mpa] 0.83 0.98 0.7 0.7 0.54 0.64 300% Modulus
[Mpa] 2.5 3 2.04 2.07 1.45 1.86 % Elongation [%] 823 777 808 846
903 838 MOCON @ 60.degree. C. cc*mm/(m.sup.2-day-mmHg) 1.2415
1.0868 1.3883 1.4979 2.1283 1.7792
[0253] As seen in Example 2 and 3, the brittleness temperature was
lowered by the addition of the PAO at all levels, no matter what
level of halobutyl the composition contained. The brittle point of
a 100 phr halobutyl recipe with PAO was lowered to the level of a
80 phr recipe without PAO. The brittle point of an 80 phr halobutyl
20 phr natural rubber with PAO was lowered to the level of a 60 phr
halobutyl 40 phr natural rubber recipe without PAO. The
permeability of the 80 phr halobutyl recipe was improved with the
addition of up to 12 phr of PAO.
[0254] The data from the Examples was used to create FIGS. 1, 2,
and 3.
[0255] All priority documents, patents, publications, and patent
applications, test procedures (such as ASTM methods), and other
documents cited herein are fully incorporated by reference to the
extent such disclosure is not inconsistent with this invention and
for all jurisdictions in which such incorporation is permitted.
[0256] When numerical lower limits and numerical upper limits are
listed herein, ranges from any lower limit to any upper limit are
contemplated.
[0257] While the illustrative embodiments of the invention have
been described with particularity, it will be understood that
various other modifications will be apparent to and can be readily
made by those skilled in the art without departing from the spirit
and scope of the invention. Accordingly, it is not intended that
the scope of the claims appended hereto be limited to the examples
and descriptions set forth herein but rather that the claims be
construed as encompassing all the features of patentable novelty
which reside in the present invention, including all features which
would be treated as equivalents thereof by those skilled in the art
to which the invention pertains.
* * * * *