U.S. patent application number 11/542836 was filed with the patent office on 2007-04-05 for amine functionalized polymer.
Invention is credited to Yuan-Yong Yan.
Application Number | 20070078232 11/542836 |
Document ID | / |
Family ID | 37453053 |
Filed Date | 2007-04-05 |
United States Patent
Application |
20070078232 |
Kind Code |
A1 |
Yan; Yuan-Yong |
April 5, 2007 |
Amine functionalized polymer
Abstract
A macromolecule includes a functional group including imine
functionality bonded to a polymer chain. Where desired, the
functional group also can contain additional (e.g., amine and/or
silane) functionality. The material can be provided by reacting a
polymer including carbonyl functionality with a compound including
a primary amino group. The functional group can interact with
particulate filler such as, e.g., carbon black and silica.
Inventors: |
Yan; Yuan-Yong; (Copley,
OH) |
Correspondence
Address: |
BRIDGESTONE AMERICAS HOLDING, INC.
1200 FIRESTONE PARKWAY
AKRON
OH
44317
US
|
Family ID: |
37453053 |
Appl. No.: |
11/542836 |
Filed: |
October 4, 2006 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60723472 |
Oct 4, 2005 |
|
|
|
Current U.S.
Class: |
525/374 ;
525/342 |
Current CPC
Class: |
C08F 236/06 20130101;
C08C 19/25 20130101; C08F 212/08 20130101; C08F 236/10 20130101;
C08F 2/06 20130101; C08F 4/08 20130101; C08F 8/30 20130101; C08L
9/06 20130101; C08C 19/22 20130101; C08F 8/42 20130101; C08K 3/013
20180101; C08C 19/44 20130101; C08F 8/32 20130101; C08K 3/013
20180101; C08L 15/00 20130101; C08K 3/013 20180101; C08L 15/00
20130101 |
Class at
Publication: |
525/374 ;
525/342 |
International
Class: |
C08F 8/30 20060101
C08F008/30 |
Claims
1. A macromolecule comprising a polymer chain and, bonded thereto,
a functional group comprising imine functionality.
2. The macromolecule of claim 1 wherein said imine functionality is
defined by the general formula >C.dbd.N--(CH.sub.2).sub.n--
where n is an integer of from 1 to 10 inclusive.
3. The macromolecule of claim 1 wherein said functional group is
bonded to a terminus of said polymer chain through said imine
functionality.
4. The macromolecule of claim 1 wherein said functional group
further comprises one of amine and silane functionality.
5. The macromolecule of claim 4 wherein said silane functionality
is provided in the form of an alkoxysilane or
alkylalkoxysilane.
6. A functional polymer comprising the reaction product of a
polymer comprising carbonyl functionality and a compound comprising
a primary amino group.
7. The functional polymer of claim 6 wherein said carbonyl
functionality is provided by reaction of a living polymer with a
compound comprising an aldehyde group.
8. The functional polymer of claim 6 wherein said carbonyl
functionality is provided by reaction of a living polymer with a
heterocyclic compound comprising within its ring structure a
nitrogen atom and a carbonyl group.
9. The functional polymer of claim 8 wherein said heterocyclic
compound is an imidazolidinone or a pyrrolidinone.
10. The functional polymer of claim 6 wherein said compound
comprising a primary amino group further comprises additional amine
functionality.
11. The functional polymer of claim 10 wherein said additional
amine functionality is primary.
12. The functional polymer of claim 6 wherein said compound
comprising a primary amino group further comprises a silane
group.
13. The functional polymer of claim 12 wherein said silane group is
provided in the form of an alkoxysilane or alkylalkoxysilane.
14. A method of making a functional polymer comprising reacting a
polymer that comprises carbonyl functionality with a compound that
comprises a primary amino group.
15. The method of claim 14 wherein said carbonyl functionality is
provided by reacting a living polymer with one of (1) a compound
comprising an aldehyde group, and (2) a heterocyclic compound
comprising within its ring structure a nitrogen atom and a carbonyl
group.
16. The method of claim 15 wherein said heterocyclic compound is
one of an imidazolidinone and a pyrrolidinone.
17. The method of claim 14 wherein said compound comprising a
primary amino group further comprises additional amine
functionality.
18. The method of claim 17 wherein said additional amine
functionality is primary.
19. The method of claim 14 wherein said compound comprising a
primary amino group further comprises a silane group.
20. The method of claim 19 wherein said silane group is provided in
the form of an alkoxysilane or alkylalkoxysilane.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application claims priority to and the benefit of U.S.
provisional application No. 60/723,472 filed on Oct. 4, 2005,
entitled "Amine Functionalized Polymer," the complete disclosure of
which is incorporated herein by reference.
BACKGROUND INFORMATION
[0002] 1. Field of the Invention
[0003] The invention relates to the manufacture and use of
functionalized polymers that can interact with fillers, in
particular carbon black and silica.
[0004] 2. Background of the Invention
[0005] Rubber goods such as tire treads often are made from
elastomeric compositions that contain one or more reinforcing
materials such as, for example, particulate carbon black and
silica; see, e.g., The Vanderbilt Rubber Handbook, 13th ed. (1990),
pp. 603-04.
[0006] Good traction and resistance to abrasion are primary
considerations for tire treads; however, motor vehicle fuel
efficiency concerns argue for a minimization in tire rolling
resistance, which correlates with a reduction in hysteresis and
heat build-up during operation of the tire. These considerations
are, to a great extent, competing and somewhat contradictory:
treads made from compositions designed to provide good road
traction usually exhibit increased rolling resistance and vice
versa.
[0007] Filler(s), polymer(s), and additives typically are chosen so
as to provide an acceptable compromise or balance of these
properties. Ensuring that reinforcing filler(s) are well dispersed
throughout the elastomeric material(s) both enhances processability
and acts to improve physical properties. Dispersion of fillers can
be improved by increasing their interaction with the elastomer(s).
Examples of efforts of this type include high temperature mixing in
the presence of selectively reactive promoters, surface oxidation
of compounding materials, surface grafting, and chemical
modifications to the terminal ends of the polymers.
[0008] Where an elastomer is made by anionic polymerization
techniques, attachment of certain functional groups is difficult.
Living polymers are terminated by active hydrogen atoms such as are
present in, e.g., primary and secondary amine groups. However,
amine functional groups can provide desirable interaction with
particulate fillers, particularly carbon black. Therefore,
commercially useful methods of providing living polymers with
terminal amine functionality remains desirable.
[0009] Additionally, methods of functionalization that allow or
provide flexibility with respect to the type(s) of functional
groups that can be attached also remain desirable. Particularly
desirable are methods that can provide functionality capable of
interacting with such diverse fillers as silica and carbon
black.
SUMMARY
[0010] In one aspect is provided a macromolecule that includes a
polymer chain and, bonded thereto, a functional group including
imine functionality.
[0011] In another aspect is provided a functional polymer that
includes the reaction product of a polymer including carbonyl
functionality and a compound including a primary amino group.
[0012] In either of the preceding aspects, the functional group can
contain additional functionality, examples of which include amine
and/or silane functionality. Where both types of functionality are
present, interactivity with diverse filler materials such as silica
and carbon black can be provided.
[0013] The functional group included in the just mentioned
macromolecule and provided in the foregoing functionalized polymer
can interact with particulate filler such as, e.g., carbon black
and silica. Compositions that include particulate fillers and the
macromolecule or the functionalized polymer also are provided.
[0014] Other aspects of the present invention will be apparent to
the ordinarily skilled artisan from the description that follows.
To assist in understanding the description of various embodiments
that follows, certain definitions are provided immediately below.
These are intended to apply throughout unless the surrounding text
explicitly indicates a contrary intention: [0015] "polymer" means
the polymerization product of one or more monomers and is inclusive
of homo-, co-, ter-, tetra-polymers, etc.; [0016] "mer" or "mer
unit" means that portion of a polymer derived from a single
reactant molecule (e.g., ethylene mer has the general formula
--CH.sub.2CH.sub.2--); [0017] "copolymer" means a polymer that
includes mer units derived from two reactants, typically monomers,
and is inclusive of random, block, segmented, graft, etc.,
copolymers; [0018] "interpolymer" means a polymer that includes mer
units derived from at least two reactants, typically monomers, and
is inclusive of copolymers, terpolymers, tetrapolymers, and the
like; [0019] "macromolecule" means a polymer that includes at least
one group or substituent not originating or derived from its
constituent mer units; [0020] "polyene" means a molecule with at
least two double bonds located in the longest portion or chain
thereof, and specifically is inclusive of dienes, trienes, and the
like; [0021] "terminus" means an end of a polymeric chain; [0022]
"terminal moiety" means a group or functionality located at a
terminus; and [0023] "substituted," when used in conjunction with a
particular species or type of functional group, means that the
group can contain a heteroatom or functionality that does not
interfere with the intended purpose of the group.
DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS
[0024] The macromolecule includes a polymeric chain with at least
one functional group attached thereto, and those group(s) can
constitute the "at least one group or substituent" in the foregoing
definition of macromolecule.
[0025] The polymeric chain can be elastomeric and can include mer
units that include unsaturation such as those derived from
polyenes, particularly dienes and trienes (e.g., myrcene).
Illustrative polyenes include C.sub.4-C.sub.12 dienes, particularly
conjugated dienes such as, but not limited to, 1,3-butadiene,
isoprene, 1,3-pentadiene, 2,3-dimethyl-1,3-butadiene, and
1,3-hexadiene. Homo- and interpolymers that include just
polyene-derived mer units constitute one illustrative type of
elastomer.
[0026] The polymeric chain also can include pendent aromatic groups
such as can be provided through incorporation of mer units derived
from vinyl aromatics, particularly the C.sub.8-C.sub.20 vinyl
aromatics such as, e.g., styrene, .alpha.-methyl styrene, p-methyl
styrene, the vinyl toluenes, and the vinyl naphthalenes. When used
in conjunction with one or more polyenes, mer units with pendent
aromaticity can constitute from about 1 to about 50% by wt., from
about 10 to about 45% by wt., or from about 20 to about 35% by wt.,
of the polymer chain; such interpolymers constitute one exemplary
class of polymers. The microstructure of such interpolymers can be
random, i.e., the mer units derived from each type of constituent
monomer preferably do not form blocks and, instead, are
incorporated in a non-repeating, essentially simultaneous manner.
Random microstructure can provide particular benefit in certain end
use applications such as, e.g., rubber compositions used in the
manufacture of tire treads.
[0027] Exemplary elastomers include poly(butadiene), (poly)isoprene
(either natural or synthesized), and interpolymers of butadiene and
styrene such as, e.g., copoly(styrene/butadiene) also known as
SBR.
[0028] Polyenes can incorporate into polymeric chains in more than
one way. Especially for tire tread applications, controlling this
manner in which polyenes incorporate themselves into the polymer
chain (i.e., the 1,2-microstructure of the polymer) can be
desirable. A polymer chain with an overall 1,2-microstructure,
based on total polyene content, of from about 10 to about 80%,
optionally from about 25 to 65%, can be desirable for certain end
use applications. A polymer that has an overall 1,2-micro-structure
of no more than about 50%, preferably no more than about 45%, more
preferably no more than about 40%, even more preferably no more
than about 35%, and most preferably no more than about 30%, based
on total polyene content, is considered to be "substantially
linear".
[0029] The number average molecular weight (M.sub.n) of the polymer
typically is such that a quenched sample exhibits a gum Mooney
viscosity (ML.sub.4/100.degree. C.) of from about 2 to about 150,
more commonly 2.5 to about 100.
[0030] Elastomers can be made by emulsion polymerization or
solution polymerization, with the latter affording greater control
with respect to such properties as randomness, microstructure, etc.
Solution polymerizations have been performed since about the
mid-20th century, so the general aspects thereof are known to the
ordinarily skilled artisan; nevertheless, certain aspects are
provided here for convenience of reference.
[0031] Solution polymerization typically involves an initiator.
Exemplary initiators include organolithium compounds, particularly
alkyllithium compounds. Examples of organolithium initiators
include N-lithio-hexamethyleneimine; n-butyllithium; tributyltin
lithium; dialkylaminolithium compounds such as
dimethylaminolithium, diethylamino-lithium, dipropylaminolithium,
dibutylaminolithium and the like; dialkylaminoalkyl-lithium
compounds such as diethylaminopropyllithium; and those trialkyl
stanyl lithium compounds involving C.sub.1-C.sub.12, preferably
C.sub.1-C.sub.4, alkyl groups.
[0032] Multifunctional initiators, i.e., initiators capable of
forming polymers with more than one living end, also can be used.
Examples of multifunctional initiators include, but are not limited
to, 1,4-dilithiobutane, 1,10-dilithiodecane, 1,20-dilithioeicosane,
1,4-dilithiobenzene, 1,4-dilithionaphthalene,
1,10-dilithioanthracene, 1,2-dilithio-1,2-diphenylethane,
1,3,5-trilithiopentane, 1,5,15-trilithioeicosane,
1,3,5-trilithiocyclohexane, 1,3,5,8-tetralithiodecane,
1,5,10,20-tetralithioeicosane, 1,2,4,6-tetralithiocyclohexane, and
4,4'-dilithiobiphenyl.
[0033] In addition to organolithium initiators, so-called
functionalized initiators also can be useful. These become
incorporated into the polymer chain, thus providing a functional
group at the initiated end of the chain. Examples of such materials
include lithiated aryl thioacetals (see, e.g., WO 2004/041870) and
the reaction products of organolithium compounds and, for example,
N-containing organic compounds such as substituted aldimines,
ketimines, secondary amines, etc., optionally pre-reacted with a
compound such as diisopropenyl benzene (see, e.g., U.S. Pat. Nos.
5,153,159 and 5,567,815).
[0034] Useful anionic polymerization solvents include various
C.sub.5-C.sub.12 cyclic and acyclic alkanes as well as their
alkylated derivatives, certain liquid aromatic compounds, and
mixtures thereof. The ordinarily skilled artisan is aware of other
useful solvent options and combinations.
[0035] In solution polymerizations, both randomization of the mer
units and vinyl content (i.e., 1,2-microstructure) can be increased
through inclusion of a coordinator, usually a polar compound, in
the polymerization ingredients. Up to 90 or more equivalents of
coordinator can be used per equivalent of initiator, with the
amount depending on, e.g., the amount of vinyl content desired, the
level of non-polyene monomer employed, the reaction temperature,
and nature of the specific coordinator employed. Compounds useful
as coordinators include organic compounds having a heteroatom with
a non-bonded pair of electrons (e.g., O or N). Examples include
dialkyl ethers of mono-and oligo-alkylene glycols; crown ethers;
tertiary amines such as tetramethylethylene diamine; THF; THF
oligomers; linear and cyclic oligomeric oxolanyl alkanes such as
2,2'-di(tetrahydrofuryl) propane, di-piperidyl ethane,
hexamethylphosphoramide, N,N'-dimethylpiperazine,
diazabicyclooctane, diethyl ether, tributylamine, and the like.
Details of linear and cyclic oligomeric oxolanyl coordinators can
be found in, e.g., U.S. Pat. No. 4,429,091.
[0036] Although the ordinarily skilled artisan understands the type
of conditions typically employed in solution polymerization, a
representative description is provided for the convenience of the
reader. The following is based on a batch process, although
extending this description to, e.g., semi-batch or continuous
processes is within the capability of the ordinarily skilled
artisan.
[0037] Solution polymerization typically begins by charging a blend
of monomer(s) and solvent to a suitable reaction vessel, followed
by addition of a coordinator (if used) and initiator, which often
are added as part of a solution or blend; alternatively, monomer(s)
and coordinator can be added to the initiator. The procedure
typically is carried out under anhydrous, anaerobic conditions. The
reactants can be heated to a temperature of up to about 150.degree.
C. and agitated. After a desired degree of conversion has been
reached, the heat source (if used) can be removed and, if the
reaction vessel is to be reserved solely for polymerizations, the
reaction mixture is removed to a post-polymerization vessel for
flnctionalization and/or quenching. At this point, the reaction
mixture commonly is referred to as a "polymer cement" because of
its relatively high concentration of polymer.
[0038] At this point, the polymer can be provided with a functional
group that includes imine functionality (>C.dbd.N--), optionally
further defined as >C.dbd.N--(CH.sub.2).sub.n-- where n is an
integer of from 1 to 10 inclusive or, in some embodiments, an
integer of from 2 to 6 inclusive. (The alkylene group is optional,
so n can be 0.) Thus, an alkylene group can be used to link the
imine nitrogen atom to other portions of the functionality such as,
e.g., additional functional groups.
[0039] One method of effecting this functionalization involves a
two steps: a polymer is provided with carbonyl functionality and
then that functionality can be reacted with an amine-containing
compound.
[0040] Carbonyl functionality can be provided by introducing to the
polymer cement an aldehyde or ketone in which the carbonyl carbon
atom is bonded directly to a heteroatom-containing leaving group.
Such materials can be represented by the general formula
R.sup.1C(O)-QR.sup.2 where [0041] R.sup.1 is a hydrogen atom or a
moiety of the formula --CH.sub.2Z where Z is a hydrogen atom or a
substituted or unsubstituted aryl, alkyl, alkenyl, alkenaryl,
aralkenyl, alkaryl, or aralkyl group; [0042] R.sup.2 is a moiety of
the formula --CH.sub.2Z where Z is defined as above or, optionally,
R.sup.1 and R.sup.2 together can form a cyclic structure
(preferably a 5-7 membered ring) optionally incorporating one or
more heteroatoms such as, e.g., N, 0, or S; and [0043] Q is an
oxygen atom, a sulfur atom, or a NR.sup.3 moiety with R.sup.3 being
a substituted or unsubstituted aryl, alkyl, alkenyl, alkenaryl,
aralkenyl, alkaryl, or aralkyl group or, optionally, R.sup.2 and
R.sup.3 together can form a cyclic structure (preferably a 5-7
membered ring) optionally incorporating one or more heteroatoms
such as, e.g., N, O, or S.
[0044] Carbonyl-containing compounds represented by the foregoing
general formula include but are not limited to esters such as alkyl
acetates (e.g., ethyl acetate), methyl methacrylate, and alkyl
benzoates; lactones such as .gamma.-valerolactone,
.epsilon.-caprolactone, propylene carbonate, and
2,2,5-trimethyl-1,3-dioxane-4,6-dione; acid anhydrides such as
4-methylphenyl-succinic anhydride, 2-dodecen-1-yl succinic
anhydride, and methyl-succinic anhydride; thiol esters such as
cyclohexyl thiolacetate, phenyl thiolacetate, and thiolesters of
aromatic acids (e.g., the cyclohexyl thiolester of benzoic acid);
amides such as dialkylformamides (e.g., N,N-dimethylformamide
(DMF)), N-formylpyrrolidine, N-formylpiperidine,
4-formylmorpholine, N-methylformanilide, and
N,N-diphenylform-amide; and lactams including imidazolidinones
(e.g., 1,3-dimethyl-2-imidazolidinone (DMI)), pyrrolidinones (e.g.,
1-methyl-2-pyrrolidinone (NMP)), pyrimidinones (e.g.,
1,3-dimethyl-3,4 ,5,6-tetrahydro-2(1H)-pyrimidinone (DMP)), and
sarcosine anhydride; and the like.
[0045] Of the foregoing materials, heterocyclic compounds that
include within their ring structures a nitrogen atom and a carbonyl
group, particularly those that contain a --NR.sup.3--C(O)-- segment
where R.sup.3 is defined as above, can provide particularly
desirable properties in some filled compositions.
[0046] When a compound of the type just described is added to a
polymer cement containing living polymer (carbanion) chains, the
carbonyl carbon atom reacts at the anion, typically located at the
end of the longest chain. (Where a multifunctional initiator is
employed during polymerization, reaction with the foregoing types
of compounds typically occurs on each terminus of the polymer.)
Where the carbonyl carbon atom is part of a cyclic structure, the
ring opens at the carbonyl carbon atom.
[0047] Because of the reactivity of living polymers with compounds
of the type just described, this reaction can be performed quickly
(e.g., .about.15-60 minutes) using relatively mild (e.g.,
.about.25.degree.-75.degree. C. and atmospheric or slightly
elevated pressures) anhydrous and anaerobic conditions. Mixing of a
type commonly employed in commercial processes is sufficient to
ensure near stoichiometric reaction.
[0048] At this point, the functionalized living polymer includes a
carbonyl-containing group, typically at a terminus. Where an
acyclic material has been used to provide the carbonyl
functionality, the functionalized polymer typically includes an
aldehyde group; where a cyclic material is used to provide the
carbonyl functionality, the functionalized polymer includes a
ketone group, with the remainder of the opened ring structure
forming the non-polymeric portion of the ketone. Use of acyclic
materials can be preferred in certain circumstances.
[0049] Imine functionality can be provided by reacting the carbonyl
group with a compound that includes an amine group, preferably a
primary amine group, and at least one additional functional group
such as, for example, an amine and/or silane group. Examples of
useful compounds include, but are not limited to, [0050] polyamines
such as, e.g., aminoethylethanolamine,
aminopropyl-monomethylethanolamine, diethylenetriamine,
trimethylenetetraamine, 1,4-cyclohexanebis (methylamine),
1,3-phenylenediamine, 1,4-phenylenediamine, m- or
p-xylylenediamine, N-aminoethylpiperazine,
dimethylaminopropylamine, polyoxyalkyleneamines such as the D-,
XTJ-, and T-series of Jeffamine.TM. materials (Huntsman LLC;
Houston, Tex.), and compounds of the general formula
H.sub.2N(CH.sub.2).sub.nNH.sub.2 where n is an integer of from 2 to
12 inclusive; [0051] amine-functional silanes such as
aminoalkyltrialkoxysilanes (e.g., 3-aminopropyltrimethoxysilane
(APMOS), 3-aminopropyltriethoxy-silane (APEOS),
[3-(methylamino)propyl]trimethoxysilane, etc.) and alkylamines with
alkoxyalkylsilane functionality such as, e.g.,
3-(diethoxymethylsilyl) propylamine; and [0052] combinations of
these, i.e., polyamines with alkoxysilane functionality such as,
e.g., N-[3-(trimethoxysilyl)propyl]ethylenediamine and
N'-[3-(trimethoxysilyl)propyl]diethylenetriamine. This
imine-creating reaction can be performed relatively quickly (e.g.,
.about.30-500 minutes) using relatively mild conditions (e.g.,
.about.25.degree.-75.degree. C. and atmospheric or slightly
elevated pressures). Anhydrous and anaerobic are not necessary but
can be maintained if desired. Mixing of a type commonly employed in
commercial processes typically is sufficient to ensure good
conversion.
[0053] The imine-functional polymer or macromolecule need not be
quenched, although such a step need not be eliminated if a
manufacturing process employing quenching already is in place.
[0054] Solvent can be removed from the polymer cement by
conventional techniques such as drum drying, extruder drying,
vacuum drying or the like, which may be combined with coagulation
with water, alcohol or steam, thermal desolventization, etc.; if
coagulation is performed, oven drying may be desirable.
[0055] The functionalized polymer can be utilized in a tread stock
compound or can be blended with any conventionally employed tread
stock rubber including natural rubber and/or non-ftinctionalized
synthetic rubbers such as, e.g., one or more of poly(isoprene),
SBR, poly(butadiene), butyl rubber, neoprene, ethylene/propylene
rubber (EPR), ethylene/propylene/diene rubber (EPDM),
acrylonitrile/butadiene rubber (NBR), silicone rubber,
fluoroelastomers, ethylene/acrylic rubber, ethylene/vinyl acetate
interpolymer (EVA), epichlorohydrin rubbers, chlorinated
polyethylene rubbers, chlorosulfonated polyethylene rubbers,
hydrogenated nitrile rubber, tetrafluoroethylene/propylene rubber
and the like. When a ftinctionalized polymer(s) is blended with
conventional rubber(s), the amounts can vary from about 5 to about
99% by wt. of the total rubber, with the conventional rubber(s)
making up the balance of the total rubber. The minimum amount
depends to a significant extent on the degree of hysteresis
reduction desired.
[0056] Amorphous silica (SiO.sub.2) can be utilized as a filler.
Silicas are generally classified as wet-process, hydrated silicas
because they are produced by a chemical reaction in water, from
which they are precipitated as ultrafine, spherical particles.
These primary particles strongly associate into aggregates, which
in turn combine less strongly into agglomerates. "Highly
dispersible silica" is any silica having a very substantial ability
to de-agglomerate and to disperse in an elastomeric matrix, which
can be observed by thin section microscopy.
[0057] Surface area gives a reliable measure of the reinforcing
character of different silicas; the Brunauer, Emmet and Teller
("BET") method (described in J. Am. Chem. Soc., vol. 60, p. 309 et
seq.) is a recognized method for determining surface area. BET
surface area of silicas generally is less than 450 m.sup.2/g, and
useful ranges of surface are include from about 32 to about 400
m.sup.2/g, about 100 to about 250 m.sup.2/g, and about 150 to about
220 m.sup.2/g.
[0058] The pH of the silica filler is generally from about 5 to
about 7 or slightly over, preferably from about 5.5 to about
6.8.
[0059] Some commercially available silicas which may be used
include Hi-Sil.TM. 215, Hi-Sil.TM. 233, and Hi-Sil.TM. 190 (PPG
Industries, Inc.; Pittsburgh, Pa.). Other suppliers of commercially
available silica include Grace Davison (Baltimore, Md.), Degussa
Corp. (Parsippany, N.J.), Rhodia Silica Systems (Cranbury, N.J.),
and J.M. Huber Corp. (Edison, N.J.).
[0060] Silica can be employed in the amount of about 1 to about 100
parts by weight (pbw) per 100 parts of polymer (phr), preferably in
an amount from about 5 to about 80 phr. The useful upper range is
limited by the high viscosity imparted by fillers of this type.
[0061] Other useful fillers include all forms of carbon black
including, but not limited to, furnace black, channel blacks and
lamp blacks. More specifically, examples of the carbon blacks
include super abrasion furnace blacks, high abrasion furnace
blacks, fast extrusion furnace blacks, fine furnace blacks,
intermediate super abrasion furnace blacks, semi-reinforcing
furnace blacks, medium processing channel blacks, hard processing
channel blacks, conducting channel blacks, and acetylene blacks;
mixtures of two or more of these can be used. Carbon blacks having
a surface area (EMSA) of at least 20 m.sup.2/g, preferably at least
about 35 m.sup.2/g, are preferred; surface area values can be
determined by ASTM D-1765 using the cetyltrimethyl-ammonium bromide
(CTAB) technique. The carbon blacks may be in pelletized form or an
unpelletized flocculent mass, although unpelletized carbon black
can be preferred for use in certain mixers.
[0062] The amount of carbon black can be up to about 50 phr, with
about 5 to about 40 phr being typical. When carbon black is used
with silica, the amount of silica can be decreased to as low as
about 1 phr; as the amount of silica decreases, lesser amounts of
the processing aids, plus silane if any, can be employed.
[0063] Elastomeric compounds typically are filled to a volume
fraction, which is the total volume of filler(s) added divided by
the total volume of the elastomeric stock, of about 25%;
accordingly, typical (combined) amounts of reinforcing fillers,
i.e., silica and carbon black, is about 30 to 100 phr.
[0064] When silica is employed as a reinforcing filler, addition of
a coupling agent such as a silane is customary so as to ensure good
mixing in, and interaction with, the elastomer(s). Generally, the
amount of silane that is added ranges between about 4 and 20% by
weight, based upon the weight of silica filler present in the
elastomeric compound.
[0065] Coupling agents can have a general formula of A-T-X, in
which A represents a functional group capable of bonding physically
and/or chemically with a group on the surface of the silica filler
(e.g., surface silanol groups); T represents a hydrocarbon group
linkage; and X represents a functional group capable of bonding
with the elastomer (e.g., via a sulfur-containing linkage). Such
coupling agents include organosilanes, in particular polysulfurized
alkoxysilanes (see, e.g., U.S. Pat. Nos. 3,873,489, 3,978,103,
3,997,581, 4,002,594, 5,580,919, 5,583,245, 5,663,396, 5,684,171,
5,684,172, 5,696,197, etc.) or polyorganosiloxanes bearing the X
and A functionalities mentioned above. One preferred coupling agent
is bis[3-(triethoxysilyl)propyl]tetrasulfide.
[0066] Addition of a processing aid can be used to reduce the
amount of silane employed. See, e.g., U.S. Pat. No. 6,525,118 for a
description of fatty acid esters of sugars used as processing aids.
Additional fillers useful as processing aids include, but are not
limited to, mineral fillers, such as clay (hydrous aluminum
silicate), talc (hydrous magnesium silicate), and mica as well as
non-mineral fillers such as urea and sodium sulfate. Preferred
micas contain principally alumina, silica and potash, although
other variants are also useful, as set forth below. The additional
fillers can be utilized in an amount of up to about 40 phr,
typically up to about 20 phr.
[0067] Other conventional rubber additives also can be added. These
include, for example, process oils, plasticizers, anti-degradants
such as antioxidants and antiozonants, curing agents and the
like.
[0068] All of the ingredients can be mixed using standard equipment
such as, e.g., Banbury or Brabender mixers. Typically, mixing
occurs in two or more stages. During the first stage (often
referred to as the masterbatch stage), mixing typically is begun at
temperatures of .about.120.degree. to .about.130.degree. C. and
increases until a so-called drop temperature, typically
.about.165.degree. C., is reached.
[0069] Where a formulation includes silica, a separate re-mill
stage often is employed for separate addition of the silane
component(s). This stage often is performed at temperatures similar
to, although often slightly lower than, those employed in the
masterbatch stage, i.e., ramping from .about.90.degree. C. to a
drop temperature of .about.150.degree. C.
[0070] Reinforced rubber compounds conventionally are cured with
about 0.2 to about 5 phr of one or more known vulcanizing agents
such as, for example, sulfur or peroxide-based curing systems. For
a general disclosure of suitable vulcanizing agents, the interested
reader is directed to an overview such as that provided in
Kirk-Othmer, Encyclopedia of Chem. Tech., 3d ed., (Wiley
Interscience, New York, 1982), vol. 20, pp. 365-468. Vulcanizing
agents, accelerators, etc., are added at a final mixing stage. To
ensure that onset of vulcanization does not occur prematurely, this
mixing step often is done at lower temperatures, e.g., starting at
.about.60.degree. to .about.65.degree. C. and not going higher than
.about.105.degree. to .about.110.degree. C.
[0071] Subsequently, the compounded mixture is processed (e.g.,
milled) into sheets prior to being formed into any of a variety of
components and then vulcanized, which typically occurs at
.about.5.degree. to .about.15.degree. C. higher than the highest
temperatures employed during the mixing stages, most commonly about
170.degree. C.
[0072] The following non-limiting, illustrative examples provide
the reader with detailed conditions and materials that can be
usefuil in the practice of the present invention.
EXAMPLES
[0073] In the examples, dried glass vessels previously sealed with
extracted septum liners and perforated crown caps under a positive
N.sub.2 purge were used for all preparations. Butadiene (21.4% by
wt. in hexane), styrene (33% by wt. in hexane), hexane,
n-butyl-lithium (1.60 M in hexane),
2,2-bis(2'-tetrahydrofuryl)propane (1.6 M solution in hexane,
stored over CaH.sub.2), and butylated hydroxytoluene (BHT) solution
in hexane were used.
[0074] Commercially available reagents and starting materials
included the following, all of which were acquired from
Sigma-Aldrich Co. (St. Louis, Mo.) and used without further
purification unless otherwise noted in a specific example: DMF,
DMI, NMP, DMP, APMOS, APEOS, 3-(diethoxymethylsilyl)propylamine,
N-[3-(trimethoxysilyl)-propyl]ethylenediamine, and
N'-[3-(trimethoxysilyl)propyl]diethylenetriamine.
[0075] Testing data in the Examples was performed on filled
compositions made according to the formulation shown in Tables 1a
(carbon black only) and 1b (carbon black and silica). In these
tables, N-phenyl-N'-(1,3-dimethylbutyl)-p-phenyldiamine acts as an
antioxidant, benzothiazyl-2-cyclohexylsulfenamide and N N'-diphenyl
guanidine act as accelerators, and N-(cyclohexylthio)phthalimide
acts as an inhibitor. TABLE-US-00001 TABLE 1a Compound formulation,
carbon black only Amount (phr) Masterbatch polymer 100 carbon black
(N343 type) 55 wax 1
N-phenyl-N'-(1,3-dimethylbutyl)-p-phenylenediamine 0.95 ZnO 2.5
stearic acid 2 aromatic processing oil 10 Final sulfur 1.3
N-cyclohexylbenzothiazole-2-sulfenamide 1.7 N,N'-diphenylguanidine
0.2 TOTAL 174.65
[0076] TABLE-US-00002 TABLE 1b Compound formulation, carbon black
and silica Amount (phr) Masterbatch polymer 100 silica 30 carbon
black (N343 type) 35
N-phenyl-N'-(1,3-dimethylbutyl)-p-phenylenediamine 0.95 stearic
acid 1.5 aromatic processing oil 10 Re-mill 60% disulfide silane on
carrier 4.57 Final ZnO 2.5 sulfur 1.7
N-cyclohexylbenzothiazole-2-sulfenamide 1.5
N-(cyclohexylthio)phthalimide 0.25 N,N'-diphenylguanidine 0.5 TOTAL
188.47
[0077] Data corresponding to "50.degree. C. Dynastat tan .delta."
were acquired from tests conducted on a Dynastat.TM. mechanical
spectrometer (Dynastatics Instruments Corp.; Albany, N.Y. using the
following conditions: 1 Hz, 2 kg static mass and 1.25 kg dynamic
load, a cylindrical (9.5 mm diameter.times.16 mm height) vulcanized
rubber sample, and 50.degree. C.
[0078] Data corresponding to "Bound Rubber" were determined using
the procedure described by J. J. Brennan et al., Rubber Chem. and
Tech., 40, 817 (1967).
Examples 1-5
[0079] To a N.sub.2-purged reactor equipped with a stirrer was
added 1.53 kg hexane, 0.41 kg styrene solution, and 2.54 kg
butadiene solution. The reactor was charged with 4.03 mL
n-butyllithium, followed by 1.18 mL of the
2,2-bis(2'-tetrahydrofuryl)propane solution.
[0080] The reactor jacket was heated to 50.degree. C., and after
.about.30 minutes the batch temperature peaked at .about.62.degree.
C.
[0081] After an additional .about.30 minutes, some of the polymer
cement was transferred from the reactor to dried glass vessels.
This became sample 1 (a control), while the remaining cement in the
reactor was allowed to undergo further reaction, i.e., the 2-step
ftnctionalization described above. To the remaining cement in the
reactor was added 0.7 mL DMF (6.0 M in toluene) in 5 mL THF and 20
mL hexane; this mixture was stirred at .about.50.degree. C. for
.about.40 minutes.
[0082] Thereafter, portions of the cement were transferred to dried
glass vessels. To each was added a further reactant: TABLE-US-00003
2 0.7 mL propylenediamine (1.0 M), 3 0.7 mL APEOS (1.0 M), 4 0.7 mL
APMOS (1.0 M), and 5 a solution of 3 mL
N-[3-(trimethoxysilyl)propyl]ethylene- diamine (1.0 M) in 10 mL
hexane.
These mixtures were stirred at .about.50.degree. C. for .about.60
more minutes.
[0083] Each of samples 1-5 was coagulated in isopropanol containing
BHT and drum dried.
[0084] Using the formulations shown in Tables 1a and 1b,
vulcanizable elastomeric compounds containing reinforcing fillers
were prepared from samples 1-5. Results of physical testing on
these compounds are shown below in Table 2; for those rows that
include two data points, the upper is for a formulation from Table
1a, and the lower is for a formulation from Table 1b.
TABLE-US-00004 TABLE 2 Testing data from Examples 1-5 1 2 3 4 5
M.sub.n (kg/mol) 100 149 178 184 176 M.sub.w/M.sub.n 1.04 1.31 1.69
1.79 1.75 % coupling 1.5 56.8 64.7 64.8 60.6 T.sub.g (.degree. C.)
-38.6 -39.0 -39.1 -39.0 -38.8 Bound rubber (%) 11.1 26.4 34.3 36.9
43.0 22.5 35.5 47.0 49.7 50.3 171.degree. C. MDR t.sub.50 (min)
3.14 2.85 2.61 2.60 2.31 7.86 7.02 6.45 6.17 5.77 171.degree. C. MH
- ML (kg-cm) 18.3 18.3 17.7 16.8 16.8 21.8 22.6 20.4 19.6 19.3
ML.sub.1+4 @ 130.degree. C. 22.3 43.6 47.1 45.9 45.2 61.4 90.5 81.2
76.5 72.9 300% modulus @ 23.degree. C. (MPa) 11.4 13.0 13.8 13.3
13.7 9.4 11.3 12.6 12.2 13.2 Tensile strength @ 23.degree. C. (MPa)
16.4 18.2 20.5 19.3 19.6 14.2 16.9 17.6 15.7 18.4 Temp. sweep
0.degree. C. tan .delta. 0.211 0.218 0.230 0.232 0.241 0.165 0.171
0.194 0.194 0.199 Temp. sweep 50.degree. C. tan .delta. 0.274 0.222
0.208 0.203 0.180 0.230 0.197 0.205 0.195 0.195 RDA 0.25-14%
.DELTA.G' (MPa) 4.423 1.747 1.669 1.419 1.023 8.364 5.208 2.712
2.661 2.310 50.degree. C. RDA strain sweep (5% strain) tan .delta.
0.2570 0.1684 0.1655 0.1521 0.1338 0.2527 0.2004 0.1741 0.1842
0.1711 50.degree. C. Dynastat tan .delta. 0.2512 0.1635 0.1617
0.1572 0.1343 0.2208 0.1936 0.1816 0.1805 0.1739
[0085] From the 50.degree. C. strain sweep data of Table 2, one can
see that styrene/butadiene interpolymers having imine functional
groups (Examples 2-5) can provide, compared to a control polymer,
significant reductions in tan .delta. (.about.35-50% for carbon
black only and .about.20-33% for carbon black plus silica
formulations, respectively). At the same time, wet traction
performance (see the tan .delta. at 0.degree. C. data, where larger
values correlate generally to better wet traction) is not
negatively impacted to any significant extent.
Examples 6-9
[0086] The procedure described with respect to Examples 1-5 was, in
substantial part, repeated. Specifically, the same amounts and
concentrations of reactant materials were used.
[0087] The reactor jacket was heated to 50.degree. C., and after
.about.28 minutes the batch temperature peaked at .about.63.degree.
C.
[0088] After an additional .about.30 minutes, some of the polymer
cement was transferred from the reactor to dried glass vessels.
This became sample 6 (a control), while the remaining cement in the
reactor was allowed to undergo further reaction, i.e., the 2-step
flnctionalization described above. To the remaining cement in the
reactor was added 5 mL DMI (1.0 M in toluene); this mixture was
stirred at .about.50.degree. C. for .about.40 minutes.
[0089] Thereafter, portions of the cement were transferred to dried
glass vessels. To each was added a further reactant: TABLE-US-00005
7 0.8 mL APEOS (1.0 M), 8 0.8 mL APMOS (1.0 M), and 9 0.8 mL
N-[3-(trimethoxysilyl)propyl]ethylenediamine (1.0 M) in hexane.
These mixture were stirred at .about.50.degree. C. for .about.60
more minutes.
[0090] Each of samples 6-9 was coagulated in isopropanol containing
BHT and drum dried.
[0091] Using the formulations shown in Tables 1a and 1b,
vulcanizable elastomeric compounds containing reinforcing fillers
were prepared from samples 6-9. Results of physical testing on
these compounds are shown below in Table 3; for those rows that
include two data points, the upper is for a formulation from Table
1a, and the lower is for a formulation from Table 1b.
TABLE-US-00006 TABLE 3 Testing data from Examples 6-9 6 7 8 9
M.sub.n (kg/mol) 99 119 98 99 M.sub.w/M.sub.n 1.06 1.19 1.06 1.11 %
coupling 2.1 32.2 2.3 3.4 T.sub.g (.degree. C.) -38.5 -39.0 -39.0
-39.0 Bound rubber (%) 11.0 38.5 37.6 39.4 18.8 33.6 27.7 27.7
171.degree. C. MDR t.sub.50 (min) 3.19 1.95 1.67 1.78 7.67 4.90
5.03 4.78 171.degree. C. MH - ML (kg-cm) 17.8 16.0 16.2 15.6 22.5
17.5 17.0 17.9 ML.sub.1+4 @ 130.degree. C. 23.3 46.1 37.1 37.1 61.7
95.0 92.9 94.0 300% modulus @ 23.degree. C. (MPa) 10.9 14.0 14.0
13.2 8.5 11.0 10.9 11.5 Tensile strength @ 23.degree. C. 16.9 20.8
19.3 19.8 (MPa) 13.1 16.0 16.5 16.4 Temp. sweep 0.degree. C. tan
.delta. 0.196 0.229 0.234 0.233 0.172 0.192 0.189 0.184 Temp. sweep
50.degree. C. tan .delta. 0.258 0.147 0.156 0.162 0.223 0.180 0.198
0.188 RDA 0.25-14% .DELTA.G' (MPa) 4.234 0.429 0.402 0.463 8.522
2.021 2.510 2.666 50.degree. C. RDA strain sweep 0.2546 0.1018
0.1050 0.1139 (5% strain) tan .delta. 0.2506 0.1612 0.1782 0.1712
50.degree. C. Dynastat tan .delta. 0.2437 0.1066 0.1100 0.1175
0.2136 0.1626 0.1742 0.1629
[0092] From the 50.degree. C. strain sweep data of Table 3, one can
see that styrene/butadiene interpolymers having imine functional
groups (Examples 7-9) can provide, compared to a control polymer,
significant reductions in tan .delta. (.about.55-60% for carbon
black only and .about.30-35% for carbon black plus silica
formulations, respectively). Comparing these results to those from
Table 2, one can see that the compound from which the carbonyl is
derived (DMF for Examples 2-5 and DMI for Examples 7-9) apparently
can have some effect on the hysteresis reduction provided by the
terminal functional group.
[0093] Turning to wet traction performance (as indicated by the tan
.delta. at 0.degree. C. data, where larger values correlate
generally to better wet traction), one can see that
styrene/butadiene interpolymers having imine functional groups
(Examples 7-9) can provide, compared to a control polymer, improved
performance. This is of particular benefit because improved
hysteresis often requires a sacrifice in wet traction
performance.
* * * * *