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CROSS-REFERENCE TO RELATED APPLICATIONS
This application is related to Ser. No. 205,400 entitled Process of Making
Saturated Hydroxylated Hydrocarbon Polymers and filed of even date.
BACKGROUND OF THE INVENTION
This application is directed to functionalized saturated liquid polymers
useful for the production of crosslinked elastomeric materials and to
compositions containing minor amounts thereof and to a process of making
them.
End terminated dihydroxypolybutadienes are known in the prior art. Such
polymers commercially available from Arco Specialty Chemicals are
unsaturated and contain a microstructure comprises of about 25% 1,2 and
about 75% 1,4 butadiene units. Similar polymers available from Colorado
Chemical Specialties' are unsaturated and contain at least 80%
1,2-structural units.
U.S. Pat. No. 4,518,753 discloses polymerization of 1,3-dienes to form
monofunctionally or difunctionally terminated polymers having enhanced
1,4-content.
SUMMARY OF THE INVENTION
This invention is directed to oxidatively stable elastomeric compositions
comprising saturated difunctional end-terminated liquid rubber polymers
having at least 25 weight percent of the molecular weight pendant to the
backbone and a number average molecular weight of from about 500 to
10,000, and to a process of making same. Accordingly, it is an object of
this invention to produce saturated end difunctional liquid polydiene
polymers having after saturation a degree of branching sufficient to
retain liquidity at low temperature. Hydrogenation of terminally
functional high-vinyl polybutadienes results in terminally functional
ethylene butene copolymers and hydrogenation of terminally functional 1,4
isoprene leads to terminally functional ethylene propylene copolymers.
DESCRIPTION OF THE SPECIFIC EMBODIMENTS
Any suitable polydiene may be used in this invention. Particularly
preferred are C.sub.4 to about C.sub.8 conjugated dienes and more
particularly, butadiene.
The molecular weight of the polydiene, e.g., polybutadiene, may vary from
about 500 to about 10,000 or more, depending on the specific intended
purpose of the polymer and preferably from about 1,000 to 10,000.
The polymers in accordance with the invention are useful for a variety of
purposes. The conjugated 1,3-dienes of the present invention will
preferably contain from 4 to 12, especially from 4 to 8, carbon atoms per
molecule. Examples of suitable compounds include but are not limited to
the following: 1,3-butadiene; isoprene; myrcene;
2,3-dimethyl-1,3-butadiene; 1,3-pentadiene;
2-methyl-3-ethyl-1,3-butadiene; 2-methyl-3-ethyl-1,3-pentadiene;
2-ethyl-1,3-pentadiene; 1,3-hexadiene; 2-methyl-1,3-hexadiene,
1,3-heptadiene; 3-methyl-1,3-heptadiene; 1,3-octadiene;
3-butyl-1,3-octadiene; 3,4-dimethyl-1,3-hexadiene;
3-n-propyl-1,3-pentadiene; 4,5-diethyl-1,3-octadiene;
phenyl-1,3-butadiene; 2,3-diethyl-1,3-butadiene;
2,3-di-n-propyl-1,3-butadiene and 2-methyl-3-isopropyl-1,3-butadiene.
Among the dialkylbutadienes, it is preferred that the alkyl groups contain
from 1 to 3 carbon atoms. Of the above monomers 1,3-butadiene, isoprene,
myrcene, 2,3-dimethyl-1,3-butadiene and 1,3-pentadiene are preferred, with
1,3-butadiene being particularly preferred. The conjugated dienes may be
polymerized alone, or in a mixture with each other to form copolymers. In
addition the above compositions may contain amounts of other anionically
polymerizable monomers such as styrene.
The liquid dicarboxy and liquid dihydroxy saturated hydrocarbon polymers
are useful as precursor materials for making polyurethanes, and the like.
They are also useful as caulking/sealant materials or cureable liquid
compositions and as additives in lubricants basestocks for various
purposes such as thickening agents, dispersants or VI improvers to provide
improved multigrade lubricating compositions. They are also useful as
compatibilizing agents in polymer blends.
The general method of preparation of the dicarboxy polydiene of this
invention consists of polymerization of the diene under anionic conditions
using a difunctional initiator. In the case of butadiene, an agent such as
tetrahydrofuran or tetramethylene diamine is used to increase the vinyl
content to .gtoreq.50%. Reaction of the resultant dianion with CO.sub.2
followed by neutralization results in the desired high-vinyl dicarboxy
polymer.
The dihydroxy polydienes are generally prepared as above, except that the
polymeric dianion is reacted with an epoxide such as ethylene oxide.
Neutralization produces a dihydroxy polymer.
Both the dicarboxy polydiene and the dihydroxy are thereafter hydrogenated
under standard conditions and in the presence of a suitable catalyst. Any
suitable hydrogenation catalyst may be used, but generally preferred are
noble metal catalysts such as platinum or palladium on activated carbon or
transition metals such as nickel on Kieselguhr.
The temperature of reaction may vary from about 50 to about 300.degree. C.,
preferably about 150.degree. C. for vrying periods of time, from about 12
to about 24 hours or more or less, depending on the specific reactants;
temperature and pressure. The pressure may vary from about 15 psig to
about 2500 psig.
The products in accordance with the invention may be crosslinked if so
desired to produce elastomeric materials by a variety of commonly known
methods such as with polyvalent metals, epoxides, and isocyanates, as
noted below. See for example, U.S. Pat. Nos. 2,876,207 and 2,875,917, and
Japan No. 7,247,313.
The following exemplary material is shown merely to illustrate this
invention, but not to limit it.
EXAMPLE 1
End-terminated, high-vinyl dihydroxy polybutadiene is prepared as follows:
Butadiene (27 grams) is added to a vessel or other suitable reaction zone
containing 300 milliliters of anhydrous tetrahydrofuran at -73.degree. C.
To this is added 2.7 milliliters of previously prepared THF solution of
sodium naphthalene (1.0 molar). The green-black color changes to a deep
red color. The reaction mixture is stirred and allowed to warm to
-20.degree. C. over two hours. To this stirred mixture is added 2.0 grams
(excess) of ethylene oxide. The dark red color immediately disappears. The
product is stirred for one (1) hour, and neutralized with diluted
hydrochloric acid.
EXAMPLE 2
High-vinyl-polybutadiene prepared as above or obtained through commercial
sources was hydrogenated as follows: The polybutadiene (85 grams, 1600 MW)
was dissolved in 150 millilters of cyclohexane. To this solution was added
20 millimeters of glacial acid and 1.00 gram of palladium on activated
carbon. The mixture was placed in a 300 cc autoclave and reduced with
hydrogen (500 psig) at 150.degree. C. for 21.5 hours. After cooling the
mixture was filtered, extracted with bicarbonate solution and water, dried
over Na.sub.2 SO.sub.4, filtered and the solvent was removed by
distillation. IR was consistent with double bond reduction. The olefinic
region was free of absorption indicating that the olefinic linkages had
been essentially completely saturated.
EXAMPLE 3
End dihydroxy polyisoprene is prepared in a manner similar to that of
polybutadiene in Example 1.
EXAMPLE 4
End dihydroxy saturated polyiosprene derived polymer is prepared by
hydrogenation under conditions and in a manner similar to Example 2.
The examples illustrate the preparation of the novel compounds of the
invention. No saturated end difunctional liquid rubbers derived from
high-vinyl (.gtoreq.50%) polybutadiene are known. The liquids of our
invention are also more stable to oxidation than current unsaturated
materials. They are readily cureable using known methods, e.g. hydroxy
polymers can be cured using titanates; urethanes can be made from hydroxy
saturated polybutadienes and polyisocyanates or epoxy cures can be
performed on the dicarboxy saturated polybutadienes. The dicarboxy
polymers are also curable with polyisocyanates and polyvalent metal salts.
Although the present invention has been described with preferred
embodiments, it is to be understood that modifications and variations may
be resorted to, without departing from the spirit and scope of this
invention, as those skilled in the art will readily understand. Such
modifications and variations are considered to be within the purview and
scope of the appended claims.
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