Organic compounds -- part of the class 532-570 series – Organic compounds – Fatty compounds having an acid moiety which contains the...
Reexamination Certificate
2000-01-24
2001-11-13
Carr, Deborah D. (Department: 1621)
Organic compounds -- part of the class 532-570 series
Organic compounds
Fatty compounds having an acid moiety which contains the...
C554S213000, C508S485000, C252S062200
Reexamination Certificate
active
06316649
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to esters of oleic acid estolides having saturated fatty acid and groups, and their use as biodegradable base stocks and lubricants.
2. Description of the Prior Art
Synthetic esters, such as polyol esters and adipates, low viscosity poly alpha olefins (PAO), such as PAO 2, vegetable oils, especially Canola oil and oleates are used industrially as biodegradable basestocks to formulate lubricants. Lubricants usually contain 80-100% wt. basestock and 0-20% wt. additives to tailor their viscometric properties, low temperature behavior, oxidative stability, corrosion protection, demulsibility and water rejection, friction coefficients, lubricities, wear protection, air release, color and other properties. Biodegradability cannot be improved by using additives.
In the recent prior art, a fair amount of attention has been given to estolides as having potential for base stocks and lubricants. An estolide is a unique oligomeric fatty acid that contains secondary ester linkages on the alkyl backbone of the molecule.
Estolides have typically been synthesized by the homopolymerization of castor oil fatty acids [Modak et al.,
JAOCS
42:428 (1965); Neissner et al.,
Fette Seifen Anstrichm
82:183 (1980)] or 12-hydroxystearic acid [Raynor et al.,
J. Chromatogr.
505:179 (1990); Delafield et al.,
J. Bacteriol.
90:1455 (1965) under thermal or acid catalyzed conditions. Yamaguchi et al., [Japanese Patent 213,387, (1990)] recently described a process for enzymatic production of estolides from hydroxy fatty acids (particularly ricinoleic acid) present in castor oil using lipase. Estolides derived from these sources are composed of esters at the 12 carbon of the fatty acids and have a residual hydroxyl group on the estolide backbone. In addition, the level of unsaturation in the produced egtolides (expressed through e.g. iodine value) is not significantly lower than that in raw materials, i.e., hydroxy fatty acids.
Erhan et al. [JAOCS, 70:461 (1993)], reported the production of estolides from unsaturated fatty acids using a high temperature and pressure condensation over clay catalysts. Conversion of the fatty acid double bond into an ester functionality is a strikingly different method than the hydroxy esterification process.
The parent application of Isbell et al., U.S. Ser. No. 09/191,907, now U.S. Pat. No. 6,018,063, issued Jan. 25, 2000, reported a novel class of estolide compounds derived from oleic acids and having superior properties for use as lubricant base stocks. These compounds are characterized by Formula I, infra, wherein the “capping” fatty acid moiety R
3
is typically oleic or stearic acid. Studies with these estolides revealed that the stearic acid has the effect of adversely raising the pour point of the lubricant; and, generally, the greater percentage of stearic acid as the capping moiety, the higher the pour point temperature.
SUMMARY OF THE INVENTION
We have now discovered a family of novel estolide compounds derived from oleic acids and certain saturated organic acids in the range of C-6 to C-14 which have unexpectedly low (superior) pour point temperatures. The discovery that estolides having acceptable pour point temperatures could be derived from an oleic/saturated fatty acid blend is particularly surprising from the previous findings of Isbell et al., U.S. Pat. No. 6,018,063. These estolide compounds are characterized by superior properties for use as lubricant base stocks. These estolides may also be used as lubricants without the need for fortifying additives normally required to improve the lubricating properties of base stocks.
The estolide esters of this invention are generally characterized by Formula I:
wherein x and y are each equal to 1 or greater than 1;
wherein x+y=10;
wherein n is 0, 1, or greater than 1;
wherein R is CHR
1
,R
2
;
wherein R
1
and R
2
are independently selected from
hydrogen and C-1 to C-36 hydrocarbon which may be
saturated or unsaturated, branched or straight chain,
and substituted or unsubstituted;
wherein R
3
is a residual fragment of oleic, myristic, lauric, decanoic, octanoic, or caproic acid; and wherein the predominant species of secondary ester linkage is at the 9 or 10 position; that is, wherein x=5 or 6 and y=5 or 4, respectively.
In accordance with this discovery, it is an object of this invention to provide novel estolide compounds having utility as lubricant base stocks and also as lubricants without the necessity for inclusion of conventional additives.
It is a further object of this invention to provide a family of estolides which are biodegradable and which have superior oxidative stability, low temperature and viscometric properties.
Other objects and advantages of this invention will become readily apparent from the ensuing description.
REFERENCES:
patent: 4428850 (1984-01-01), Zoleski et al.
patent: 4567037 (1986-01-01), Ciaudelli
patent: 4639369 (1987-01-01), Ciaudelli
patent: 5204375 (1993-04-01), Kusakawa et al.
patent: 5380894 (1995-01-01), Burg et al.
patent: 5658863 (1997-08-01), Duncan et al.
patent: 6018063 (2000-01-01), Isbell et al.
Terry A. Isbell et al. “Acid-Catalyzed Condensation of Oleic Acid into Estolides and Polyestolides”JAOCS, vol. 71, No. 2 (Feb. 1994) pp. 169-174.
Terry A. Isbell et al. “Characterization of Estolides Produced from the Acid-Catalyzed Condensation of Oleic Acid”JAOCS, vol. 71, No. 4 (Apr. 1994) pp. 379-383.
Selim M. Erhan et al. “Estolide Production With Modified Clay Catalysts and Process Conditions”JAOCS, vol. 74, No. 3 (1997) pp. 249-254.
Terry A. Isbell et al. “Optimization of the Sulfuric Acid-Catalyzed Estolide Synthesis from Oleic Acid”JAOCS, vol. 74 No. 4 (1997) pp. 473-476.
T. Kusakawa et al. “Biodegradable estolide-hindered alcohol ester composition for lubricating oil”, SciFindersearch on Mar. 20, 2000.
Cermak Steven C.
Isbell Terry A.
Carr Deborah D.
Fado John D.
Ribando Curtis P.
Silverstein M. Howard
The United States of America as represented by the Secretary of
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