Note: Descriptions are shown in the official language in which they were submitted.
1~5~52~L
B~CKGROUMD OF THE INVENTION
Field of the Invention
This invention relates to greases and more particularly, to
greases which contain a calcium or calcium~lead complex thickener.
Description of the Prior Art
Calcium soaps have been used for a long time as grease thickeners.
For example, J. I. Clower referred to the use of lime base greases in
"Lubricants and Lubrication", First Edition, McGraw-Hill, New York 1939,
page 68 et ~ The soaps are produced by the saponification of fatty
materials (naturally occurring triglyceride esters or the fatty acids
derived from the glycerides) with lime, as is conventional in the art.
The use of various complex soap thickeners such as the mixed calcium
salts and soaps is also known. For ex~mple,Boner in "Manufacture and
Application of Lubricating Greases", ~ieger, 1971 (reprint of 1954
edition), Chapter 16 refers extensively to such complex soap thickeners
and Liddy U.S. Patent No. 2,999,065 discloses the use of calcium complex
thickeners derived from low, intermediate and high molecular weight
acids. Schott U.S. Patent No. 2,898,297 describes a calcium complex
thickener which includes calcium soaps derived from nut oil acids.
The lubricating vehicle base stocks which have been used with
these thickeners have been naphthenic in nature. That is, the
hydrocarbons in the base stock have been predominantly alicyclic rather
than straight chain. These base stocks have been preferred because they
give a firm-bodied grease whereas paraffinic base stocks yield soft-
bodied greases with the same amount of a given soap thickener. Thus,
the naphthenic base stocks give a better yield of grease in relation
to the amount of thickener. Although it would be possible to use a
greater amount of thickener to produce a grease of given consistency
.,
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using a paraffinic base stock, the high cost of soap relative to
that of the oil has generally made this uneconomical. In addi-
tion the amount of soap necessary to produce a thick bodied base
with a paraffinic base, e.g. NLGI Grade 3, can lead to an un-
stable grease structure. Such a grease might soften during use
(as a result of which it might run out of the bearings in which
it was being used) or it might harden in use and block the bearing
completely.
U. S. Patent 3,705,853 to Fau et al describes the use of
~ 10 certain ethylene terpolymers as improvers in calcium and
; calcium/lead thickened greases.
SUMMARY OF THE INVENTION
I have now diseovered that firm bodied greases can be
made economically from paraffinie base stoeks. The thickeners
used in these greases may be ealcium complex or caleium/lead -
complex thickeners, although the former are preferred. In
addition to the lubricating vehiele base and the eomplex thick-
ener the greases contain a terpolymer improver and any other
additive desired, e.g. rust inhibitors, extreme-pressure agents
and antioxidants.
According ts the present invention I therefore provide
a grease composition comprising (i) a pr~dominantly paraffinie
lubricating vehiele, (ii) a thickener comprising a ealcium or
ealeium/lead complex and (iii~ an organic terpolymer improver.
More particularly, the present invention in one aspect
- resides in a lubricating grease eomprising (i) a predominantly
paraffinic nineral oil lubrieating vehicle/ (ii~ a thickener cc~prising a
~lcium or calcium/lead ~ plex soap and (iii) from O.Ol to 10 weight percent
of an organic te ~ lymer improver having a melt index of from 0.5 to 200 and
~0 (1) at least 65% by weight, of ethylene, (2) at least 5% by weight, of a
se ~ d, ethylenically unsaturated monomer which is an ester of the group
~nsisting of: the ~nyl esters of saturated aliphatie earboxy~e aci~
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having 1-6 carbons; the alkyl acrylates, the alkyl methacrylates,
the dialkyl maleates and the dialkyl fumarates of aliphatic
alcohols having 1-6 carbons; and (3) 0.01 to 3% by weight, of a
third ethylenically unsaturated monomer of the group consisting
of: acrylic, methacrylic, itaconic, maleic, and fumaric acids;
:` the anhydrides of itaconic, maleic and fumaric acids; the alkyl
hydrogen maleates and the alkyl hydrogen fumarates; the mono-
acrylates and monomethacrylates of glycols; 2-hydroxy-3-amino-
propyl allyl ether, allyl glycerol ether, divinyl glycol, 2-
dimethylaminomethyl acrylate, 2-dimethylaminoethyl methacrylate
and N-vinyl pyrrolidone.
In another aspect the present invention resides in a
method for improving grease formation, in a process for manu-
facturing a calcium complex grease in which there is incorporated : ~ -
an ethylene-vinyl ester-organic acid terpolymer as an improving
agent, which method comprises introducing said terpolymer to the . ~
charge of lubricating vehicle and thickening agent components ~.
prior to saponification.
DESCRIPTION OF SPECIFIC EMBODIMENTS
As stated above, the grease has three essential compo-
nents, namely, the paraffinic lubricating vehicle, the thickener
and the terpolymer. These will be discussed ~eparately below.
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Lubricating Vehicle
This is predominantly a paraffinic lubricating stock At
least 30%, generally at least 50% and preferably at least 80% by weight
is a paraffinic lubricating oil. The balance of the lubricating
vehicle may be a naphthenic lubrlcant but since these stocks are
more expensive than paraffinic stocks, their use is economically un-
favorable particularly since the present invention enables the greases
to be produced wholly fron the paraffinic stocks, i.e. the lubricant
vehicle is entirely a paraffinic stock. If their use is desired fQr
any particular purposes, asphaltic stocks may be used in combination
with the paraffinic. As will be explained below, however, it is desirable
to use the paraffinic stock during the saponifications and to add the
other stocks later.
If desired, non mineral oil lubricating vehicles may be blended
` with the paraffinic oil. This may be desirable if particular
properties are desired in the final grease. Suitable synthetic lubricating
vehicles which may be included are, for example, synthetic ester lubricants,
e.g. the dibasic acid esters such as di-ethylhexyl azelate or sebacate,
the hlndered polyol esters such as the neopentyl glycol esters, e.g. the
' 20 trimethylol propane and pentaerythritol esters of C6 to C10 monocarboxylic
acids; synthetic hydrocarbons such as the hydrogenated olefin polymers
desoribed in U.S. Patent NoO 3,149,178 to Lyle A. Hamilton et al. Mixtures
of three or more lubricating vehicles may also be used, although the
paraffinic mineral;oil should normally comprise at least 50% by weight of
t~e lubricating vehicle in the grease.
me paraffinic stocks used in the greases will generally have a `-
viscosity of from 40 to 10,000 SUS at 100F., preferably 60 to 6000 SUS
at 100F. t4 to 2000 cS at 38C, preferably 10 to 1200 cS at 38C). If a
.
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52~
minor amount of a naphthenic mineral oil is blended with the paraffinic,
it too will generally have a viscosity in this range. In both cases,
viscosity indexes from 30 to 100 are preferred.
The paraffinlc base stocks will normally be acid-treated, solvent-
refined or hydrofinished paraffinlc oils. The various treatments to
which the oils may be subjected are intended to remove the less paraffinic
constikuents and~ by so doing, to raise the viscosity index. For example,
solvent-refining removes the less paraffinic constituents and hydrofinishing
converts the non-paraffinics to paraffinics, acid reacts with the non-
paraffinics and enables them to be removed.
Thickening Agent
Both calcium complex and calcium~lead complex thickeners may be
used, although the former are preferred. Both types of thickener are
derived from a mixture of acids and the thickeners are conveniently
characterized by a description of the acids used to form the salt/soap
mixtures. Since these complex thickeners invarlably contain acetate salts~
they are o~ten referred to as calcium and calcium~lead acetate complex
thickeners.
.:
he acids preferably comprise a complex mixture of low, inter-
~ 20 mediate and hi~h molecular weight carboxylic aclds. The molecular weights
i (carbon atom content) of the acids and the proportions in which they are
i .
used are as follows:
No. of Wt. Percent of total acids
Acid aton~s Broad _ Preferred
Low Mol. Wt. 1-6 10-60 20-45
Inter. Mol. Wt. 7-12 10-80 25-50
High Mol. Wt. 13 or more 2-75 15-50
Acetic acid is the preferred low molecular weight carboxylic acid and
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~5~524
caprylic is a preferred intermediate wei~ht carboxylic acid. As it has an
even number of carbon atoms it is conveniently available from natural
sources. Naturally occurring oils are convenient sources for the high
molecular weight carboxylic acids (normally C13-C36 although hi~her molecular
wei~ht materials may be present). Coconut oil is a convenient source of
C12-C15 acids and tallow a convenient source of Clg acids. Hydrogenated
tallow (C18) acids are preferred. Candelilla wax is a source of higher
(C20+) acids.
Preferred complex acid mixtures of this type are as follows (weight
~10 percent of total acids):
BroadPre~erred
Acetic Acid 20-30~4~ 25
~ Caprylic Acid 15-20~u~ 17
`' Coconut oll aclds 40-45~ ~ 43
Tallow acids 10-20 ~ 15
me tallcw acids are preferably hydrogenated to reduce resldual unsaturation.
Another preferred type of calcium or calcium/lead complex salt/soap
mixture ls that which is derived ~rcm a number of high molecular weight
carboxylic acids and also has a low molecular weight carboxylic acid.
Preferably a saturated and an unsaturated acid are present ln order to obtain
' satisfactory consistency in the grease. Such mixtures are made up as follows
;~ (wei~ht percent):
Broad Preferred
Hi~h molecular wt. acids (Cl ~) 7~-90 80-90
~25 Low molecular wt. aclds (C i ~) 10-30 10-20
m e high molecular weight acids are preferably a blend o~ C18 unsaturated
carboxylic aclds7 e.g. oleic acid, C18 saturated carboxylic acids~ e.g.
hydrogenated tallow acids and higher (C20t) carboxylic acids. Ihe pre~erred
~ low n~lecular weight acid is acetic acid. m e prererred ranges ~or the high
,30 molecular welght aclds are as follows (weight percent o~ t~tal aclds):
~road Preferred
Unsaturated C18 aclds 3~-40 30~40
Satur~at~d Clg aclds 30-90 30-50
Acids 10-30 10-20
~s~
Another type of co~plex thickener is that biased on a mixture of low and
intermediate molecular weight acids, for example, a mixture of acetic
acid with capric or caprylic acid. In these complexes, the ratio of
low molecular weight acid to intermediate molecular weight acid is
preferably from 0.25:1 to 10:1.
me acids are converted to their respective salts and soaps
by reaction with lime (in the case Or calcium thickened greases) or
lime/lith3rge (PbO) (in the case Or calc~um/lead thickened greases).
; The ratio of line to litharge for the mixed base greases is preferably
at least 5:1 (CaO:PbO) more preferably at least 10:1.
O Calcium complex and calcium/lead complex thickeners Or these
types are described in U.S. Patent Nos. 3,170,878, 2,999,065, 2,197,263,
2,898,297 and 2,878,187,
i
Terpolymer
~.5 The terpolymers used in the present greases are those described
.:, in U. S~ Patent No. 3,705,853 to Fau et al.
. That is, the terpolymers have a melt index of 0.5 to 200
and contain:
(1) at least 65%, by weight, of ethylene, (2) at least 5%, by
~0 weight, o~ a second ethylenically unsaturated monomer which is an ester
of the group consisting of the vinyl esters o~ the lower (1-6 carbon)
saturated al1phatl~- carboxylic acids, the alkyl acrylates, the aIkyl
methacrylates, the dialkyl naleates and the dialkyl ~umarates of the
;~ lower (1-6 carbon) aliphatic alcohols; and ~3) 0.01 to 3Z, by weight, of
.;: :
~5 a third ethylenically unsaturated monomer Or the group conslsting of
acrylic, methacrylic, itaconlc, maleic and fumarlc acids; the anhydrldes ;~
Or ltaconi~, maleic and rumaric aclds; the alkyl hydrogen maleates and
the alkyl hydrogen ~umarates; the m~noacrylates and monomethacrylates
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of glycols, 2-hydro~y-3-amino-propyl allyl ether, allyl glycerol ether,
divinyl glycol, 2-dimethylaminoethyl acrylate, 2-dimethylaminoethyl
methacrylate and N-vinyl pyrrolidone
The preparation of these terpolymer improving agents is described
in U.S. Patent 3,215,657, issued November 2, 1965.
e preferred terpolymers contain from about 20 to about 30%, by
weight, of the group (2) component, i.e. the second ethylenically un-
saturated monomer component, and from about 0.1 to about 1%, by weight, of
the group (3) component, i.e. the third çthylenically unsaturated monomer
com~onent. Representative preferred terpolymers comprise, in addition to
ethylene, from about 20 to about 30%, by weight, vinyl acetate and from
` about 0.1 to about 1%, by weight, acrylic acid; from about 20 to about 30%,
- by weight, vinyl acetate and from about 0.1 to about 1%, by weight, meth-
; crylic acid; from about 20 to about 30~, by weight, ethyl acrylate and
l 15 from about 0.1 to about 1%, by weight, acrylic acid; from about 20 to
J about 30%, by weight, ethyl acryla~e and from about 0.1 to about 1~, by
weight methacrylic acid; from about 20 to about 30%, by weight, methyl
methacrylate, and from about 0.1 to about 1%, by weight, acrylic acid;
and from about 20 to about 30%, by weight, methyl methacrylate and from
about 0.1 to about 1%, by weight, methacrylic acid.
e most preferred terpolymers comprise (i) at least 65 wt.
~- percent of ethylene, (ii) 20-30 wt. percent of vinyl acetate and ~iii)
- 0.01 to 3 wt. percent of an unsaturated acid or anhydride, preferably
methacrylic acid. A particularly preferred terpo~ner comprises 71.8 wt.
percent ethylene, 25 wt. percent vinyl acetate and about 0.71 wt. percent
methacrylic acid.
~; The terpolymer is essential to produce the desired consistency
and stability in the finished grease. In addition, it also improves
;~ the water wash-out resistance and the resistance to softening at high
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temperatures. The greases of the present invention are therefore
characterized by hav~ng a heavier consistency than they would have in
the absence of the terpolymer (if the grease is otherwise identical).
Proportions
The proportion of thickener relative to the oil depends, of
course, on the consistency required in the finished grease. Although
experience in the past indicated that predominantly paraffin base stocks
produced greases w~ich were not as firm as those produced from naphthenic
base stocks (Boner, op cit pp. 384,~511), I have found that paraffinic
stocks produce a grease which is ~ust as firm as that produced from
naphthenic stocks with the same amount Or a given thickener. mus, the
greases are characterized by a content of predominantly paraffinic
lubricating oil which is not substanti.ally less than that of a naphthenic
base oil required in a grease of substantially the same consistency.
, 15 The amount of thickener will, as stated above, be determined
by the grade (firmness) of the grease. Consistency is normally measured
. ` .
by the ASTM D 217-68 Test (Cone Penetration of Lubricating Grease) in the
case of firm~bodied greases and by the Brookf~eld viscosity for semi-
fluid greases.
The National Lubricating Grease Instikute has classified greases
according to their consistency as measured by the worked penetration.
Penetration values for the NLGI grades are as follows:
, ~ NI~7I Grade ASTM D 217-68 (worked9 60 strokes)
1 3 220-250
`~ 25 2 265-295
1 310-340
- o 355-385
:~ 00 . 400-430
: 000 445-475
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ese classifications are arbitrary; it is, of course, possible
to produce greases with consistencies intermediake the ranges listed.
The amount of thickener needed in a grease may be calculated
by reference to the amount of saponifiable fatty material. m is is used
as the basis for all such calculations in this specification.
The approximate amounts of thickener used for greases of various
consistencies are shown in Table 1 below.
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The figures given in Table 1 above are for a hom!ogenized grease
with a calcium complex thickener derived fram a mixture Or low, inter-
mediate and high molecular weight fatty acids (approx~mately 25% acetic
acid3 18% cap~ylic acid, 14g high molecular weight acids, 42% coconut
oil acids).
If the grease is not homogenized (as in the case with ropey-
textured greases~ greater contents of thickener may be desired. For
example, an NLGI Grade 0 grease of this type would contain approx~mately
7 to 15% thickener and a No. 1 Gl~de approximately 10 to 20%. The
~) figures given above are with reference to the NLGI grades. As previously
mentioned, it is possible, of course, to produce greases of any desired ~ :
cons~stency by varying the amount of thickener in the approprlate
1 manner. For example a grease of the type referred to in Table 1 could
have a penetration ~lgure of 240-270 at a n~xninal thickener content o~
11% o
The consistency wlll also vary with the exact type of complex
~ thickener used since each di~erent complex thickener system w~ll vary
i ~n lts thickening power.
- qhe amount of the terpolymer is fron 0.01 to 10 wt. percent,
~) - usually 0.1 to 5%. T!he additives will be present in their normal 2mounts.
Preparation_
The greases are prepared by the method described in my U. S. Patent
. . .
;~ No. 3,904,534, issued September 9, 1975. That is, the terpolymer is
` introduced into the charge of lubricating vehicle and thicke ~ agent
i; component~ prior to saponi~ication. In a typical procedure, the fatty
~j materials whlch are to form the thickener are charged to a contactor
together with the terpolymer, llme (or lime and litharge~, water and oil.
Ihe charge in the cGntactor is then heated to saponify the fatty ma~erial
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and so form the complex thickener. The grease is then partly dehydrated.
After saponification has proceeded to the desired extent, the partly
dehydrated charge is transferred to the finishing kettle where the
dehydration is completed. Cooling, addition of various additives,
homogenization and final additions of lubrieating vehicle eomplete the
procedure.
If a second type of lubricating vehicle is used (in addition
to the paraffinie mineral oil stoek), it is added to the grease after
dehydration. The paraffinie stoek is always present in the eharge to
the eontaetor beeause the effeet of the terpolymer on the grease is mueh
more marked when the paraffinie stock is added at this stage. Thus, if
a mixed paraffinic/asphaltie grease is to be prepared, the saponifieation
will be earried out with the paraffinic base stoek and the asphaltie
lubrieating stoek will be added after dehydration, when the grease is
brought to its final desired consistency. The viscosity of the paraffinic
base stock which is in the charge to the contactor will be in the range
of 40 to 2000 SUS at 100F, generally in the range of 60 to 1,000 SUS
at 100F (4 to 420 cS at 38C, generally 10 to 220 cS at 38C).
~, .
The greases produced in this way are thicker in consistency
than the greases produced by adding the terpolymer to the finishing -~
-~ kettle with an otherwise identical grease.
The additives which may be present in the greases may be added
at any convenient stage. Suitable additives include rust inhibitors
such as sodium nitrite, antioxidants sueh as alkylated phenolies, aromatie
amines such as p~p'-dioctyl-diphenylamine and extreme pressure agents such
as ehlorinated hydroearbons. Coloring materials may also be used, if
desired.
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Examples
The following Examples are given by way of lllustration only.
The grease-maklng technique employed in the Examples below involves
charging a contactor with appropriate amounts of fatty saponifiable
materlal, lime~ litharge, water and base oil. After saponification, the
soap base is discharged to a finishing kettle. In some Examples the
terpolymer was added at this point whereas in other Examples it constituted
a part of the original charge to the contactor. In the former cases
dehydration of the soap base is concurrent with dlspersion of the terpolymer.
Cooling, addition of various additives, homogeni~ation and final addition
of oil, campflete the manufacture.
e terpolymer employed in the Examples had a melt index of
about 6 and contained about 71.8%, by weif~ht, ethylene, about 25%, by
` weiff~ht, vinyl acetate and about 0.71%, by weight, methacrylic acid. The
amount of terpolymer was approximately 0.5 wt.% of the total grease.
The base oils employed in Examples 1 to 6 were either a 500 SUS
(100 cS) solvent-refined parafflnic neutral oil, with a V.I. of 60 or
300 SUS (70 cS~) solvent-refined paraffinic neutral oil havin~ a V.I. o~
90. The base oils employed in Examples 7-12 were either a 900 SUS (200 cS)
solvenjt-refined naphtnenic neutral oil having a V.I. of 65 or a 300 SUS
(70 c~) solvent paraf~inic neutral oil having a V.I. of 90.
The thickener was either a calcium or calcium/lead acetate
, :
ca~olex derived from a mixture of low, intermediate and high molecular
wel~ht fatty acids of the type referred to in Table 1 above. The amount
of thickener used is shown with reference to the amount of saponifiable
` fatty material.
The results are shown in Tables 2 f~nd 3 below.
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~`_ N cr, O t--~0 cr 2 ~ ~ ~ 2
~r~ 3 (`f) N ~ ~ (~) N ~ N N (r~ ~r) N
C~ ~) N N ~) ~Y) N N N N N N N
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As will be apparent from Tables 2 and 3, higher amounts of
fatty material or softer consistency results are encountered in the
finished grease ~Ihere the terpolymer is either absent, or introduced into
the finished grease contrasted with the presence of smaller amounts of
i fatty material or firmer consistency results when the terpolymer is
introduced in the charge to the contactor.
The effect of the terpolymer improver was investigated further
by preparing two greases of similar consistencies, one with terpolymer
and the other without. A solvent-refined paraffinic base stock of 300
) SUS at 100F (70 cS at 38C) ~iscosity and 90 V.I. was used. The finished
grease was tested in the extended working test (ASTM D 217-68,/Q000 strokes)
and the High Temperature Churn Test both with and without water. m e High
Temperature Churn Test is a modified RIV Test, a simulated rotatin~ ball
bearing test. m e RIV Test is described in NLGI Spokesman, April 1955,
pp. 38-43. This te~t is modifled by operation at a higher tem~erature,
93C, at 300 rpm. The test apparatus is modified by the use of a l~eavier
he~d to retain the ~.~ter ~hich is mixed ~rith the grease in the boql during
the part of the test in which ~ater is added.
The results are shown in Table 4 below.
Table 4
Ex~mple No. 13 14
Poly~.er amount, ~.% 0.5 ~one
Fatty ~aterial, wt.% 14.0 15.7
Penetration, worked 60X 204 212
j Penetration change
i a~er lO,OOOX, % 60 78
Penetr~tion chan~e after
Churn Te6t at 9~C, % 10 ` 112
Penetr~t,ion ch~nge after
3 ~u m Test ~ith water
at 93ac, % 114 132
.
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These results show that the yield is better and that the
~ grease has better work stability, as shown by the Extended Working Test
; and the High Temperature Churn Test, and that it also has better
stability in the presence of wAter at higher temperatures.
The invention has been described with re~erence ko specific
working embqdiments. It is not limited to those embodiments.
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