Note: Descriptions are shown in the official language in which they were submitted.
STEEL MILL GREASE
BACKGROUND OF THE INVENTION
This invention pertains to lubricants and, more par-
ticularly, to a grease for lubrication in steel mills,
especially lubrication of hot steel slab casters.
In steel mills, hot molten steel is formed into slabs
in a hot steel slab caster. In slab casters, molten steel
enters a formation chamber. One or more steel slabs
emerge from the formation chamber with a thin skin of sol-
idified steel holding them together. The steel emerging
from the formation chamber can be in the form of a series
of discrete slabs or, alternatively, as one unbroken slab
which is cut into discrete slabs at the far end of the
slab caster. This latter process is characteristic of the
more modern facilities and is usually referred to as a
continuous caster. Steel slabs can vary in width and
thickness depending on the particular steel mill, but a
standard width for a single strand of steel on a contin-
uous caster is about six feet with a thickness of 9-12
inches. Steel slabs. once cut, are typically about 25
feet long.
In order to convey the steel slab from the formation
chamber, the slab is supported by a series of rotatable
caster rollers. Each of these caster rollers has a bush-
ing or bearing, usually a tapered roller bearing, at each
end which allows the caster roller to turn. The line or
lines of caster rollers in steel mills can be as long as
three miles with a caster roller every two feet. Such a
line or lines can use three million pounds of grease per
... , ~01~924
year. Because the caster rollers are not much wider than
the steel slab it supports, the steel slab typically comes
within only a very few inches of the bearings. The bear-
ings and grease used to lubricate those bearings experi-
ence very high thermal stress, with the steel slab surface
often irradiating at temperatures of 1,500F to 2,000F.
Also, steel slabs exert a large force on e~ch caster
roller due to the heavy weight of the slabs causing high
loading pressures on the bearings and bearing grease.
High performance greases are important to minimize
failure of the caster bearings. Such bearing failures
will cause the caster to stop rotating under the progress-
ing steel slab. If this occurs, the dragging force
between the slab surface and the nonrotating caster roller
can rupture the slab skin causing a breakout which can
endanger operating personnel, damage property and inter-
rupt steel mill operations and production.
For example, when the hot steel slab moves along the
series of caster rollers, the slab is quickly quenched and
cooled to strengthen and thicken the solid skin of the
slab. If quenching is not done properly, the tenuous skin
can rupture causing molten steel to flow out onto the
caster rollers, bearing housings, and eventually the plant
floor. Such an occurrence (breakout) is very costly in
terms of plant downtime and maintenance cost. To minimize
breakouts, rapid quenching, cooling and strengthening of
the skin is accomplished by high velocity water spray from
all directions. The spray velocity can be as high as
1,000 gallons per minute. With such water spray force,
even well sealed bearings will not totally exclude water.
Therefore, the bearing grease will experience water con-
tamination with a physical force that tends to wash
(flush) the grease out of the bearings.
Another problem associated with conventional steel
mill greases which is becoming of great concern is the
increasing number and intensity of grease fires. Grease
Z~
fires can occur from hot molten metal, from acetylene
torches during periodic maintenance, and from other
sources of ignition. Grease fires can be costly in terms
of loss of equipment, operational downtime, and loss of
life. It is highly desirable to have a high performance
steel mill grease which also reduces the occurrence of
grease fires.
Once formed and sufficiently cooled, steel slabs can
be fabricated into other more commercially useful forms in
process mills, such as hot strip mills, cold strip mills,
billet mills, plate mills, and rod mills. Although the
lubricant environment for process mills are not as severe
as slab casters, grease specifications are quite stringent
because of the high operating temperature and extreme
pressure, antiwear requirements. Grease mills which
purify, form, and process other metals such as aluminum
encounter many similar problems as steel mill greases.
Preferably, the grease used to lubricate the bearings
of hot slab casters should: (a) reduce wear and friction;
(b) prevent rusting even in presence of water sprays;
(c) be passive, non-corrosive, and unreactive with the
bearing material; (d) resist being displaced by high
velocity water sprays; and (e) maintain the integrity of
its chemical composition and resulting performance proper-
ties under operating conditions near thermal sources which
irradiate at temperatures of 1,500~F to 2,000F.
In order to enhance the safety, health, and welfare
of operating personnel, greases used in steel mills should
be non-toxic, reduce the incidence of grease fires, and be
of a safe composition. Materials known to be serious skin
irritants, carcenogenic, and mutogenic should be av.oided
in steel mill greases.
Grease used to lubricate tapered roller bearings of
slab casters and process mills in steel mills should
desirably have good adherence properties as well as resist
displacement by water spray. The grease should retain
Z~lQ9,~4
these properties during use without exhibiting any adverse
effects such as lacquer deposition on the tapered roller
bearing parts due to high temperature oxidation, thermal
breakdown, and polymerization of the lubricating grease.
Such lacquering problems have been a common occurrence in
hot slab casters especially where aluminum complex and
lithium complex thickened greases have been used. When
such lacquering becomes severe enough, the results are
similar to rusting: the caster bearing fails and a break-
out can occur.
Since hot slab caster bearing grease may be used in
other applications in the steel mill, additional proper-
ties such as good elastomer compatibility and protection
against other types of wear such as fretting wear is
desirable. Also, many steel manufacturers prefer a grease
which would work well in slab casters and in process
mills, thereby allowing a multi-use consolidation of
lubricants and a reduction in lubricant inventory.
Over the years, a variety of greases and processes
have been suggested for use in steel mills and other
applications. Typifying such greases and processes are
those found in U.S. Patent Nos. 2,964,475, 2,967,151,
3,344,065, 3,843,528, 3,846,314, 3,920,571, 4,107,058,
4,305,831, 4,431,552, 4,440,658, 4,514,312, and Re.
31,611. These prior art greases and processes have met
with varying degrees of success. None of these prior art
greases and processes, however, have been successful in
simultaneously providing all the above stated properties
at the high performance levels required in steel mills.
It is, therefore, desirable to provide an improved
steel mill grease which overcomes many, if not all, of the
preceding problems.
SUMMARY OF THE INVENT ION
An improved high performance lubricating grease is
provided which is particularly useful to lubricate caster
20~4
--5
bearings in hot slab casters and process mills, especially
of the type used in steel mills. This novel grease compo-
sition exhibited surprisingly good results over prior art
grease compositions.
Desirably, the new grease provides superior wear pro-
tection under low loads as well as under high loads. The
new grease also reduces friction and prevents rusting
under prolonged wet conditions. Desirably, the novel
grease is substantially nonreactive, non-corrosive, and
passive to ferrous and nonferrous metals at ambient and
metal processing temperatures, resists displacement by
water spray, and minimizes water contamination. The
grease also retains its chemical composition for extended
periods of time under operating conditions.
Advantageously, the novel grease produced unexpect-
edly good results and achieved unprecedented levels of
high performance during extensive testing on hot steel
slab casters by a major U.S. steel producer. Signif-
icantly, during the tests water contamination levels inthe caster bearings and rotatable caster rollers were
reduced by about 90~ with the novel grease, thereby virtu-
ally eliminating wear, rust, and corrosion in the bearings
of the slab casters. Also, breakouts on the casting line
were prevented and downtime was significantly decreased
with the subject grease.
Another significant benefit of the subject steel mill
grease is that it decreases the amount of grease used
(grease consumption) by over 80% in comparison to the
amount of conventional steel mill greases previously used.
Desirably, the novel grease performs well at high
temperatures and over long periods of time. The grease
also exhibits excellent stability, superior wear pre-
vention qualities, and good oil separation properties even
at high temperatures. Furthermore, the grease is econom-
ical to manufacture and can be produced in large quanti-
ties.
20~
--6--
In use, the improved lubricating grease is period-
ically and frequently injected into rotatable caster roll-
ers and particularly the tapered caster roller bearings of
slab casters in steel mills which are subject to extreme
thermal stresses by supporting the heavy loads of hot
steel slabs while being substantially continuously
quenched (sprayed) with water or some other liquid at high
pressure and velocities. The improved lubricating grease
can also be injected into the bearings and caster rollers
of process mills, such as hot strip mills, cold strip
mills, strip mills, billet mills, plate mills, and rod
mills, or other metal forming mills, such as aluminum
mills.
The improved lubricating grease has: (a) a substan-
tial proportion of a base oil, (b) a thickener, such as
polyurea, triurea, biurea or combinations thereof, (c) a
sufficient amount of an additive package to impart extreme
pressure antiwear properties to the grease, (d) a boron-
containing material to inhibit oil separation especially
at high temperatures, and (e) a sufficient amount of a
high temperature, non-corrosive, oxidatively stable ther-
mally stable, water-resistant, hydrophobic, adhesive-im-
parting polymeric additive in the absence of sulfur. The
polymeric additive cooperates and is compatible (non-in-
terfering) with the extreme pressure antiwear additive
package to minimize water contamination in the grease as
well as resist displacement by water spray while not
adversely affecting low temperature mobility properties of
the grease.
The polymeric additive can comprise: polyesters,
polyamides, polyurethanes, polyoxides, polyamines, polya-
crylamides, polyvinyl alcohol, ethylenç vinyl acetate, or
polyvinyl pyrrolidone, or copolymers, combinations, or
boronated analogs (compounds) of the preceding. Prefera-
bly, the polymeric additive comprises: olefins (polyalky-
lenes), such as polyethylene, polypropylene,
2 [9~0924
_ 7
polyisobutylene, ethylene propylene, and ethylene butyl-
ene; or olefin (polyalkylene) arylenes, such as ethylene
styrene and styrene isoprene; polyarylene such as poly-
styrene; or polymethacrylate.
In one form, the extreme pressure antiwear (wear-re-
sistant) additive package comprises tricalcium phosphate
in the absence of sulfur compounds, especially oil soluble
sulfur compounds. Tricalcium phosphate provides many
unexpected advantages over monocalcium phosphate and
dicalcium phosphate. For example, tricalcium phosphate is
~ water insoluble and will not be extracted from the grease
if contacted with water. Tricalcium phosphate is also
very nonreactive and non-corrosive to ferrous and nonfer-
rous metals even at very high temperatures. It is also
nonreactive and compatible with most if not all of the
elastomers in which lubricants may contact.
On the other hand, monocalcium phosphate and dical-
cium phosphate are water soluble. When water comes into
significant contact with monocalcium or dicalcium
phosphate, they have a tendency to leach, run, extract,
and washout of the grease. This destroys any significant
antiwear and extreme pressure qualities of the grease.
Monocalcium phosphate and dicalcium phosphate are also
protonated and have acidic hydrogen present which can at
high temperature adversely react and corrode ferrous and
nonferrous metals as well as degrade many elastomers.
In another form, the extreme pressure antiwear addi-
tive package comprises carbonates and phosphates together
in the absence of sulfur compounds including oil soluble
sulfur compounds and insoluble arylene sulfide polymers.
The carbonates and phosphates are of a Group 2a alkaline
earth metal, such as beryllium, magnesium, calcium, stron-
tium, and barium, or of a Group la alkali metal, such as
lithium, sodium, potassium, rubidium, cesium, and fran-
cium. Calcium carbonate and tricalcium phosphate are pre-
-8- ~ 924
ferred for best results because they are economical,
stable, nontoxic, water insoluble, and safe.
The use of both carbonates and phosphates in the
additive package produced unexpected surprisingly good
results over the use of greater amounts of either carbon-
ates alone or phosphates alone. For example, the use of
both carbonates and phosphates produced superior wear pro-
tection in comparison to a similar grease with a greater
amount of carbonates in the absence of phosphates, or a
similar grease with a greater amount of phosphates in the
absence of carbonates. Furthermore, the synergistic com-
bination of calcium carbonate and tricalcium phosphate can
reduce the total additive level over a single additive and
still maintain superior performance over a single addi-
tive.
Furthermore, the combination of the above carbonates
and phosphates in the absence of insoluble arylene sulfide
polymers achieved unexpected surprisingly good results
over that combination with insoluble arylene sulfide
polymers. It was found that applicant's combination
attained superior extreme pressure properties and antiwear
qualities as well as superior elastomer compatibility and
non-corrosivity to metals, while the addition of insoluble
arylene sulfide polymers caused abrasion, corroded copper,
degraded elastomers and seals, and significantly weakened
their tensile strength and elastomeric qualities. Insolu-
ble arylene sulfide polymers are also very expensive,
making their use in lubricants prohibitively costly.
The use of sulfur compounds, such as oil soluble sul-
fur-containing compounds, should generally be avoided in
the additive package of steel mill greases because they
are chemically very corrosive and detrimental to the metal
bearing surfaces at the high temperatures encountered in
hot slab casters. Oil soluble sulfur compounds often
destroy, degrade, or otherwise damage caster bearings by
high temperature reaction of the sulfur with the internal
2(~109Z4
bearing parts, thereby promoting wear, corrosion, and
ultimately failure of the bearings. Such bearing failures
can actually cause a breakout which can result in complete
shut-down of the hot slab caster. Oil soluble sulfur com-
pounds are also very incompatible with elastomers and will
typically destroy them at elevated temperatures.
While the novel lubricating grease is particularly
useful for steel mill and process mill lubrication, espe-
cially lubrication of caster bearings, it may also beadvantageously used in the constant velocity joints of
front-wheel or four-wheel drive cars. The grease may also
be used in universal joints and bearings which are sub-
jected to heavy shock loads, fretting, and oscillating
motions. It may also be used as the lubricant in sealed-
for-life automotive wheel bearings. Furthermore, the sub-
ject grease can also be used as a railroad track lubricant
on the sides of a railroad track.
As described herein, steel or other metal can be
formed, treated, fabricated, worked, or otherwise pro-
cessed in a steel mill or a process mill, such as a hot
strip mill, cold strip mill, billet mill, plate mill, or
rod mill, and conveyed on caster rollers with bearings.
In the preferred process, the described special high per-
formance grease is injected into and prevented from leak-
ing out of the bearings so as to lubricate and enhance the
longevity and useful life of the bearings. Desirably, the
bearings are protected against rust and corrosion at high
temperatures during casting, working, fabricating, and
other processing, as well as at lower and ambient temper-
atures. In the preferred process, this is accomplished by
the described special non-corrosive, oxidatively stable,
thermally stable, adhesive-imparting grease which also
hermetically seals the bearings, substantially eliminates
grease leakage and toxic emissions, and does not normally
irritate the skin or eyes of workers in the mill. Advan-
- 2~
--10--
tageously, substantially less grease is required, con-
sumed, and used with the described special grease.
In steel mills, molten steel is fed to a formation
chamber where it is formed into a hot steel slab and dis-
charged on a slab caster. The hot steel slab is conveyed
on caster rollers with tapered roller bearings. The hot
steel slab is quenched and cooled with a high velocity
water spray from above and below the caster rollers and
bearings. Advantageously, the special high performance
grease prevents the grease from being flushed and washed
out of the bearings.
The application also discloses a process for prevent-
ing grease fires, which is especially useful in steel
mills and other metal processing mills, such as strip
mills, billet mills, plate mills, and rod mills. In the
process, when a flame is ignited, such as from molten
steel or other hot metal or from acetylene torches, or
other welding equipment, and approaches near and contacts
the described special grease, which can be injected into
the caster bearings or rollers in a metal processing mill,
the special grease emits a sufficient amount of carbon
dioxide to blanket and extinguish the flame or otherwise
substantially prevent the grease from igniting, burning,
and combusting. In the preferred process, carbon dioxide
is emitted from thermal decomposition of calcium carbonate
in the grease.
As used in this application, the term "polymer" means
a molecule comprising one or more types of monomer-ic units
chemically bonded together to provide a molecule with at
least six total monomeric units. The monomeric units
incorporated within the polymer may or may not be the
same. If more than one type of monomer unit is present in
the polymer the resulting molecule may be also referred to
as a copolymer.
The term "bearing" as used in this application
includes bushings.
--1 1--
A more detailed explanation of the invention is pro-
vided in the following description and appended claims.
S DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
A high performance lubricating grease and process are
provided to effectively lubricate the caster bearings of
hot steel slab casters, hot strip mills, cold strip mills,
billet mills, plate mills, rod mills, and other process
units used in commercial steel mills. The novel steel
mill grease exhibits excellent extreme pressure (EP) prop-
erties and antiwear qualities, resists displacement by
water, prevents rusting even in a constant or prolonged
wet environment, and is economical, nontoxic, and safe.
Desirably, the steel mill grease is chemically inert to
steel even at the high temperatures which can be encount-
ered in hot steel slab casters.
Advantageously, the steel mill grease is chemically
compatible and substantially inert to the elastomers and
seals commonly used in other parts and operations common
to steel mills, thereby increasing its utility. Also, the
grease will not significantly corrode, deform, or degrade
silicon-based elastomers nor will it significantly
corrode, deform, or degrade silicone-based seals with min-
imal overbasing from calcium oxide or calcium hydroxide.Furthermore, the grease will not corrode, deform, or
degrade polyester and neoprene elastomers.
The preferred lubricating grease comprises by weight:
45% to 85% base oil, 6% to 16% polyurea thickener, 2% to
30% extreme pressure wear-resistant additives, 0.1% to 5%
boron-containing material for inhibiting oil separation,
and 1% to 10% of a high temperature non-corrosive, ther-
mally stable, oxidatively stable water-resistant, hydro-
phobic, adhesive-imparting, high performance polymeric
additive. The polymeric additive also promotes good low
temperature grease mobility for outside tank storage and
transportation. For best results, the steel mill lubri-
;~924
cating grease comprises by weight: at least 70% base oil,8~ to 14% polyurea thickener, 4% to 16~ extreme pressure
wear-resistant additives, 0.25% to 2.5% boron-containing
material for inhibiting oil separation, and 2~ to 6%
polymeric additives. The polymeric additives are compat-
ible (non-interfering) with the extreme pressure wear-re-
sistant additives so as to not adversely affect the
positive performance characteristics of the extreme pres-
sure wear-resistant additives.
Sulfide polymers, such as insoluble arylene sulfide
polymers, should be avoided in the grease because they:
(1) corrode copper, steel, and other metals, especially at
high temperatures, (2) degrade, deform, and corrode sili-
con seals, (3) significantly diminish the tensile strengthand elastomeric properties of many elastomers, (4) exhibit
inferior fretting wear, and (5) are abrasive.
Sulfur compounds, such as oil soluble sulfur com-
pounds, can be even more aggravating, troublesome, and
worse than oil insoluble sulfur compounds. Sulfur com-
pounds and especially oil soluble sulfur compounds should
be generally avoided in the grease because they are often
chemically incompatible and detrimental to silicone,
polyester, and other types of elastomers and seals. Oil
soluble sulfur compounds can destroy, degrade, deform,
chemically corrode, or otherwise damage elastomers and
seals by significantly diminishing their tensile strength
and elasticity.
Furthermore, oil soluble sulfur compounds are
extremely corrosive to copper, steel and other metals at
the very high temperatures experienced in steel mills.
Such chemical corrosivity is unacceptable in steel mills.
Generally, any sulfur-containing compounds should be
avoided in the additive composition of the steel mill
grease, especially the sulfurized hydrocarbons and orga-
nometallic sulfur salts. Sulfur compounds of the type to
be avoided in the grease include saturated and unsaturated
~Q~Q924
-13-
aliphatic as well as aromatic derivatives that have from 1
to 32 or 1 to 22 carbon atoms. Included in this group of
oil soluble sulfur compounds to be avoided in the grease
are alkyl sulfides and alkyl polysulfides, aromatic sul-
fides and aromatic polysulfides, e.g. benzyl sulfide and
dibenzyl disulfide, organometallic salts of sulfur con-
taining acids such as the metal neutralized salts of dial-
kyl dithiophosphoric acid, e.g. zinc dialkyl
dithiophosphate, as well as phosphosulfurized hydrocarbons
and sulfurized oils and fats. Sulfurized and phosphosul-
furized products of polyolefins are very detrimental and
should be avoided in the grease. A particularly detri-
mental group of sulfurized olefins or polyolefins are
those prepared from aliphatic or terpenic olefins having a
total of 10 to 32 carbon atoms in the molecule and such
materials are generally sulfurized such that they contain
from about 10 to about 60 weight percent sulfur.
The aliphatic olefins to be avoided in the grease
include mixed olefins such as cracked wax, cracked petro-
latum or sinqle olefins such as tridecene-2, octadecene-l,
eikosene-l as well as polymers of aliphatic olefins having
from 2 to 5 carbon atoms per monomer such as ethylene,
propylene, butylene, isobutylene and pentene.
The terpenic olefins to be avoided in the grease
include terpenes (CloH16), sesquiterpenes (C15H24) and
diterpenes (C20H32). Of the terpenes, the monocyclic ter-
penes having the general formula CloHl6 and their mono-
cyclic isomers are particularly detrimental.
Inhibitors
The additive package may be complemented by the addi-
tion of small amounts of an antioxidant and a corrosion
inhibiting agent, as well as dyes and pigments to impart a
desired color to the composition.
Antioxidants or oxidation inhibitors prevent varnish
and sludge formation and oxidation of metal parts. Typi-
Z0~0~2~
-14-
cal antioxidants are organic compounds containing nitro-
gen, such as organic amines, sulfides, hydroxy sulfides,
phenols, etc., alone or in combination with metals like
zinc, tin, or barium, as well as phenyl-alpha-naphthyl
amine, bis(alkylphenyl)amine, N,N - diphenyl-p-phenylene-
diamine, 2,2,4 - trimethyldihydroquinoline oligomer,
bis(4 - isopropylaminophenyl)-ether, N-acyl-p-aminophenol,
N - acylphenothiazines, N of ethylenediamine tetraacetic
acid, and alkylphenol-formaldehyde-amine polycondensates.
Corrosion inhibiting agents or anticorrodants prevent
rusting of iron by water, suppress attack by acidic
bodies, and form protective film over metal surfaces to
diminish corrosion of exposed metallic parts. A typical
corrosion inhibiting agent is an alkali metal nitrite,
such as sodium nitrite. Other ferrous corrosion inhibi-
tors include metal sulfonate salts, alkyl and aryl suc-
cinic acids, and alkyl and aryl succinate esters, amides,
and other related derivatives. Borated esters, amines,
ethers, and alcohols can also be used with varying success
to limit ferrous corrosion. Likewise, substituted amides,
imides, amidines, and imidazolines can be used to limit
ferrous corrosion. Other ferrous corrosion inhibitors
include certain salts of aromatic acids and polyaromatic
acids, such as zinc naphthenate.
Metal deactivators can also be added to further pre-
vent or diminish copper corrosion and counteract the
effects of metal on oxidation by forming catalytically
inactive compounds with soluble or insoluble metal ions.
Typical metal deactivators include mercaptobenzothiazole,
complex organic nitrogen, and amines. Although such metal
deactivators can be added to the grease, their presence is
not normally required due to the extreme nonreactive, non-
corrosive nature of the steel mill grease composition.
Stabilizers, tackiness agents, dropping-point
improvers, lubricating agents, color correctors, and/or
_ -15- ~Q~0~24
odor control agents can also be added to the additive
package.
Base Oil
The base oil can be naphthenic oil, paraffinic oil,
aromatic oil, or a synthetic oil such as a polyalphaolefin
polyolester, diester, polyalkyl ethers, polyaryl ethers,
silicone polymer fluids, or combinations thereof. The
viscosity of the base oil can range from 50 to 10,000 SUS
at 100F.
Other hydrocarbon oils can also be used, such as:
(a) oil derived from coal products, (b) alkylene polymers,
such as polymers of propylene, butylene, etc., (c) olefin
(alkylene) oxide-type polymers, such as olefin (alkylene)
oxide polymers prepared by polymerizing alkylene oxide
(e.g., propylene oxide polymers, etc., in the presence of
water or alcohols, e.g., ethyl alcohol), (d) carboxylic
acid esters, such as those which were prepared by esteri-
fying such carboxylic acids as adipic acid, azelaic acid,suberic acid, sebacic acid, alkenyl succinic acid, fumaric
acid, maleic acid, etc., with alcohols such as butyl alco-
hol, hexyl alcohol, 2-ethylhexyl alcohol, etc., (e) liquid
esters of acid of phosphorus, (f) alkyl benzenes,
(g) polyphenols such as biphenols and terphenols,
(h) alkyl biphenol ethers, and (i) polymers of silicon,
such as tetraethyl silicate, tetraisopropyl silicate,
tetra(4-methyl-2-tetraethyl) silicate, hexyl(4-methol-
2-pentoxy) disilicone, poly(methyl)siloxane, and
poly(methyl)phenylsiloxane.
The preferred base oil comprises about 60% by weight
of a refined solvent-extracted hydrogenated dewaxed base
oil, preferably 850 SUS oil, and about 40% by weight of
another refined solvent-extracted hydrogenated dewaxed
base oil, preferably 350 SUS oil, for better results.
~)92~
-16-
- Thickener
Polyurea thickeners are preferred over other types of
thickeners because they have high dropping points, typi-
cally 460F to 500F, or higher. Polyurea thickeners arealso advantageous because they have inherent antioxidant
characteristics, work well with other antioxidants, and
are compatible with all elastomers and seals.
The polyurea comprising the thickener can be prepared
in a pot, kettle, bin, or other vessel by reacting an
amine, such as a fatty amine, with diisocyanate, or a
polymerized diisocyanate, and water. Other amines can
also be used.
Biurea (diurea) may be used as a thickener, but it is
not as stable as polyurea and may shear and loose consist-
ency when pumped. If desired, triurea can also be
included with or used in lieu of polyurea or biurea.
Additives
In order to attain extreme pressure properties, anti-
wear qualities, and elastomeric compatibility, the addi-
tives in the additive package comprise tricalcium
phosphate and calcium carbonate in the absence of sulfur
compounds. Advantageously, the use of both calcium carbo-
nate and tricalcium phosphate in the additive package
adsorbs oil in a manner similar to polyurea and, there-
fore, less polyurea thickener is required to achieve the
desired grease consistency. Typically, the cost of tri-
calcium phosphate and calcium carbonate are much less than
polyurea and, therefore, the grease can be formulated at
lower costs.
Preferably, the tricalcium phosphate and the calcium
carbonate are each present in the additive package in an
amount ranging from 1% to 15% by weight of the grease.
For ease of handling and manufacture, the tricalcium
phosphate and calcium carbonate are each most preferably
ZQ~0924
_ -17-
present in the additive package in an amount ranging from
2% to 8% by weight of the grease.
Desirably, the maximum particle sizes of the trical-
S cium phosphate and the calcium carbonate are 100 micronsand the tricalcium phosphate and the calcium carbonate are
of food-grade quality to minimize abrasive contaminants
and promote homogenization. Calcium carbonate can be pro-
vided in dry solid form as CaCO3. Tricalcium phosphate
can be provided in dry solid form as Ca3(PO4)2 or
3Ca3(PO4)2 Ca(OH)2-
If desired, the calcium carbonate and/or tricalciumphosphate can be added, formed, or created in situ in the
grease as by-products of chemical reactions. For example,
calcium carbonate can be produced by bubbling carbon diox-
ide through calcium hydroxide in the grease. Tricalcium
phosphate can be produced by reacting phosphoric acid with
calcium oxide or calcium hydroxide in the grease. Other
methods for forming calcium carbonate and/or tricalcium
phosphate can also be used.
The preferred phosphate additive is tricalcium phosp-
hate for best results. While tricalcium phosphate is pre-
ferred, other phosphate additives can be used, if desired,
in conjunction with or in lieu of tricalcium phosphate,
such as the phosphates of a Group 2a alkaline earth metal,
such as beryllium, magnesium, calcium, strontium, and
barium, or the phosphates of a Group la alkali metal, such
as lithium, sodium, and potassium.
Desirably, tricalcium phosphate is less expensive,
less toxic, more readily available, safer, and more stable
than other phosphates. Tricalcium phosphate is also supe-
rior to monocalcium phosphate and dicalcium phosphate.
Tricalcium phosphate has unexpectedly been found to be
noncorrosive to metals and compatible with elastomers and
seals. Tricalcium phosphate is also water insoluble and
will not washout of the grease when contamination by water
occurs. Monocalcium phosphate and dicalcium phosphate,
2~10924
-18-
however, have acidic protons which at high temperatures
can corrosively attack metal surfaces such as found in the
caster bearings of hot steel slab casters. Monocalcium
phosphate and dicalcium phosphate were also found to cor-
rode, crack, and/or degrade some elastomers and seals.
Monocalcium phosphate and dicalcium phosphate were also
undesirably found to be water soluble and can washout of
the grease when the caster bearing is exposed to the con-
stant high velocity water spray of slab casters, whichwould significantly decrease the antiwear and extreme
pressure qualities of the grease.
The preferred carbonate additive is calcium carbonate
for best results. While calcium carbonate is preferred,
other carbonate additives can be used, if desired, in con-
junction with or in lieu of calcium carbonate, such as the
carbonates of Group 2a alkaline earth metal, such as
beryllium, magnesium, calcium, strontium, and barium.
Desirably, calcium carbonate is less expensive~, less
toxic, more readily available, safer, and more stable than
other carbonates. Calcium carbonate is also superior to
calcium bicarbonate. Calcium carbonate has been unexpect-
edly found to be non-corrosive to metals and compatible to
elastomers and seals. Calcium carbonate is also water
insoluble. Calcium bicarbonate, however, has an acidic
proton which at high temperatures can corrosively attack
metal surfaces such as found in the caster bearings of hot
steel slab casters. Also, calcium bicarbonate has been
found to corrode, crack, and/or degrade many elastomers
and seals. Calcium bicarbonate has also been undesirably
found to be water soluble and experiences many of the same
problems as monocalcium phosphate and dicalcium phosphate
discussed above. Also, calcium bicarbonate is disadvanta-
geous for another reason. During normal use, either the
base oil or antioxidant additives will undergo a certain
amount of oxidation. The end products of this oxidation
are invariably acidic. These acid oxidation products can
, ~1~2~
--19--
react with calcium bicarbonate to undesirably produce
gaseous carbon dioxide. If the grease is used in a moder-
ately sealed application such as slab caster bearings, the
calcium carbonate generated would build up pressure and
eventually weaken the seal in order to escape. Once~weak-
ened, the seal would be much less effective in minimizing
water contamination of the bearing.
The use of both tricalcium phosphate and calcium car-
bonate together in the extreme pressure antiwear (wear-re-
sistant) additive package of the steel mill grease was
found to produce unexpected superior results.
Borates
It was found that borates or boron-containing materi-
als such as borated amine, when used in polyurea greases
in the presence of calcium phosphates and calcium carbo-
nates, act as an oil separation inhibitor, which is espe-
cially useful at high temperatures, such as occurs in slab
casting and other operations in steel mills. This discov-
ery is also highly advantageous since oil separation, or
bleed, as to which it is sometimes referred, is a property
which needs to be minimized in steel mill greases.
Such useful borated additives and inhibitors include:
(l) borated amine, such as is sold under the brand name of
Lubrizol 5391 by the Lubrizol Corp., and (2) potassium
triborate, such as a microdispersion of potassium tribo-
rate in mineral oil sold under the brand name of OLOA 9750
by the Oronite Additive Division of Chevron Company.
Other useful borates include borates of Group la
alkali metals, borates of Group 2a alkaline earth metals,
stable borates of transition metals (elements), such as
zinc, copper, and tin, boric oxide, and combinations of
the above.
The steel mill grease contains 0.01% to 10%, prefera-
bly 0.1% to 5%, and most preferably 0.25% to 2.5%, by
weight borated material.
2~09~4
-20-
It was also found that borated inhibitors minimized
oil separation even when temperatures were increased from
210F to 300F or 350F. Advantageously, borated inhibi-
tors restrict oil separation over a wide temperaturerange. This is in direct contrast to the traditional oil
separation inhibitors, such as high molecular weight
polymer inhibitors such as that sold under the brand name
of Paratac by Exxon Chemical Company U.S.A. Traditional
polymeric additives often impart an undesirable stringy or
tacky texture to the lubricating grease because of the
extremely high viscosity and long length of their mole-
cules. As the temperature of the grease is raised, the
viscosity of the polymeric additive within the grease is
substantially reduced as is its tackiness. Tackiness
restricts oil bleed. As the tackiness is reduced, the
beneficial effect on oil separation is also reduced.
Borated amine additives do not suffer from this flaw since
their effectiveness does not depend on imparted tackiness.
Borated amines do not cause the lubricating grease to
become tacky and stringy. This is desirable since, in
many applications of lubricating greases, oil bleed should
be minimized while avoiding any tacky or stringy texture.
It is believed that borated amines chemically inter-
act with the tricalcium phosphate and/or calcium carbonate
in the grease. The resulting species then interacts with
the polyurea thickener system in the grease to form an
intricate, complex system which effectively binds the
lubricating oil.
Another benefit of borated oil separation inhibitors
and additives over conventional "tackifier" oil separation
additives is their substantially complete shear stability.
Conventional tackifier additives comprise high molecular
weight polymers with very long molecules. Under condi-
tions of shear used to physically process and mill
lubricating greases, these long molecules are highly prone
to being broken into much smaller fragments. The result-
~ -21- 2~09-24
ing fragmentary molecules are greatly reduced in their
ability to restrict oil separation. To avoid this prob-
lem, when conventional tackifiers are used to restrict oil
separation in lubricating greases, they are usually mixed
into the grease after the grease has been milled. This
requires an additional processing step in the lubricating
grease manufacturing procedure. Advantageously, borated
amines and other borated additives can be added to the
base grease with the other additives, before milling, and
their properties are not adversely affected by different
types of milling operations.
In contrast to conventional tackifiers, borated
amines can be pumped at ordinary ambient temperature into
manufacturing kettles from barrels or bulk storage tanks
without preheating.
Inorganic borate salts, such as potassium triborate,
provide an oil separation inhibiting effect similar to
borated amines when used in polyurea greases in which cal-
cium phosphate and calcium carbonate are also present. Itis believed that the physio-chemical reason for this oil
separation inhibiting effect is similar to that for
borated amines. The advantages of borated amines over
conventional tackifier additives are also applicable in
the case of inorganic borate salts.
Polymers
It has been unexpectedly and surprisingly found that
the polymeric additives comprising the polymers described
below, in the absence of sulfur and particularly in the
absence of organically bonded sulfur, when used in the
presence of and in combination and conjunction with the
above described tricalcium phosphate and calcium carbonate
extreme pressure wear-resistant additives and preferably
with the above described boron-containing material,
imparts requisite adhesive strength and water resistance
properties to the finished grease to substantially prevent
-22- 2~
the grease from running, bleeding, and being washed
(flushed) out of caster bearings and caster rollers of hot
slab casters in steel mills when the hot steel slab is
S substantially continuously quenched with high velocity,
high pressure water sprays. The polymers are thermally
stable and substantially minimize high temperature oxida-
tion, corrosion, thermal breakdown, detrimental polymeri-
zation of the grease, and lacquering (lacquer deposition)
of tapered roller bearing (caster bearings) in steel mills
and process mills from the heat, load, and stress of the
hot steel slabs. Advantageously, such polymers are hydro-
phobic and also extend the useful life of the grease and
decrease overall grease consumption in steel and process
mills. Polymers containing organically bonded sulfur
should be avoided due to their high temperature corrosive
nature.
It has also been unexpectedly found that the
preferred and most preferred polymers described below,
when used in the presence of and in combination and con-
junction with the described tricalcium phosphate and cal-
cium carbonate extreme pressure wear-resistant additives
and preferably the described boron-containing material, do
not adversely affect the low temperature mobility and pum-
pability properties of the finished steel mill grease.This is most surprising since polymers generally will
cause large adverse effects on the low temperature flow
properties of greases. Low temperature properties are
important for steel mills since bulk grease storage tanks
at steel mills are often outside and exposed to winter
temperatures.
Polymers which are applicable for use in steel mill
greases to attain the desired characteristics described
above desirably have molecular weights in the range from
about 1,000 to about 5,000,000 or more. Preferably, the
polymer molecular weight should be between 10,000 and
20~0924
-23-
1,000,000. For best results the polymer molecular weight
should be between 50,000 and 200,000.
Acceptable polymers for attaining many of the grease
characteristics described above include: polyolesters
(polyesters), polyamides, polyurethanes, polyoxides, pol-
yamines, polyacrylamide, polyvinyl alcohol, ethylene vinyl
acetate, and polyvinyl pyrrolidone. Copolymers with
monomeric units comprising the monomeric units of the pre-
ceding polymers and combinations thereof may also be used.Also, boronated polymers or boronated compounds comprising
the borated or boronated analogs of the preceding polymers
(i.e., any of the preceding polymers reacted with boric
acid, boric oxides, or boron inorganic oxygenated mate-
rial) may also be used when nucleophilic sites are avail-
able for boration.
For better results, the preferred polymer comprises:
polyolefins (polyalkylenes), such as polyethylene, poly-
propylene, polyisobutylene, ethylene propylene copolymers,
or ethylene butylene copolymers; or polyolefin (polyalky-
lene) arylene copolymers, such as ethylene styrene copo-
lymers and styrene isoprene copolymers. Polyarylene
polymers, such as polystyrene, also provide good results.
Most preferably for best results, the polymer should
be a methacrylate polymer or copolymer. Particularly
useful polymethacrylate polymers are those sold under the
trade name TC 9355 by Texaco Chemical Company as well as
those sold under the trade name HF-420 by Rohm and Haas
Company.
Grease Flammability
Grease properties (performance factors) which tend to
lessen the occurrence of grease fires in steel mills
include the following:
1. Reduction in the amount of grease used per unit
time, i.e., decrease in grease consumption.
zo~o9z~
-24-
2. Reduction in the amount of grease which leaks
past the bearing seals and out of the bearing
housings.
3. Ignition resistance.
The importance of the above performance factors is
explained as follows. If less grease is used over a given
time interval, less grease will be exposed to direct con-
tact of ignition sources. If the amount of grease leaking
- 10 out of the sealed bearings is reduced, this will also
reduce the fire potential. Furthermore, if a grease has
intrinsic resistance to ignition, it is less likely to
fuel grease fires.
It was unexpectedly and surprisingly found that the
described novel steel mill grease does have all three of
the above mentioned properties. The novel grease desira-
bly has a significant level of resistance to ignition by
direct flame contact.
It is believed the above ignition resistance proper-
ties are attributable to the thermal decomposition of cal-
cium carbonate in the grease to produce carbon dioxide.
When the flame contacts the grease surface, carbon dioxide
can form, dropping the local oxygen level below the 15~
required to sustain combustion. This in turn causes the
flame to be blanketed and smothered with carbon dioxide.
The process for preventing grease fires is especially
useful in steel mills and other metal processing mills,
such as strip mills, billet mills, plate mills, and rod
mills. In the process, when a flame is ignited, such as
from molten steel or other hot metal, or from acetylene
torches or other welding equipment, and approaches near
the described special grease, which can be injected into
the caster bearings or rollers in a metal processing mill,
the special grease emits a sufficient amount of carbon
dioxide to blanket and extinguish the flame or otherwise
substantially prevent the grease from igniting, burning,
and combusting. In the preferred process, carbon dioxide
-
-25- 2010924
is emitted from thermal decomposition of calcium carbonate
in the grease.
The ignition resistance of the grease of this
invention was tested in a laboratory and in a large mid-
western steel mill, as discussed hereinafter in Exam-
ples 48-58.
Metal Working Process
In the metal working process, steel, iron, or other
metal is cast, formed, treated, fabricated, worked, or
otherwise processed in a steel mill or a process mill,
such as a hot strip mill, cold strip mill, billet mill,
plate mill, or rod mill, and conveyed on caster rollers
with bearings. In the process, the described special high
performance grease is injected, fed, and placed into the
bearings and prevented from leaking out of the bearings so
as to lubricate and enhance the longevity and useful life
of the bearings. Desirably, the bearings are protected
against rust and corrosion at high temperatures during
casting, working, and fabricating, as well as at ambient
and lower temperatures. Preferably, this is accomplished
by the described special non-corrosive, oxidatively
stable, thermally stable, adhesive-imparting grease which
also hermetically seals the bearings, substantially elimi-
nates grease leakage, prevents toxic emissions, and does
not normally irritate the skin or eyes of workers in the
mill. Advantageously, substantially less grease is
required, consumed, and used with the described special
grease.
During casting in steel mills, molten steel is fed to
a formation chamber where it is cast and formed into a hot
steel slab and discharged onto a slab caster. The hot
steel slab is conveyed on caster rollers with tapered rol-
lers bearings. The hot steel slab is quenched and cooledwith a high velocity water spray from above and below the
caster rollers and bearings. Advantageously, the special
-26- ZOl ~92
high performance grease prevents the grease from being
flushed and washed out of the bearings.
The following Examples are for purposes of illus-
tration and not for purposes of limiting the scope of the
invention as provided in the appended claims.
Example 1
Polyurea thickener was prepared in a pot by adding:
(a) about 30% by weight of a solvent extracted neutral
base oil containing less than 0.1% by weight sulfur with a
viscosity of 600 SUS at 100F. and (b) about 7.45% by
weight of primary oleyl amine. The primary amine base oil
was then mixed for 30-60 minutes at a maximum temperature
of 1~0F with about 5.4% by weight of an isocyanate, such
as 143 L-MDI manufactured by Upjohn Company. About 3~ by
weight water was then added and stirred for about 20 to
30 minutes, before removing excess free isocyanates and
amines.
The polyurea thickener can also be prepared, if
desired, by reacting an amine and a diamine with diisocya-
nate in the absence of water. For example, polyurea can
be prepared by reacting the following components:
l. A diisocyanate or mixture of diisocyanates
having the formula OCN-R-NCO, wherein R is a
hydrocarbylene having from 2 to 30 carbons, pre-
ferably from 6 to 15 carbons, and most prefera-
bly 7 carbons;
201092~
-
-27-
2. A polyamine or mixture of polyamines having a
total of 2 to 40 carbons and having the formula:
/ ~o \ / Ro Ro
H------N-Rl x ~ R2 ~ ~ z
wherein Rl and R2 are the same or different
types of hydrocarbylenes having from 1 to
30 carbons, and preferably from 2 to 10 carbons,
and most preferably from 2 to 4 carbons; Ro is
selected from hydrogen or a Cl-C4 alkyl, and
preferably hydrogen; x is an integer from 0 to
4; y is 0 or 1; and z is an inte~er equal to 0
when y is 1 and equal to 1 when y is 0.
3. A monofunctional component selected ~rom the
group consisting of monoisocyanate or a mixture
of monoisocyanates having 1 to 30 carbons, pref-
erably from 10 to 24 carbons, a monoamine or
mixture of monoamines having from 1 to
30 carbons, preferably from 10 to 24 carbons,
and mixtures thereof.
The reaction can be conducted by contacting the three
reactants in a suitable reaction vessel at a temperature
between about 60F. to 320F., preferably from 100F. to
300F., for a period of 0.5 to 5 hours and preferably from
1 to 3 hours. The molar ratio of the reactants present
can vary from 0.1-2 molar parts of monoamine or monoisoc-
yanate and 0-2 molar parts of polyamine for each molar
part of diisocyanate. When the monoamine is employed, the
molar quantities can be (m+l) molar parts of diisocyanate,
(m) molar parts of polyamine and 2 molar parts of monoa-
mine. When the monoisocyanate is employed, the molar
quantities can be (m) molar parts of diisocyanate, (m+l)
- 2~0924
-28-
molar parts of polyamine and 2 molar parts of monoisocya-
nate (m is a number from 0.1 to 10, preferably 0.2 to 3,
and most preferably 1).
Mono- or polyurea compounds can have structures
defined by the following general formula:
/C C~ \ : O
I
(1)
10R3-NH--C-NH-R4-NH-~-N~-R5-NH~ C-NH-R4-NH-~-NH-R3
G /3 ~ ~ O
~ 2)
R3NH - ~-NH-R5NH -~-NH-R4-NH-~-NH-R5-NH~s--;-NH-R3
/~ ~ \ C
(3)
~3-N~ ~ -N~-R4-NH-C-NH-R5-NH 1 ~-NH-R3
wherein n is an integer from 0 to 3; R3 is the same or
different hydrocarbyl having from 1 to 30 carbon atoms,
preferably from 10 to 24 carbons; R4 is the same or
different hydrocarbylene having from 2 to 30 carbon atoms,
preferably from 6 to 15 carbons; and R5 is the same or
different hydrocarbylene having from 1 to 30 carbon atoms,
preferably from 2 to 10 carbons.
As referred to herein, the hydrocarbyl group is a
monovalent organic radical composed essentially of hydro-
gen and carbon and may be aliphatic, aromatic, alicyclic,
or combinations thereof, e.g., aralkyl, alkyl, aryl,
cycloalkyl, alkylcycloalkyl, etc., and may be saturated or
olefinically unsaturated (one or more double-bonded car-
bons, conjugated, or nonconjugated). The hydrocarbylene,as defined in Rl and R2 above, is a divalent hydrocarbon
radical which may be aliphatic, alicyclic, aromatic, or
09~
-29-
combinations thereof, e.g., alkylaryl, aralkyl, alkylcy-
cloalkyl, cycloalkylaryl, etc., having its two free
valences on different carbon atoms.
The mono- or polyureas having the structure presented
in Formula 1 above are prepared by reacting (n+l) molar
parts of diisocyanate with 2 molar parts of a monoamine
and (n) molar parts of a diamine. (When n equals zero in
the above Formula 1, the diamine is deleted). Mono- or
polyureas having the structure presented in Formula 2
above are prepared by reacting (n) molar parts of a dii-
socyanate with (n+l) molar parts of a diamine and 2 molar
parts of a monoisocyanate. (When n equals zero in the
above Formula 2, the diisocyanate is deleted). Mono- or
polyureas having the structure presented in Formula 3
above are prepared by reacting (n) molar parts of a dii-
socyanate with (n) molar parts of a diamine and 1 molar
part of a monoisocyanate and 1 molar part of a monoamine.
(When n equals zero in Formula 3, both the diisocyanate
and diamine are deleted).
In preparing the above mono- or polyureas, the
desired reactants (diisocyanate, monoisocyanate, diamine,
and monoamine) are mixed in a vessel as appropriate. The
reaction may proceed without the presence of a catalyst
and is initiated by merely contacting the component
reactants under conditions conducive for the reaction.
Typical reaction temperatures range from 70F. to 210F.
at atmospheric pressure. The reaction itself is
exothermic and, by initiating the reaction at room temper-
ature, elevated temperatures are obtained. External heat-
ing or cooling may be used.
The monoamine or monoisocyanate used in the formu-
lation of the mono- or polyurea can form terminal end
groups. These terminal end groups can have from 1 to 30
carbon atoms, but are preferably from 5 to 28 carbon
atoms, and more desirably from 10 to 24 carbon atoms.
Illustrative of various monoamines are: pentylamine, hex-
201~1Z~
-30-
ylamine, heptylamine, octylamine, decylamine, dodecyla-
mine, tetradecylamine, hexadecylamine, octadecylamine,
eicosylamine, dodecenylamine, hexadecenylamine, octadece-
nylamine, octadeccadienylamine, abietylamine, aniline,toluidine, naphthylamine, cumylamine, bornylamine, fenchy-
lamine, tertiary butyl aniline, benzylamine, beta-phene-
thylamine, etc. Preferred amines are prepared from
natural fats and oils or fatty acids obtained therefrom.
These starting materials can be reacted with-ammonia to
give first amides and then nitriles. The nitriles are
reduced to amines by catalytic hydrogenation. Exemplary
amines prepared by the method include: stearylamine, lau-
rylamine, palmitylamine, oleylamine, petroselinylamine,
linoleylamine, linolenylamine, eleostearylamine, etc.
Unsaturated amines are particularly useful. Illustrative
of monoisocyanates are: hexylisocyanate, decylisocyanate,
dodecylisocyante, tetradecylisocyanate,
hexadecylisocyanate, phenylisocyanate, cyclohexylisocya-
nate, xyleneisocyanate, cumeneisocyanate, abietyl-
isocyanate, cyclooctylisocyanate, etc.
Polyamines which form the internal hydrocarbon
bridges can contain from 2 to 40 carbons and preferably
from 2 to 30 carbon atoms, more preferably from 2 to 20
carbon atoms. The polyamine preferably has from 2 to 6
amine nitrogens, preferably 2 to 4 amine nitrogens and
most preferably 2 amine nitrogens. Such polyamines
include: diamines such as ethylenediamine, propanedia-
mine, butanediamine, hexanediamine, dodecanediamine,
octanediamine, hexadecanediamine, cyclohexanediamine,
cyclooctanediamine, phenylenediamine, tolylenediamine,
xylylenediamine, dianiline methane, ditoluidinemethane,
bis(aniline), bis(toluidine), piperazine, etc.; triamines,
such as aminoethyl piperazine, diethylene triamine, dipro-
pylene triamine, N-methyldiethylene triamine, etc., and
higher polyamines such as triethylene tetraamine, tetrae-
thylene pentaamine, pentaethylene hexamine, etc.
20~0924
-31-
Representative examples of diisocyanates include:
hexane diisocyanate, decanediisocyanate, octadecanediisoc-
yanate, phenylenediisocyanate, tolylenediisocyanate,
bis(diphenylisocyanate), methylene bis(phenylisocyanate),
etc.
Other mono- or polyurea compounds which can be used
are:
x n - NH - C - NH Y
\ 4 ~ n
wherein nl is an integer of 1 to 3, R4 is defined supra; X
and Y are monovalent radicals selected from Table 1 below:
-32- 201~9Z~
Table I
X Y
s
O
R7-C-N~ R7-~-NH-R5
G O
\ / \
/
~6 R6 N-R5 -
C C
C O
R8
In Table 1, R5 is defined supra, R8 is the same as R3
and defined supra, R6 is selected from the groups consist-
ing of arylene radicals of 6 to 16 carbon atoms and alky-
lene groups of 2 to 30 carbon atoms, and R7 is selected
from the group consisting of alkyl radicals having from 10
to 30 carbon atoms and aryl radicals having from 6 to 16
carbon atoms.
Mono- or polyurea compounds described by formula (4)
above can be characterized as amides and imides of mono-,
di-, and triureas. These materials are formed by react-
ing, in the selected proportions, suitable carboxylic
acids or internal carboxylic anhydrides with a
- 2~109Z4
-33-
diisocyanate and a polyamine with or without a monoamine
or monoisocyanate. The mono- or polyurea compounds are
prepared by blending the several reactants together in a
vessel and heating them to a temperature ranging from
70F. to 400F. for a period sufficient to cause formation
of the compound, generally from 5 minutes to 1 hour. The
reactants can be added all at once or sequentially.
The above mono- or polyureas can be mixtures of com-
pounds having structures wherein n or nl varies from 0 to
8, or n or nl varies from 1 to 8, existent within the
~rease composition at the same time. For example, when a
monoamine, a diisocyanate, and a diamine are all present
within the reaction zone, as in the preparation of ureas
having the structure shown in formula (2) above, some of
the monoamine may react with both sides of the diisocya-
nate to form diurea (biurea). In addition to the
formulation of diurea, simultaneous reactions can occur to
form tri-, tetra-, penta-, hexa-, octa-, and higher polyu-
reas.
Example 2
This test served as the control for subsequent tests.A base grease was formulated with about 15~ by weight
polyurea thickener and about 85% by weight paraffinic sol-
vent extracted base oil. The polyurea thickener was pre-
pared in a vessel in a manner similar to Example 1. The
paraffinic solvent extracted base oil was mixed with the
polyurea thickener until a homogeneous base grease was
obtained. No additive package was added to the base
grease. Neither tricalcium phosphate nor calcium carbo-
nate were present in the base grease. The EP (extreme
pressure)/antiwear properties of the base grease, compris-
ing the last nonseizure load, weld load, and load wear
index were measured using the Four Ball EP method as
described in ASTM D2596. The results were as follows:
- ;2010~24
-34-
Last nonseizure load, kg 32
Weld load, kg 100
Load wear index 16.8
Example 3
A grease was prepared in a manner similar to Example
2, except that about 5% by weight of finely divided, pre-
cipitated tricalcium phosphate with an average mean diam-
eter of less than 2 microns was added to the base grease.The resultant mixture was mixed and milled in a roll mill
until a homogeneous grease was produced. The Four Ball EP
Test showed that the EP/antiwear properties of the grease
were significantly increased with tricalcium phosphate.5
Last nonseizure load, kg 63
Weld load, kg 160
Load wear index 33.1
Example 4
A grease was prepared in a manner similar to Example
3, except that about 10% by weight tricalcium phosphate
was added to the base grease. The Four Ball EP Test
showed that the EP/antiwear properties were further5 increased with more tricalcium phosphate.
Last nonseizure load, kg 80
Weld load, kg 250
Load wear index 44.40
Example 5
A grease was prepared in a manner similar to Example
4, except that about 20% by weight tricalcium phosphate
was added to the base grease. The Four Ball EP Test
showed that the EP/antiwear properties of the grease were
somewhat better than the 5~ tricalcium phosphate grease of
- 2~09Z4
-35-
Example 3, but not as good as the 10% tricalcium phosphate
grease of Example 4.
Last nonseizure load, kg 63
Weld load, kg 250
Load wear index 36.8
Example 6
A grease was prepared in a manner similar to Example
2, except that about 5% by weight of finely divided pre-
cipitated tricalcium phosphate and about 5~ by weight of
finely divided calcium carbonate were added to the base
grease. The tricalcium phosphate and calcium carbonate
had an average mean particle diameter less than 2 microns.
The resultant grease was mixed and milled until it was
homogeneous. The Four Ball EP Test showed that the
EP/antiwear properties of the grease were surprisingly
better than the base grease of Example 1 and the trical-
cium phosphate greases of Examples 2-5.
Last nonseizure load, kg 80
Weld load, kg 400
Load wear index 52.9
Example 7
A grease was prepared in a manner similar to Example
6, except that 10% by weight tricalcium phosphate and 10%
by weight calcium carbonate were added to the base grease.
The Four Ball EP Test showed that the weld load was
slightly lower and the load wear index were slightly
better than the grease of Example 6.
Last nonseizure load, kg 80
Weld load, kg 315
Load wear index 55.7
-36- 20~0924
Example 8
A grease was prepared in a manner similar to Example
7, except that 20% by weight tricalcium phosphate and 20%
calcium carbonate were blended into the base grease. The
Four Ball EP Test showed that the EP/antiwear properties
of the grease were better than greases of Examples 6 and
7.
Last nonseizure load, kg 100
Weld load, kg 500
Load wear index 85.6
Example 9
A grease was prepared in a manner similar to Example
2, except that about 10% by weight of finely divided cal-
cium carbonate with a mean particle diameter less than 2
microns, was added to the base grease. The resultant
grease was mixed and milled until it was homogeneous. The
Four Ball EP Test showed that the weld load and load wear
index of the calcium carbonate grease were better than the
base grease of Example 2.
Last nonseizure load, kg 80
Weld load, kg 400
Load wear index 57
Example lO
A grease was prepared in a manner similar to Example
6, except that about 3% by weight tricalcium phosphate and
about 5% by weight calcium carbonate were added to the
base grease. The Four Ball EP Test showed that the weld
load and load wear index of the grease were better than
the greases of Example 4 (lO~ tricalcium phosphate alone)
and Example 9 (10% calcium carbonate alone), even though
the total combined level of additives was only 8%. This
result is most surprising and unexpected. It illustrates
2~10924
-37-
how the two additives can work together to give the sur-
prising improvements and beneficial results.
Last nonseizure load, kg 80
Weld load, kg 500
Load wear index 61.8
Example 11
The grease of Example 6 (5~ by weight tricalcium
phosphate and 5% by weight calcium carbonate) was sub-
jected to the ASTM D4048 Copper Corrosion Test at a tem-
perature of 300F for 24 hours. No significant corrosion
appeared. The copper test sample remained bright and
shiny. The copper strip was rated la.
Example 12
The grease of Example 10 (3% by weight tricalcium
phosphate and about 5% by weight calcium carbonate) was
subjected to the ASTM D4048 Copper Corrosion Test at a
temperature of 300F for 24 hours. The results were simi-
lar to Example 11.
Example 13
A grease was prepared in a manner similar to Example
6, except that about 3.5% by weight tricalcium phosphate,
about 3.5% by weight calcium carbonate, and about 7~ by
weight of an insoluble arylene sulfide polymer, manufac-
tured by Phillips Petroleum Company under the trade name
RYTON, were added to the base grease. The grease contain-
ing insoluble arylene sulfide polymer was subjected to the
ASTM D4048 Copper Corrosion Test at a temperature of 300F
for 24 hours and failed miserably. Significant corrosion
appeared. The copper test strip was spotted and colored
and was rated 3b.
2010924
-38-
Example 14
A grease was prepared in a manner similar to Example
3, except as follows. The base oil comprised about 60% by
weight of 850 SUS paraffinic, solvent extracted, hydrogen-
ated mineral oil, and about 40~ by weight of 350 SUS
paraffinic, solvent extracted, hydrogenated mineral oil.
The base grease comprised 16.07% polyurea thickener.
Instead of adding tricalcium phosphate, 11.13 and dical-
cium phosphate, sold under the brand name of Biofos byIMC, were added to the base grease. The resultant grease
was milled in a manner similar to Example 2 and subjected
to an Optimol SRV stepload test (described in Example 19).
The test grease failed. The coefficient of friction
slipped and was highly erratic, indicating rapid wear.
The scar on the disk was rough and showed a lot of wear.
Example 15
The grease of Example 13 containing oil-insoluble
arylene polymers was subjected to the ASTM D4170 Fretting
Wear Test and an Elastomer Compatibility Test for Silicone
at 150C for 312 hours. The results were as follows:
Fretting Wear, ASTM D4170, 72 hr
mg loss/race set 5.6
Elastomer Compatibility with Silicone
% loss tensile strength 17.4
% loss total elongation 16.9
Example 16
The grease of Example 6 was subjected to the ASTM
D4170 Fretting Wear Test and an Elastomer Compatibility
Test for Silicone at 150C for 312 hours. The grease dis-
played substantially better fretting resistance and elas-
tomer compatibility than the grease of Example 15containing insoluble arylene polymers.
-
-39- 201~9Z4
Fretting Wear, ASTM D4170, 72 hr
mg loss/race set 3.0
Elastomer Compatibility with Silicone
5% loss tensile strength 9.9
loss total elongation 12.2
Example 17
A grease was prepared in a manner similar to Example
6, except as described below. The polyurea thickener was
prepared in a manner similar to Example 1 by reacting
676.28 grams of a fatty amine, sold under the brand name
Armeen T by Armak Industries Chemicals Division, 594.92
grams of a diisocyanate, sold under the brand name Mondur
CD by Mobay Chemical Corporation, and 536 ml of water.
The base oil had a viscosity of 650 SUS at 100F and was a
mixture of 850 SUS paraffinic, solvent extracted, hydro-
genated mineral oil, and hydrogenated solvent extracted,
dewaxed, mineral oil. Corrosive inhibiting agents, sold
under the brand names of Nasul BSN by R. T. Vanderbilt Co.
and Lubrizol 5391 by the Lubrizol Corp., were added to the
grease for ferrous corrosion protection. The anti-oxi-
dants were a mixture of arylamines. The grease was
stirred and subsequently milled through a Gaulin Homogen-
izer at a pressure of 7000 psi until a homogeneous greasewas produced. The grease had the following composition:
Component % (wt)
850 SUS Oil 47.58
350 SUS Oil 31.20
Polyurea Thickener 9.50
Tricalcium Phosphate 5.00
Calcium Carbonate 5.00
Nasul BSN 1.00
Lubrizol 5391 0.50
Mixed Aryl Amines 0.20
Dye 0.02
2010924
-40-
The grease was tested and had the following perform-
ance properties:
Worked Penetration, ASTM D217 307
Dropping Point, ASTM D2265 501F
Four Ball Wear, ASTM D2266 at
40 kg, 1200 rpm for 1 hr 0.50
Four Ball EP, ASTM D2596
last nonseizure load, kg 80
weld load, kg 400
load wear index 57
Timken, ASTM D4170, lbs - 60
Fretting Wear, ASTM D4170, 24 hr
mg loss/race set 0.8
Corrosion Prevention Test, ASTM D1743
Elastomer Compatibility with Polyester
% loss tensile strength 21.8
% loss maximum elongation 12.9
Elastomer Compatibility with Silicone
% loss tensile strength 7.4
% loss maximum elongation 24.2
Example 18
The grease of Example 17 was subjected to an oil sep-
aration cone test (bleed test), SDM 433 standard test of
the Saginaw Steering Gear Division of General Motors. In
the test, the grease was placed on a 60 mesh nickel screen
cone. The cone was heated in an oven for the indicated
time at the listed temperature. The percentage decrease
in the weight of the grease was measured. The test showed
that minimum oil loss occurred even at higher temperatures
over a 24-hour time period. The results were as follows:
20~09Z4
-41-
time thr) temp (F) % oil loss
6 212 1.9
24 212 4.4
24 300 2.1
24 350 3.4
Example 19
The grease of Example 17 was subjected to an Optimol
SRV stepload test under conditions recommended by Optimol
Lubricants, Inc. and used by Automotive Manufacturers such
as General Motors for lubricant evaluation. This method
was also specified by the U.S. Air Force Laboratories Test
Procedure of March 6, 1985. In the test, a 10 mm steel
ball is oscillated under load increments of 100 newtons on
a lapped steel disc lubricated with the grease being
tested until seizure occurs. The grease passed the maxi-
mum load of 900 newtons.
Examples 20-21
Two greases were prepared from a polyurea base grease
in a manner similar to Example 17. Test grease 20 was
prepared without a borate additive. In test grease 21, a
borated amine was added, and the resultant mixture was
mixed and subsequently milled until a homogeneous grease
was produced. Test grease 21 with the borated amine
decreased oil separation over test grease 20 by over 31~
to 45% at 212F, by over 50% at 300F, and by over 51% at
350F.
20~09Z4
_ . -42-
Test Grease 20 21
Base Oil Viscosity; ASTM D445
SUS at 100F 600 600
5 % Thickener (polyurea) 9.6 9.6
% Tricalcium Phosphate 5.0 5.0
% Calcium Carbonate 5.0 5.0
~ Borated Amine (Lubrizol 5391) 0 0-5
Worked Penetration, ASTM D217 300 297
10Dropping Point, ASTM D2265, F 490 494
Oil Separations, SDM 433, %
6 hr, 212F 4.17 2.27
24 hr, 212F 5.53 3.77
24 hr, 300F 8.03 4.01
1524 hr, 350F 12.18 5.85
Examples 22-23
Test greases 22 and 23 were prepared in a manner sim-
ilar to Examples 20 and 21, except greases 22 and 23 were
formulated about 14 points of penetration softer. Test
grease 23 with the borated amine decreased oil separation
over test grease 22 without borated amine by over 31% to
38% at 212F, by over 18% at 300F, and by over 48% at
350F
- ` 201092~
-43-
Test Grease 22 23
Base Oil Viscosity, ASTM D445
SUS at 100F 600 600
5 % Thickener (polyurea) 9.6 9.6
% Tricalcium Phosphate 5.0 5.0
% Calcium Carbonate 5.0 5.0
% Borated Amine (Lubrizol 5391) 0 0.5
Worked Penetration, ASTM D217 312 315
Dropping Point, ASTM D2265, F 491 497
Oil Separations, SDM 433, %
6 hr, 212F 5.45 3.34
24 hr, 212F 8.71 5.97
24 hr, 300F - 9.71 7.88
24 hr, 350F 15.71 8.06
Examples 24-26
Three greases were made from a common polyurea base.
The base oil viscosity was reduced from the previous value
of 600 SUS at 100F to a new value of 100 SUS at 100F.
The worked penetrations of the three greases were also
substantially softened from earlier values. Both of these
changes tend to increase oil separation values. Except
for these changes, all three greases were prepared in a
manner similar to Examples 20-?3. Test grease 24 was pre-
pared without a borated amine. Test grease 25 contained
0.5% by weight borated amine. Test grease 26 contained 1%
by weight of a conventional tackifier oil separation inhi-
bitor (Paratac). To prevent the conventional tackifier
oil separation additive from shearing down, it was added
to the grease after the milling was complete. The supe-
rior performance of the borated amine additive over the
conventional tackifier oil separation additive is appar-
ent. Test grease 25 containing borated amine decreased
oil separation over test grease 26 containing a conven-
tional tackifier oil separation additive by over 38% at
150F, by 40~ at 212F, and by over 44~ at 300F. Test
2~1092~
-44-
grease 25 containing borated amine decreased oil sepa-
ration over test grease 24 without any oil separation
additive by 50% at 150F, by over 42% at 212F and at
300F, and by over 12% at 350F. The Paratac gives some
benefit at 150F, but this benefit vanishes as the test
temperature increases.
Test Grease 24 25 26
Base Oil Viscosity, ASTM D445
SUS at 100F 600 600 600
% Thickener (polyurea) 6.0 6.0 6.0
% Tricalcium Phosphate 5.0 5.0 5.0
~ Calcium Carbonate 5.0 5.0 5.0
~ Borated Amine (Lubrizol 5391)0 0.5 0
% Conventional Tackifier Oil Separation
Additive (Paratac) 0 0 1.0
Worked Penetration, ASTM D217383 384 359
Oil Separations, SDM 433, %
24 hr, 150F 9.6 4.8 7.8
24 hr, 212F 12.1 6.9 11.5
24 hr, 300F 9.7 5.6 10.1
24 hr, 350F 34.3 30.0 30.6
Inorganic borate salts, such as potassium triborate,
provide an oil separation inhibiting effect similar to
borated amines when used in polyurea greases in which cal-
cium phosphate and calcium carbonate are also present. It
is believed that the physio-chemical reason for this oil
separation inhibiting effect is similar to that for
borated amines. This discovery is particularly surprising
since inorganic borate salts had not been used as oil sep-
aration inhibitors. The advantages of borated amines over
conventional tackifier additives are also applicable in
the case of inorganic borate salts.
2(~10924
-45-
Examples 27-29
Test grease 27 was prepared in a manner similar to
Example 17 but without any tricalcium phosphate, calcium
carbonate, or a borate additive. A 2% potassium triborate
was added to test grease 27 prior to mixing and milling.
Test grease 28 was prepared in a manner similar to Exam-
ple 27 but with 5~ tricalcium phosphate, 5% calcium carbo-
nate, and 0.5% borated amine. Test grease 28 did not
contain potassium triborate. Test grease 29 was prepared
by mixing equal weights of unmilled test greases 27 and 28
until a homogeneous mixture was attained. The resultant
mixture was subsequently milled under conditions similar
to Examples 27 and 28. The borated amine test grease 28
produced superior results over test grease 27, which con-
tained no tricalcium phosphate or calcium carbonate. Test
grease 29 was prepared in a manner similar to Example 28
but with 2.5% tricalcium phosphate, 2.5% calcium carbo-
nate, 0.25% borated amine, and 1% potassium triborate.
The borated test grease 28 decreased oil separation over
test grease 27 by over 35% to 44% at 212F, by over 55% at
300F, and by over 38% at 350F. Test grease 29 contained
about one-half of the borated amine of test grease 28 but
also contained about 1% by weight potassium triborate
(OLOA 9750). The borated amine, potassium triborate, test
grease 29 produced even better results than either test
grease 27 or test grease 28. The borated amine, potassium
triborate, test grease 29 dramatically reduced oil sepa-
ration over test grease 28 by 13% to over 15% at 212F, by
over 20% at 300F, and by over 38% at 350F. Even though
test grease 27 also contained about 2% by weight potassium
triborate (OLOA 9750), similar to test grease 29, test
grease 27 did not contain tricalcium phosphate or calcium
carbonate. Test grease 29 decreased oil separation over
test grease 27 by over 45% to 50% at 212F, by over 64% at
300F, and by over 62% at 350F.
2~109Z4
-46-
Test Grease 27 28 29
Base Oil Viscosity,
SUS at 100F 600 600 600
5 % Tricalcium Phosphate 0 5.0 2.5
% Calcium Carbonate 0 5.0 2.5
Borated Amine (Lubrizol 5391) 0.0 0.5 0.25
~ Potassium Triborate (OLOA 9750)2.0 0.0 1.0
Worked Penetration 310 295 300
Dropping Point, F 533 506 489
Oil Separation, SDM 433, %
6 hr, 212F 5.2 3.0 2.6
24 hr, 212F 9.9 6.4 5.4
24 hr, 300F 8.9 4.0 3.2
24 hr, 350F 10.0 6.2 3.8
Examples 30-33
A grease was made in a manner similar to that of
Example 17. However, additives were used such that the
final compositions was as follows:
Component % (wt)
850 SUS Oil 45.88
350 SUS Oil 30.35
Polyurea Thickener10.00
Tricalcium Phosphate5.56
Calcium Carbonate5.56
Nasul BSN 2.22
Lubrizol 5391 0.56
Mixed Aryl Amines0.22
Four portions of this grease were placed into sepa-
rate vessels. To the first was added 850 SUS Oil and 350
SUS Oil only. This grease served as the control for com-
parison of the other three greases in Examples 31-33. To
the second portion was added 850 SUS Oil and 350 Oil and
polymethacrylate sold by Texaco Chemical Company under the
2~:~0924
-47-
trade name of TC 9355. To the third portion was added 850
SUS Oil, 350 SUS Oil, and an ethylene-propylene copolymer
sold by Functional Products, Inc. under the trade name
Functional V-157Q. To the fourth portion was added 850
SUS Oil, 350 SUS Oil, and Paratac. The four greases were
heated and stirred to homogenously mix the oil and polym-
ers into the grease. Then each grease was given one pass
through a Gaulin homogenizer at 7,000 psi. The resulting
final test greases were evaluated to determine the effect
of the various polymers on low temperature properties.
~ Compositions and test results are given below:
Test Grease Ex. 30 Ex. 31 Ex. 32 Ex. 33
Component, % (wt)
850 SUS Oil 46.98 44.58 45.78 44.58
350 SUS Oil 31.32 29.72 30.52 29.72
20 Polyurea Thickener9.00 9.00 9.00 9.00
Tricalcium Phosphate5.00 5.00 5.00 5.00
Calcium Carbonate 5.00 5.00 5.00 5.00
Nasul BSN 2.00 2.00 2.00 2.00
Lubrizol 5391 0.50 0.50 0.50 0.50
25 Mixed Aryl Amines 0.20 0.20 0.20 0.20
TC 9355
Functional V-157Q 0 0 2.00 0
Paratac 0 0 0 4.00
Test Results
Worked Penetration 372 384 400 370
Dropping Point, F 533 530 532 533
Low Temperature Torque
at -10 F, ASTM D1478
Starting, g-cm3,245 2,065 6,343 1,623
Running, g-cm 738 295 443 443
2010924
-48-
Low Temperature Torque
at -20F, ASTM D1478
Starting, g-cm6,343 4,425 11,9485,310
Running, g-cm 531 738 1,269 738
The grease of Example 31 which contained the polyme-
thacrylate polymer TC9355 gave the least increased torques
when compared to the control grease of Example 30. In
fact, at -10F, both starting and running torques of Exam-
ple 31 were less than that of Example 30. Example 31 was
the only polymer containing test grease of this set which
had that property. Of Examples 31-33, Example 31 had the
best overall low temperature properties as measured by low
temperature torque. The grease of Example 33 which con-
tained the Paratac was the second best in low temperature
properties. However, Example 33 had very little adhesive
character when compared with the control grease of Example
33. This was due to the very high shear sensitivity of
the high molecular weight polyisobutylene polymer Paratac.
The test grease of Example 32 had the largest increase in
low temperature torque when compared to the control grease
of Example 30. The test greases of Examples 31 and 32 had
a significantly increased adhesive character when compared
to the test grease of Example 30.
Examples 34-37
Four samples similar to the samples of Examples 30-33 were
prepared using a method similar to that described in Exam-
ples 30-33. However, the final thickener level was
increased to 10% so as to increase the grease hardness.
Also, 2% of potassium triborate (OLOA 9750) was added to
assist in reduction of oil separation. Compositions and
test results are given below.
20~924
-49-
Test Grease Ex. 34 Ex. 35 Ex. 36 Ex. 37
Component, % (wt)
850 SUS Oil 45.18 42.78 43.98 42.78
350 SUS Oil 30.12 28.52 29.32 28.52
Polyurea Thickener 10.00 10.00 10.00 10.00
Tricalcium Phosphate 5.00 5.00 5.00 5.00
Calcium Carbonate 5.00 5.00 5.00 5.00
Nasul BSN 2.00 2.00 2.00 2.00
OLOA 9750 2.00 2.00 2.00 2.00
Lubrizol 5391 0.50 0.50 0.50 0.50
Mixed Aryl Amines 0.20 0.20 0.20 0.20
TC 9355 4.00
Functional V-157Q 0 0 2.00 0
Paratac 0 4-00
Test Results
Worked Penetration 369 329 369 325
Dropping Point, F 538 534 507 535
Oil Separation, SDM 433, %
24 hr, 212F 6.0 6.0 6.3 4.1
24 hr, 300F 5.5 8.9 8.9 4.5
24 hr, 350F 6.5 9.8 10.8 6.2
Four Ball Wear,
ASTM D2266, mm 0.44 0.44 0.44 0.44
Four Ball EP, ASTM D2596
Weld Load, Kg 400 400 400 400
Load Wear Index 48.1 48.4 44.3 48.7
Optimol SRV Stepload
Test, Newtons 900 900 900 900
Water Washout, ASTM D1264
at 170F, % loss 0 0 27 0
Corrosion Prevention
201~924
-50-
Properties, ASTM D1743 Pass 1 Pass 1 Pass 1 Pass 1
Copper Strip Corrosion,
ASTM D4048, 300F,
24 hr. lA lA lA lA
Steel Strip Corrosion,
300 F, 24 hr. -~ ---No Discoloration---------
Low Temperature Torque
Test, ASTM D1478 at -10F
10Starting Torque,
gram-cm 3,540 3,686 5,753 3,983
Running Torque,
gram-cm 295 443 443 295
U.S. Steel Grease
15Mobility Test, S-75,
at -10F, grams/minute
50 PSI 0.87 0.55 0.47 0.58
100 PSI 4.96 3.99 2.65 2.78
150 PSI 8.67 7.60 4.89 4.58
20 Panel Stability Test
at 350F for 24 hr. ------No oil separation----------
------Remained grease-like-------
------No lacquer deposition------
All polymers except the Functional V-157Q improved
(hardened) the grease consistency as shown by the worked
penetrations. The Functional V-157Q had no effect. The
Functional V-157Q polymer significantly reduced the water
resistance of the grease as measured by the Water Washout
Test. The polymethacrylate polymer (TC 9355) and the
ethylene-propylene copolymer (Functional V-157Q) increased
the oil separation properties somewhat compared to the
grease of Example 34 which contained no polymer. The Par-
atac of Example 37 reduced oil separation at the lowest
test temperature but this effect dropped off as the test
temperature increased.
ZQ~09Z4
-51-
All of the greases had good dropping points, extreme
pressure/antiwear properties, and corrosion, oxidative,
and rust preventative properties. None of the polymers
caused any high temperature chemical corrosion to copper
or steel as shown by the ASTM D4048 Copper Strip Corrosion
Test and the Steel Strip Corrosion Test (similar to ASTM
D4048 except that a polished steel strip is used instead
of a copper strip). ~igh temperature grease stability was
measured by the Panel Stability Test, the details of which
are described in Example 38. All four greases gave compa-
rable results, indicating the superior high temperature
stability of polyurea greases, the additional beneficial
effect of the tricalcium phosphate and calcium carbonate
additive system.
When measured by ASTM D1478 Low Temperature Torque,
Example 36 which contained the ethylene-propylene copo-
lymer (Functional V-157Q) gave the largest overall
increase in torque when compared to the control grease of
Example 34. Example 35 gave the smallest overall torque
of the three greases which contained polymers. When the
greases of Examples 34-37 were tested by the U.S. Steel
Mobility Test, S-75, the polymethacrylate (TC 9355) was
significantly superior to either ethylene-propylene copo-
lymer (Functional V-157Q) or Paratac. This is evidenced
by the minimal amount by which mobility decreased for
Example 35 compared to the control grease of Example 34.
Compared to Example 34, Example 35 had a mobility at 150
PSI which was reduced by 12% compared to Example 34.
Example 36 and Example 37 had mobility reductions at 150
PSI of 44% and 47%, respectively, when compared to Example
34.
The greases of Examples 34-37 were also examined for
adherence properties. The control grease of Example 34
had the least amount of adherence. Examples 35 and 36
were significantly increased in adherence; Example 37 was
less adherent than Examples 35 and 36.
-52- 2 ~ ~ 92
Example 38
A steel mill grease was made by a procedure similar
to that given in Example 17. However, several changes
were made in the type and amount of additives added to the
polyurea base grease. The grease had the following compo-
sition:
Component ~ (wt)
850 SUS Oil 45.48
350 SUS Oil 30.32
Polyurea Thickener12.50
Tricalcium Phosphate2.00
Calcium Carbonate 2.00
TC 9355 4.00
OLOA 9750 1.00
Zinc Naphthenate 1.00
Nasul BSN 1.00
Lubrizol 5391 0.50
Aryl Amines 0.20
The grease was tested and had the following basic
properties:
Work Penetration, ASTM D217 318
Dropping Point, ASTM D2265, F 496
Four Ball Wear, ASTM D2266 at
40 kg, 1200 rpm for 1 hr 0.43
Four Ball EP, ASTM D2596
last nonseizure load, kg 80
weld load, kg 250
load wear index 42
The steel mill grease of Example 38 was further
tested for extreme pressure and wear resistance properties
by the Optimol SRV Test, low temperature flow properties
by the Low Temperature Torque Test, resistance to water by
2olo92~
the Water Washout Test, resistance to rusting under wet
conditions by the Corrosion Prevention Properties Test,
resistance to oil separation by the SDM-433 Oil Separation
Test, and resistance to high temperature breakdown by
Panel Stability Test. The latter test involves applying a
film of controlled thickness to a stainless steel panel.
A draw-down bar and appropriately sized template is used
to accomplish the controlled film thickness 0.065 inches.
The steel panel is then bent into a 30 bend and placed in
an aluminum pan. The entire assembly is then placed in an
oven at the temperatures and for the time indicated below.
The assembly is then removed and allowed to cool to room
temperature. The film of grease is then evaluated for
hardness and consistency. Any oil separation or drainage
from the grease film is noted. Also, any sliding of
grease from the steel panel to the aluminum pan is noted.
This test procedure is well known and commonly used by
those practiced in grease technology and is often used to
measure how a grease will hold up when exposed to very
high temperatures. Test results are given below.
Optimol SRV Stepload Test, Newtons 1,000
Low Temperature Torque Test,
ASTM D1478 at -10F,
Starting Torque, gram-cm5,310
Running Torque, gram-cm 443
Water Washout, ASTM D1264
at 170F, % loss 7.0
Corrosion Prevention Properties,
ASTM D1743
Oil Separations, SDM 433, ~
24 hr, 212F 3.4
24 hr, 300F 2.1
24 hr, 350F 2.0
Panel Stability Test All grease remained on the
at 350F for 24 hr. panel. There was no oil
2ol~24
-
-54-
separation. The grease
remained unctuous, smooth
and pliable. There was
no lacquer formation.
Copper Strip Corrosion,
ASTM D4048, 24 hr, 300F lA
Steel Strip Corrosion,
24 hr, 300F No Discoloration
Results were very good. A very high maximum passing
load on the Optimol SRV test indicated excellent extreme
pressure and wear resistance properties. Oil separation
was low especially at the high temperatures. Acceptable
water washout results and good corrosion/rust prevention
properties were obtained. Low temperature torque at -10F
was good. The most impressive results were obtained on
the Panel Stability Test at 350F. Even after 24 hours
the grease remained pliable and smooth. There was no oil
separation and no lacquer formation on or within the
grease or on the steel panel. The grease was completely
non-agressive, non-reactive, and non-corrosive to both
copper and steel, even after 24 hours at 300F.
Example 39
Yet another grease similar to those of Examples 34-37
was prepared. This time, however, the Nasul BSN and Zinc
Naphthenate was replaced by Nasul BSN HT, manufactured by
King Industries Specialty Chemicals, and Vanlube RI-G,
manufactured by R. T. Vanderbilt Company, Inc. The Nasul
BSN HT is a barium dinonylnaphthalene sulfonate further
stabilized by a complexing agent. The Vanlube RI-G is an
imidazoline material. Final grease composition is given
below.
20~092~
Component ~ (wt)
850 SUS Oil 46.98
350 SUS Oil 31.32
Polyurea Thickener10.00
Tricalcium Phosphate2.00
Calcium Carbonate 2.00
TC 9355
OLOA 9750 1.00
Vanlube RI-G 0.50
Nasul BSN HT 1.50
Lubrizol 5391 0.50
Aryl Amines 0.20
The grease was tested in a manner similar to Examples
34-37 and the following results were obtained.
Worked Penetration, ASTM D217 345
Dropping Point, ASTM D2265, F 520+
Four Ball Wear, ASTM D2266 at
40 kg, 1200 rpm for 1 hr 0.42
Four Ball EP, ASTM D2596
last nonseizure load, kg 80
weld load, kg 315
load wear index 39.7
Optimol SRV Stepload Test, Newtons 600
Low Temperature Torque Test,
ASTM D1478 at -10F,
Starting Torque, gram-cm 3,393
Running Torque, gram-cm 148
U.S. Steel Grease
Mobility Test, S-75,
at -10F, grams/minute
50 PSI 1.86
100 PSI 8.51
150 PSI 15.0
Water Washout, ASTM D1264
2~10924
-
-56-
at 170 F, % loss 11.0
Corrosion Prevention Properties,
ASTM D1743 Pass 1
Corrosion Prevention Properties,
ASTM D1743, 5% Synthetic Sea Water Pass 1
Oil Separations, SDM 433, %
24 hr, 212F 6.5
24 hr, 300F 4.3
24 hr, 350F 4.4
Panel Stability Test All grease remained
at 350F for 24 hr. on the panel. There
was no oil separation.
The grease remained
unctuous, smooth and
pliable. There was
no lacquer formation.
Copper Strip Corrosion,
ASTM D4048, 24 hr, 300F lA
Steel Strip Corrosion,
24 hr, 300F No Discoloration
Results are similar to that of Example 35. Example
39 also gave an acceptable passing result on the ASTM
D1743 Corrosion Prevention Properties Test when modified
to include 5% of a synthetic sea water solution.
Example 40
Another steel mill grease was made similar to the one
of Example 38. However, this time a different blend of
base oils was used to produce a higher viscosity base oil
blend in the final grease. This was accomplished by using
paraffinic bright stock as a third, higher viscosity base
oil. The bright stock had a viscosity of about 750 cSt at
40C. The grease was evaluated in a manner similar to
-57- 2~9~
Example 38. Final grease composition and test data are
given below:
Component ~ (wt)
850 SUS Oil 30.64
350 SUS Oil 30.64
Bright Stock 15.32
Polyurea Thickener12.00
Tricalcium Phosphate2.00
Calcium Carbonate 2.00
TC 9355
OLOA 9750 1.00
Zinc Naphthenate 1.00
Nasul BSN 1.00
Lubrizol 5391 0.50
Aryl Amines 0.20
The grease was tested in a manner similar to Example
38 and the following results were obtained.
Work Penetration, ASTM D217 324
Dropping Point, ASTM D2265, F 500
Four Ball Wear, ASTM D2266 at
40 kg, 1200 rpm for 1 hr 0.45
Four Ball EP, ASTM D2596
last nonseizure load, kg 80
weld load, kg 250
load wear index 36.85
Optimol SRV Stepload Test, Newtons 1,100
Low Temperature Torque Test,
ASTM D1478 at -10F,
Starting Torque, gram-cm 7,375
Running Torque, gram-cm 590
Water Washout, ASTM D1264
at 170F, ~ loss 3.8
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Corrosion Prevention Properties,
ASTM D1743 Pass 1
Oil Separations, SDM 433, %
24 hr, 212F 4.9
24 hr, 300F 3.4
24 hr, 350F 5.9
Panel Stability Test All grease remained
at 350F for 24 hr. on the panel. There
was no oil separation.
The grease remained
unctuous, smooth and
pliable. There was
no lacquer formation.
Copper Strip Corrosion,
ASTM D4048, 24 hr, 300F lA
Steel Strip Corrosion,
24 hr, 300F No Discoloration
Results are similar to that of Example 38, showing
the same excellent qualities.
Examples 41-42
Samples of two commercially available prior art steel
mill greases, an aluminum complex thickened grease and a
lithium complex steel mill grease, were obtained and eval-
uated in a manner similar to the steel mill grease of
Example 38. The lithium complex thickened grease was sold
by Chemtool Incorporated under the trade name Rollube
EP-l. The aluminum complex thickened grease was sold by
Brooks Technology under the trade name Plexalene Grease
No. 725. Test data is tabulated below.
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-59-
Test Grease 41 42
Thickener Type Aluminum Lithium
Complex Complex
Work Penetration, ASTM D217 303 305
Dropping Point, ASTM D2265 511 545
Optimol SRV Stepload Test, Newtons 600 400
Low Temperature Torque Test,
ASTM D1478 at -10 F
Starting Torque, gram-cm 4,278 2,950
Running Torque, gram-cm 1,133 1,033
Water Washout, ASTM D1264
at 170F, % loss 14 3.0
Corrosion Prevention Properties,
ASTM D1743 Fail 3 Pass 1
Oil Separations, SDM 433, %
24 hr, 212F 0.9 4.2
24 hr, 300F 4.6 11.0
24 hr, 350F 17.5 24.8
Copper Strip Corrosion,
ASTM D4048, 24 hr, 300F 4A (Black) 4B (Black)
Steel Strip Corrosion,
24 hr, 300F Black Black
25 Panel Stability Test at 350F Most slid off. Grease turned
at 350F for 24 hr. Lacquer-hard lacquer-hard.
coating
remained.
Both the prior art, conventional aluminum complex and
lithium complex steel mill greases gave poor high temper-
ature oil separation results despite their tacky texture.
The lithium complex grease was especially poor in this
regard. Optimol SRV results for both were much lower than
the grease of Example 38, indicating the superior extreme
pressure and wear resistance properties of Example 38.
20~0924
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Example 41 was also inferior on Water Washout Test, ASTM
D1264 and miserably failed the Corrosion Prevention Prop-
erties Test. Both greases were inferior to Example 38 in
the low temperature running torque. Both greases were
chemically corrosive to copper and steel at 300F. This
is especially bad since grease temperatures will greatly
exceed temperatures of 300F in continuous slab casters.
The lacquering effect so often a problem with aluminum
complex and lithium complex thickened greases was very
obvious in the greases of Examples 41 and 42. Unlike the
grease of Example 38, the greases of both Example 41 and
42 exhibited severe lacquering in the Panel Stability
Test.
Examples 43-44
Two more commercial prior art, conventional steel
mill greases, a lithium 12-hydroxystearate thickened
grease and an aluminum complex thickened grease, were
evaluated in a manner similar to Examples 41 and 42. The
lithium 12-hydroxystearate grease was sold by Chemtool
Incorporated under the trade name of Casterlube. The alu-
minum complex grease was sold by Magee Brothers. Test
data is tabulated below.
Test Grease 43 44
Thickener Type Lithium Aluminum
12-HSt Complex
Work Penetration, ASTM D217 303 316
Dropping Point, ASTM D2265 380 500+
Optimol SRV Stepload Test, Newtons 200 500
Low Temperature Torque Test,
ASTM D1478 at -10F
Starting Torque, gram-cm 5,753 4,278
Running Torque, gram-cm 443 1,180
Water Washout, ASTM D1264
20~0924
-
-61-
at 170F, % loss 10.0 9.3
Corrosion Prevention Properties,
ASTM D1743 Pass 1 Fail 3
Oil Separations, SDM 433, %
24 hr, 212F 6.7 3.1
24 hr, 300F 11.2 6.8
24 hr, 350F 41.8 16.4
Copper Strip Corrosion,
ASTM D4048, 24 hr, 300F lA 4B (Black)
Steel Strip Corrosion,
24 hr, 300F No Discoloration Black
Panel Stability Test at 350F Most slid off. Most slid off.
at 350F for 24 hr. Lacquer-hard Lacquer-hard.
coating coating
remained. remained.
Both the lithium 12-hydroxystearate and aluminum com-
plex thickened steel mill greases gave inferior high tem-
perature oil separation results despite their tacky
texture. The lithium 12-HSt grease was especially unsat-
isfactory in this regard. Optimol SRV results for both
were much lower than the grease of Example 38, indicating
the superior extreme pressure and wear resistance proper-
ties of Example 38. Examples 43 and 44 were also inferior
in Water Washout Test, ASTM D1264 and Example 44 failed
the Corrosion Prevention Properties Test. Both greases
were overall inferior in Example 38 in the Low Temperature
Torque Test. The grease of Example 44 was chemically cor-
rosive to copper and steel at 300F. This is very trou-
blesome since grease temperatures will greatly exceed
temperatures of 300F in continuous slab casters.
Although the grease of Example 43 was not chemically cor-
rosive to copper or steel, it had virtually no extremepressure/antiwear properties, as shown by the very low
maximum passing load on the Optimol SRV Step Load Test.
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-
-62-
The lacquering effect so often a problem with aluminum
complex and lithium complex thickened greases was very
apparent in the greases of Example 43 and 44. Unlike the
grease of Example 38, the greases of Example 43 and 44
exhibited severe lacquering in the Panel Stability Test.
Example 45
A 25,000 pound commercial batch of steel mill grease
with composition similar to that of Example 38 was pre-
pared. The major difference between this grease and that
of Example 38 was in the milling step. In Example 38, the
polymeric additive was blended into the grease with all
the rest of the additives before any milling had occurred.
In Example 45, the grease was cyclically milled for two
average passes without the polymeric additive present.
Just before the final milling pass, when the grease would
be milled out into containers, the polymeric additive was
added and blended into the grease by stirring. Then the
final grease was milled out. By this procedure the polym-
eric additive only experienced one pass through the Gaulin
homogenizer. The resulting grease was evaluated by vari-
ous bench tests; results are tabulated below:
25 Worked Penetration, ASTM D217 313
Dropping Point, ASTM D2265 526
Oil Separations, SDM 433, %
24 hr, 212F 3.8
24 hr, 300F 3.4
24 hr, 350F 4.9
Oil Separation During Storage,
ASTM D1742, % 0.62
Four Ball Wear, ASTM D2266 at
40 kg, 1200 rpm for 1 hr 0.50
Four Ball EP, ASTM D2596
Last Nonseizure Load, kg 80
Weld Load, kg 250
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Load Wear Index 40.1
Fretting Wear, ASTM D4170, 24 hr
mg loss/race set 0
5 Optimol SRV Stepload Test, Newtons 1,200
Optimol SRV Stepload Test, w/5% water,
Newtons 1,100
Water Washout, ASTM D1264
at 170F, % loss 0
10 Corrosion Prevention Properties,
ASTM D1743 Pass 1
Copper Strip Corrosion,
ASTM D4048, 24 hr, 300F lA
Copper Strip Corrosion,
ASTM D4048, 24 hr, 400F lA
Steel Strip Corrosion,
24 hr, 300F No Discoloration
Steel Strip Corrosion,
24 hr, 400F No Discoloration
Low Temperature Torque Test,
ASTM D1478 at -10F
Starting Torque, gram-cm 5,163
Running Torque, gram-cm 295
U.S. Steel Grease
Mobility Test, S-75,
at -10F, grams/minute
50 PSI 0 47
100 PSI 2.40
150 PSI 5.26
Panel Stability Test
at 350F for 24 hr. All grease remained on the
panel. There was no oil
separation. The grease
remained unctuous, smooth
and pliable. There was
no lacquer formation.
-64- 2V~092~
As the test data indicates the novel steel mill
grease of Example 45 had all the.aforementioned desirable
properties without any of the flaws of the prior art
greases of Examples 41-44. Oil separation properties of
the novel steel mill grease of Example 45 were excellent,
even at high temperatures. Good extreme pressure proper-
ties were obtained with the steel mill grease of Exam-
ple 45 while at the same time avoiding any corrosive
tendencies towards copper or steel. Significantly, the
grease provided excellent non-corrosive properties and was
non-corrosive to copper and steel even at 400F. The
grease of Example 45 was far more non-corrosive at 400F
than previously described prior art greases at 300F.
Desirably, the grease of Example 45 had excellent rust
prevention, resistance to water displacement, and thermal
stability, as indicated by the Panel Stability Tests. No
tendency towards lacquer deposition was observed. Low
temperature properties were good. The grease also had
good adhesive-imparting properties.
Example 46
Another batch of steel mill grease similar to that of
Example 45 was prepared and evaluated for elastomer com-
25 patibility. Test results are given below:
Elastomer Compatibility with Polyester
% loss tensile strength 25.6
% loss maximum elongation 15.6
30 Elastomer Compatibility with Silicone
% loss tensile strength 30.6
% loss maximum elongation 22.8
These results taken with the previous test results
given in Example 45 establish this novel grease to be wellsuited for use in general process purpose applications
within steel mills.
21~1~92~
-65-
Example 47
The grease of Example 45 was tested by a large mid-
western steel manufacturer and achieved spectacular
results: (1) a total elimination of all lubricant-related
bearing failures and (2) an 81~ reduction in grease con-
sumption. Advantageously, the grease of Example 45 formed
a hermetic seal around the edges of the mechanical seals
and housings of the bearings and eliminated leakage of
grease. Also, the amount of water mixed in the grease of
Example 45 within the bearings was dramatically reduced
compared to the water levels in the prior art conventional
grease which had been previously used. Water levels in
grease went from more than 30~ to about 3% when the grease
of Example 45 was used.
Example 48
The inventive steel mill grease of Example 47 was
tested in a test for flame resistance. In the ignition
test a rounded ridge of grease is formed by careful use of
a stainless steel spatula. The ridge is formed on the
center of a large circular steel lid to a five gallon
pail. The ridge is approximately 3/4 inch wide at the
base and 3/4 inch high at the top. The ridge is rounded
in cross sectional contour. On top of the grease ridge is
placed a match from an ordinary paper matchbook. The
match is perpendicular to the direction of the grease
ridge so that the match head is on one side of the ridge.
The match is also centered so that an equal length is on
either side of the central axis of the match ridge. The
match is then lit with another lighted match while shield-
ing (blocking) the flame from surrounding air flow (air
currents). As the flame progresses down the match it
eventually contacts the grease.
The grease of Example 47 was repeatedly tested with
the above test. During the test the flame went out when
the flame touched the grease. It generally took between
20iO924
-66-
four to six attempts to ignite the grease. When the
grease ignited, it slowly burned until only oil was left
and then the flame went out. The oil did not ignite.
Example 49
The prior art aluminum complex grease of Example 41
was tested using the test procedure described in Example
48. The grease immediately ignited and burned profusely
as soon as the flame contacted the grease.
Example S0
The prior art lithium complex grease of Example 42
was tested using the test procedure described in Example
48. The grease immediately ignited and burned as soon as
the flame contacted the grease.
Example 51
The conventional lithium 12-hydroxystearate grease of
Example 43 was tested using the test procedure described
in Example 48. The grease melted and flowed when the
flame contacted the grease. When enough grease had melted
away from the lit portion of the match, the match slumped
over until it hit the surface of the steel lid. When this
occurred, the flame was no longer in contact with grease
and subsequently became extinguished.
Example 52
The prior art aluminum complex grease of Example 44
was tested using the test procedure described in Example
48. The grease immediately ignited and burned as soon as
the flame contacted the grease.
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Example 53
To better measure the ignition resistance of grease,
the greases were tested with an ignition resistance test.
~ 5 In the ignition resistance test, a six inch diameter petri
dish is filled with the grease to be tested. The surface
of the grease is struck flush with the glass petri dish so
that a substantially flat circular surface of grease is
obtained. A paper match is placed in the center of the
grease so that it is perpendicular to the grease surface
with the match head just above the grease surface. This
match is referred to as the fuse match. Another match is
placed flat on the grease surface so that its head is up
against the base of the fuse match. The fuse match is lit
and as the flame progresses down, it lights the other
match. If the matches go out without igniting the grease,
then the test is repeated. This time two matches are
placed flat on the grease surface with both of their heads
up against the base of the fuse match. The matches which
are flat on the grease surface are always placed so that
they extend out from each other by a maximum amount. In
the case of two, they extend at an angle of 180. The
fuse match is lit and it in turn lights the two base
matches, causing an even larger initial flame on the sur-
face of the grease then was produced by one base match.In this way the test is repeated, adding more and more
matches until the grease ignites and begins to burn. The
number of matches required to ignite the grease is a meas-
ure of the flammability and ignition resistance of the
grease.
The inventive steel mill grease of Example 47 was
tested with the above test procedure and failed to ignite
and burn even when eight base matches were placed around
the fuse match. This test was repeated several times with
the same result.
201~924
_
-68-
Example 54
The prior art aluminum complex grease of Example 41
was tested by the test procedure described in Example 53.
Ignition failed to occur with one base match. With two
base matches, however, the grease ignites and begins to
burn as oil begins to separate on the grease surface.
Example 55
The prior art lithium complex grease of Example 42
was tested by the test procedure described in Example 53.
Ignition failed to occur with one and two base matches.
With three base matches, however, the grease ignited and
burned as oil began to separate on the grease surface.
Example 56
The conventional lithium 12-hydroxystearate grease of
Example 43 was tested by the test procedure described in
Example 53. Ignition failed to occur with one base match.
With two base matches, however, the grease ignited and
burned as oil began to separate on the grease surface.
The separated oil formed a pool on the surface of the
grease under the base matches. The base matches acted as
a wick and continue to burn, being fed by the hot oil from
the grease.
Example 57
The prior art aluminum complex grease of Example 44
was tested by the test procedure described in Example 53.
Results are similar to that described in Example 54.
Example 58
During extensive testing of the inventive grease of
Example 47 over a 16-month period in a large midwestern
steel mill, no grease fires occurred in contrast to con-
ventional greases which had frequently caused fires in the
2o~0924
-69-
steel mill. Performance of the novel grease was outstand-
ing .
- - - _ _ _ _ _ _ _
Among the many advantages of the novel steel mill
grease and process are:
1. High performance of slab casting units in steel
mills as well as other processing units in steel
mills.
2. Longer life in the caster bearings in steel
mills and substantial reduction in grease con-
sumption.
3. Superior flame and ignition resistance.
4. Excellent resistance to displacement by water.
5. Outstanding protection against rusting even
under prolonged exposure to water.
6. Superior non-corrosivity to copper, iron, and
steel at prolonged high temperatures.
7. Excellent extreme pressure and wear resistance
properties.
8. Oxidatively and thermally stable at high temper-
atures and at lower temperatures.
9. Prevention of lacquer-like deposits.
10. Excellent pumpability at low temperatures.
11. Remarkable compatibility and protection of elas-
tomers and seals.
12. Excellent oil separation qualities, even at high
temperatures.
13. Nontoxic
14. Safe
15. Economical
Although embodiments of this invention have been
described, it is to be understood that various modifica-
tions and substitutions, as well as rearrangements of pro-
'- 2010924
-70-
cess steps, can be made by those skilled in the art
without departing from the novel spirit and scope of this
invention.
