FIELD OF THE INVENTION
The present invention relates to an improved high performance lubricating grease
composition useful for preventing seizure of work roll bearings in stands of cold rolling
mills by effective lubrication and protection of the mating surfaces of the rolling elements
in actual practice through lowering of bearing temperature and minimizing friction and
wear. More particularly the improved high performance lubricating grease composition
comprises at least 75% by weight of base oil, from about 7% to about 15% by weight of
calcium 12-hydroxy stearate soap thickener, from about 6% to about 12% by weight
extreme pressure, anti wear and friction modifier additives, from about 0.2% to about 3%
by weight of a water resistant, high temperature, non-corrosive thermally stable,
adherence-imparting, high performance polymeric additive fully compatible with said
EP-AW additives for substantially resisting displacement by water spray without any
adverse effect on mobility and properties of the grease, from about 0.2% to about 2% by
weight of rust/corrosion and oxidation inhibitors for enhancing the performance and
longevity of said grease.
BACKGROUND OF THE INVENTION
Grease is a non-Newtonian lubricant that under certain loads and within its range of
temperature application exhibits the properties of a solid body, undergoes plastic strain
and starts to flow like a fluid should the load reach the critical point, and regains solid-
body properties after the removal of the stress caused due to application of load.
Lubricating grease is best described as a thickener or gellant diluted by a lubricating
fluid. To improve certain functional properties, additional components are sometimes
included (often called "additives"). This controversial way to define the thickener as
being diluted by a lubricating fluid, rather than the more common way to describe it as
thickening the fluid, comes from recent research. This work shows the active part, the
gellant, at least when being a metal soap, takes in the actual lubrication contact zone.

Lubricating grease properties depend on both its composition and the manufacturing
process used.
The prior art discloses, various lubricating grease compositions adapted for particular
uses.
CN 1252434 described composite lithium- and calcium-base lubricating grease contains
base oil, condensed oil and additives. The condensed oil is compound metallic soap
produced through the reaction of 12-hydroxy stearic acid, decanedioic acid, boric acid
and naphthenic acid with calcium hydroxides (Lime) to generate endothermic reaction,
where the weight proportion among 12-hydroxy stearic acid, decanedioic acid, boric acid
and naphthenic acid.
WO 2008065158 relates to an improvement to lubricating compositions, and in particular
relates to a semi-solid lubricating composition with excellent heat resistance, mechanical
stability, load resistance, water resistance, corrosion resistance and flame resistance.
EP 0995790 discloses titanium complex grease compositions having performance
additives and to a process and compositions thereof. The additives envisaged by the
invention include anti-oxidants, extreme pressure and ant-wear additives, rust inhibitors,
friction modifiers, structural modifiers, polymers, solid lubricants, biodegradable
additives/ash less additives, multifunctional additives etc.
Low Viscous base oil with 140 to 150 cSt at 40°C was in use to lubricate the work roll
bearings. This grease was getting washed out from the bearing pocket as it has a better
flow ability characteristic. The developed grease of the present invention is having a
considerably higher viscosity of the base oil which is more than 350 cSt at 40°C. This
grease is thus has more resistance to flow with decrease fluidity and hence retains in the
bearing pocket because of tachyness. Oil in water emulsion is used to cool the work rolls
during production of cold rolled sheets. This emulsion gets into the bearing once the
seals are broken. It causes wash out of the grease present in the bearing pocket and

subsequently gets mixed up and re-circulates with oil in water emulsion. Grease present
in emulsion burns because of generation of high pressure and temperature during rolling
processes. Sometime this burning of grease causes black patches in the steel strips being
produced in the rolling mill which is considered as a defect in the rolled coil and is a
undesirable phenomenon in cold strip coil production.
Modern cold rolling mill demands better grease to sustain higher rate of production
without compromising in the quality of finished product. The operating temperature of
the mating surface of the bearing goes as high as 100°C. Grease is placed in between the
mating surfaces and viscosity of the lubricant falls with the rise of operating temperature.
Viscosity of the lubricant takes care of the load the bearing is subjected to. The prior art
grease was having a lower viscosity and was susceptible for metal to metal contact
resulting in the failures of bearings. Thus grease with higher base stock was postulated
and developed.
Further in prior art the concept of thickening oils by soaps for lubrication purpose is well
known. The usage of metallic soaps or their complex soaps as thickeners still dominates
in lubricating greases. These metallic or complex metallic soap base greases are generally
derived from metals such as lithium, calcium, sodium, barium, aluminum etc. Calcium
base greases are mainly used probably for their better performance, easily availability and
relatively cheaper. Metallic soaps based on other metals have also been reported in prior
art (C.J. Boner. Ind.Eng.Chem, 29,59,1937).
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. Pat. 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 and 4,514,312. These prior art greases and
processes have met with varying degrees of success. None of these prior art greases and
processes, however, has been successful in simultaneously providing all the above stated
properties at the high performance levels required in cold rolling steel mills.

The disadvantage of the above-mentioned prior art is that the variety of lubricating
greases are not able to meet fully the various requirements of modern high-speed steel
mills. These greases require addition of certain performance additives, which are costly,
and many of them are environmentally unsafe.
Thus there is a need to provide an improved high performance lubricating grease
composition useful for preventing seizure of work roll 4 row taper roller bearings in
Tandem Mill, Skin Pass Mill and Double Cold Reversing rolling mills by effective
lubrication and protection of the mating surfaces of the rolling elements in actual practice
through lowering of bearing temperature and minimizing friction and wear at a
reasonably water ingress.
OBJECT OF THE INVENTION
Basic object of the present invention is to overcome the disadvantages/problems of the
prior art.
Another object of the present invention is to provide an improved high performance
lubricating grease compositions incorporating certain performance additives.
Another object of the present invention is to provide an improved high performance
lubricating grease compositions useful for preventing seizure of work roll bearings in the
mill stands during cold rolling.
Another object of the present invention is to provide an improved high performance
lubricating grease compositions with improved properties of protection of the mating
surfaces of the rolling elements.
Another object of the present invention is to provide an improved high performance
lubricating grease compositions with improved wear and friction properties.

Another object of the present invention is to provide an improved high performance
lubricating grease compositions for preventing rust and corrosion in presence of water
spray and be un-reactive with the bearing materials.
Another object of the present invention is to provide an improved high performance
lubricating grease compositions with good adherence properties as well as resist
displacement by water spray.
Another object of the present invention is to provide an improved high performance
lubricating grease compositions which performs with adequate load bearing capacity in
presence of water.
Still another object of the present invention is to provide novel improved high
performance lubricating grease compositions to retain all these above mentioned
properties during use without exhibiting any adverse effect such as lacquer deposition on
the tapered roller bearing parts due to oxidation, thermal breakdown, discolourisation and
polymerization of the lubricating grease.
SUMMARY OF THE INVENTION
According to one aspect of the present invention there is provided an improved high
performance lubricating grease composition useful for preventing seizure of work roll
bearings in the rolling stands of cold rolling mill comprising:
a) atleast 75 % of a base oil;
b)about 7 % to about 15 % of thickener;
c)performance additives comprising
about 6% to about 12 % extreme pressure ,anti wear , friction modifier
additives and
about 1 % to 5 % of solid lubricant;;

d) about 0.2 % to about 3 % polymeric additive adapted for substantially
resisting displacement by water spray without any adverse effect on mobility
of said grease;
e) inhibitors comprising
About 0.2 % to 2 % of rust/ corrosion agent,
About 0.2 to 2 % of anti seal swell
About 0.6 to 0.8% of metal deactivator and
About 0.5 to 2 % of oxidation inhibitors/anti oxidants for enhancing the
functional performance and longevity of said grease.
DETAILED DESCRIPTION OF THE INVENTION
The present invention relates to an improved high performance lubricating grease
composition useful for preventing seizure of work roll bearings in the stand of cold
rolling mill by effective lubrication and protection of the mating surfaces of the rolling
elements in actual practice through lowering of bearing temperature and minimizing
friction and wear.
The bearings used in the finishing stands of cold rolling mill are 4-row tapered roller type
and the mill operates under high loads and at medium to high speed. The bearing and
grease used to lubricate the components experience a very large load at such a high speed
and also a thermal stress due to friction of bearing elements and to some extent from
radiated heat from steel strip surface during rolling process. To minimize the effect of
radiated and conducted heat on bearings and the heat generated due to high-speed
rotation of bearing under heavy load, cooling is accomplished by high velocity emulsion
spray on the rolls and bearing housing from all directions. With such water spray force,
in absence of seal swell additive package even well sealed bearings will not totally
exclude water ingress. Therefore, the bearing grease will experience water contamination
with a physical force that tends to wash the grease out of the bearings.

Yet another object of this intention is to drive the ease of flow of the grease into the
bearing pockets for better grease dynamics.
High performance grease is important to minimize failure of bearings used in work roll.
Such bearing failures cause sudden breakdown of the mill that can endanger operating
personnel, interrupt steel mill operations with more work load to maintenance personnel,
cause damage or loss of production, raise lubricant consumption and make shop floor
dirty.
The improved high performance grease used to lubricate such bearings under such
operating conditions of cold rolling mill has:
a) reduce wear and friction;
b) prevent rust and corrosion in presence of water spray and be un-reactive with
the bearing materials;
c) have good adherence properties as well as resist its displacement by water
spray;
d) retain these properties during use without exhibiting any adverse effect such
as lacquer deposition on the tapered roller bearing parts due to oxidation,
thermal breakdown and polymerization of the lubricating grease.
e) Produce clean and defect free cold rolled coils as to restrict intermixing of
grease and cooling oil in water emulsion which a likely cause of black patch
generation in CR coils
The developed improved high performance grease has:
a) A substantial proportion of a base oil;
b) A sufficient amount of thickener,;
c) 8% to 16%of performance additives comprising
extreme pressure ,anti wear, friction modifier additives and
solid lubricant;;
d) A sufficient amount of a high temperature, non-corrosive thermally stable
,water resistant, adherence-imparting polymeric additive adapted for

substantially resisting displacement by water spray without any adverse
effect on mobility of said grease;
e) 0.5% to 2.5% of inhibitors comprising
rust/ corrosion agent,
anti seal swell
0.6% to 0.8% metal deactivator and
oxidation inhibitors/anti oxidants ,said inhibitors adapted for enhancing
the functional performance and longevity of said grease.
The preferred improved lubricating grease composition comprising by weight at least
75% base oil, from about 7% to about 15% lithium-calcium 12-hydroxy stearate soap
thickener, from about 6% to about 12% extreme pressure, anti wear and friction modifier
additives, from about 0.2% to about 3% of a water resistant, high temperature, non-
corrosive thermally stable, adherence-imparting, high performance polymeric additive
fully compatible with said EP-AW additives for substantially resisting displacement by
water spray without any adverse effect on mobility of the grease, from about 0.2% to
about 2% of rust/corrosion, oxidation inhibitors and seal swell additives for enhancing
the performance and longevity of said grease.
The lubricating grease composition has been prepared consisting of the ingredients with
proportions as described below in Table 1:

The improved lubricating grease prepared according to the above composition exhibited
the physico chemical characteristics indicated in the Table 2.

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.
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
esterifying 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 alcohol,
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 a mixture of a refined solvent extracted hydrogenated
dewaxed base stock derived from paraffinic, naphthenic or mixed base crudes and having
viscosity of 320 est to 360 est at 40°C.
Thickener
Ideally, the thickener improves the lubricating properties, by building a thicker film at the
lubricated surfaces than can be achieved with the included fluid alone. At the same time,
it is necessary to have lubricating grease that can replenish itself into the contact area
through microscopic flow behavior for better dynamics. When using lubricating greases
that are subjected to very high centrifugal acceleration forces, it becomes evident that the
density of the thickener is important for the degree of separation. The smaller the
difference between thickener and fluid, the less the separation will be, even at extreme
conditions.
The preferred thickener in the present composition is calcium complex 12-hydroxy
stearate soap thickener, 12-hydroxy stearic acid, in its refined fatty acid form or as the
triglyceride (hydrogenated castor oil), is the most commonly used anion, several other
anions are used. Tallow, lard, stearic acid, oleic acid and many other fatty acids or fats
are used either as the major anion or as modifiers for the desired soap structure.
Inhibitors
The additive package may be complemented by the addition of small amounts of an
antioxidant, a corrosion-inhibiting agent, an anti seal swell and a metal deactivator.
Oxidation inhibitor prevents varnish and sludge formation and oxidation of metal parts.
The anti oxidant used in this invention is of aminic type, alkylated phenyl or
diphenylamine.
Corrosion inhibiting agent prevents rusting of iron by water, suppress attack by acidic
bodies and form protective film over metal surfaces to diminish corrosion of exposed
metallic parts. Anti-rust and anti-corrosion agents used are neutral metallic salt of
dinonyl naphthalene sulphonate and metal alkyl dithiocarbamate.
Metal deactivator prevents or diminishes copper corrosion and counteracts the effects of
metal on oxidation by forming catalytically inactive compounds with soluble or insoluble
metal ions. Typical metal deactivators used include mercaptobenzothiazole and complex
organic amines.
Polymer
Polymer, which is used in the above-developed grease to attain the desired characteristics
described in the table, has molecular weight in the range of 3,00,000 to 5,00,000.
Acceptable polymers for attaining many of the grease characteristics described above
include: polyolesters (polyesters), polyamides, polyurethanes, polyoxides, polyamines,
polyacrylamide, polyvinyl alcohol, ethylene vinyl acetate, and polyvinyl pyrrolidone.
Copolymers with monomeric units comprising the monomeric units of the preceding
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 material) may also be used when nucleophilic sites are
available for boration. The preferred polymer comprises: polyethylene, polypropylene,
poly isobutylene and ethylene-propylene copolymers.
Performances Additives
The extreme pressure and anti wear additives, friction modified and solid lubricant
additives can be selected from one or more of the following:
1)Sulfurized oxymolybdenum organo phosphorodithioate;
2) Organomolybdenum dithiocarbamate;
3) Zinc or other metal dialkyl dithiophosphate or carbamate;
4) Colloidal Grapahite;
5) Molybdenum disulphide.
Different embodiments of the invention are possible to achieve the best method of
performance and to obtain the product as stated above to meet the object of the invention.
It will be understood that skilled persons with many modifications, variations and
adaptations may carry out the invention into practice without departing from its spirit or
exceeding the scope of claims in describing the invention for the purpose of illustration.
WE CLAIM
1. An improved high performance lubricating grease composition useful for
preventing seizure of work roll bearings in the rolling stands of cold rolling mill
comprising:
a) atleast 75 % of a base oil;
b)about 7 % to about 15 % of thickener;
c)performance additives comprising
about 6% to about 12 % extreme pressure ,anti wear , friction modifier
additives and
about 1 % to 5 % of solid lubricant;;
d) about 0.2 % to about 3 % polymeric additive adapted for substantially
resisting displacement by water spray without any adverse effect on mobility
of said grease;
e) inhibitors comprising
About 0.2 % to 2 % of rust/ corrosion agent,
About 0.2 to 2 % of anti seal swell
About 0.6 to 0.8% of metal deactivator and
About 0.5 to 2 % of oxidation inhibitors/anti oxidants for enhancing the
functional performance and longevity of said grease.
2. Improved high performance lubricating grease composition as claimed in claim 1,
wherein said base oil comprises a mixture of Ester and refined solvent extracted
hydrogenated dewaxed base stock derived from paraffinic, naphthenic or mixed
base crudes.
3. Improved high performance lubricating grease composition as claimed in claims 1
and 2, wherein said base oil is having viscosity in excess of 320 cSt at 40°C
preferably 30 cSt at 100 °C.
4. Improved high performance lubricating grease composition as claimed in claim 1,
wherein said thickener comprises calcium soap of fatty acids or a mixture of
lithium-calcium soap of fatty acids.
5. Improved high performance lubricating grease composition as claimed in claims 1
to 4 having drop point in excess of 290 °C
6. Improved high performance lubricating grease composition as claimed in claim 1,
wherein said performance additives selectively comprises one or more
comprising Sulfurized oxymolybdenum organo-phosphorodithioate,
Organomolybdenum dithiocarbamate, Zinc or other metal dialkyl dithiophosphate
or carbamate, Colloidal Grapahite,Molybdenum disulphide.
7. Improved high performance lubricating grease composition as claimed in claim 1,
wherein tsaid corrosion inhibiting agent comprises anti-rust and anti-corrosion
additives selected from group of neutral metallic salt of dinonyl naphthalene
sulphonate polyacrylate polymerwhich can stand a temperature range of 150 to
175°C and metal alkyl dithiocarbamate.
8. Improved high performance lubricating grease composition as claimed in claim 1,
wherein said metal deactivator additives selectively comprise
mercaptobenzothiazole and/or complex organic amines.
9. Improved high performance lubricating grease composition as claimed in claim 1,
wherein said anti oxidant additives are selected from the group of aminic type, or
diphenylamine.
10. Improved high performance lubricating grease composition as claimed in claim 1,
wherein said polymeric additives are selected from group of polyethylene,
polypropylene, poly isobutylene and ethylene-propylene copolymers.
11. Improved high performance lubricating grease composition as claimed in claim 1,
wherein said anti seal swell additives are Polyacrylates.
12. An improved high performance lubricating grease composition useful for
preventing seizure of work roll bearings in the rolling stands of cold rolling mill
substantially as herein described.

The present invention relates to an improved high performance lubricating grease
composition comprises at least 75% by weight of lubricating base oil, from about 7% to
about 15% by weight of calcium 12-hydroxystearate soap thickener, from about 6% to
about 12% by weight extreme pressure, anti wear and friction modifier additives, from
about 0.2% to about 3% by weight of a water resistant, high temperature, non-corrosive
thermally stable, adherence-imparting, high performance polymeric additive fully
compatible with said EP-AW additives for substantially resisting displacement by water
spray without any adverse effect on mobility of the grease, from about 0.2% to about 2%
by weight of rust/corrosion, anti-seal swell and oxidation inhibitors for enhancing the
functional performance and longevity of said grease.