FIELD OF THE INVENTION .
To develop an optimized composition used for lubricating Marine Cylinder. BACKGROUND OF THE INVENTION
Low speed two stroke crosshead diesel engines are generally used as prime movers on ships, the term low speed is applied to engines having a rotational speed of up to 300 rpm and output per cylinder between' 400 Kilowatts to 6000 Kilowatts generally. In these types of engines the piston is not connected to the crankshaft directly with the connecting rod but an . additional member called the crosshead is provided. The piston has a long piston rod which sits on the crosshead. The crosshead converts the linear motion of the piston into the rotational motion of the crankshaft with the help of the connecting rod. The piston rod reciprocates up and down through the stuffing box which seals the crankcase from the under-piston space. The function of the crosshead is that it absorbs the transverse thrust of the engine. The isolation of the crankcase allows lower cost residual fuels to be burnt without the fear of any fuel contamination of the lubricating oil of the crankcase.
The piston rings on the liner surface mostly operate under boundary or thin film lubrication conditions. The high operating temperature, pressure, and the presence of a corrosive environment make the working condition very harsh. The two stroke crosshead type of marine diesel engines burning residual fuel provides the largest percentage of propulsive power for ships globally.
Over eighty percent of total lubricant consumption is on cylinder oil alone and it represents a major expense in the daily operation of the engine. Also over the years, engine developments aimed at giving higher output per cylinder and adapting the engine to burn ever deteriorating fuel grades have worsened the problem of cylinder liner lubrication. The liner average surface temperature has increased from 200 degrees C to 275 degrees C from the 1970s to the 2000s,

thus making lubrication more difficult. Similarly the maximum pressure and mean effective pressure also have increased drastically.
From the mechanical point of view, the working conditions are about the worst possible for the establishment of hydrodynamic lubrication. The piston slows to rest before reversing direction on the return stroke. Thus at top dead center where the temperature is at maximum and also the radial pressure of the rings on the walls is highest, the piston slows down. Under such extreme conditions it is impossible for hydrodynamic conditions to exist except perhaps about mid-stroke.
Gas temperature exceeding 1667 degrees Celsius are encountered at the beginning of the firing stroke and the local temperature may be appreciably higher if the combustion is poor resulting in flame impingement on cylinder walls. The temperature of water cooled liner surface varies from 230 degrees C to 120 degrees C depending upon the design. Engine developments from the 1960s to the 2000s have led to higher average temperatures of liners in the upper zone (about 270 degrees C), which has also made lubrication difficult. Cylinder lubricant is injected into each cylinder to provide a uniform film of lubricant on the liner wall. The main purposes of the lubricant are to ensure the basic functions of lubricating the piston and liner, and sealing the gap between piston ring, piston and liner wall. The additive package in the cylinder lubricant maintains the stability of the lubricant neutralizes acid condensation on the liner wall and scavenges fuel and lubricant debris The condition of the lubricant changes as it proceeds from the point of injection until the drain. The change in the characteristics of the lubricant reflects the conditions of combustion and lubrication in each cylinder. Type of Oil Used in Cylinder Lubricating System
Solvent refined base oils are commonly called Group I base oils which are characterized as = M those)r|a\fing les^than percentsaturate,;; (^tp^e/cen^aromatics^apd^pre than 300 ppm

sulfur. To maintain viscosity it is required to use significant amounts of bright stock However, the use of bright stock is not desirable because of the presence of oxidatively unstable aromatics".
Typically, marine cylinder lubricants for use in marine diesel engines have a viscosity in the range of 16.5 to 25 centistokes (cSt) at 100° C. In order to formulate such a lubricant, a brightstock is combined with low viscosity oil, e.g., oil having a viscosity from 10 to 12 cSt at 100° C. However, supplies of bright stock are in a slow decline and therefore bright stock cannot be relied upon to increase the viscosity of marine cylinder lubricants to the range of 16.5 to 25 cSt at 100° C. that manufacturers recommend. In addition, Hart's Lubricant World, September 1997, pp. 27-28, (referenced in EP 1967571) discloses that "Due to low-operating speeds and high loads in marine engines, high viscosity oils (SAE 40, 50, and 60) typically
are required.
The cylinder lubricant must be of a higher viscosity so that it can form a good lubricating
film between the liner and the piston rings.
It must also withstand the heat variations in the combustion area and must deal with the combustion products.
Using the Correct Feed Rate for Cylinder Lubrication
Once the correct lubricating oil is chosen the correct feed rate must be established in accordance with the engine builder's recommendations.
The feed rate has a critical effect on good engine operation apart from the question of oil consumption. With a too low feed rate the danger of the oil film breaking down causing blow by or additional wear is increased.
Too high a feed rate results in excessive consumption and is not cost effective. The correct
feed rate will allow the formation of the lubricating film between the liner and the rings and
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Effect of Under Lubrication and Over Lubrication of Cylinder
A correct viscosity is important in order to ensure the spreadability of the cylinder oil, and the applied feed rate and injected amount of oil per stroke are key factors in the delicate balance between under- lubrication and over- lubrication:
If too little cylinder oil is supplied, starvation will occur which might result in corrosion, accumulated contamination from unburned fuel and combustion residues, and in the worst case, metal to metal contact, known as "scuffing".
If too much cylinder oil is supplied, the loss of fresh, unused oil into the scavenge space will be high, and the piston rings might be prevented from moving (rotating) in their grooves by the so called "hydraulic lock".
Furthermore, the cylinder liner running surface structure might over time become closed and smooth like a mirror, and will no longer be able to retain the lubricating oil. This is sometimes called "chemical bore polish", and when alkaline deposit build-up on the piston top land from excessive cylinder oil is in contact with the cylinder liner running surface, it can cause what is sometimes called "mechanical bore polish". All of these phenomena might eventually result in scuffing.
Cylinder lubricant is injected into each cylinder to provide a uniform film of lubricant on the liner wall. The main purposes of the lubricant are to ensure the basic functions of lubricating the piston and liner, and sealing the gap between piston ring, piston and liner wall. The condition of the lubricant changes as it proceeds from the point of injection-until the drain. The change in the characteristics of the lubricant reflects the conditions of combustion and lubrication in each cylinder.
Reference can be made to US Patent Application 20080287327 which discloses about a
method of lubricating a marine diesel engine, comprising supplying to said engine a marine
N diese^^ylii^erlubriQa^cgni^sHitjin a^^eedfjr^epf^J^ess^h^n. l^g/kW hr, wherein

said lubricant composition has a ratio of I (wt % overbased detergent)/£(wt % of boron from antiwear additives + wt % of phosphorus-containing antiwear additives) of greater than 12.5. Reference can be made to European Patent 1486556 which discloses a marine diesel cylinder lubricant composition for a marine diesel engine running on fuel having a sulphur content of less than 1.5%, the composition, having a total base number, as determined according to ASTM D2896, of more than 30 and less than 70, and comprising:
At least 40 wt% of an oil of lubricating viscosity, and at least one detergent prepared from at least two surfactants, one of which is a salicylate.
The inventor has found that the marine diesel cylinder lubricant composition defined above is capable of preventing deposit formation, particularly on the pistons, and is also capable of improving resistance to high temperature-induced wear.
Reference can be made to US Patent Application 20150126422 which discloses about a marine diesel cylinder engine lubricating oil composition is provided which comprises (a) a major amount of one or more Group II basestocks, and (b) a detergent composition comprising (i) one or more alkaline earth metal salts of an alkyl-substituted hydroxyaromatic carboxylic acid having a total base number (TBN) of greater than 250, and (ii) one or more high overbased alkyl aromatic sulfonic acids or salts thereof; wherein the aromatic moiety of the alkyl aromatic sulfonic acids or salts contains no hydroxyl groups; and wherein the marine diesel cylinder lubricating oil composition has a TBN of about 5 to about 120.
NEED OF THE INVENTION
Requirement of Marine Cylinder oils is that they should be able to maintain the balance
between viscosity and film thickness hence the proposed marine cylindrical lubricant should
be thin enough to spread quickly over the cylinder surface but yet thick enough to provide a
: M -continuous ^y^dymai^ film, Jhat wi{l jpj e^vapo/ajeppff -the yaljs. 0f the upper cylinder

when exposed to high combustion temperatures. This makes cylinder lubrication in case of marine cylinder critical, and any deficiency in it may lead to failure of the engine. To overcome the above shortcomings it was required to develop a formulation which improves the oiliness and helps in maintaining the requisite oil film thickness without using a bright stock into the formulation.
OBJECTIVE OF THE INVENTION
The principal object of the present invention is to provide a formulation package for Marine
Cylinder Lubricant which is devoid of bright stock.
Another objective of the present invention is to provide adequate viscosity at high working
temperatures and still be sufficiently fluid to spread over the entire working surfaces to form
a good adsorbed oil film.
Another objective of the present invention is to provide new formulation packages that
reduce sliding friction, thereby minimizing metal to metal contact and frictional wear.
Another objective of the present invention is to provide an effective seal in conjunction with
the piston rings, preventing gas blow by and burning away of the oil film and lack of
compression.
Another objective of the present invention is that it must burn cleanly, leaving as little and as
soft a deposit as possible.
Another objective of the present invention is to provide a cost effective marine cylinder
lubricant.
Yet another objective of the present invention is to effectively neutralize the corrosive effects
of mineral acids formed during combustion of the fuel.

SUMMARY OF THE INVENTION
The present invention comprises a new formulation devoid of Bright Stock which is effective to provide adequate viscosity at high working temperatures and still be sufficiently fluid to spread over the entire working surfaces of marine cylinder to form a good adsorbed oil film.
DETAILED DESCRIPTION OF THE PRESENT INVENTION
Various preferred features and embodiments will be described below by way of non-limiting illustration.
The present, invention provides a new formulation devoid of Bright Stock which is effective to provide adequate viscosity at high working temperatures and still be sufficiently fluid to spread over the entire working surfaces of marine cylinder to form a good adsorbed oil film. It has been found that the marine cylinder oil of the present invention achieves a comparable viscosity to that of prior art blends but reduces the high viscosity lubricating oil (e.g. bright stock oil) component, this substantially reduces the cost of the finished marine cylinder oil. Component A (Detergents)- Metal Sulphonate Detergent
Overbased detergents are known in the art. Overbased materials otherwise referred to as overbased or superbased salts are generally single phase, homogeneous systems characterized by a metal content in excess of that which would be present for neutralization according to the stoichiometry of the metal and the particular acidic organic compound reacted with the metal. The overbased materials are prepared by reacting an acidic material (typically an inorganic acid or lower carboxylic acid, typically carbon dioxide) with a mixture comprising an acidic organic compound, a reaction medium comprising at least one inert, organic solvent (mineral oil, naphtha, toluene, xylene, etc.) for said acidic organic material, a stoichiometric excess of a metal base, and a promoter such as a calcium chloride, acetic acid, phenol or

Overbased sulphonates typically have a TBN of 250 to 600 mg KOH/gm, or 300 to SOO.The
metal sulphonate detergent may be an alkaline earth metal or alkali metal sulphonate. For
example the metal may be sodium, calcium, barium, or magnesium. Typically other detergent
may be sodium, calcium, or magnesium containing detergent (typically, calcium, or
magnesium containing detergent). In one embodiment the metal may be calcium.
Alkaline Earth Metal Phenol-Based Detergent
Phenate detergents are typically derived from p-hydrocarbyl phenols. Alkylphenols of this
type may be coupled with sulfur and overbased, coupled with aldehyde and overbased, or
carboxylated to form salicylate detergents. Suitable alkylphenols include those alkylated with
oligomers of propylene, i.e. tetrapropenylphenol (i.e. p-dodecylphenol or PDDP) and
pentapropenylphenol. Suitable alkylphenols also include those alkylated with oligomers of
butane, especially tetramers and pentamers of n-butenes. Other suitable alkylphenols include
those alkylated with alpha-olefins, isomerized alpha-olefins, and polyolefins like
polyisobutylene.
Detergent may be chosen from a non-sulphur containing phenate, a sulphur-coupled phenate,
a salixarate, a salicylate, a saligenin, and mixtures thereof.
Component B (Dispersant)-
The lubricating oil composition may comprise 1 to 20 % by weight active dispersant additive.
Suitable dispersant additives comprise one or more oil soluble polymeric hydrocarbon
backbones, each having one or more functional groups which are capable of associating with
particles to be dispersed. The functional groups may be amine, alcohol, amide, or ester
groups.
Suitable dispersants are for example polyisobutylene succinic anhydride polyamines (also
sometimes referred to as PIBSA polyamines or PIBSA PAM).

The preferred dispersant used in the formulation are for example polyisobutylene succinic anhydride polyamines (also sometimes referred to as PIBSA polyamines or PIBSA PAM). The oil soluble polymeric hydrocarbon backbone is typically an olefin polymer, especially a polymer comprising of a C2 to C18 olefin, typically of a C2 to CIO olefin. The oil soluble polymeric hydrocarbon backbone may be a homopolymer or a copolymer of two or more olefins. A preferred class of olefin polymers is polybutylenes and more preferably, polyisobutylenes. Other preferred classes of olefin polymers are ethylene alpha-olefin copolymers, alpha-olefin homopolymer and alpha-olefin copolymers. The oil soluble polymeric hydrocarbon backbone usually has a number average molecular weight (Mn) in the range of 300 to 15,000, preferably 500 to 10,000, more preferably 700 to 5,000. The molecular weight may be determined by gel permeation chromatography. Component C (Polymer)-
Suitable compounds are polymeric or oligomeric compounds. Most suitable are polymeric or oligomeric compounds including mono- and polycarboxylic acid, for example, mixed C3-C20 fatty acid therefore can be, but not limited to adipic acid, lauric acid, myristic acid, palmitic acid, stearic acid, octanoic acid, pelargonic acid, behenic acid, Iignoceric acid, linoleic acid, usnic acid, stearidonic acid, arachidonic acid, ricinoleic acid, capric acid, decanoic acid, gadoleic acid, myristoleic acid, palmitoleic acid, oleic acid, petroselenic acid, esters thereof or a plurality of fatty acids obtained from a natural resource, for example tallow fat, or soya oil, or coconut oil, or sunflower' oil (oleic) and mixtures thereof along with hydrocarbyl-substituted carboxylic acid or anhydride, for example, polyisobutylene succinic anhydride, the polymer also contains polyalcohols of the group consisting of ethylene glycol, propylene glycol, glycerol, trimethylolpropane, pentaerythritol, diethanolamine, triethanolamine and hypophosphorus acid.

Other Performance Additives-
The lubricating composition optionally contains at least one other performance additive. Typically the other performance additives include metal deactivators, defoamers, dispersant, antioxidants, antiwear agents, corrosion inhibitors, antiscuffing agents, extreme pressure agents, foam inhibitors, demulsifiers, friction modifiers, viscosity modifiers, pour point depressants and mixtures thereof. Typically, fully-formulated lubricating oil will contain one or more of these performance additives. Base Oils-
The term "Group I base oil" as used herein refers to a petroleum derived lubricating base oil having a saturates content of less than 90 wt. % (as determined by ASTM D 2007) and/or a total sulfur content of greater than 300 ppm (as determined by ASTM D 2622, ASTM D 4294, ASTM D 4297 or ASTM D 3120) and has a viscosity index (VI) of greater than or equal to 80 and less than 120 (as determined by ASTM D 2270).
In general, a Group II base oil and Group III base oil can be any petroleum derived base oil of lubricating viscosity as defined in API Publication 1509, 14th Edition, Addendum 1, December 1998. API guidelines define a base stock as a lubricant component that may be manufactured using a variety of different processes. Group II base oils generally refer to a petroleum derived lubricating base oil having a total sulfur content equal to or less than 300 parts per million (ppm) (as determined by ASTM D 2622, ASTM D 4294, ASTM D 4927 or ASTM D 3120), a saturates content equal to or greater than 90 weight percent (as determined by ASTM D 2007), and a viscosity index (VI) of between 80 and 120 (as determined by ASTM D 2270).
Group III base oils generally have less than 300 ppm sulfur, saturates content greater than 90 weight percent, and a VI of 120 or greater. In one embodiment, the Group III base stock

contains at least about 95% by weight saturated hydrocarbons. In another embodiment, the Group III base stock contains at least about 99% by weight saturated hydrocarbons.
EXAMPLES
Example - 1 HIGH FREQUENCY FRICTION MACHINE (HFFM)
The test is based upon the well-known Cameron-Plint TE-77 high frequency friction machine (HFFM) ball-on-plate configuration in which a moving Dia 10 mm ball specimen (52100) is reciprocated against a stationary plate (A1SI 52100). As test specimen a steel plate of closely specified hardness and surface finish was selected. The plate is immersed in oil & preheated to 80°C. A specific load of 200 N is applied on the ball. The temperature is gradually raised from 80°C to 200°C. The reciprocating frequency is kept constant throughout the run in &
test. The resulting friction force, contact potential and the wear scar diameter at the end of the
LltfJl^EJSJLi^_CJ±EJ&.l^ r7r-
test are captured. Depending on the contact potential developed in the rig the nlm formation

capacity of the oil at a certain temperature during the test sequence can be verified. The test is based upon the well-known Cameron-Plint TE-77 high frequency friction machine (HFFM) ball-on-plate configuration in which a moving Dia 10 mm ball specimen (52100) is reciprocated against a stationary plate (AISI 52100). As test specimen a steel plate of closely specified hardness and surface finish was selected. The plate is immersed in oil & preheated to 80°C. A specific load of 200 N is applied on the ball. The temperature is gradually raised from 80°C to 200°C. The reciprocating frequency is kept constant throughout the run in & test. The resulting friction force, contact potential and the wear scar diameter at the end of the test are captured. Depending on the contact potential developed in the rig the film formation capacity of the oil at a certain temperature during the test sequence can be verified. Further, using above mentioned components (Table-1) a series of formulation were prepared and labelled as example-1, example-2 and example-3 along with comparative example-1, comparative example-2 and comparative example-3 and inventive examples from A to C, the corresponding data generated for the examples are represented from table-2 to table-4 as described below.