SHEET ROLLING IN TANDEM MILLS

FIELD OF THE INVENTION

[01] This invention relates in general to lubricating oils and in particular to a composition of oil suitable for steel rolling. The oil can form a metastable emulsion with water and separates oil, cream or their mixture during rolling application. The oil composition shows good lubrication, load carrying and reduction properties and is useful for steel cold rolling, particularly for thin or thick gauge steel rolling in high speed tandem rolling mills. Several optimum rolling emulsion properties are found to be required for the above lubrication properties.

BACKGROUND OF THE INVENTION AND PRIOR ART

[02] Lubricants play a very important role in any process of metal forming.

Lubrication varies widely, depending upon the metal processing involved. Cold rolling of steel is widely practiced by numerous manufacturers of rolled steel products, which are in a very price- sensitive market. In this era of rapidly increasing lubricant costs and competition between different suppliers, efforts must be made for maximum utilization of cold rolling lubricants. Steel is required for almost all types of industrial, construction and daily use. Cold rolling oil for steel is therefore used in significant volumes by steel mills. Its performance and particularly lubrication properties are critical to the proper rolling of steel, maintaining good shape and surface cleanliness of steel sheet. Good lubrication also removes iron particles (generated during rolling) from the surface. Good lubrication also helps the user to reduce cost of production and lower power consumption of steel rolling process. This can be achieved by a metastable cold rolling emulsion with good oil separation property during rolling. Poor lubrication leads to oil residue left on the steel sheet after rolling, which is converted into black powdery material during annealing treatment and it poses difficulties in next operations like coating, painting, etc. Now-a- days steel industry demands rolling oils with lower oil consumption, good lubrication and surface cleaning properties. [03] In the rolling process, the thickness of the strip is reduced by the action of stretching from side and loading from the top. The roll coolant provides both lubrication as well as cooling characteristics during rolling. The oil and water separate in the roll bite and provide lubrication and cooling characteristics respectively. After rolling, the oil and water again mix forming emulsion and is re-circulated through pipes, coolant tanks and rolling mill. Oil and water must be separated at the roll bite for good lubrication and cooling property. Thus the rolling oil must form a metastable (loose) emulsion, otherwise the oil and water will not separate properly. This leads to poor lubrication and cooling as well, which is in the case of tight emulsion.

[04] Composition of rolling oils are quite complex. The performance or nonperformance of rolling oil becomes quickly evident during its use in rolling mills. The performance of water-soluble rolling oils is dependent on several parameters e.g., additives, saponification value of oil, water quality, emulsion characteristics e.g., oil separation (metastability) characteristics, Emulsion Stability Index (ESI) and rolling plant parameters, work roll hardness and quality of materia] to be rolled, its hardness etc and handling practices adopted at the mill site. The rolling operation becomes more complex and difficult within few days of operation as contaminations (tramp oil) and iron fines mix with the roll coolant as the actual mill starts, which require corrective actions. The factors affecting the performance of rolling oils are multi-faceted and require special attentions of the formulator as well as user. Performance of the same oil may vary significantly from one use to other depending upon the metastability of emulsion, metallurgy and maintenance practices.

[05] In rolling operation, a liquid coolant (emulsion) obtained by emulsifying and dispersing a suitable concentration of rolling oil in water (50-60°C) by means of mechanical agitation in a tank is sprayed on work rolls for cooling and the surface of steel sheets for lubrication and the coolant is re-circulated through magnetic separator, filter and tanks as per requirement of the thickness of final sheet.

[06] The oil composition of the rolling oil depends on the customer requirement and is mill specific. The plant may be slow, medium or high speed. Depending upon the mill speed, load, quality of water, stirring rate of the coolant, the formulation of the rolling oil also changes to a great extent. The formulation variations are observed in terms of saponification value/fat and synthetic ester content, extreme pressure additives, quantity and quality of emulsifier, dispersant, antifoam etc. Keeping all the above parameters constant, the formulation performance finally depends on the stability/metastability/ESI of the roll coolant. The lubrication requirement also changes from mill to mill depending upon the final thickness of the rolled sheet.

[07] The lubricity, load carrying capacity, % reduction and surface cleanliness property are some of the most important characteristics of a cold rolling oil formulation. The lubricity property of a cold rolling oil formulation is dependent probably on parameters like the lubricating additives selected, saponification value and the metastability of the O/W emulsion i.e., oil separation property. The metastability, oil separation from rolling emulsion and lubrication characteristics are highly correlated and a linear correlation exists between them. But they are measured in different scale. A stable and tight emulsion brings about insufficient lubrication. Although oil separation/metastability are the desirable properties, the extreme values of these properties are also not desired as these lead to unstable emulsion as well as high oil consumption during rolling. So an optimum quantity of oil separation/metastability is required for a good cold rolling oil. In this study we have measured the metastability as a function of oil separation which is better to define. The cold rolling oil emulsion may be a tight emulsion without much oil separation. This is not a desirable characteristic for lubrication. Actually a cold rolling oil emulsion requires a "metastable" emulsion (stable to loose emulsion with to some extent oil or mixture of oil and cream separation characteristics). The metastable emulsion separates oil to some extent at the roll bite and the separated oil takes care of the lubrication property and just after the rolling operation the oil and water mix together to form the emulsion again which is possible as the separated oil also contains emulsifiers. Thus the measurement of emulsion stability, oil separation and metastability is an important criterion for rolling oil emulsion.

[08] The lubrication property during rolling is probably the most important criterion and basic requirement for good cold rolling oil. In actual customer site, % reduction during rolling, the surface cleanliness property and iron pick up mark of cold rolling oil are dependent on proper lubrication. The burn off characteristics is the laboratory measured property which correlates with the good surface cleanliness property of the rolled sheet. The lubrication characteristic can be assessed by falex jaw load, Roll Specific Force (RSF) and % reduction. Good lubrication also relates to good surface cleanliness properties, no iron pick up mark after annealing of the cold rolling process. [09] US Patent 6,497,127 discloses the method for supplying rolling oil for cold rolling. US Patent 7,260,968 describes cold rolling oil systems e.g., tank pumps, filter for multi stand tandem rolling mill and two independent cooling and lubricating system. US Patent 5,919,707 discloses the monitoring of active ingredient of rolling oil emulsions by peak absorbing wavelength of a dye. US Patent 5,282,376 describes the method and apparatus for lubricating metal strip with an oil-water emulsion.

[10] US Patent 4,346,014 discloses a specific cold rolling oil containing a nitro compound which produces smut free steel sheet after batch annealing. US Patent 4,152,916 discloses a rolling oil emulsion containing stabilized silicic acid solution for the processing of steel strip. US Patent 4,390,438 describes a rolling oil formulation which used a dibasic acid along with other ingredients refined animal fat, minor portions of lubricity additives, antioxidants, emulsifiers and other additives to reduce the friction coefficient of the formulation. US Patent 4,693,839 discloses a rolling oil composition which comprises a composition containing a water soluble cationic or amphoteric compound gives a stable size distribution of large sizes for better lubrication and rolling performance.

[1 1] US Patent 5,122,288 discloses a rolling oil composition which includes a combination of polymeric nonionic surfactant and a nonionic surfactant to increase the dispersion and anti-coalescence property of emulsified oil particles. The invention of US Patent 4,666,617 describes cold rolling oil formulation with oil soluble high molecular compound.

[12] US20050011243 describes use of oil and emulsion for cold rolling of strips in a multi-stand tandem rolling mill. US2008190162 describes a method of supplying lubricating oil in cold-rolling by emulsion lubrication. US2008116011 and US2008087066 disclose a method of supplying cold rolling oil. US2007022797 discloses the plant system of multi stand tandem rolling mill for ferrous and nonferrous metals.

[13] GB1171889 discloses a rolling oil composition which comprises an emulsion formed from a base stock having the composition 5-99% water and 95-1 wt% of a C12-C40 alkylaromatic compound having 1-3 aromatic rings and an emulsifying agent. Alkyl aromatics specified are nonyl benzene, dodecyl benzene, nonyl naphthalene, and dinonyl naphthalene. 1-3 wt% of the alkyl aromatic may be replaced by a mineral oil. Emulsifiers specified are alkali and alkaline earth metal sulphonates, phenates, phosphates and soaps, polyalkylene oxide compounds and cyclohexanol. [14] Another rolling oil composition is described in GB 1173631. The invention describes the rolling of magnesium and aluminium metals and alloys. The oil-in-water emulsion containing: (a) 1-10 wt% of a soluble oil compounded with anionic or non-ionic emulsifying agents, a bactericide, a high pressure lubricant and water; and (b) one or more corrosion inhibitors which are either organophosphates or alkali metal salts of these (see Division C5).

[15] GB1179291 discloses a rolling oil composition where the mills are sprayed with an emulsion of a light hydrocarbon oil, bactericide and an emulsifier, in water which contains an inorganic hardness complexing agent for rolling of magnesium and aluminium. GB1154303 discloses a re-usable lubricant-coolant oil in water emulsion (20% max. oil) for use in the shaping of a metal by a process. The neat concentrate oil comprises 70-90% by wt. of a light mineral oil, 1-20% of one or more anionic or non-ionic oil-in-water emulsifying agents, a bactericide and coupling agent. The lubricant emulsion may be used in the rolling of magnesium, aluminium, copper and ferrous metal. The pH of the emulsion is 5 to 11. The oil phase being in the form of globules of diameter is less than 50 A and average diameter 1 - 25 A.

[16] GB997634 discloses a composition for use in cold-rolling sheet metal comprises a water emulsion containing 0.7-6.5% of a lubricant selected from palm oil, cottonseed oil, di-n- butyl sebacate, n-butyl stearate, di-2-ethylhexyl phthalate and dioctyl sebacate, 0.02-0.85% of an emulsifier, and chromate ions affording 0.3-1.6% of chromium, the emulsifier. GB1018791 deals with a rolling oil composition comprises a water emulsion of from above 6.5% up to 15% of a lubricant selected from the group consistent of palm oil, cottonseed oil, di-n-butyl sebacate, n- butyl stearate, di-2-ethylhexyl phthalate, and dioctyl sebacate, containing from above 0.85% up to 1.78% of an emulsifier, and chromate ions affording from 0.3-1.6% of chromium.

[17] GB701684A discloses an oil-water emulsion for cold rolling of steel sheets and the emulsion stability of the said roller oil is described as unstable or marginally stable. However there is not mentioned particularly about the kinematic viscosity or saponification value of the roller oil.

[18] GB1094053 describes a cold-rolling lubricant consists of epoxidized soyabean oil or an emulsion. GB1146479 discloses a cold rolling lubricants comprises an aqueous emulsion of a fatty acid and polyethylene. Acids specified are oleic, palmitic, stearic, and palm oil, coconut oil and cotton seed oil fatty acids. The emulsion may also contain a polyglycol ester, an ammonium salt of an alkyl phenol polyglycol sulphate, sodium bis(tridecyl) sulpho-succinate, triethanolamine, alkali metal salts of ethylene diamine tetra-acetic acid, benzotriazole, triethanolamine benzoate, N-acyl derivatives of N-methyl glycine, and substituted imidazolines.

[19] US4431554 discloses a cold rolling oil composition comprises 1000 Parts by weight of oil-in-water emulsion contain 10-70 parts by weight of palm kernel oil as reaction layer former, 5-20 parts by weight of poly-ethoxylated sorbitanoleate as emulsifier, 5-25 parts by weight of unsaturated, long chain monocarboxylic acids as inhibitor against hydrogen embrittlement and rusting, 1-25 parts by weight hexamethylenetetramine as stabilizer, fungicide and bactericide, rest deionized water. The emulsion is particularly suitable for cold rolling aluminum and aluminum alloys.

[20] Whereas numerous cold rolling oil lubricants based on different additive system have been developed, there is a continuing need for new products. This is particularly so where the new products present economic advantages, customer requirement and/or performance advantages. Performance advantages can include greater latitude in the ability to effectively formulate the lubricant. It can also include improvement in one or more of the properties of the lubricant. It is particularly effective if these improvements are achieved without adversely affecting the other essential properties of the lubricant. This type of work is also required for greater interest of science as well as commercial interest.

[21] Several disadvantages are associated and recognized with the. known compositions based on the above patents. The formulations are based on the advantage of general formulations based on performance additives, emulsifiers arid/or base oil as a combined entity or specific or few ingredients and general application/design of the system. The formulations are also based on general stable emulsions.

[22] One disadvantage is that the metastability /oil separation of rolling oil emulsion is not properly studied. Further the metastability, oil separation and their correlation are not studied systematically. Still further the oil separation, metastability and the lubrication property are not studied together properly.

[23] Another disadvantage is that the effect of ratio of emulsifiers or surface active agents on oil separation, metastability, ESI and lubrication parameter is not properly studied. Further, formulations are based on good/stable emulsions. ESI and lubrication properties are also not studied. One of the important properties of rolling oil emulsion is lubrication which is also not quantified properly. [24] Yet another disadvantage is that the formulations do not possess superior lubrication properties. None of the formulations describes the rolling plant lubrication parameter, Roll Specific Force (RSF), % reduction as a function of laboratory parameters e.g., oil separation, metastability, ESI and Falex Jaw Load. Still further, the formulations do not describe simultaneously lubrication, oil separation, % reduction and Roll specific force (RSF) on the overall formulations. Further, the optimum range of ratio of emulsifiers and ESI are not studied for oil separation for required metastability, lubrication properties, RSF and % reduction during rolling.

[25] Keeping in view of all the above properties of rolling oil composition, a program was initiated at the authors' laboratory for development of a rolling oil formulation with excellent i.e. optimum metastable (loose) emulsion characteristics. A large number of chemical additives, esters, fats, emulsifiers, surfactants, dispersants etc used and emulsion and lubrication properties studied in the development of rolling oil composition with metastable emulsion characteristics are described in the present invention.

DESCRIPTION OF THE INVENTION WITH DIFFERENT EMBODIMENTS

[26] According to the present invention, there is provided a composition of oil suitable for thin and thick gauge steel sheet rolling in Tandem Rolling Mills comprising a blend of emulsifier(s)/surfactant(s) and/or dispersant(s) in one or more oils/fats along with different performance additives selected from extreme pressure, antiwear, anti-oxidants, antifoam etc which forms a metastable emulsion with water.

[27] The oils/fats used are selected from natural oils/fats, synthetic esters, fatty acids high viscosity mineral oil. The dispersant can be an emulsifier or a surfactant or any surface active agent or a mixture or any combination thereof. One of the emulsifiers or surfactants or surface active agents can be a co-emulsifier or a self emulsifying ester. The emulsifier further can be a nonionic or cationic or a mixture of nonionic or mixture of cationic or a mixture of both nonionic and cationic emulsifiers. The ratio of major and minor co-emulsifier or surface active agent is 2-8 to achieve the desired ESI and oil separation characteristics. The HLB value of the non-ionic emulsifiers or surfactants or dispersants is in the range of 3.5 to 14.5. [28] According to the invention, the invented composition has a combined concentration of natural fat(s)/oil(s)/synthetic ester(s) mixture thereof, fatty acid or mixture of fatty acids, mineral base oil and performance additives 80-99.5% by weight, emulsifier/s, surfactants or surface active agent/s and mixture thereof 0.5 to 15% by weight and dispersant 0- 5% by weight and Falex Jaw Load in the range of 1200-1600 lbs. The composition has a saponification value of 100-210 mg KOH/g, preferably, 160-200 mg KOH/g and a kinematic viscosity of 30 to 70 cSt at 40°C preferably in the range of 45-60 cSt at 40°C and having a flash point above 160°C. The composition gives a Role Specific Force (RSF) between 0.50 to 1.1 MT/mm during tandem rolling of steel sheet for achieving desired percentage reduction and surface cleanliness and the total percentage reduction of steel during tandem rolling is obtained in the range of 50-90.

[29] This invention also provides for a cold rolling metastable oil-in-water emulsion for high speed thin and thick gauge steel sheet rolling which comprises a composition of oil as described above, emulsified with water.

[30] The said emulsion has an emulsion stability index (ESI) of 0.4-0.7 and is capable of separating oil/cream/mixture of oil and cream in a range of 30 to 70% (v/v). The emulsion has an oil concentration in the range of 0.2 to 5.0% (v/v) in water for steel rolling in tandem mills. The metastability of the emulsion is directly proportional to the separated oil from the emulsion limited to 70% (v/v) maximum oil separation. The invented emulsion has Falex Jaw Load in the range of 2200 to 3200 lbs preferably in the range of 2500 to 3000 lbs.

[31] The present invention further provides for a method of cold rolling of thin/thick steel sheet in tandem rolling mills in which an oil-in-water emulsion as described above is used therein.

[32] In cold rolling of steel sheets, a fluid dispersion is prepared by emulsifying and dispersing a cold rolling oil in hot water (50-60°C) at a concentration of 0.4-10% by stirring and supplying the lubricating oil to the rolling rolls and steel sheets.

[33] According to one embodiment of the invention there is provided a cold rolling oil composition for use as a lubricant with lubrication and a cold rolling oil emulsion with additional metastability, oil separation, load carrying and sheet reduction characteristics comprising emulsifiers or surface active agents by weight of 0.5 to 15% by weight, dispersant by weight of 0-5% by weight in a mixture of natural fats/oils , synthetic esters , fatty acid or mixture of fatty acids, antioxidant or mixtures of antioxidants, extreme pressure and antiwear additives or mixtures, antifoam and mineral base oil 80 to 99.50% by weight.

[34] According to the invention an emulsifier may be co-emulsifier and any co- emulsifier may be emulsifier. The one used in lower concentration in the formulation is termed as co-emulsifier and the one used in the higher concentration is termed as emulsifier.

[35] The natural fat used in the present invention is based on the vegetable and/or animal based and mixture thereof and selected from fatty acid ester of C-8 to C-22 fatty acid, preferably C-12, C-14, C-16, CI 8, C-22, its mixture and/or its isomers. The kinematic viscosity of the oil varies between 30 cSt to 250 cSt at 40°C and flash point typically higher than 160°C. Example of vegetable fats are palm oil, coconut oil etc. Animal fat is generally tallow based.

[36] The synthetic ester used as an additive in the present invention based on fatty acid ester of CI 2 to CI 8, its isomers and mixtures including complex and self emulsifying esters.

[37] The kinematic viscosity of the synthetic ester varies between 1 cSt to 60 cSt, preferably 30 to 50 cSt at 40°C having flash point more than 160°C. Example of synthetic ester is TMP trioleate.

[38] The fatty acid used in the additive of the present invention is selected from C-12 to C-22 fatty acids, preferably C12-C18 fatty acids and/or its isomers.

[39] The natural fats and esters have a tendency to decompose to fatty acid with time, heating and to hydrolyze during use in the cold rolling operation. Antioxidant used to prevent the conversion of ester to the fatty acid. The antioxidants used in the present invention are amine and /or hindered phenolic based their mixtures and isomers thereof.

[40] Extreme pressure and antiwear additives are also required to take care of the load during the actual process of rolling and reduction in the mill. The additives selected and used in the present invention are based on sulphur, phosphorous, chlorine and zinc as single component or mixture of components of above. Examples of extreme-pressure and anti-wear agents are dilauryl phosphate, didodecyl phosphite, trialkylphosphate such as tri(2-ethylhexyl)phosphate, tricresylphosphate (TCP), zinc dialkyl(or diaryl)dithiophosphates (ZDDP), phospho-sulphurized fatty oils, zinc dialkyldithiocarbamate), mercaptobenzothiazole, sulphurized fatty oils, sulphurized terpenes, sulphurized oleic acid, alkyl and aryl polysulphides, sulphurized sperm oil, sulphurized mineral oil, sulphur chloride treated fatty oils, chlornaphta xanthate, cetyl chloride, chlorinated paraffinic oils, chlorinated paraffin wax sulphides, chlorinated paraffin wax, trixylylphosphate (TXP), dilauryl phosphate, respectively.

[41] Antifoam is required to prevent the foam and frothing characteristics of the oil in the presence of water during use. Sometimes the formulation itself is enough to take care of the antifoaming characteristics. Hence the formulation may or may not contain antifoam. The antifoam selected in the formulation is silicone based antifoam. Examples of anti-foaming agents are silicone based, especially polydimethylsiloxane.

[42] The base stock oil can be paraffinic or naphthenic, hydrocracked or mixture of these.

[43] The base oil typically has a viscosity from 5 to 60 cSt at 40°C and preferably from 12 to 58 cSt at 40°C. Viscosity of the formulation can be adjusted by mixing adequate quantity of the required different base oils.

[44] The flash point of the base oil should be greater than 150°C and typically 200°C.

[45] The base fluid contains different combination and concentration of one or mixture of more than one CIO to C22 based vegetable oils like palm oil, castor oil, karanja oil, mahua oil, rapeseed oil, coconut oil etc, animal fat like lard oil, synthetic ester like glycerol trioleate, C4-C8 long chain fatty acid ester, TMP ester, PE ester etc, mineral base oil of Gr I, Gr II or Gr. Ill, extreme pressure and antiwear additives like tricresylphosphate (TCP), sulphurized fatty oils, long chain C8-C22 most preferably C12-C18 fatty acid like oleic acid, stearic acid, palmitic acid etc, amine and hindered phenolic based antioxidant and anti-foaming agent like polydimethylsiloxane etc.

[46] The emulsifier, surfactant and dispersant are required for the emulsion formation and the metastability of the formulation as a lubricant. Different types of emulsifiers are possible with different chemistry and charges. Depending upon the charges of the polar group of the emulsifier, surfactant and dispersant are characterized as nonionic, anionic, cationic and amphoteric. The emulsifier, surfactant and dispersant used in the formulations are nonionic, cationic, anionic, amphoteric as individual or the mixtures of two or more thereof. The preferred anonic emulsifiers are phosphate esters.

[47] Examples of the nonionic emulsifiers, surfactants and dispersant having HLB value of 3.5 to 16.2 includes sorbitan monooleate, glycerol monooleate, sorbitan trioleate (ARLACEL 85), sorbitan stearate (ARLACEL 60), sorbitan mono laurate (ARLACEL 20)), POP steryl alcohol, copolymers of propylene glycol and ethylene glycol, POE(40) sorbitol hexaoleate, POE(2) synthetic primary C13/C15 alcohol (Synperonic A7), POE(9) synthetic primary C13/C15 alcohol (Synperonic A9), POE(20) synthetic primary C13/C15 alcohol (Synperonic A20), POE(9) nonyphenol, POE(4) nonyphenol, ATLAS G1086, ATLAS G 1096 as well as esters or polyesters prepared from fatty acids, poly fatty acids or poly condensed fatty acids and alcohols such as ethylene glycol, glycering, sorbitol, sorbitan and the like or polyalcohols, polyoxyethylene alcohol ether, polyoxyethylene nonylphenyl ether, polyoxyethylene fatter ester, polyoxyethylene sorbitol ester e.g, Tween 20, Tween 60, Tween 80, Tween 85, POE Laryl alcohol e.g., BRIJ 30, BRIJ 35, POE Oleyl alcohol e.g. BRIJ 96, BRIJ 98, POE Cetyl Stearyl alcohol e.g. BRIJ 52, BRIJ 56, Nonyl Phenol ethoxylates e.g. Cresmer 101 1, Cresmer 1 122 and the like.

[48] Examples of cationic emulsifiers are imidazoline, Oxazoline or its derivatives, different amine, amide or ammonium salt derivative e.g., aminoethyl,hydroxy ethyl,amido ethyl, amide blends. Commercial examples are Imidazoline 18 OH, Imidazoline 12 OH, Imidazoline 18 NH, Imidazoline 18 CA, Imidazoline 18 DA, ALKATERGE-E, ALKATERGE-T, Cresmer SC 739, Unitop-TA-2, Unitop-TA-15, CIRRASOL NCSN, CIRLASOL NY-LF, EDUNINE AK, EDUNINE CSA.

[49] Anionic emulsifiers are carboxylate, fatty alcohol sulphate and phosphate esters.

The phosphate esters are preferred combination in the formulation. Examples include phosphated alcohols, phosphated alcohols phosphate alcohol, ethyoxylates, phosphated phenol ethoxylates.

[50] Commercially available examples are Lakeland PA 800, PAE 185, PPE 156,

Cresmer 2457, Cresmer 2229, Cresmer SC 191 1, Cresmer DAP etc.

[51] The amphoteric surfactants/emulsifiers are the surface active agents which contain both negative and positive charge on the same molecule and they are broadly categorized as propionates and betanes. Commercial samples are Lakeland AMA, Lakeland AMA LF 40, Lakeland AMA 70, Lakeland ACP 70, Lakeland CAB, Lakeland CTA/N, AMPHOTERGE K, AMPHOTERGE K-2, AMPHOTERGE LF, AMPHOTERGE W, LONZAINE CS, LONZAINE CO, VELVETEX OLB50, VELVETEX CDC.

[52] Examples of dispersants are EO/PO block copolymer e.g., Synperonic PE/L62,

PE/L64, PE/L101, PE/25R2, Cresmer SC 676, Cresmer SC168, Cresmer SC 171, nonionic block copolymer e.g., Hypermer B261 , Hypermer B246, Cresmer B 246M, Polyester Surfactant e.g., Hypermer A 60, Hypermer A 70, metal particles and metal soap e.g., iron soap, iron particles, calcium and magnesium soap etc.

[53] To prepare the cold oil composition of the present invention, the base oil and/or fat, ester mixture is heated to 40-45 °C with stirring followed by adding the extreme pressure and antiwear additives, emulsifiers, antioxidant/s etc to the base oil or the mixture of base oil, fat and ester one by one under stirring condition. Reasonable time (5-10 minutes for each additive) was given to dissolve one additive before addition of the next additive. The final (after addition of the final additive) rolling oil blend is stirred for another 30-40 minutes with heating. Ordinary Remi stirrer is used for the stirring and dissolving the additives to the base stock and/or fat and ester. Precaution is taken for avoiding excessive heating (> 60°C) of the oil phase. Thus the cold rolling oil formulation finalized. The water used for making the emulsion was either DM water with a pH of 6.8-7.2 and hardness <30 ppm as CaC0 ₃ or the synthetic hard water prepared as per requirement of customer by dissolving CaCl ₂ (anhydrous), MgS0 ₄ , H ₂ 0 and NaHC0 ₃ in distilled water and adjusting the pH of the synthetic water at 6.8-7.2. In actual site of the customers, the customer water which varies from DM water to 200 ppm water used for the preparation of emulsion preparation and rolling operation. The emulsion metastability and oil separation characteristics in the laboratory is evaluated by addition of cold rolling oil phase of required quantity to the water phase (50°C) and stirring the emulsion under high shear at 1 1000 rpm for 5 minutes with a special homogenizer (ULTRA TURRAX, T-25, basic unit with dispersing tool spindle No: S 25 N-25 F of IKA LABORTECHNIK, GmbH, Staufen). The total emulsion prepared was 100 ml. The condition of the emulsion (oil separation and metastability) was checked time to time for 24 hrs keeping the emulsion (100 ml in a measuring cylinder with stopper) in a preset 50°C air oven. The emulsion stability and metastabilty of the emulsion is then assessed by the separation of the amount of oil or cream or mixture of both. The emulsion stability index (ESI) is measured by preparing 200 ml 5% v/v oil in water emulsion for 2 minutes by the above model of ULTRA TURRAX model at 1 1,000 rpm and the water temperature kept for 50°C. Then the prepared emulsion is poured in a glass column of 400 ml capacity and kept in 50°C preheated air oven for 30 minutes. After 30 minutes the column removed from the oven, immediately separating the top and bottom phase (100 ml each) and the oil from the emulsion is separated by splitting with 20 ml acid e.g., hydrochloric acid, nitric acid or the mixture of both depending upon the type and nature of emulsifiers, surface active agents, dispersion and emulsion. The ESI is calculated by dividing the oil content of the bottom phase by the oil content of the top phase.

[54] The metastability and oil separation properties of the emulsion are calculated by the emulsion stability index (ESI) and the amount of oil separated from the emulsion as per the experiments stated above. Lower ESI value and greater oil separation signify metastable emulsion. But extreme values of either two of the above properties are also not desirable for metastable emulsion as it will make the emulsion unstable.

[55] The lubrication property of the formulations can be evaluated in terms of Falex

Jaw Load (load carrying capacity of the rolling oil and its emulsion), % reduction and specific roll force (RSF). The Falex Jaw load is carried out in the applicant's laboratory as per ASTM-D 3233. % reduction and roll specific force (RSF) are obtained from reputed industrial rolling plants.

Experimental Results

[56] In order to establish the suitability of the developed oil composition, a number of compositions using various components comprising natural fats/oils, synthetic esters, high viscosity mineral oil and other performance additives such as extreme pressure, antiwear, emulsifiers, antioxidants, antifoam etc were prepared and evaluated for emulsion meta-stability, oil separation from emulsion, Falex Jaw Load, Roll Specific Force (RSF) and % reduction.

[57] It can be appreciated that only combination of emulsifiers and natural fats/oils is not sufficient for making good quality steel cold rolling oil. Therefore, an optimized combination and ratio of emulsifiers, surface active agents, dispersant, other performance additives and required saponification value were selected based on the chemistry and nature of the emulsifiers to get a composition of rolling oil suitable for thin and thick gauge steel sheet rolling.

[58] The compositions and results of various experiments carried out are compiled as follows:

Example -1 [59] A blend of 70 %wt mixture of vegetable oils, 5.0 %wt of synthetic ester, 5.0 %wt of long chain fatty acid, 1.0 %wt antioxidant, 3 %wt of extreme pressure additive, 3.3 % polyoxyethlene sorbitan ester, 0.7 %wt sorbitan ester and 12.0 %wt high viscosity index Group I mineral base oil.

Example -2

[60] A blend of 55 %wt of mixture of vegetable oils, 15.0 %wt of animal fat, 20.0 %wt of synthetic ester, 2.0 %wt of long chain fatty acid, 1.0 %wt of mixture of antioxidants, 1 %wt of extreme pressure additive, 3 %wt antiwear additive, 2% alcohol ethoxylate, 0.8 %wt of hydroxy ethyl imidazoline and 0.2 %wt nonionic polyester as dispersant.

Example -3

[61] A similar composition of blend- 1 where 4.75 %wt of Gr I base oil replaced by 4.0

%wt polyoxyethlene sorbitan ester, 0.7 %wt amino betaine, 0.05 %wt of Iron soap as dispersant.

Example -4

[62] A blend of 65.0 %wt of mixture of Vegetable oils, 1.0 %wt of long chain fatty acid, 2.0 %wt mixture of antioxidants, 2 %wt of EP additive, 18.0% polyoxyethlene sorbitan ester, 12.0 %wt sorbitan ester.

Example - 5

[63] 40.0 %wt of vegetable oil, 52.0 %wt of synthetic ester, 1.2 %wt antioxidant, 4.0

%wt antiwear additive , 2.7 %wt sorbitan ester, 0.1 %wt Glycerol ester.

Example - 6

[64] An emulsion (roll coolant) of blend -1 which contain 2% of blend - 3 and 98% of

DM water.

Example -7

[65] An emulsion (roll coolant) of blend - 2 which contain 3.5% of blend -2 and 96.5

%wt of 100 ppm hardness (as CaC0 ₃ ) water. Example -8

[66] An emulsion (roll coolant) of blend - 3 which contain 6% of blend -3 and 94 %wt of 200 ppm hardness (as CaC0 ₃ ) water.

Example -9

[67] An emulsion (roll coolant) of blend-4 which contain 15% of blend-4 and 85% wt of DM water.

Example -10

[68] An emulsion (roll coolant) of blend-5 which contain 1.0% of blend-5 and 99.0% wt of 400 ppm hardness (as CaC0 ₃ ) water.

Test Results

[69] The results obtained on various blends explained above are compiled in the following tables based on the studies carried out on particular characteristics:

Table -1. Emulsifiers Ratio, Emulsion Stability Index (ESI) and Meta Stability

Table -2. % oil Separation and Emulsion Stability

Table - 3. Lubrication Properties

Table - 4. Emulsion Stability, Rolling & Lubrication Properties

[70] Different embodiments of the invention referred to in the description and examples are for illustrations only and not to be construed as limitative. Other possible embodiments of the invention would be apparent to those skilled in the art from consideration of the specification and practice of the invention disclosed herein. The exact scope and spirit of the invention are governed by the following claims.