OIL

FIELD OF THE INVENTION

[01] The present invention relates to composition of cutting oil for metal working applications. More particularly, the invention relates to high performance semi-synthetic bio- stable and operator friendly soluble cutting oil composition for metal working applications comprising high viscosity index base oil, an amine, a fatty acid, an ester, emulsifiers and other performance additives like co-solvent, corrosion inhibitor and biocide etc.

BACKGROUND OF THE INVENTION AND PRIOR ART

[02] Today, the soluble cutting oils market has increased manifold in size and a variety of such oils are being used in a large number of applications. Although, soluble cutting oils are used by various manufacturing industries, oil specifications are scanty in the cutting fluid area and, generally, oil performance is governed by customer assessment of performance and OEM specifications in most of the cases. Traditionally, soluble cutting oils are still holding the largest share of metal working fluids, but their market has been witnessing continuous changes ii¾ perception and practices over the past few years and now high quality, high cost and high performance semi-synthetic cutting oils have penetrated into the market place. The driving force for acceptability and use of high cost semi synthetic cutting oils is longer sump life, higher performance benefits, cleanliness etc. Use of these oils reduces the performance hassles and enables trouble free operation for the production units. These oils are optimized combination of chemical constituents and oil. They have lower oil content but contain more emulsifier and performance chemicals. These oils have moderate to excellent lubrication, high cooling efficiency, high rust inhibition and excellent cleanliness properties. Sulfur, chlorine, and phosphorous, esters type additives are also added to these oils to improve the extreme pressure/anti wear/lubricity characteristics. These products are ideally suited for both ferrous and non-ferrous type applications. [03] A variety of chemicals, additives and surfactants have been used to formulate the semi-synthetic cutting oils. Some of the common ingredients are base oils, polyolesters, sodium petroleum sulphonates, salts of fatty acids, nonionic surfactants, ethanol amines, sulphurised fatty material, fatty acid esters, chlorinated paraffin, fatty alcohols, hindered phenols, borate, biocides, odorizing agent, azo-dyes, alkali etc. The composition of semi-synthetic cutting oils is specific for each company due to complexity of the formulations and possibility of a large number of permutation and combinations. Most recent compositions of some of these semisynthetic compositions disclosed by researchers are listed below:

[04] US 4,414,121 assigned to Shell Oil Company disclosed water-based metal- working lubricants containing an emulsion-type anionic, soluble oil comprising a low viscosity index (LVI) lubricating oil, sodium sulfonates as an emulsifier, a soluble oil co-emulsifier base containing naphthenic acids, potassium hydroxide, anti-rust and anti-microbial agents and an effective amount of block copolymers of ethylene oxide and propylene oxide or other alkylene oxides having a molecular weight between about 800 and about 8,000.

[05] US 4,440,654 disclosed a method for producing a cooling emulsion, particularly for use as an auxiliary means in boring, cutting and grinding in the metalworking industry, in which organic substances which are per se insoluble in water are rendered water-dispersible and are emulsified with water. A mixture of about 3% to 15% by weight of natural wax(es) of animal and/or 0.1% to 0.45% by weight of a 'commercial emulsifier, and the remainder an aqueous di/tri- ethanol mixture comprising about 50% by weight of water, 37.5% by weight of di-ethanolamine and about 12.5% by weight of tri-ethanolamine is produced. Then the mixture is brought to a boil while stirring; after dissolution of the wax component, it is cooled to a reaction temperature while stirring, and subsequently, after aminization of the wax component by the di/triethanol mixture is cooled down to application temperature. For use it is further diluted with water.

[06] US 4,578,202A by Merck Patent Gesellschaft disclosed a cutting oil suitable for the working of nonferrous metals, in particular for milling and engraving copper cylinders employed in gravure printing, is based on fatty acid esters of monohydric or polyhydric alcohols in an organic solvent which is selected from glycols, oligoglycols, polyglycols or their monoethers, diethers, monoesters or diesters, and also contains a surfactant, preferably an anionic surfactant. [07] US 4,778,614 by The British Petroleum Company disclosed a composition for the preparation of a soluble-oil for use in a cutting fluid comprises a mineral oil and, as an emulsifier, an effective amount of a sulphonate of a branched polymer of C3 to C5 olefin. Preferably the polyolefin chain of the sulphonate has an average molecular weight in the range 275 to 560 and the polyolefin is polyisobutene. The soluble-oil can be prepared from the above composition by the addition of a conventional corrosion inhibitor and diluted with water to make a cutting fluid. Advantages of the novel emulsifier are that they are resistant to breakdown by micro-organisms and do not require the addition of a coupling agent.

[08] US 4,781,848 by Aluminum Company of America disclosed a metalworking lubricant comprising an oil-in- water microemulsion and containing about 1-30 wt% natural or synthetic oil; about 0.5-30 wt% of a water-soluble surfactant, preferably a nonionic surfactant; about 1-20 wt% of an organic co-surfactant, preferably 1,2-octanediol; and about 45-97.5 wt% water containing less than about 1 wt% dissolved inorganic salts .

[09] US 4,781,849 by Aluminum Company of America disclosed a metalworking lubricant comprising about 1-20 wt% natural or synthetic oil; about 0.5-30 wt% of a water- soluble surfactant, preferably a nonionic surfactant; about 1-20 wt% of an organic co-surfactant, preferably 1,2-octanediol; and about 50-97.5 wt% water containing less than about 1 wt% dissolved inorganic salts. The lubricant is preferably a lyotropic liquid crystal.

[10] Exxon Chemical Patents Inc. (US 4,956,110) disclosed the use of a water-soluble hydroxyl di- or tri-carboxylic acid, generally in combination with an alkanolamine in an oil water fluid especially metal working or hydraulic fluids which resulted in a fluid having excellent hard water compatibility, low foaming tendency in soft water and a good biostability; other additives such as emulsifiers, copper passivators and the like were generally present.

[11] US 4,946,612 assigned by Idemitsu Kosan Company Limited disclosed a lubricating oil composition both for lubrication of sliding surface of machine tools and for lubrication of working part of machine tools which is free from the conventional problems. This composition comprises a reaction product of a dibasic acid of 16-24 carbon atoms with a piperazine compound, a lubricating oiL an emulsifier and, if necessary, an extreme pressure agent and/or an oiliness agent.

[12] US 4,956,109 by The Nisshin Oil Mills, Ltd. and Nippon Steel Corporation disclosed a lubricating oil comprising at least one member selected from the group consisting of esterified products obtained by reacting: (A) a compound selected from the group consisting of alcohols represented by the following general formula (I), alcohols represented by the following general formula (II) and hydrogenated derivatives thereof; with (B) a fatty acid having not less than 6 carbon atoms or a mixture of the fatty acid with a rosin selected from the group consisting of rosin, hydrogenated rosins, disproportionated rosins and polymerized rosins. The lubricating oil was used as rolling mill oils, hydraulic oils cutting-grinding oils, lubricating oils for metal plastic working and those for internal combustion engines.

[13] US 5,322,631 by Yushiro Chemical Industry Co., Ltd disclosed a water-soluble lubricant composition for a sleeve surface lubricating oil, an operating fluid, a cutting oil, a rolling oil, a drawing oil, a press oil or the like, which did not pollute the environment and has superior lubricity, metal corrosion preventing property, antifoaming property and antiseptic property. The water-soluble lubricant composition of this invention containing surfactants (a) and one or two salts (b) selected from among carboxylates and sulfonates was characterized in that the above one or two salts (b) selected from among carboxylates and sulfonates are alkaline earth metal salts or zinc salts and that substantially no nitrogen ingredients were contained and the amount of nitrogen contained represented its amount in impurities, or 0.5 wt% or below of nitrogen.

[14] Mobil Oil Corporation disclosed (US 5,417,869) bio-resistant surfactants and cutting fluid compositions which utilize them. The surfactants consisted of soaps of carboxylic acid compounds having from 10 to 30 carbon atoms, the carbon skeleton of which was branched and not straight chain. It was the branching which lent the resistance to biodegradation to the products of the invention. Further enhanced bio-resistance was obtained by utilizing a branched lubricating base stock material in the cutting fluid composition.

[15] US 5,523,431 by Berol Nobel AB and Castrol Ltd disclosed a method of producing an amide product mixture having a low content of secondary amines by reacting an amide product mixture having a high secondary amine content with an aliphatic alkylene oxide in the absence of an essential amount of any alkoxylation catalyst. The amide product mixture obtained contained a minor amount of tertiary amines and exhibited advantageous properties when used for the formulation of cosmetic products, such as shampoos and creams; foam cleaning compositions, e.g. for textiles and cars; and functional fluids, such as lubricants, metal working fluids and hydraulic fluids. [16] US 5,693,596 disclosed a method of producing water-soluble cutting fluid in which the soluble cutting oil was produced by dissolving a polymer fatty acid triglyceride imidazole, 2-methyl-1-stearate, and boric acid imidazole in the dispersion of inorganic bentonite in water thereby preparing a main component and adding oleic acid (agent for enhancing the lubricity), Na salt of ethylenediamine tetraacetic acid (metallic ion adsorbent), benzotriazole (rust-preventing auxiliary agent), and a silicone type defoaming agent to the main component.

[17] Nalco Chemical Company disclosed an additive composition for metal- working fluids and a method for producing the additive composition (US 5,866,521). The additive composition comprised from about 0.01 to about 25.0 mole weight of iso-stearic acid to 2- amino-2-methyl-1-propanol whereby a salt of iso-stearic acid-2-amino-2-methyl-1-propanol was formed. The metal-working fluid composition comprised from about 0.01 to about 40 percent by weight of iso-stearic acid-2-amino-2-methyl-1-pr0panol salt and from about 99.99 to about 60 percent by weight of a synthetic or semi-synthetic metal-working fluid.

[18] Dainippon Ink and Chemicals Inc disclosed a sulfur-based extreme-pressure additive (US 6,413,917) that is completely soluble in water without using a surfactant, and had satisfactory odor and hue. In addition, the invention provides a cutting liquid and grinding liquid having superior defoaming property and rust preventive characteristics, while also having high load resistance and lubrication performance comparable to cutting oils and grinding oils of the prior art. The extreme-pressure additive comprised of the salt of a condensation product of a sulfurized hydroxy-unsaturated fatty acid, the condensation product having a sulfur content of 8 to 15% by weight (mass), color of 6 or less, and acid value of 80 to 200, and a grinding liquid comprising that extreme-pressure additive and water.

[19] US 6,605,575 assigned to Ajinomoto Co, Inc disclosed a cutting oil composition, which was excellent in solubility, lubricity, cutting properties, antirust ability, safety, and washing ability and reduced in foaming, and for that purpose, an N-acylamino acid having a long chain acyl group and/or a salt thereof, or an N-alkylamino acid having a long chain alkyl group and/or a salt thereof was used concurrently with an alkylalkylene oxide and/or an acylalkylene oxide.

[20] US 6,525,006 disclosed a lubricant composition comprised of (1) at least one member selected from the group consisting of carboxylic acid compounds each obtained by the addition of an oxyalkylene group to a hydroxy! group of a hydroxy carboxylic acid and alkali metal salts and amine salts thereof; and (2) at least one base oil selected from the group consisting of alkyl benzene, normal paraffin, isoparaffin and .alpha. -olefin. The lubricant composition was highly resistant to putrefaction when it was used as a metal-processing oil composition and showed excellent cutting characteristics in the metal-processing, which required an extremely high lubricating action, such as form-rolling tap and deep hole boring. Moreover, the composition made operations such as metal-processing operations easy since the liquid obtained by diluting it with water was transparent or translucent.

[21] US 6,705,142 assigned to Henkel Kommanditgesellschaft auf Aktien disclosed a process for the cutting or non-cutting forming of metals using two cooling lubricants, wherein an oil or a first emulsion having an oil content of at least 10 wt% was applied to the work piece, as a first cooling lubricant, at the tribo-zone and, at the same time, an oil-free cooling lubricant or a second emulsion that was an oil-in- water emulsion having an oil content of less than 10 wt% was applied, as a second cooling lubricant, adjacent to the tribo-zone. Depending on the metal- working technique, a two-component nozzle was preferably used for supplying the first and second cooling lubricants, the jet of second cooling lubricant surrounding the jet of first cooling lubricant concentrically. Alternatively, it was possible to supply the first cooling lubricant directly to the tribo-zone through channels in the tool, while the second Cooling lubricant was applied at the periphery. The cooling lubricants that ran off were together fed to a storage container, where phase separation of the first and second cooling lubricantstook place.

[22] US 6,716,801 disclosed a stable, clear water-in-oil emulsion consisting of from about 5 to about 40 wt% aqueous phase and from about 95 to about 60 wt% non-aqueous phase, said aqueous phase being dispersed in said non-aqueous phase in the form of droplets having an average droplet size no greater than about 0.1 mu.m, said emulsion comprising at least 60 wt% of an oil selected from fuel oils, lubricating oils and mixtures thereof, from about 5 to about 30 wt% of an emulsifier composition, and the balance to 100 wt% water, wherein said emulsifier composition consisting essentially of i) a mixture of C6-C15 alcohol ethoxylates, each comprising from 2 to 12 EO groups, ii) from 0 to about 25 wt% of an emulsifier selected from polyisobutylsuccinimide, a sorbitan ester and mixtures thereof, and iii) from 0 to about 90 wt% of an amine ethoxylate. The microemulsion was useful as a fuel and/or lubricant/coolant.

[23] US 6,858,569 assigned to Nippon Mitsubishi Oil Corporation disclosed cutting or grinding oil compositions, which were suitable for use in a minimal quantity lubrication system in which a minimal quantity of an oil was supplied to the spot to be cut or ground of a work, together with air are reduced in stickiness and improved in lubricity.

[24] Thus it is apparent from the prior art that semi-synthetic compositions are not able to address various issues such as emulsion life, use of operator friendly components etc and other soluble cutting oil related problems exhaustively. Therefore, there exists a requirement for present day large scale manufacturing industry to develop a soluble cutting oil that overcomes the problems of prior art. Efforts are therefore, made to develop a high performance semisynthetic soluble cutting oil composition for metal working applications.

[25] Metal cutting fluids are generally combination of highly refined mineral oil, specially selected esters and tailor made optimized emulsifier systems. These oils may require high amount of emulsifier additives so as to accommodate higher concentration of performance additives. The emulsifier additives adsorb over oil globules and help in dispersing oil in water phase. The fluid concentrate usually includes other additives such as chlorinated or sulfurized mineral oils, fatty oils, or mixtures thereof, biocides, corrosion/rust inhibitors etc. to improve performance and lengthen the life of the fluid.

[26] Semi-synthetic cutting oils provide good lubrication characteristics. In addition, they provide excellent cooling characteristics also. Emulsions of these oils provide longer sump life and enhanced bacterial resistance. Due to low content of petroleum base oil compared to general purpose soluble cutting oils and good amount of high performance chemicals at times these oils give better performance in the field applications. Semi-synthetic cutting oil generally contains esters and other performance chemicals besides petroleum base oils.

[27] Formulations of soluble type metal working oils are quite complex. These oils in general constitute an area of lubrication technology where chemistry is very much in action in the whole application regime. The performance or non-performance of a fluid during operation becomes quickly evident. Unlike other industrial oil lubricants, where the performance of the oil will be known only after some time, the performance of soluble type metalworking oil will be known as soon as it is put into the machining operation. A defect in a soluble oil, for example cutting oil or rolling oil, will show up immediately after starting operation or at the most in a couple of days and will call for quick corrective action. The factors affecting the performance of these oils are multi faceted; therefore, these oils require special attention of the formulator as well as user. Performance of the same oil may vary significantly from one user to other depending upon the nature of application, metallurgy and maintenance practices followed by the user. Water quality significantly contributes towards performance of the oil.

DESCRIPTION OF THE INVENTION

[28] According to the present invention there is provided a high performance semisynthetic, bio-stable and operator friendly soluble cutting oil composition comprising an optimized combination of a high viscosity index base oil, an amine, a fatty acid, an ester, a biocide, a co-solvent, a corrosion inhibitor and emulsifiers. The high viscosity index base oil can be HVI spindle oil having kinematic viscosity of 10-16 est at 40°C. The amine preferably is triethanolamine, the fatty acid is preferably oleic acid, the ester is a high molecular weight complex ester and preferably is Hostaglis D, the biocide is preferably a triazine derivative, the co-solvent is preferably lauryl alcohol, the corrosion inhibitor is preferably Corfree Ml and the emulsifier are non-ionic and preferably sorbitan monooleate and Emulsogen M. The concentration of base oil preferably HVI spindle oil is between 58 to 85 wt% preferably between 65 to 75 wt%, oleic acid between 4 to 8 wt% preferably between 5.0 to 6.5 wt%, triethanolamine between 3.5 to 10.2 wt% preferably between 5.0 to 7.5 wt%, Emulsogen M between 1.5 to 5.0 wt% preferably between 3.5 to 5,0 wt%, sorbitan monooleate between 1.5 to 5.6 wt% preferably between 4.0 to 5.5 wt%, lauryl alcohol between 1.0 to 3.3 wt% preferably between 1.5 to 2.5 wt%, triazine derivative type biocide between 1.5 to 6.0 wt%, preferably 2.0 to 4.0 wt%, Corefree Ml between 1.0 to 2.5 wt% preferably between 1.0 to 2.0 wt% and Hostaglis D between 1.0 to 2.0 wt%. The invented composition additionally has water at a concentration of 0.5 to 2.5 wt% to provide better emulsion characteristics and blend stability.

[29] It is an embodiment of the present invention to provide a high performance semisynthetic soluble cutting oil composition, which is used as oil in water emulsion for metal working operations.

[30] Another embodiment of the present invention is to provide a high performance semi-synthetic soluble cutting oil composition that can advantageously be used to give good hard water stability and forms milky emulsion when mixed with water and gives longer emulsion/sump life during use in spite of longer shut down periods during machining operations. [31] The high performance semi-synthetic soluble cutting oil composition of the invention when used in metal working operations, provides very good rust protection, excellent bacterial resistance and also retards bacterial growth, thus increasing the serviceable life of the emulsion. The high performance semi-synthetic soluble cutting oil composition has excellent swarf removal characteristics during metal working operations and provides excellent tool life during prolonged use of the oil. This cutting oil composition also gives excellent surface finish to work piece in metal cutting operations like grinding, milling, turning, drilling etc.

[32] Another embodiment of the present invention is to provide a high performance semi-synthetic soluble cutting oil composition, which is operator friendly in nature and does not contain chlorine, sulphur, boron, nitrite or diethnolamine type chemicals in it.

[33] The high performance semi-synthetic soluble cutting oil of the present invention forms milky emulsion when mixed with water. The emulsion so formed can be employed for various metal working operations particularly metal cutting operations like grinding, milling, turning, drilling etc. The semi synthetic cutting oil composition provides longer emulsion life and very good bacterial resistance, besides providing other performance benefits like cooling, swarf removal and corrosion protection etc. The composition is suitable for ferrous and non ferrous machining particularly of aluminium alloys.

[34] The invention is particularly described with reference to the following non- limiting examples giving the names of the different chemical components used in the composition, their various proportions and evaluations of the performances of different embodiments of the invented oil composition.

Chemical names of the compounds are as follows:

Example 1:

[35] Soluble cutting oil blends were prepared by changing concentration oftriazine derivative, triethanol amine, oleic acid and emulsogen M in blend 1 to blend 5. Blends 1 to 5 were hazy and therefore these were discarded.

JfV l/llN AUli/ '

Example 2:

[36] Soluble cutting oil blends were prepared by changing concentration of Tri ethanolamine in blend 6 to blend 8. Blends 6 to 8 were hazy and failed in Thermal Stability at 50°C and therefore these were discarded.

Example 3:

[37] Soluble cutting oil blends were prepared by changing Oleic acid in blend 9 to blend 11. Blends 9 to 11 were also hazy and failed in Thermal Stability at 50°C and therefore these were discarded.

Example 4:

[38] Soluble cutting oil blends were prepared by changing Lauryl alcohol in blend 12 to blend 14. Blends 12 to 14 failed in Thermal Stability at 50°C and therefore these were discarded.

Example 5:

[39] Soluble cutting oil blends were prepared by adding water in blend 15 to blend 17.

Blends 15 to 17 failed in Thermal Stability at 50°C and therefore these were discarded.

Example 6:

[40] Soluble cutting oil blends were prepared by adding 20% Alkali in blend 18 to blend 20. Blends 18 to 20 failed in Thermal Stability at 50°C and therefore these were discarded.

Example 7:

[41] Soluble cutting oil blends were prepared by changing water and Triethanolamine in blend 21 to blend 23. Blends 21 and 22 failed in Thermal Stability at 50°C and therefore these were discarded. Blend no. 23 passed in Thermal Stability and therefore taken for further study. Blend no. 23 was studied for emulsion stability and cast iron corrosion test and has shown good performance.

Example 8:

[42] The performance of the blend 23(Example 7) for cast iron corrosion characteristics was evaluated in presence of 400 ppm hardness water as well as 400 ppm chloride ions. However, the blend 23 was failing in these severe conditions. Therefore, modified blends 24 and blend 25 were evaluated in similar condition and the blend 25 was meeting in cast iron corrosion characteristics even in sever condition.

Example 9:

[43] The corrosion protection characteristics of the blend 23 were further improved by addition of CorfreeMl and triethanol amine and the 5% vol/vol emulsion of resultant blend in water having high water hardness and chloride content gave e excellent corrosion protection in cast iron corrosion test.

Example 10:

[44] The blend 23 was further subjected to bio-stability test as per ISO 12927 test method vis-a-vis a commercial cutting fluid commonly used in the machine shops. It was observed that the biostability of the blend 23 was about two times better as compared to the commercially used cutting fluid.