US 3791974 A
Description (OCR text may contain errors)
BACTERIAL SPOILAGE lNI-IIBITED METAL WORKING LUBRICANT COMPOSITIONS Earl E. Borchert, Valley View'Village, Ohio, assignor to Ferro Corporation, Cleveland, Ohio No Drawing. Filed Apr. 6, 1972, Ser; No. 241,843
. Int. Cl. C10m N06 US. Cl. 252-495 8 Claims ABSTRACT OF THE DISCLOSURE Metal working lubricant compositions used to cool and lubricate metal in cutting, grinding, rolling, drawing and similar metal working operations are protected against bacterial spoilage during use by the presence of 10 to n is the number 2 or 3, and m is the number 0,1, 2 or 3.
BACKGROUND OF THE INVENTION Field of the invention This invention relates to metal working lubricant compositions that in metal working operations will comprise an aqueous phase and an oil phase containing certain unique inhibitors against bacterial spoilage during use.
Description of the prior art It is common practice in many metal working opera tions to circulate 'aliquid over the metal surface being worked to cool and lubricate the surface and the cutting tool or other device which is working the metal. Such metal working lubricant compositions are used in the cutting, grinding, rolling, drawing and similar metal working operations including metal pressing, wire drawing, metal extrusion and the like. Generally, the lubricant composition which is circulated over the worked metal surface is a mixture of a dissolved or emulsified lubricant component in a large excess of water. The choice of the lubricant component is often determined by the degree of lubrication desired at the metal surface, as well as the susceptibility of metals being worked to corrosion under .the given operating conditions. Generally, the lubricant component will be an oil of hydrocarbon, animal or vegetable origin existing as an oil phase emulsified by a water phase. In a typical metal working operation, the lubricant emulsion is formed by mixing the product referred to in the metal working trade as a soluble oil with a large excess of water. Soluble oils generally are a mixture of lubricant oil with emulsifying agents, wetting agents and modifying agents of various types to provide easy emulsifiability of the oil in water, a stable emulsion once formed and the desired cutting and cooling characteristics to the resulting lubricant, emulsion. The emulsion may be a water-in-oil type, but more frequently it is of the oil-in-water type. A wide variety of emulsifying or wetting agents are used in compounding these soluble oils including alkanolamides, alkyl sulfonates, arylsulfonates, sulfated amines and amides, ethxylated alcohols, ethoxylated alk'yl phenols, fatty acid, soaps, glycerol esters,
United States Patent Ofice 3,791,974 Patented Feb. 12, 1974 glycol esters, sulfosuccinates, alcohol sulfates, sulfated fatty acids and esters, phosphate derivatives and sorbitan derivatives.
In keeping with the general usage in the metal working and related industries, the basic composition from which the metal working lubricant emulsions are formed will be referred to hereinafter as soluble oil, the emulsions made by mixing such soluble oil with a large excess of water will be referred to as lubricant emulsion and all of these materials will be generally referred to by the generic term metal working lubricant composition.
Lubricant emulsions during use in metal working operations are subject to a significant degree to microbial degradation. The organisms which bring this about are very numerous and are universally present in the ambient atmospheres and metal working systems in which the lubricant emulsions are used. The emulsions can become severely contaminated by simple exposure to air after a few hours or days. Once present in the emulsion, the organisms start to grow and divide immediately and their population can increase rapidly. There may be hundreds of different species present, each adept at some particular degradation and most active under certain specified conditions. In general, continuously used well-aerated systems at close to ambient temperatures degrade quickly and are dominated by aerobic bacteria such as Psuedomonas, Alcaligenes and Achromo'bacter. Systems not wellaerated, intermittently used or with a slow turnover will also contain anaerobic organisms (such as Clostridium and Desulfovidrio desulfuricans) and facutative anaerobic organisms. These are responsible for sickening, clinging smells-the so-called Monday morning odors.
The most obvious visible evidence of microbial growth is the microbes themselves. They appear as slimes and sediments wherever they are allowed to accumulate, and are also removed from systems as deposits in centrifugal or other separators. Also obvious are the objectionable smells due to degradation products, usually accompanied by darkening color.
The chemical changes which have taken place may affect lubricating properties and viscosity. They can also degrade additives included to increase oil film strength, inhibit corrosion or the like.
The degradation of the emulsifying chemicals by the micro-organisms is of considerable engineering significance. The emulsion progressively changes from finely dispersed oil droplets in water to a coarse dispersion and eventually free oil separates.
Rapid corrosion of parts after machining is associated with bacterial contamination of the oils and emulsions. A stable oil film no longer forms on the part machined and as any added corrosion inhibitor will also be altered or depleted by the organisms, the result can be a very costly accumulation of unusable corroded products.
Adverse effects produced by high microbial activity in lubricant emulsions include:
(a) Short oil life; costly oil changes; time loss during changes; excessive topping up with oil to maintain the emulsion strength;
(b) Poor surface finish; roll-slip in rolling steel and aluminum; corrosion on steel sheet;
(c) Short tool life; fouled grinding wheels; wheel burn;
(d) Excessive solid loads on filters and clarifiers; slimes and deposits;
(e) Rapid corrosion after machining;
(f) Smells and discolorations.
The prevention of excessive microbial growth by the inhibitors is the principal means of minimizing the adverse, effects. Among the more widely used anti-microbial additives are hexahydro l,3,5-tris(2-hydroxyethyl)-s-triazine and hexahydro-1,3,S-triethyl-s-triazine. The present invention involves the novel use and unexpected superiority of hexahydro-1,3,5-tris(alkoxyalkyl)-s-triazines.
A variety of other materials have been used as inhibitors against bacterial action upon soluble oils and lubricant emulsions, e.g., see -U.S. 3,013,973.
The utility of soluble oils and lubricant emulsions would be advanced if improvements could be made in the prevention of bacterial spoilage of these materials. Accordingly, it is a principal object of this invention to provide certain unique inhibitors against bacterial spoilage of soluble oils and lubricant emulsions, to provide improved metal working lubricant compositions containing improved bacterial spoilage inhibitors and to provide certain new and novel compounds useful as such inhibitors.
Other objects and further scope of applicability of the present invention will become apparent from the detailed description given hereinafter; it should be understood, however, that the detailed description, while indicating preferred embodiments of the invention, is given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description. It should also be understood the foregoing abstract of the disclosure is for the purpose of providing a non-legal brief statement to serve as a searchingscanning tool for scientists, engineers and researchers and is not intended to limit the scope of the invention as disclosed herein nor is it intended it should be used in interpreting or in any way limiting the scope or fair meaning of the appended claims.
SUMMARY OF THE INVENTION Objects of the invention are attained, in part, by the provision of metal working lubricant compositions protected against bacterial spoilage during use in metal working operations by the presence of to 3000 p.p.m. of a triazine compound of the formula:
n is the number 2 or 3, and m is the number 0, 1, 2 or 3.
Objects of the invention are also attained, in part, by new methods of inhibiting bacterial spoilage of metal working lubricant emulsions normally subject to bacterial spoilage by providing in such emulsions between about 10 to 3000 p.p.m. of triazine compound of the foregoing formula.
According to one embodiment of the invention, oil soluble compositions for admixture with water to form a metal working lubricant emulsion are provided comprising an aqueous phase and an oil phase, said compositions containing as an inhibitor against bacterial spoilage of said emulsion during use in metal working operations a minor amount of hexahydro-l,3,5-tris(alkoxyalkyl)-s-triazine in which the alkoxy moiety contains 1 to 4 carbon atoms and the alkyl moiety contains 2 or 3 carbon atoms and especially where the alkoxy moiety contains 1 to 2 carbon atoms and the alky1 moiety is CH CH or -CH CH OH In another embodiment of the invention, metal working lubricant emulsions comprise an aqueous phase, an oil phase and between about 50 to 2000 p.p.m. of a hexahydro-l,3,5-tris(alkoxyalkyl)-s-triazine in which the alkoxy contains 2 or 3 carbon atoms.
4 DESCRIPTION OF PREFERRED EMBODIMENTS The following details of operations in accordance with the invention and reported data illustrate the further principles and practice of the invention to those skilled in the art. In these examples and throughout the remaining specification and claims, all parts and percentages are by Weight unless otherwise specified.
EXAMPLE 1 Preparation of l,3,5-tris(3-methoxypropyl)-shexahydrotriazine Into a closed reaction vessel equipped with internal stirrer, external heating and cooling jacket and liquid inlet tube, there was charged 490 parts formalin (37% HCHO) and 6 parts K 00 Through the inlet tube, there was added 525 parts of 3-methoxypropylamine at a rate slow enough to allow the temperature of the exothermic reaction to be maintained with external cooling at 50- 55 C. After the completion of such addition, the reaction mixture was held at a temperature of 55 C. for 45 minutes.
Water present in the resulting reaction mass was removed by vacuum distillation at a pressure of 20 mm. Hg with a heating temperature of 60 C. The yield of crude product was 570 parts (95.5% of theory). A portion of the crude product was used as an inhibitor of bacterial spoilage in a metal working lubricant composition.
Another portion was purified by high vacuum distillation and the portion (91% of original crude) boiling at 130l43 C. at 0.03 mm. Hg was collected as a clear white liquid (Ref. Index at 25 C., Na-D line=l.466) having a density of 0.99. When tested as a microbiologic inhibitor, it was comparable in activity to the crude product.
EXAMPLE 2 Preparation of 1,3,5-tris(alkoxyalkyl)-s-hexahydrotriazines Using the general procedure described in Example 1 of the triazines of the invention were prepared. The prop erties of the compounds are given in the following table:
TABLE 1 R R.I. D B.P. Yield --5 1.460 0.95 143-152 (0.06 mm.) 94 (90) 1.459 0.97 123-130 (0.13 mm.) 88 (83) (OHz):OCH| 1.466 1.02 113-122 (0.2 nun.) 87
Evaluation of bacterial spoilage inhibition properties A series of lubricant emulsions were modified by addition of certain triazine compounds to evaluate the ability of the compounds to inhibit bacterial spoilage. The lubricant emulsions were prepared by diluting soluble oils with tap water in a 1:40 ratio. About 1500 ml. of the resulting emulsion was placed in a wide mouth glass jar and 1 ml. of an emulsion highly contaminated with bacteria obtained from a commercial metal working operation was added as an inoculum. The jar was kept uncovered in air at ambient temperature (2025 C.) and a gentle stream of air (unmeasured) was bubbled through the inoculated emulsion. Every 7 days a count was made of the microorganism population of the emulsion using standard clinical practice. When the count reached l 10"/cc., the test was terminated and the number of days recorded as the criteria of inhibition. This test when repeatedfor each compound produced the results reported in the following table:
TABLE 2.-DAYS TO FAILURE OF COOLING OIL EMUL- SIONS CONTAINING VARIOUS ADDITIVES 1 N 0 data available.
In Table 2, the einulsions were prepared from soluble oils identified as follows:
Column X reports the days to termination of emulsion containing. 1000' 11pm. of 1,3,5-triethyl-s-hexahydrotriazine (prior art compound as control).
Column Y reports the days to termination of emulsion containing 1000 p.p.m. of 1,3,5-tris(2-hydroxyethyl)-shexahydrotriazine (prior art'compound as control).
Column Z1 reports the days to termination of emulsion containing 1000 p.p.m. of compound of Example 1.
Columns Z2, Z3 and Z4 report the days to termination of emulsions containing 1000 p.p.m. of hexahydro-l,3,5- tris (2 methoxyethyl)-s-triazine, hexahydro-l,3,5-tris(2- ethoxyethyl)-s-triazine and hexahydro-1,3,5-tris(3-ethyoxypropyl)-s-triazine, respectively.
In the case of Z1, the tests were terminated after 210 days. In the cases of Z2, Z3 and Z4, the data given reflect the state of the oils after 77 days of testing.
Concentrations of the additives of this invention less than 1000 p.p.m. gives somewhat less protection. Thus, at 500 p.p.m., the additive Z1 afforded 70 days of effective protection to emulsion A. Even at 250 p.p.m., the additive of Z1 afforded commercially useful periods of protection for emulsions D, F and G.
Concentrations higher than 1000 p.p.m. (e.g. 2000 or 3000 p.p.m.) provide long-term protection. Oils will usually begin to deteriorate from non-microbial causes after a while and it is generally uneconomical to use concentrations in excess of 3000 p.p.m.
EXAMPLE 4 Further evaluation of inhibition properties A soluble oil was provided of the following composition:
Parts Heavy petroleum lubricating oil 90 Sodium petroleum sulfonate Sodium naphthenate 3 Ethanol 1 This soluble oil was mixed with water in a 1:40 oil: water ratio to form an oil-in-water emulsion which was sterilized in an autoclave. Compounds to be tested as bacterial spoilage inhibitors were added in 50 p.p.m., '100 p.p.m., 500 p.p.m'.and='1000p.p.m. to'aliquots of the sterilized emulsion forming a series of emulsion test samples. To each sample was added 0.1% of an inoculum (emulsion heavily contaminated with bacteria obtained from industrial metal working operation). The samples were allowed to stand at ambient temperature in covered jars for 48 hours. A transfer of a drop of each sample was then made using a 4 mm. wire loop to nutrient agar plates. The plates were incubated and checked for evidence of bacterial growth at 24-hour intervals up to 72 hours. A sample to which no inoculum was added (designated Control 1) and another sample to which inoculum was added but no inhibitor (designated Control 2) were similarly processed for comparison. The data produced by the test are reported in the following table:
TABLE 3 Sample 50 500 1, 000
N N N N 48 N N N L L 24 48 The success of the invention is due to the discovery of critically superior properties for the specific class of triazines defined above as inhibitors for bacterial spoilage of metal working lubricating compositions. A preferred inhibitor of the invention is 1,3,5-tris(ethoxy-ethyl)-shexahydrotriazine. Other inhibitors of the invention include the corresponding methoxyethyl, 3-methoxypropyl, 3-ethoxy propyl, propoxyethyl, propoxypropyl, butoxy ethyl and butoxypropyl compounds. Mixtures of two or more may be used.
The quantity of inhibitor compound provided in the lubricant emulsion can be varied and will depend, at least in part, upon the use-life demands of the metal working operation employing the emulsion. Most satisfactory results are obtained when the emulsion contains between about 10 to 2000 p.p.m. of the inhibitor. It may be added directly to the ultimate emulsion or to the soluble oil from which the emulsion is prepared by mixture with water. Generally, the emulsion will contain 25 to 100 parts of water for each part of soluble oil and the inhibitor content of the soluble oil will vary accordingly, e.g., 1 to 20 parts of inhibitor in each 100 parts of soluble oil, especially 1 to 5% inhibitor. Preferred soluble oils of the invention will have the following formulations:
Percent Organic lubricant 75-90 Emulsifying agent 5-20 Inhibitor l-S Other additives 0-15 The bacterial spoilage inhibition methods of the invention are particularly useful with lubricant emulsions that contain an organic lubricant, but they may also be applied to metal working lubricant compositions that comprise an inorganic base, e.g., polyphosphates. The metal working industry divides these compositions into three general categories, i.e., petroleum base, synthetic base and inorganic base. Commercial examples of petroleum base include Citgo Coolant, Vantrol, Sun Seco, Texaco Soluble C, Enco Kutwell and Shell Dromis. Commercial examples of synthetic base include Trim, Monroe Bluecut, Chemtool, Lusol and Primecut. A
commercial example of inorganic base is Norton Wheelmate.
Petroleum base soluble oils typically employ petroleum source lubricating oils, e.g., mineral oil, naphthene base distillate oil, paratfin wax and equivalent oils and waxes. Synthetic base soluble oils may employ fatty acid soaps, organic amines, organic borates, vegetable oils and fats, animal oils and fats, vegetable or insect waxes. Combinations of these are frequently employed, e.g., 90% mineral oil and 10% oleic acid or 70% tallow, 28% parafiin wax and 2% beeswax.
A wide variety of emulsifying agents are used in forming the soluble oils. General classes have been delineated hereinbefore. Frequently, they are anionic, but may also be non-ionic, cationic or combinations. Specific examples of emulsifying agents include sodium sulfosuccinate, sodium alkylphenoxypoly(ethylenoxy)ethyl sulfate, polyoxyethylene monolaurate, polyethoxylated quaternary ammonium chlorides, esters of ethoxylated sorbitol, ethoxylated nonylphenol, sodium lauryl sulfate, sodium dodecylbenzenesulfonate, 'glyceryl monostearate, quaternary ammonium salts of alkylphosphoric acids, lauryl dimethyl amine oxide, coconut acid diethanolamide and similar emulsifiers, e.g., see McCutcheons Detergents and Emulsifiers Annual.
Additives include rust inhibitors, Wetting agents, defoamers, graphite, solvents, dyes, viscosity modifiers, and various other agents used to modify the machining effect, stability, color, foaming or other properties of the soluble oils or the lubricant emulsions made from them.
Many examples of soluble oils, lubricant emulsions and their ingredients can be found in the literature and patents, e.g., see US. 3,013,973; 3,429,909 and 3,442,805.
The data and information reported above demonstrate that the class of triazine compounds as hereinbefore defined provide exceptional protection to metal working lubricant compositions against bacterial degradation. The resulting emulsion preservation methods are applicable to the total spectrum of soluble oils and lubricant emulsons.
The embodiments of the invention in which an exclusive property or right is claimed are defined as follows:
1. A soluble oil composition for admixture with water to form a metal working lubricant emulsion comprising an aqueous phase and an oil phase, said composition containing a. lubricating oil, an emulsifying agent and as an inhibitor against bacterial spoilage of said emulsion during use in metal working operations between about 1 and by weight of a hexahydro-1,3,5-tris(alkoxyalkyl)striazine in which the alkoxy moiety contains 1 to 4 carbon atoms and the alkyl moiety contains 2 or 3 carbon atoms.
2. A soluble oil composition for admixture with water to form a metal working lubricant emulsion comprising an aqueous phase and an oil phase, said composition consisting essentially of the following ingredients in about the percentages by weight indicated:
Percent A lubricating oil 75-90 Emulsifying agent 5-20 Bacterial spoilage inhibitor 1-5 8 wherein said inhibitor is a hexahydro-l,3,5-tris(alkoxyalkyl)-s-triazine in which the alkoxy moiety contains 1 to 4 carbon atoms and the alkyl moiety contains 2 or 3 carbon atoms.
3. The soluble oil composition of claim. 1 wherein said alkoxyalkyl moiety is selected from the group consisting of methoxypropyl, ethoxy'propyl, ethoxyethyl, methoxyethyl and butoxypropyl. I
4. A metal working lubricant emulsion comprising a continuous aqueous phase having dispersed therein as a discontinuous oil phase a lubricating oil, said emulsion containing an emulsifying agent and between about 10 to 3000 p.p.m. of a hexahydro-l,3,5-tris(alkoxyalkyl)-striazine in which the alkoxy moiety contains l to 4 carbon atoms and the alkyl moiety contains 2 or 3 carbon atoms.
5. The emulsion of claim 4 wherein said aqueous phase amounts to about 25 to 100 parts for each part of the oil phase.
6. The emulsion of claim 5 which contains about 5 to 20 parts emulsifying agent for each 100 parts of lubricating oil. I
7. The emulsion of claim 6 wherein said lubricating oil is a mineral lubricating oil.
8. A soluble oil composition for admixture with water to form a metal working lubricant emulsion comprising a continuous aqueous phase and a discontinuous oil phase, said emulsion exhibiting low tendency toward bacterial spoilage in use as a metal working lubricant, said composition consisting essentially of the following ingredients in about the percentage by weight indicated:
Percent Mineral lubricating oil -90 Emulsifying agent 5-20 Bacterial spoilage inhibitor 1-5 wherein said inhibitor is a hexahydro-1,3,S-tris(alkoxyalkyl)-s-triazine in which the alkoxyalkyl group is selected from the group consisting of methoxypropyl, ethoxypropyl, ethoxyethyl, methoxyethyl and butoxypropyl.
References Cited UNITED STATES PATENTS 2,701,187 2/ 1955 Andress 44--63 3,228,829 1/1966 Wolf et al. 25249.5X 3,408,843 11/ 1968 Treat 252-495 X FOREIGN PATENTS 2,004.678 11/ 1969 France.
WARREN H. CANNON, Primary Examiner US. Cl. X.R. 72-42; 424249