Patent Publication Number: US-2013244916-A1

Title: Corrosion inhibitor

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention concerns corrosion inhibitors. More particularly, the present invention relates to corrosion inhibitors for use with lubricants. Even more particularly, the present invention concerns food grade corrosion inhibitors for use with lubricants and lubricants prepared therefrom. 2. Description of the Prior Art 
     As is known to those skilled in the art, lubricants are used in practically every environment where two parts undesirably mesh or rub together to create friction. Thus, every conceivable type of machinery including, for example, vehicles, factory equipment, agricultural equipment, simple mechanical devices, such a lawn mowers, etc. all employ lubricants of some sort to minimize the wear and tear and to reduce friction. 
     While each type of lubricant is selected according to the environment in which it is employed, petroleum-based oil compositions are the most popular and widely employed lubricants. Other lubricant compositions are the soap-type lubricants prepared from organic fatty acids, as well s synthetic lubricant compositions based upon diamines, silicones, etc. 
     For example, within the food processing industry, lubricants are employed for maintaining lubricity between conveyors and the containers passing therealong. Likewise, food-handling equipment such as fillers, sprayers, etc. also employ lubricants. It is to be appreciated that because of the environment in which the lubricants are employed it is essential that the lubricant not contaminate the comestible which is being processed at the location. Such contamination creates obvious difficulties and potential hazards. Thus, great care must be taken not only in lubricant selection, but lubricant use as well. 
     Alternatively, in machining plants lubricants must be used for conveyors, transmissions, etc. Although contamination may not be a problem, it is essential to the composition or formulation of a good lubricant that a corrosion inhibitor be incorporated therewith. Just as bacteriostatic compounds, buffers, etc. must be incorporated into such formulations, necessarily, because of the environments in which the lubricants are employed, it is essential that corrosion inhibitors be incorporated therewith in order to enhance the efficacy of the lubricant. 
     It is to be appreciated, again, that in a food processing environment it would be most advantageous to employ a food-grade corrosion inhibitor which can be easily admixed and incorporated into the lubricant to thereby further reduce the hazards attendant the use of such lubricant. Furthermore, it is to be appreciated that a food-grade corrosion inhibitor also reduces the risk of using lubricants where the potential for ingestion of the lubricant, whether by accident or otherwise, is a factor. 
     In. U.S. Pat. No. 5,614,479, the disclosure of which is hereby incorporated by reference, there is disclosed a previously acknowledged food grade or GRAS (Generally Regarded as Safe) corrosion inhibitor which incorporates a ketone as an essential component. However, because of the odor of the inhibitor, attributable to the ketone, this lubricant is no longer deemed food grade. 
     Thus, the present invention, as will be subsequently detailed, provides a corrosion inhibitor comprising an admixture of components which is deemed food grade or GRAS, as defined by present Federal regulations. 
     SUMMARY OF THE INVENTION 
     In accordance with the present invention there is provided a corrosion inhibitor comprising an admixture of: 
     (a) a food-grade ester; 
     (b) an alkane or paraffin; and 
     (c) an imidazoline. 
     The components hereof are, as noted, food grade or GRAS components. By the term “food-grade” or GRAS is meant those compounds which have been denoted by the Federal Government and, in particular, the Food and Drug Administration, as being acceptable in foodstuffs or which can be used in environments which come into contact with foodstuffs. 
     The food-grade esters can comprise a single ester or mixtures thereof. 
     Likewise, the paraffinic compound or alkane is, preferably, an isoalkane can, also, comprise a mixture thereof. 
     The composition hereof can be admixed with a suitable lubricant composition. Preferably, it is admixed with a food-grade petroleum distillate lubricant composition, such as mineral oil or the like. 
     For a more complete understanding of the present invention, reference is made to the following detailed description and accompanying illustrative examples. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     As noted above, and in accordance with the present invention, there is provided a food-grade corrosion inhibitor for use with lubrication compositions or lubricants, as well as the resulting lubricant composition. 
     The corrosion inhibitor hereof generally comprises an admixture of: 
     (a) a food-grade ester; 
     (b) a food-grade alkane; and 
     (c) an imidazoline. 
     The corrosion inhibitor comprises an admixture of the components which can be blended with a suitable lubricant, such as a petroleum-based lubricant, preferably mineral oil, to form the use lubricant hereof. 
     The alkane which is used herein is either linear or branched and is preferably a liquid, unsubstituted branched alkane (isoalkane) or isoparaffin, i.e., an isoalkane having from about six to about twenty carbon atoms and mixtures thereof. 
     In practicing the present invention a preferred class of isoalkanes are those sold commercially by Exxon Mobil under the name ISOPAR. A particularly preferred isoalkane is that sold under the name ISOPAR G. Isopar G is described as a clear, odorless petroleum distillate. Other useful isoalkanes include those sold under the names ISOPAR H, L and/or M. Mixtures of these isoalkanes can be used. 
     In use, the isoalkane is present in an amount ranging from about 70% to about 95%, by volume of the additive, based upon the total volume of the additive and, preferably, from about 75% to about 90%, by volume, based on the total volume thereof. 
     The food grade ester is traditionally denoted as one derived from a fatty acid. The fatty acid esters utilized herein generally correspond to the formula: 
       R—C—R′
 
     wherein R′ is a hydrocarbon radical having from about 12 to about 20 carbon atoms in the alkyl portion thereof. R′ is, preferably, a lower alkyl such as methyl, ethyl, propyl or the like. 
     Amongst the useful higher fatty acid-based esters are, for example, oleates, palmitates, laureates, linoleates, and the like as well as mixtures thereof. 
     In practicing the present invention, the ester is present in an amount ranging from about 5% to about 15%, by volume, based upon the total volume of the additive and, preferably, is present in an amount ranging from about 10% to about 15% by volume, based on the total volume of the additive. 
     In practicing the present invention it is advantageous that the organic portion of the ester and that of the isoalkane alkane be the same. In other words, when the isoalkane is palmitate, it is highly desirable, although not essential, that R likewise be palmitate. 
     The imidazoline is present in an amount ranging from about 1% to about 10%, by volume, based upon the total volume of the corrosion inhibiting additive and is, preferably, present in an amount ranging from about 5% to about 10%, by volume, based upon the total weight of the additive. 
     The additive, itself, is prepared by admixing the components together under ambient conditions. 
     In use, the corrosion inhibitor hereof is preferably admixed with any suitable petroleum-based lubricant. Generally, the corrosion inhibitor hereof comprises from about 1% to about 20%, by volume, based on the total weight of the lubricant composition. 
     Preferably, the petroleum-based lubricant is mineral oil. The mineral oil defines a transport medium into which the additive can be readily added and admixed therewith. Since the other components are organic in nature, the components are readily admixed with the mineral oil without separation or suspension. The term “mineral oil” as used herein defines a refined hydrocarbon oil without animal or vegetable additives. Mineral oil, as such, is a widely known and commercially available product. A particularly preferred refined grade of mineral oil which is denoted as mineral oil is “white oil.” 
     In practicing the present invention, generally, the white oil, comprises from about 80 to 99%, by weight, of the total volume hereof. Preferably, the white oil is present in an amount ranging from about 85% to about 95% by volume, based upon the total volume of the composition. 
     In this regard, other food-grade lubricants, such as glycerine or glycerol, coconut oil, etc. and the like, as well as mixtures thereof, may be used herein either alone or in admixture with the white oil. However, the white oil is preferred. 
     The additive hereof is admixed with the lubricant by any conventional means at ambient conditions. 
     The composition hereof is solvent neutral and may be used in any of a wide variety of environments. In addition to its utility as a lubricant, the composition also functions as a functional fluid, such as an automatic transmission fluid, brake fluid or the like. 
     For a more complete understanding of the present invention, reference is made to the following examples. In the examples, which are to be construed as illustrative rather than limitative of the present invention, all parts are by volume absent indications to the contrary. 
     EXAMPLE I 
     This example illustrates the preparation of a corrosion inhibitor additive in accordance with the present invention. Into a suitable vessel equipped with stirring means is added the following at room temperature: 
     
       
         
           
               
               
               
             
               
                   
                   
               
               
                   
                 Ingredient 
                 Amount, pbv 
               
               
                   
                   
               
             
            
               
                   
                 ISOPAR G 
                 4.0 
               
               
                   
                 Methyl laureate 
                 1.0 
               
               
                   
                 Imidazoline 
                 0.5 
               
               
                   
                   
               
            
           
         
       
     
     The above corrosion inhibitor composition is then admixed with 94.5 parts of white oil at ambient conditions. The resulting composition is useful as a transmission fluid. 
     EXAMPLE II 
     This example illustrates the preparation of a lubricant composition in accordance herewith. 
     Into a suitable vessel equipped with a suitable stirrer is charged a quantity of white oil. To the white oil is added, serially, food grade corrosion inhibiting components to form a lubricant. 
     The following sets forth the components and the amounts thereof. 
     
       
         
           
               
               
               
             
               
                   
                   
               
               
                   
                 Ingredient 
                 Amount, pbv 
               
               
                   
                   
               
             
            
               
                   
               
            
           
           
               
               
               
            
               
                   
                 White oil 
                 90.00 
               
               
                   
                 ISOPAR G 
                 8.00 
               
               
                   
                 Methyl laurate 
                 1.00 
               
               
                   
                 Imidazoline 
                 1.0