Abstract:
A corrosion inhibitor for metallic crown caps used in packed products. The corrosion inhibitor comprises: one or more zinc sources of food grade, such as zinc oxide; one or more acid sources like carboxylic acids, such as citrus acid; a pH regulator compouse, such as sodium hydroxide; and water, preferably soft water, as aqueous phase for the concentrate formed by the combination of said compounds, as well as soft water as a concentrate solvent for its application. A method and system for applying the corrosion inhibitor is also presented, which ensure that the corrosion inhibitor impregnates both the crown cap perimeter rim and the crown cap internal surface adjacent to the surface of the nozzle of the container.

Description:
TECHNICAL FIELD OF THE INVENTION 
       [0001]    This invention relates to a corrosion inhibitor compound and to an application method and system of the same to prevent corrosion on the metallic parts of containers used for packing drinks, food or other products; especially to prevent corrosion in metallic crown caps used for said containers. 
       BACKGROUND OF THE INVENTION 
       [0002]    Nowadays, drinks, foods, and packed products are available in several kinds of containers; such as glass bottles that during their manufacturing and filling processes their nozzles are closed with crown caps, which are usually made of metal. Such crown caps, typically called crown caps, caps, or tops are manufactured from a metallic plate or sheet, then a cutting and printing process is applied to it, as well as an ink printing and varnishing process; in addition, a plastic liner is added to it to form the internal seal of the crown cap. Before this, the metallic plate or sheet can be treated with a galvanizing process in order to prevent its corrosion. 
         [0003]    During the different cutting and printing process stages of the metallic plate or sheet in which crown caps are formed, a perimeter rim is generated with an unprotected edge against corrosion, in such a way that when the crown cap is installed over the container nozzle, the perimeter rim of the crown cap is exposed to the environmental conditions in which the packed products are immersed. 
         [0004]    When the crown cap is placed over the container nozzle and it is exposed to the conditions that initiate corrosion, the perimeter rim is attacked by this phenomenon which shows up as metallic oxide, and tends to deposit itself inside the crown cap and also inside the container upper rim; then, when the crown cap is removed to consume the product, the oxide residues adhered to the nozzle edge produce a bad appearance and can also become a contamination source for the packed product and for the consumer. 
         [0005]    In addition to this, most of the corrosion inhibitors compounds, zinc-based, used for the treatment of metallic plates or surfaces contain in their formulations compounds and/or concentrations which are generally out of permissible standards. Thus, it is not feasible to use them as a second stage treatment to prevent corrosion once the crown cap is printed and cut because the operation costs would increase, and applying them when the crown cap is placed over the container nozzle would be the least advisable because they would be a contamination source for the consumer. 
       SUMMARY OF THE INVENTION 
       [0006]    According to what has been previously described, the object of the present invention is to provide a corrosion inhibitor for crown caps and a method and system for its application, having the inhibitor cost-effective, free of contaminant compounds and whose concentrations of active compounds do not harm health; additionally, being applied once a crown cap is placed over the container nozzle. 
         [0000]    In addition to this, it is also the objective of the present invention to provide a system and a method for applying the corrosion inhibitor to a crown cap once it is placed over the container nozzle. 
     
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
         [0007]    The proper details of the method and system for applying a corrosion inhibitor to metallic crown caps are described in the “application mode” section, as well as in the figures that come with it, whose purpose is to define the method and system, but without restricting its scope. 
           [0008]      FIG. 1  illustrates a schematic diagram of the present invention of a system for applying a corrosion inhibitor on crown caps. 
           [0009]      FIGS. 2A and 2B  illustrate a lateral and superior view of a spray orientation of the corrosion inhibitor for metallic crown caps seen from  FIG. 1  perspective. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0010]    First, the proper and composition details of the corrosion inhibitor for metallic crown caps are described in the following paragraphs, whose purpose is to define the features and composition of such inhibitor, but without restricting its scope. 
         [0011]    The corrosion inhibitor for metallic crown caps shows components that can also consist of multiple components in its concentrate composition. 
         [0012]    The components are individually described below. 
       Component I 
       [0013]    The corrosion inhibitor for metallic crown caps contains an active component I, which is one or more zinc sources of food grade which can be metallic zinc, zinc oxide, or a mixture of these. 
         [0014]    We found that zinc salt, such as zinc gluconate, zinc chloride, zinc sulphate, zinc carbonate, zinc citrate, or a mixture of these can be used as Component I, among other zinc sources of food grade. 
       Component II 
       [0015]    The corrosion inhibitor for crown caps contains an active component II, which is one or more acid sources that can be carboxylic acids, such as citrus acid, its salt, or a mixture of these. 
         [0016]    Acetic acid, adipic acid, alginic acid, lactic acid, estearic acid, tartaric acid, tannic acid, succinic acid, or a mixture of these can also be the carboxylic acid used in the composition. 
         [0017]    Other kind of acid sources used are: sulphuric acid, glutamic acid, gluconic acid, phosphoric acid, ascorbic acid, eritorbic acid, sorbic acid, hydrochloric acid, or a mixture of these. 
       Component III 
       [0018]    The corrosion inhibitor for crown caps contains a component III, which is a regulator component of pH, such as sodium hydroxide, potassium hydroxide, ammonium hydroxide, or a mixture of these, which give stabilization features to the corrosion inhibitor and avoid its precipitation. The pH range of the corrosion inhibitor is from pH 2 to pH 8. 
       Component IV 
       [0019]    The corrosion inhibitor for metallic crown caps contains water as component IV as aqueous phase for the dispersion of the remaining components during the concentrate preparation of the corrosion inhibitor. It is best to use soft water for this purpose. 
         [0020]    Once the corrosion inhibitor for metallic crown caps is elaborated as a concentrate, it is then diluted in water, preferably soft water, to provide an easy application on the crown caps. 
       Concentrate Blend 
       [0021]    The corrosion inhibitor for metallic crown caps, in its elaboration as a concentrate, combines components I, II, III, and IV in the following weight percentage concentrations:
       (a) from 0.0005% to 50% of the zinc source (component I);   (b) from 0.001% to 60% of the acid source (component II);   (c) from 0.001% to 25% of the pH regulator composite (component III); and   (d) from 0% to 99.997% of water (component IV).       
 
         [0026]    Table 1 illustrates examples of the corrosion inhibitor composition for metallic crown caps, in concentrate form, showing the weight percentage concentrations of each component, its operative pH and the corrosion residues found in the nozzles of the test glass containers: 
         [0000]    
       
         
               
               
               
             
               
               
               
               
               
             
               
               
               
               
               
             
           
               
                   
                 TABLE 1 
               
             
             
               
                   
                   
               
               
                   
                 Weight percentage of each component 
                   
               
             
          
           
               
                   
                 Compound 
                 Ex. 1 
                 Ex. 2 
                 Ex. 3 
               
               
                   
                   
               
             
          
           
               
                   
                 Zinc oxide 
                 5.50 
                 0 
                 0 
               
               
                   
                 Zinc sulphate 
                 0 
                 22.60 
                 0 
               
               
                   
                 Metallic zinc 
                 0 
                 0 
                 45 
               
               
                   
                 Citric acid 
                 14.50 
                 0 
                 0 
               
               
                   
                 Gluconic acid in 
                 0 
                 54.90 
                 0 
               
               
                   
                 aqueous solution 
               
               
                   
                 Hydrochloric acid 
                 0 
                 0 
                 55 
               
               
                   
                 in aqueous 
               
               
                   
                 solution 
               
               
                   
                 Sodium hydroxide 
                 12.00 
                 22.50 
                 0 
               
               
                   
                 Potasium hydroxide 
                 0 
                 0 
                 0 
               
               
                   
                 Soft water as 
                 68.00 
                 0 
                 0 
               
               
                   
                 aqueous phase for 
               
               
                   
                 the concentrate 
               
               
                   
                 pH 
                 6.0 
                 6.7 
                 2.3 
               
               
                   
                 Corrosion present 
                 No 
                 No 
                 No 
               
               
                   
                   
               
             
          
         
       
     
         [0027]    In a particular embodiment in its concentrate composition, the corrosion inhibitor for metallic crown caps shows the following content in weight percentage concentrations:
       (a) from 0.00055% to 15% of zinc oxide (component I);   (b) from 0.00145% to 20% of citric acid (component II);   (c) from 0.0012% to 24% of sodium hydroxide (component III); and   (d) from 41 to 99.997% of soft water (component IV).       
 
         [0032]    Table 2 illustrates examples of corrosion inhibitor composition for metallic crown caps, in concentrate form, showing the weight percentage concentrations for each component, its operative pH and the corrosion residues found in the nozzles of the test glass containers: 
         [0000]    
       
         
               
               
               
             
               
               
               
               
               
             
               
               
               
               
               
             
           
               
                   
                 TABLE 2 
               
             
             
               
                   
                   
               
               
                   
                 Weight percentage of each component 
                   
               
             
          
           
               
                   
                 Compound 
                 Ex. 1 
                 Ex. 2 
                 Ex. 3 
               
               
                   
                   
               
             
          
           
               
                   
                 Zinc oxide 
                 5.50 
                 6.20 
                 4.40 
               
               
                   
                 Citric acid 
                 14.50 
                 15.80 
                 11.60 
               
               
                   
                 Sodium hydroxide 
                 12.00 
                 10.00 
                 9.60 
               
               
                   
                 Soft water as 
                 68.00 
                 68.00 
                 74.40 
               
               
                   
                 aqueous phase for 
               
               
                   
                 the concentrate 
               
               
                   
                 pH 
                 6.0 
                 6.5 
                 6.4 
               
               
                   
                 Corrosion present 
                 No 
                 No 
                 No 
               
               
                   
                   
               
             
          
         
       
     
       Concentrate Dilution 
       [0033]    The corrosion inhibitor concentrate for metallic crown caps is dissolved in water to facilitate its application on metallic crown caps, according to the following weight percentage concentrations:
       (a) from 0.01% to 100% of the corrosion inhibitor concentrate (component I+component II+component III+component IV) and   (b) from 0% to 99.99% of water as solvent.       
 
         [0036]    Table 3 illustrates examples of corrosion inhibitor composition for metallic crown caps, in diluted form, showing the weight percentage concentration of each component, its operative pH, and the corrosion residues in the nozzles of the test glass containers: 
         [0000]    
       
         
               
               
             
               
               
               
               
               
               
               
             
               
               
               
               
               
               
               
             
           
               
                   
                 TABLE 3 
               
             
             
               
                   
                   
               
               
                   
                 Weight percentage of each component 
               
             
          
           
               
                 Compound 
                 Ex. 1 
                 Ex. 2 
                 Ex. 3 
                 Ex. 4 
                 Ex. 5 
                 Ex. 6 
               
               
                   
               
             
          
           
               
                 Concentrate 
                 10 
                 20 
                 50 
                 2 
                 1 
                 0.5 
               
               
                 (component I + 
               
               
                 component II + 
               
               
                 component III + 
               
               
                 component IV) 
               
               
                 Soft water as 
                 90 
                 80 
                 50 
                 98 
                 99 
                 99.5 
               
               
                 solvent of the 
               
               
                 concentrate 
               
               
                 pH 
                 7.62 
                 7.43 
                 7.14 
                 7.59 
                 7.75 
                 7.80 
               
               
                 Corrosion present 
                 No 
                 No 
                 No 
                 No 
                 No 
                 No 
               
               
                   
               
             
          
         
       
     
       Concentrate Preparation Mode 
       [0037]    The corrosion inhibitor concentrate for metallic crown caps is prepared, for example, at a temperature from 40° C. to 60° C.; where, first, an aqueous solution of soft water and acid source is prepared (component IV); later, a zinc source is slowly added (component I), being shaken vigorously afterwards; slowly adding the pH regulator component (component III) to stabilize the solution and to avoid reaction precipitation from the zinc source and acid source, and additionally to regulate the pH desired in the concentrate, in the range of pH 2 to pH 8. 
         [0038]    Finally, the active composition (component I+component II+component III) is diluted in dilution water in the right amounts according to the application requirements. 
       Application Mode 
       [0039]    The corrosion inhibitor for metallic crown caps can be applied immersing the crown cap that is placed in the container nozzle, in a recipient with corrosion inhibitor; another application alternative is to spray the corrosion inhibitor manually on the crown cap using a paintbrush, sponge, tow, etc. In all cases, it the corrosion inhibitor must be permitted to impregnate the crown cap rim, as well as the crown cap inner surface adjacent to the container nozzle surface. 
         [0040]    In the case of the spray application alternative,  FIG. 1  shows the application system of a corrosion inhibitor in crown caps providing a smooth and optimum application of the right amount of corrosion inhibitor for that purpose. Here, system  10  has a couple of spray nozzles  20  generally placed opposite each other, with a lightly ascendant spray angle directed to the base or perimeter rim of the crown cap, specially towards its edge. Such spray nozzles  20  are connected to a pneumatic system  30  that contains the corrosion inhibitor. System  10  has a proximity detector  40  to detect the presence of container  50  with crown cap  60  placed when containers  50  are transported through chain conveyor  70 . 
         [0041]    Under configuration of system  10 , containers  50  are transported through a conveyor belt  70  to system  10  for the corrosion inhibitor application. When container  50 , with crown cap  60  installed, is near spray nozzles  20 , the latter is detected by proximity detector  40 , which orders the pneumatic system  30  to spray the corrosion inhibitor on crown cap  60  through spray nozzles  20 , favoring the impregnation and adherence of the corrosion inhibitor to the perimeter rim of crown cap  60 , as well as to the inner surface of it, which is adjacent to container nozzle surface  50 . Finally, allow the corrosion inhibitor to dry and to form a corrosion inhibitor layer in crown cap  60 . 
         [0042]    Referring to  FIGS. 2A and 2B , which illustrate a lateral and superior view of the spray orientation of corrosion inhibitor for metallic crown caps, seen from  FIG. 1  perspective. In order to promote the corrosion inhibitor&#39;s impregnation and adherence to the perimeter rim of crown cap  60 , as well as to the inner surface of it, which is adjacent to container nozzle surface  50 ; spray nozzles  20  are generally placed opposite each other with a lightly ascendant angle β directed to crown cap  60  in container  50 , specially to the base or perimeter rim of crown cap  60 , specially towards its exposed edge. 
         [0000]    Based on the previously described composition embodiments of the corrosion inhibitor, it is contemplated that the modifications of described composition and embodiments, as well as the alternative composition and embodiments, will be considered as evident for an expert person in the art under the present description. Therefore, it is considered that the claims include said modifications and alternatives that are in the scope of the corrosion inhibitor of this invention.