Abstract:
An environmentally benign and water dispersible corrosion inhibitor is disclosed. The corrosion inhibitor comprises a combination obtained by combining at least one of water dispersible polymers, water soluble silicates, water, additives, among other components.

Description:
[0001]    The subject matter disclosed and claimed herein claims benefit of prior filed U.S. patent application Ser. No. 60/246,886, filed on Nov. 08, 2001; the disclosure of which is hereby incorporated by reference. 
     
    
     
       FIELD OF THE INVENTION  
         [0002]    The field of the invention relates to corrosion inhibitors for reducing the corrosion rate of metallic surfaces.  
         BACKGROUND OF THE INVENTION  
         [0003]    It is well know in this art to apply one or more inhibitors upon a metallic surface to reduce the corrosion rate. Conventional corrosion inhibitors typically contain components that are environmentally desirable. Such components are partiuarally undesirable when employed in applications wherein the components may be released upon water or other environmentally sensitive areas.  
         SUMMARY OF THE INVENTION  
         [0004]    The instant invention solves problems associated with conventional methods by providing an environmentally benign and water dispersible corrosion inhibitor. The inventive corrosion inhibitor comprises a combination obtained by combining at least one of water dispersible polymers, water soluble silicates, water, additives, among other components. The inventive composition is typically employed in applications were relatively short term (depending upon the application) corrosion inhibition is desired. The inventive composition and process can also be employed for increasing the effective life of metallic surfaces previously treated to impart relatively long term corrosion protection, e.g., painted metallic surfaces.  
         DETAILED DESCRIPTION  
         [0005]    The instant invention relates to compositions, and method for applying the composition to reduce dusting and/or corrosion of a metallic surface. The metallic surface can comprise an anchor chain such as that used on commercial and military boats and ships. The chain can comprise detachable links such as those described in U.S. Pat. No. 5,974,779, issued Nov. 02, 1999 in the named of Orscheln et al.; hereby incorporated by reference.  
           [0006]    While the inventive composition can comprise a wide range of components, normally the composition is substantially free of toxic components and those leaving a film or sheen upon water. By “substantially free” it is meant that the composition comprises less than about 10 wt. % and normally about 0 wt. % of such components.  
           [0007]    The inventive method can be employed to apply the inventive composition(s) in order to:  
           [0008]    1) Use silicates and salt water for corrosion inhibition of metal on ocean vessels or platforms,  
           [0009]    2) Use polyvinyl alcohol or silicate blends for corrosion control,  
           [0010]    3) Use polyvinyl alcohol as a rust binder for anchor chain or other metal structure,  
           [0011]    4) Use silicates as rust binder for anchor chain or other metal structures,  
           [0012]    5) Use silicate solutions as deck or platform wash using salt water diluent, among other applications wherein it is desirable to inhibit corrosion.  
           [0013]    In one aspect of the invention, the inventive composition comprises at least one of polyvinyl alcohol, ethylene vinyl acetate (and copolymers) thereof, among other water soluble or dispersible and non-toxic polymeric compounds, and water. Normally, the polymeric compound comprises polyvinyl alcohol. The amount of water in the inventive composition normally ranges from about 70 to at least 90 wt. %. If desired, the water can comprise salt water including naturally occurring brackish and ocean/sea water (e.g., water comprising about 5 to at least 7 wt. % sodium chloride). The composition of this aspect of the invention is particularly effective at controlling release of dust and debris from a corroded or rusted surface. If desired, the inventive composition can further comprise at least one de-foaming compound, e.g., a silicon modified dispersion of olefinic solids. The inventive composition can be applied upon an anchor chain (e.g., as the chain is being hoisted and placed into a storage locker upon a boat or ship), in order to reduce, if not eliminate, rust and debris from being released into the air when the anchor is redeployed from the storage locker.  
           [0014]    In a second aspect of the invention, the inventive composition comprises at least one water soluble silicate, e.g., sodium silicate, potassium silicate, among other water dispersible silicates, and water. Normally, the water soluble silicate comprises sodium silicate (e.g., density ratio 3:22). The amount of water in the inventive composition normally ranges from about 70 to at least 90 wt. %. If desired, the water can comprise salt water including naturally occurring brackish and salt water (e.g., water comprising about 5 to at least 7 wt. % sodium chloride). The composition has a relatively high pH that ranges from about 8 to about 12, e.g., normally about 11. In general, the higher the pH the greater the effectiveness of the composition at reducing corrosion. If desired at least one pH modifying compound can be added to the composition, e.g., sodium hydroxide. The composition of this aspect of the invention is particuarally effective at controlling release of dust and debris from a corroded or rusted surface as well as reducing the rate of continued corrosion. The inventive composition can be applied upon an anchor chain (e.g., as the chain is being hoisted and placed in a storage locker), in order to reduce corrosion during storage and reduce, if not eliminate, rust and debris from being released into the air when the anchor is redeloyed from the storage locker.  
           [0015]    The inventive composition can further comprise at least one additive such as defoaming agents, anti-microbial, surfactants, anti-freeze, dyes, thickeners, among other components. Examples of a suitable anti-freeze materials are proplyene glycol, methanol, among others. Using environment friendly materials is desirable for applications wherein the composition directly contacts water. An example of suitable defoaming agent comprise silicone based agents.  
           [0016]    The inventive composition can be prepared by combining the components by using any suitable method. Examples of suitable methods comprise hand mixing, agitation, spray mix heads, among other methods known in the art. The combination rate can be enhanced by heating, e.g., 180 F. for a period of about 30 minutes. In some cases, the composition forms an emulsion.  
           [0017]    The inventive composition can be applied upon a desired surface by using any suitable method. Examples of suitable methods comprise dipping, immersing, spraying, wiping, among other delivery methods known in this art. In some cases, it is desirable to prepare a concentrate or an intermediate comprising all components of the inventive composition except water (e.g., salt water). The intermediate is then combined with a readily available source of water (e.g., ocean water in the case of a marine vessel or structure), and applied upon the desired surface. If desired, the intermediate comprises all of the components wherein only a portion of the water (e.g., tap or potable water) is present and remainder of the water (e.g., salt water) is added in situ prior to usage.  
           [0018]    While the above description has emphasized using the inventive composition on marine applications, the compositions can be employed on piers (e.g., as a wash and protectant for concrete), pipe flanges and joints before or after welding, as water blast additive for pipe or flange cleaning and repair, temporary coatings during shipment of metallic articles and intermediates (e.g., coil steel, rod used for making wire rope and strand, among others), anchor chain lockers, wash for off-shore structures (e.g., oil rigs), among other applications. 
       
    
    
     EXAMPLES  
       [0019]    The following Examples are provided to illustrate certain aspects of the instant invention and shall not limit the scope of any claims appended hereto. The following Table lists the components that were used to prepare the aspects of the inventive composition test below.  
                                       Trade Name   Chemical Composition   Supplier                   PQ GRADE G   Sodium silicate solid   PQ Corporation       PQ GRADE N   Sodium silicate liquid   PQ Corporation       AIRFLEX 500BP   Vinyl acetate emulsion   Air Products       AIRVOL 203S   Polyvinyl alcohol   Air Products       VINAC RP 710   Polyvinyl acetate   Air Products       DAPRO U-99   Anionic/non surfactant blend   Elementis       DAPRO DF 3163   Modified polyol foam suppressor   Elementis       DAPRO DF 1161   Silicon modified olefinic solids   Elementis           dispersion foam suppressor                  
 
         [0020]    [0020]                                                                                                                                         Material   Amount                                    FORMULATION 1                AIRVOL 203S   101.5 g           H 2 O TAP     405 cc            Preparation: MIXED ON HOTPLATE STIRRER @ 185° F.       FOR 30 MINUTES       FORMULATION 2                PQ GRADE G     10 g           H 2 O TAP     390 cc            Preparation: MIXED ON HOTPLATE STIRRER @ 190° F.       FOR 30 MINUTES       FORMULATION 3                AIRVOL 203S    150 g           H 2 O TAP    350 cc            Preparation: MIXED ON HOTPLATE STIRRER @ 190° F.       FOR 30 MINUTES       FORMULATION 4                PQ GRADE G     20 g           H 2 O TAP     400 cc            MIXING: MIXED ON HOTPLATE STIRRER @ 208° F.       FOR 30 MINUTES                    
         [0021]    The following Table describes the Testing Parameters for the Formulations  
                                           DESCRIPTION:       Anchor chain coating for marine applications with               the primary purpose of eliminating/reducing the               iron oxide dust generated when anchor is dropped       PARAMETERS:   1.   Spray applied during conventional anchor wash               down procedures that are employed when anchor               is hoisted           2.   Non-flammable.           3.   Water based to allow coating to be incorporated               into the current wash down equipment.           4.   Can not leave oily film or sheen on water as the               coating will likely go overboard during anchor               wash down.           5.   Can not leave long duration foam on water.           6.   After coating dries, it must dissolve in salt               water to prevent coating build up which could               lead to flakes or debris floating on water when               anchor is deployed or debris clogging chain               locker drains.           7.   No environmental hazards or impact.           8.   Coating concentrate must be able to be diluted to               working solution strength using sea water as this               is what the Navy uses for wash down.           9.   Coating can be applied using commercially               available equipment.                  
 
       Testing Parameter Descriptions  
       [0022]    1. FOAMING: This was a visual observation of foaming characteristics when spray applying the coating/protectant.  
         [0023]    2. DISSOLUTION TEST: Formula being tested was applied to a bare steel panel and dried. Pigments and tension modifiers can be added to allow for a uniform coating (bare steel having a different surface tension than corroded steel) and to give a visual indication if coating dissolves. Coated panel was partially immersed in a 5% salt water solution. After 2 hours, coating was checked to see if it is or has dissolved. The water was also checked for film, flakes or oily sheen on the surface.  
         [0024]    3. RUB TEST: 10 light double rubs with a white paper towel on a dry anchor chain link. The amount of rust on paper towel is rated from 0 to 5. 0=no rust evident. 5=rust on paper towel same as amount of rust rubbed off uncoated anchor chain (control).  
         [0025]    4. SALT FOG: Bare clean chain was coated, allowed to dry and placed into salt fog chamber. The type of chain, coating method, and time in chamber will be noted. Results were compared against uncoated chain of same type (control). Rating is from 1 to 5. 1=more corrosion than control, 2=slightly more, 3=same as control, 4=slightly less, 5=less than control  
         [0026]    5. HUMIDITY: Bare clean chain was coated, allowed to dry and placed in a 100 F. oven onto a perforated plastic shelf that is directly above a pan of water. Results were compared against uncoated chain of same type (control). Rating is from 1 to 5. 1 =more corrosion than control, 2=slightly more, 3=same as control, 4=slightly less, 5=less than control  
                                                                     TABLE A                           FORMULATION EVALUATION                Trial Number                001   002   003   004                        FORMULATION                       COMPONENTS       PQ GRADE G   15       AIRFLEX 500 BP       50       AIRVOL 203S           15       VINAC RP710               15       H 2 O DISTILLED   100       H 2 O TAP       50   100   100 HOT       5% SALT WATER       TESTS       DISSOLUTION TEST           DISSOLVED, NO FLAKES,                   FILM OR OILY SHEEN ON                   WATER       FOAMING           FOAMS ON                   SPRAYING       RUST RUB OFF       MIXING   STIRRED BY HAND   STIRRED BY HAND   MIXED ON   STIRRED BY HAND                   HOTPLATE/STIRRER HEAT                   SETTING = 2.5 SPEED = 6                   FOR 30 MINUTES       APPLICATION   DIP COAT, HANGER CHAIN   DIP COAT, HANGER CHAIN   DUST TEST-COATING                   APPLIED USING GARDEN                   SPRAYER SET TO                   8 OZ/GALLON                   DISSOLUTION-                   FOAM BRUSH,                   STEEL PANEL                  
 
         [0027]    [0027]                                                           TABLE B                           FORMULATION EVALUATION       Trial Number                005   006   007   008                        FORMULATION                       COMPONENTS       PQ GRADE G       AIR FLEX 500 BP       0.3       AIRVOL 203S       VINAC RP710       Formulation 1   20   2   80       Formulation 2       1   20       Formulation 3               100       DAPRO U-99       0.07       DAPRO DF 3163   .25   0.07   1   0.5       H 2 O DISTILLED       H 2 O TAP   10       5% SALT WATER       TESTS       DISSOLUTION TEST       NO DISSOLUTION       FOAMING   FOAMS BUT DISSPATES           QUICKLY       RUST RUB OFF           BETTER THAN CONTROL   POOR-SAME AS                   BUT NOT RATED   CONTROL BUT NOT                       RATED       MIXING   MIXED BY HAND   ALL INGREDEINTS ADDED   MIXED BY HAND   MIXED BY HAND               TO TEST TUBE AND               SHAKEN BY HAND       APPPLICATION   GARDEN SPRAYER SET AT   FOAM BRUSH, BARE STEEL   GARDEN SPRAYER   GARDEN SPRAYER           8 OZ/GALLON       SET AT 8 OZ/   SET AT 8 OZ/                   GALLON.   GALLON.                   SALTWATER   SALTWATER                   SOAKED RUSTED   SOAKED RUSTED                   ANCHOR   ANCHOR                   CHAIN COATED   CHAIN. COATED                   WHILE STILL   WHILE STILL WET                   WET       COMMENTS   NO SUBSTRATE COATED,   MIXTURE IS STABLE. THIS   BETTER THAN CONTROL   RELATIVELY HIGH           FOAMING   WAS TO TEST THE   ON RUB TEST BUT NOT           OBSERVATION ONLY   STABILITY OF 500 BP IN A   AS GOOD AS USING               PVA SOLUTION AND IF IT   B001-0005 ALONE.               ALSO AFFECTED THE   WHEN B0001-0005               COATING SOLUBILITY   ONLY WAS APPLIED THE                   SAME METHOD AS ABOVE                   WAS USED                    
         [0028]    [0028]                                                       TABLE C                           FORMULATION EVALUATION                PVA (PolyVinyl Alcohol)                   RATIO STUDY   PVA RATIO STUDY   PVA RATIO STUDY                        FORMULATION                       COMPONENT       PQ GRADE G       AIRFLEX 500 BP       AIRVOL 203S   100       VINAC RP710       Formulation 1       NEAT   10   10       Formulation 2       Formulation 3       DAPRO U-99       DAPRO DF 3163       DAPRO DF 1161   2       H 2 O DISTILLED       H 2 O TAP   300       10   20       5% SALT WATER       TESTS       RUST RUB OFF   MODERATE, BETTER THAN   RATING = 0   RATING = 0   RATING = 1           008 BUT NOT AS GOOD AS           USING B001-0005 IN A           8 OZ/GALLON           RATIO, NOT RATED.       MIXING   MIXED ON HOTPLATE   NO MIX, APPLIED NEAT   MIXED BY HAND   MIXED BY HAND           STIRRER @ 190° F. FOR           30 MIN       APPLICATIONS   DILUTED WITH WATER TO   FOAM BRUSH APPLIED TO   FOAM BRUSH APPLIED TO   FOAM BRUSH           GIVE A 9 g PVA PER   A DRY RUSTED ANCHOR   A DRY RUSTED ANCHOR   APPLIED TO A           GALLON DILUTED 009 WAS   CHAIN LINK. DRIED USING   CHAIN LINK. DRIED   DRY RUSTED           PLACED INTO A GRACO   HEAT GUN   USING HEAT GUN   ANCHOR CHAIN           SPRAY GUN AND SPRAYED           LINK. DRIED           ONTO A WET ANCHOR           USING HEAT GUN           CHAIN THAT HAD           BEEN IMMERSED IN A           3% SALT WATER SOLUTION       COMMENTS   SOLUTION HAS THE SAME   STUDY TO DETERMINE THE   STUDY TO DETERMINE THE   STUDY TO           RATIO THAT WAS   AMOUNT OF PVA NEEDED   AMOUNT OF PVA NEEDED   DETERMINE THE           ATTEMPTED   TO PRODUCE AN   TO PRODUCE AN   AMOUNT OF PVA           WITH 008 IN THE 8 OZ/   ACCEPTABLE COATING.   ACCEPTABLE COATING.   NEEDED TO           GALLON SPRAYER . . .   B001-0005 NEAT   10 g OF B001-0005   PRODUCE AN               EQUATES TO 2 g   DILUTED WITH 10 cc OF H 2 O   ACCEPTABLE               PVA/8 cc H 2 O   EQUATES TO 2 g OF PVA TO   COATING. . . 10 g                   18 cc H 2 O   OF B001-0005                       DILUTED WITH                       20 cc OF H 2 O                       EQUATES TO 2 g OF                       PVA TO 28 cc H 2 O                    
         [0029]    [0029]                                                           TABLE D                           FORMULATION EVALUATION                PVA RATIO STUDY   010   011   012                        FORMULATION                       COMPONENT       PQ GRADE G       AIRFLEX 500 BP       AIRVOL 203S       40   40   40       VINAC RP710       Formulation 1   10       Formulation 2       Formulation 3       Formulation 4               300       DAPRO U-99       DAPRO DF 3163       DAPRO DF 1161       1   1   1       H 2 O DISTILLED       H 2 O TAP   52   300   300       5% SALT WATER       TESTS       RUST RUB OFF   RATING = 1   RATING = 1   RATING = 1       SALT FOG       16 HOURS, RATING = 3       MIXING   MIXED BY HAND   MIXED ON HOTPLATE   MIXED ON HOTPLATE   MIXED ON               STIRRER @ 19O° F. FOR   STIRRER @ 19O° F. FOR   HOTPLATE               30 MIN   30 MIN   STIRRER @ 190° F.                       FOR 30 MIN       APPLICATION   FOAM BRUSH APPLIED TO   RUB TEST-DILUTED AND   DILUTED AND APPLIED   NOT TESTED           A DRY RUSTED ANCHOR   APPLIED USING A   USING A PRESSURE           CHAIN LINK. DRIED USING   PRESSURE SPRAYER TO   SPRAYER TO A           HEAT GUN   A WET RUSTED ANCHOR   WET RUSTED ANCHOR               CHAIN LINK THAT HAD   CHAIN LINK THAT               BEEN IMMERSED IN A 3%   HAD BEEN IMMERSED IN               SALT WATER SOLUTION.   A 3% SALT WATER               CHAIN WAS ALLOWED   SOLUTION. CHAIN               TO AIR DRY.   WAS ALLOWED TO AIR               SALT FOG-DILUTED AND   DRY.               DIP APPLIED TO BARE               CLEAN HANGER CHAIN               AND ALLOWED TO               DRY THEN PLACED INTO               SALT FOG ALONG WITH               AND UNCOATED HANGER               CHAIN       COMMENTS   STUDY TO DETERMINE THE   DILUTED WITH 900 cc H 2 O   DILUTED WITH 900 cc OF 5%           AMOUNT OF PVA NEEDED   EQUATES TO 1 g OF PVA TO   SALT WATER. THIS IS THE           TO PRODUCE AN   30 cc H 2 O THE RUB TEST IS   SAME BATCH AS 010 BUT           ACCEPTABLE COATING . . .   ACCEPTABLE.   SALT WATER IS USED AS           10 g OF B001-0005       THE DILUENT TO CHECK           DILUTED WITH 52 cc       IT EFFECT ON SOLUTION           OF H 2 O EQUATES       STABILITY AND COATING           TO 1 g OF PVA 30 cc       PERFORMANCE. SOLUTION           H 2 O       IS STABLE AND                   PERFORMANCE IS SAME AS                   010                    
         [0030]    [0030]                                                     TABLE E                           FORMULATION EVALUATION                Trial Number                013   014                        FORMULATION               COMPONENT       PQ GRADE G       PQ GRADE N (liquid)   100   300       AIRVOL 203S       VINAC RP710       Formulation 1       Formulation 2       Formulation 3       Formulation 4       DAPRO U-99       DAPRO DF 3163       DAPRO DF 1161       H 2 O DISTILLED       H 2 O TAP       5% SALT WATER       300       TESTS       RUST RUB OFF   RATING = 0   RATING = 1       SALT FOG       RATING = 1       MIXING   NONE, USED NEAT   MIXED BY HAND       APPLICATION   FOAM BRUSH   RUB TEST-APPLIED           APPLIED TO DRY   USING A PRESSURE           RUSTED ANCHOR   SPRAYER TO A           CHAIN, DRIED   WET RUSTED           WITH HEAT GUN   ANCHOR CHAIN               LINK THAT               HAD BEEN               IMMERSED IN A               3% SALT WATER               SOLUTION. CHAIN               WAS ALLOWED TO               AIR DRY SALT               FOG-APPLIED               USING A               PRESSURE               SPRAYER TO               CLEAN BARE               HANGER CHAIN               AND ALLOWED               TO DRY       COMMENTS   ANCHOR CHAIN   DILUTED WITH           HAS SURFACE   SALT WATER           CORROSION AND           PITTING BUT           LITTLE SCALE.           COATINGS           SEEM TO SOAK           INTO THIS           TYPE OF           SURFACE.