US2516008A - Composition and process for treating metal surfaces - Google Patents

Description

J. c. LUM 2,516,008

COMPOSITION AND PRocEss FOR TREATING METAL sURFAcEs July 18, 1950 Rm O VI TNIL N E. R VC O mn L n m J 'WITNESSES:

Patented `uly 18, I195() COMPOSITION PROCESS FOR TREATIN G METAL SURFACES John C. Lum, East Orange, N.`J., assignor to Westinghouse Electric Corporation, East Pittsburgh, Pa., a Vcorporatonof Pennsylvania Application June 19, 194s, seri1N0.34,11o

9 claims. (clins-6.15)

y This invention relates to the art of producing y corrosion resistant phosphate coatings on the sur- `faces lof iron, Zinc, cadmium, aluminum, and

other metals and alloys.

' It, is a common and extensive practice at Athe present time to treat thesurfaces of metals, such as iron,`"z`inc,` cadmium and aluminum and the like,` with phosphate solutions that react' with the metal `surface to lproduce tl'lereon'a'` protective phosphate' coating.'V Such phosphate coatings provide for a high corrosion resistance' andk'form an excellent base' for paints `or other subsequently applied organic finishes.` i 1 vIt has been known" that for a` given metal the surfaces vary considerably in their degree 'of 'r'eactivity to the phosphate solutions so that nonuniiorm and widely varying phosphate coatings result. On' vsome metals, such, for instance,r as zinc the rfornratior'l lof a protective phosphate coatingV is usually difficult because of its inherent acteristics of phosphate' coatings on zincis `much poorer than secured withviron or steel. However, even between sheets of steel, which sas a whole react'morev completely and more uniformlywith phosphates than does zinc, there vmay beaconsiderable variation in the'amunt land protective quality of the applied phosphate coating not `only between differentlsheet's but with different areas on a single sheet. `It has long been held desirable to be able to treat metal surfaces, regardless off their inherent characteristics, to produce a? high quality phosphate coating that is rela-` tively uniform at all times.

The prior art practicesfor producing protective phosphate coatings on metals, such, for example, as sheet steel comprised the following essential steps: first, vthe cleaning of the sheet in an alkaline solution consisting, for instance, of 'soda ash dissolved in water; secondly, the applicationof the phosphate coating composition to the sheet steel fora period of time of the order of onemin ute; and lastly, applyingY a dilute water solution of chromic acid to sealthe"v phosphate coating passivitmand the uniformity and protective char- H 5`f`i'.9,2'74,` Vled December 21, 1944, now "Patent y2,456,947, and r510,251, filed lNovember 13, 1943, `now abandoned, it has been .further suggested that the activating compositionbe combined with the alkaline metal cleaner so that the metal surfaces may` `be simultaneously cleaned and. acti- ,vated. The advantages of such a combined op,-

eration :are that the conventional processing equipment need not be `changed and the time for complete treatment of a piece of metal is not increased over that required `when no activating composition is produced. However,` it has been discovered that when the activating composition is combined with the` alkaline cleaner, ,the Aactivating composition deteriorates rapidlyr at temperatures above F.

whereas the` alkali cleaner itself is most effective atltemperatures of fromr F.;to 212 F. Thus,

`it lhasbeen found that the use of the alkaline cleaner containing the activating composition at a temperature of 200 1F. results in the activating eifect disappearing in aboutan hour. Itis obviously bcthuneconomical and undesirable. to repleriishV the activ-ating composition frequently,

particularly `since vthe changein its effect becomes noticeable in :less than an hour, and therefore erratic'results may occur. V 1 "The, object. of this invention` is, to provide a composition containing both an alkaline cleaning component 'and` an activating component, plus a ,stabilizerA so that the composition has a llong life at elevatedtemperatures.

.A `further .object of the invention is to provide l ,af process foreffectively and reliably treating the :surfaces of Inetal members, wherebyy to simul. taneo'uslyfclean and activate them atan elevated temperature. f ,.Qther objects of the invention will, in partbe obviousland will, in part, appear hereinafter.

" For abetter understanding offthe nature and objects `of the invention, reference should be had tofthe following detailed description .and drawf ing, lin which the single gure is a view in elevation `tio" of anapparatus for carrying out the invento provide from 0.1% to of the activating composition in solution and from i2 to '10 .ounces per gallon of the alkali cleaner composition.

The alkaline composition may be any suitable alkali metal compound which, when .in water Solution, produces a pH of between 1.0 and 12.5, :y

and is effective in removing surface dirt from metal surfaces. Suitable alkaline-compounds are soda ash, sodium bicarbonate, sodium silicates, trisodiurn phosphate, sodium hydroxide, borax, Land mixtures thereof. Also, there maybe employed l,alkaline soaps Vof the alkali metals, and ammonia or ,amine soaps, such for instance, as the-reactionproduct of ammonia or triethanolamine withI oleic or stearic acid, palmitic acid or otherfatty acids having 16 carbon atoms. The soaps maybe employed in the form of an emul- 'sionwith a hydrocarbon solvent, such as kerosene.

Theactivating composition is prepared by dissolving in waterfrom"0.005 to 20 parts by weight a watersoluble compound of at least one 'metal of the lgroup consisting of-titanium, zirconium, `lead or tin, all of i these metals being in' group IV o f the periodic table, with from 80 to 100 parts by weight of disodium orthophosphate. The ,aqueous solution soprepared is evaporated to drynessand' the dried residue possesses the vcharacteristics of activating metal surfaces when dissolved in water or Water containing an alkali that does not exced a pH 'of 1,2;5, or'water that is not acid.

'Examples of water soluble compounds of titanium, zirconium, tin and lead, that-have been foundA satisfactory for producing' the activating composition are titanium carbide, titaniumtetrachloride, titanium trichloride, :titanium hydroxide, titanium nitride, titanium potassium oxalate, titanium dioxide, zirconium chloride, zirconium sulphate, lead acetate, tin tetrachloride andstannic sulphate. Since only relativelysmall amounts of any titanium, zirconium, lead and tin compound need be dissolved, the compounds selected need be lonly slightly soluble in water to be suitable. Since the weight proportion of the required `metal present varies from compound to compound, the amount of metallic "compound employed should be selected accordingly.

As an example of the preparation of the activating composition, in150 pounds of watervthere was dissolved 100 pounds ofdisodium orthophosphate and 3 pounds titanium potassium oxalate. The solution was heated to about 75C. and slowly evaporated to a dry residue. The dry residue was a powerful activator for metal surfaces and was ready for use for activating metals by simply dissolving it in Water. l

Suitable organic acids for stabilizing the4 activating compositions are water soluble organic carboxylic acids having a carboxyl radical attached directly to an aliphatic group. Examples of such acids are citric acid, tartaric acid, oxalic acid, acetic acid, propionic acid,'succinic acid, maleic acid, lactic acid and glycolic acid. Acids in whichthe carboxyl group is directly attached to an aryl group such, for example, as benzoic acid have been found to be ineiective. The amount of the acid should comprise at least 2% of the weight of the dried activating composition, and preferably be of the order of 10%. The organic acid may be present in an amount equal tov50% of the weight of the activating composition. ,The maximum amount of any particular organic acid usable may be limited by its relative solubility in the solution.

The compositions combining the alkaline cleaning composition, the activating composition and the-organic acid stabilizer may be prepared, withoutany water-or only a small amount of Water, as

.a .composite mixture which may be shipped and need .only bedissolved in suicient water to produce a relatively dilute solution capable of simultaneously cleaning and activating metal surfaces at l.elevated temperatures. If desired, the three components may be shipped as mixtures of any two or else may be combined at the time .the aqueous Isolution is prepared at the time the metal is being treated.

Theorganic acid stabilizer cannot be incorporated with the activated composition when it is being made by evaporation to a `dry residue since itlhas'been found that the resulting dry residue containing the organic acid is useless for its intended purpose if so prepared.

The'followingtypical examplesof compositions whose aqueous solutions in the proportions of from 2'to 10 ounces of .the alkaline cleaner per gallon of water will function .extremely effectively to simultaneously clean and activate metal surfaces:

Eample I Parts by weight Activating composition (containing 5% titanium) 2 Soda ash 6 Citric acid '0.2

Example II Parts by weight Activating composition (containing 1% titanium) 3 Sodium sesquisilicate 10 Tartaric acid 0.6

Example HI Parts by .Weight Activating composition (containing 10% tiy tanium) 6 Trisodium phosphate 13 Oxalic acid 1.0

Example IV I Parts by Weight Activating composition (containing 1% titanium) 0.2 Soda ash 5 Trisodium phosphate '5 Lactic acid 0.01 y Ewample V Parts by weight Activating composition (containing 1% tita- Thecompositions ineach-of the above examples may be dissolved in water inthe amount of from 2 to, 10 ounces of the alkalinecomposition per `gallon and providing a pI-Iof from-$to 12.5

may be employedl at any"'desired temperature,

preferably above 160 F. A composition similar to Example I was used for over a week at near boiling temperature without loss offa-ctivity. The same solution withoutthe citric acid-wasincapable of activating metalfsurfaces shortly after `one hour at 200 F.

sheets of aluminum andl aluminum alloys,` and alloys in which these metals predominate. The time of application of thehot cleaning and activating solution need `not be long. `A few minutes is ordinarilysuiicient to remove surface grease and loose oxides and dirt. The composition may be applied by spraying, lif necessary, under high pressure to remove the more `adherent particles o-f dirt. Ifthe metal is badly rusted or oxidized or scaled, it may be necessary towire brush or acid etch the metal before it is subj ected to the activating alkaline solutions o f this invention. l

After the metal surface has been treated with the component alkaline cleaner and activating composition so that it is clean and in a highly active state, it may be subjected to an appropriate phosphate coatingsolution.v A suitable solution for treating steel or other metals is thev follow- Manganese phosphate pounds `1.75 Phosphoric acid (83%) do 5 Sodium` nitrate do 0.5

Cupric nitrate 1 ounces-- .25 Waterto make one gallon. l

Iron per cent 0.25 Zinc phosphate do 0.04 Sodium nitrate .do l I 0.5 Phosphoric acid (85%) `do. 1.0 Remainder Water Numerous other solutions for producing phosphate coatings are known in the art and it is believed unnecessaryto list them in detail; lEssentially, such solutions compriseia phosphate, free phosphoric acid and an oxidizing agent, such as sodium or potassium nitrate or nitrite.` They may be applied by spraying, brushing or dipping of the metal surfaces thereim' l y When applied `to the activated and cleaned surfaces, such phosphate coating compositions will produce protective phosphate coatings thereon within a short period ,of time, about seconds being suiiicient. However, the greatest advantage derived from activation is the fact that metal surfaces acquire a highly uniforml phosphate coating. In most cases the phosphate coatings are almost velvety in appearance.` Under the microscope they exhibit a very ne crystalline structure. There are no bare spots, Inor 'do they show a gross blotchy effect which often `occurswith metal-that has notlbeenlactivatedd- A f Referring tothe single figure ofthe drawing, there is illustrated an apparatus I0 for carrying outthe complete process disclosed herein. The apparatus comprises a track`I2 for'supporting a plurality of roller mounted hangers I3 on'which depend metal members Ill` to be provided-with a protective phosphate coating. The members initially are moved intoV position over a tank I6 and drop therein for immersion-or for spraying if desired, in a solution i 8 having a pH of from 10 to 12.5, in which solution the membersld are cleaned and activated simultaneously. The solution I8 comprises an alkaline cleaner, the activating composition and the organic stabilizer. The solution is used hot, that is between 160 F. and boiling, and, therefore, operates rapidly andeifectively to remove any surface contamination, such as grease and dirt. It has been found that while being cleaned the metal is most responsive to activation so, that the highest degree of lactivation of the metal takes place under these conditions. l i

After being treated with thesolution I8 until clean, usually in a short period of time, the clean and activated metal member I4 is subjected `to a water rinse in tank 20. The water rinse will remove any material whose presence is not desired in subsequently applied phosphate coating compositions. Immediately after rinsing 01min some cases dispensing with the Water rinse, the

member I4 is conveyed to a tank 22 containing a phosphate coating composition 24. The phosphate composition reacts rapidly and uniformly over the entire pretreated surface of the vmemf' ber I6 to produce thereon a smooth, fine, uniform protective phosphate coating. Thence, the coated member I4 may be moved along the con- Veyer I2 to a second water rinse tank 26. rThe last step in the process is to dip the member I4 in a tank 28 containing a hot aqueous solution 30 of chromic acid in the proportion of 7.5 ounces of chromic acid to gallons of water. The chromic acid functions so that ina-'few seconds it seals the phosphate coating thereby improving its corrosion' resistance. If the chromic acid solution is about 200 'E., the heat imparted to the members I4 is ordinarily sufficient to dry them by simple exposure to the `atmosphere. lin some cases, however, the members may be conveyed to a drying oven wherein any water on the surface is completely evaporated leaving a. dry sealed phosphate coating having the utmost protective value. i

The apparatus shown in the gure corresponds tothat vconventionally employed at the present time for phosphate coating without theV use of an activating pretreatment. It will be apparent that by being able to combine the cleaning and activating solution to effect a'simultaneous cleaning and activation of metal in the single tank I6, no changes in the apparatus are re'- quired. Otherwise, the` necessity for a separate tank for the solution for activating the metal surfaces would require extensive changes, such asrebuilding of a conveyer and shifting of tanks. Also the extra time required for an additional treating step is avoided by the present invention. Furthermore, the effectiveness of the combined .cleaning and activatingv solution is greater than that processed by separate applications of a cleaning solution and an activating solution.

Both the alkaline cleaner andthe activating composition may be replenished from time to time as they areused up. The proportion 'of activated composition tov cleaner may be Areadily v.detelrriirled. from exprience forV metal pf-aegiven .degree of cleanliness and a combined sal t `or the like may be added that Areplenishes.bcth,in

the proportions in which they are used up. vSince certain changes may be in :the above linvention and. different embodiments ofthe ine vention may be made without departing from the scope hereof, it is intended that all matter contained in the disclosure shall'be interpreted as illustrative and not in a limiting sense.

I claim as my invention:

1. An aqueous composition suitable vfor hot treating the surface of a metal selected from the group consisting of iron, zinc, cadmium,

aluminum and alloys in which these metals ypredominate to provide fiorvsimultaneoiusly cleaning and activating-the surfaceitherein for expediting the subsequent formation of protective coatings thereon, consisting of (a) between 0.1%

and by weight of the dried residue of an,

activating composition derived by dissolving in Water from 0.005% to by weight of a water :soluble compound of at least one ofthe group of metals consisting of titanium, zirconium, .lead and tin and the balance being disodium yorthophosphate, and evaporating the solution so,pro duced to dryness, (b) from 2% `to 50%, based on the weight of the dried residue, of a water group consisting `of iron, zinc, cadmium, aluminum and alloys in which these metals predominate to provide for simultaneouslycleaning Vand activating the surfaces therein for expediting the subsequent formation of .protective coatings thereon, consisting of (a) between 0.1% andf10% by Weight of the dried residue of an activating composition derived by dissolving in `water'from 0.005% to 20% by weight of a Water soluble vcompound of at least one of the group yof metals consisting of titanium, zirconium, lead and tin and the balance being disodium orthophosphate,l

and evaporating the'solution so produced to dryness, (b) from 2% to 50%,'based onthe weight of the dried residue, of a water soluble organic acid having a carboxyl radical attached `directly to an aliphatic group to stabilize 4the activating composition, (c) an alkalinecomposition including substantial amounts of at least onealkali metal compound from .the groupconsisting of phosphates, silicates and carbonates, thealkaline composition being suitable for'cleaning metal surfaces in an amount to provide a @pH of from 10 to 12.5 in the aqueous composition, and the balance being water.

3. An aqueous composition suitable for hot treating the surface of a metal selected from the group consisting of iron,l zinc, cadmium-aluminum and alloys in which these metals,y predominate to provide for simultaneously cleaning and activating the surfaces thereinfor expediting the. subsequent formation of protective coatings thereon, consistingV of (al) betWeen-f,0.1%pand :10% by weightiof thedried residue ofan activating composition derived by dissolving in-water `from f0.005% to1 20% byweightof a gwatervsolu- ..=.ble1comp.0und. ofrtat least lone ofthe rgroup of metals lconsistingfof titanium, zirconium, lead andtinandjthe .balance being disodiumorthophosphate,,and,evaporating the solution so produced torlryriessl (b) ,fromr2% to 50%, based Lonfthe .weight Qfthadriedresidue, of a water solubleorganic acid having a carboxyl radical attached directly-.to `an aliphatic group to stabi- -lize the activating ..composition, (c) an alkaline composition, including a substantial proportion -ofan-,amine soap, the alkaline composition be- ;ing,suitable for cleaning metal surfaces in an amountto providea pH of from 10 to 12.5 in the aqueous composition, andthebalance being Water. l f

4. Acompositioncomposed of (a) from 0.10

to 10,partsby weight of the activating composi- .tion derived by dissolving in water from 0.005% -to 20% vby Weight of atleast one water soluble .compound of ametal from the group consisting of titanium, zirconium, lead and tin, and the balance being disodium orthophosphate, and

evaporating the solution to dryness, (b) from 0.002 to 5 partsbyweight of a water.l soluble orgarlic acidfhavng carboxyl group attached directly to an aliphatic group, the amount of the organic acid being between 2% and 50% by weight of theiactivating composition, and (c)v from 2to20 parts by weight of an alkaline compositionvselected from the groupconsisting of .alkaline a1- Akali metal compounds, ammonia soaps and amine soaps capable of cleaning .metal when dissolved in ,-water, the alkaline composition. being present in an amount to produce a pH of from l0 to 12.5 when 4 to 10 ounces of the entire composition is dissolved in a gallon of water.

5. A composition composed of (a) from 0.10 to v10 parts by weighty of the activating composition derived by dissolvingin water from 0.005% to 20% by Weight of atleast one water soluble compound Aof -ametal from the group consistingv of titanium,v zirconium, ylead and tin, andthe balance being disodium orthophosphate, and evaporating thesolutionto dryness, (b) from 0.002 to 5 parts by Weight of a water soluble organic acid lhaving a carboxyl group attached directly to an `aliphatic group, theamountv of the organic acid .in water, thealkaline composition being present in.l an amount torproduce arpH of from 10 to 12.5 when 4 to 1,0 ounces `of the entire composition is dissolved in a galloriof water.

6. A. composition composed of (a)` from 0.10 to 10 partsibyweight of theactivating composition derivedby dissolving in water from'f0.005% to 20% by Weightpf-atleast one water soluble compoundof a metal from the group consisting of Ytitanium,-.zirconium, lead and tin, -and the balance beingdisodium orthophosphate, and evaporating the solution to, dryness, .(b) from 0.002to .5 partsby weight of aI waterv soluble organic acid having a: carboxyl. group attached directly to an aliphatic group; the amount of the organic acid. being between 21%. and 50% by weight of 44the activating composition, and (c) from 2 to 20. parts vby -weightzof an alkaline composition yincludingan aminesoap, the alkaline composition beingl capable .of cleaning metal when dissolvedgnwfwater, ,thealkalme composition being 9 present in an amount to produce a pH of from 10 to 12.5 when 4 to 10 ounces of the entire composition is dissolved in a gallon of Water.

7. In the process of applying phosphate coatings on metals, wherein simultaneous cleaning and activating of the surfaces of metals from the group consisting of iron, zinc, cadmium, aluminum and alloys in which these metals predominate is effected to enhance the subsequent formation of protective phosphate coatings thereon, the step comprising applying to the metal surface 'a hot aqueous solution consisting of (a) between 0.1% and 10% by weight of the dried residue of an activating composition derived by dissolving in water from 0.005% to by weight of a Water soluble compound of at least one of the group of metals consisting of titanium, zirconium, lead and tin and the balance being disodium orthophosphate, and evaporating the solution so produced to dryness, (b) from 2% to 50%, based on the weight of the dried residue, of a water soluble organic acid having a carboxyl radical attached directly to an aliphatic group to stabilize the activating composition, (c) an alkaline composition selected from the group consisting of alkaline alkali metal compounds, ammonia soaps and amine soaps suitable for cleaning metal surfaces, in an amount to provide a pH of from 10 to 12.5

in the aqueous composition, and the balance be- ,i

ing Water.

8. In the process of applying phosphate coatings on metals, wherein simultaneous cleaning and activating of the surfaces of metals from the group consisting of iron, zinc, cadmium, alurninum and alloys in which these metals predominate is effected to enhance the subsequent formation of protective phosphate coatings thereon, the step comprising applying to the metal surface a hot aqueous solution consisting of (a) between 0.1% and 10% by weight of the dried residue of an activating composition derived by dissolving in water from 0.005% to 20% by weight of a Water soluble compound of at least one of the group of metals consisting of titanium, zirconium, lead and tin and the balance being disodium orthophosphate, and evaporating the solution so produced to dryness, (b) from 2% to 50%, based on the weight of the dried residue, of a water soluble organic acid having a carboxyl radical attached directly to an aliphatic group to stabilize the activating composition, (c) an alkaline composition selected from the group consisting of alkaline alkali metal compounds, am-

monia soaps and amine soaps suitable for cleaning metal surfaces, in an amount to provide a pH of from 10 to 12.5 in the aqueous composition, and the balance being water, the aqueous solution being at a temperature of between F. and the boiling point, the organic acid enabling the acti- Vating composition to function at the high temperature for long periods of time.

9. The process of simultaneously cleaning and activating the surfaces of metals from the group consisting of iron, zinc, cadmium, aluminum and alloys in which these metals predominate, to enhance the subsequent formation of protective phosphate coatings thereon comprising applying to the metal surface a hot aqueous solution consisting of (a) between 0.1% and 10% by weight of the dried residue of an activating composition derived by dissolving in Water from 0.005% to 20% by weight of a water soluble compound of at least one of the group of metals consisting of titanium, zirconium, lead and tin and the balance being disodium orthophosphate, and evaporating the solution so produced to dryness, (b) from 2% to 50%, based on the weight of the dried residue, of a water soluble organic acid having a carboxyl radical attached directly to an aliphatic group to stabilize the activating composition, (c) an alkaline composition selected from the group consisting of alkaline alkali metal compounds, ammonia soaps and amine soaps suitable for cleaning metal surfaces, in an amount to provide a pH of from 10 to 12.5 in the aqueous composition, and the balance being Water, the aqueous solution being at a temperature between 160 F. and the boiling point, the organic acid enabling the activating composition to function at the high temperature for longer periods of time, and immediately thereafter applying to the cleaned and activated metal surfaces a phosphate coating composition comprising a solution of phosphoric acid, phosphates and .an oxidizing agent to produce a protective phosphate coating thereon.

JOI-IN C. LUM.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTSy

Claims (1)

1. 8. IN THE PROCESS OF APPLYING PHOSPHATE COATINGS ON METALS, WHEREIN SIMULTANEOUS CLEANING AND ACTIVATING ON THE SURFACES OF METALS FROM THE GROUP CONSISTING OF IRON, ZINC, CADMIUM, ALUMINUM AND ALLOYS IN WHICH THESE METALS PREDOMINATE IS EFFECTED TO ENHANCE THE SUBSEQUENT FORMATION OF PROTECTIVE PHOSPHATE COATING THEREON, THE STEP COMPRISING APPLYING TO THE METAL SURFACE A HOT AQUEOUS SOLUTION CONSISTING OF (A) BETWEEN 0.1% AND 10% BY WEIGHT OF THE DRIED RESIDUE OF AN ACTIVATING COMPOSITION DERIVED BY DISSOLVING IN WATER FROM 0.005% TO 20% BY WEIGHT OF A WATER SOLUBLE COMPOUND OF AT LEAST ONE OF THE GROIUP OF METALS CONSISTING OF TITANIUM. ZIRCONIUM, LEAD AND TIN AND THE BALANCE BEING DISODIUM ORTHOPHOSPHATE, AND EVAPORATING THE SOLUTION SO PRODUCED TO DRYNESS, (B) FROM 2% TO 50%, BASED ON THE WEIGHT OF THE DRIED RESIDUE, OF A WATER SOLUBLE IORGANIC ACID HAVING A CARBOCYL RADICAL ATTACHED DIRECTLY TO AN ALIPHATIC GROUP TO STABLIZE THE ACTIVATING COMPOSITION, (C) AN ALKALINE COMPOSITION SELECTED FROM THE GROUP CONSISTING OF ALKALINE ALKALI METAL COMPOUNDS, AMMONIA SOAPS AND AMINE SOAPS SUITABLE FOR CLEANING METAL SURFACES, IN AN AMOUNT TO PROVIDE A PH OF FROM 10 TO 12.5 IN THE AQUEOUS COMPOSITION, AND THE BALANCE BEING WATER, THE AQUEOUS SOLUTION BEING AT A TEMPERTATURE OF BETWEEN 160*F. AND THE BOILING POINT, THE ORGANIC ACID ENABLING THE ACTIVATING COMPOSITION TO FUNCTION AT THE HIGH TEMPERATURE FOR LONG PERIODS OF TIME.

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