[1]2 1 7 9 3 P I 3 8 United States Pate - n''t-@'@'-Office P a t e n t e d M a y 2 1 , 1 9 $ 7 2,793,138 COATING WET METAL SURFACES WrM ASPHALT CUTBACK CONTOSITIONS 5 Clarence E. WiMnson, Port Neches, Tex., assignor to The Texas Company, New York, N. Y., a corporation of Delaware No Drawing. Application April 20, 1956, 10 SerM No. 579,438 4 Claims. (Cl. 117-49) Th is in-vention is concerned with the coating of wet 15 sur faces of metal objects with asphalt compositions capable of adherin.- to the wet surfaces and forming a protec tive co vering over the metal. This application is a co ntinuation-in-part of my similarly-entitled patent applitati on Serial No. 218,905, filed on April 2, 1951. 20 It is frequently desired to apply an asphalt coating to suc h moist surfaces. It has b-cen a problem to provide an asphalt composition possessing sufficient water re@- pel lency and adbesion to the moist metal so that a sufflcie ,ntly good bond c-an be effected between the aspha-It 25 ah d the'gurface for development of a suitable protective co at' ing. par ticular problem has resided in the inability to pr ov:ide @h asphalt cutback composition containing a filler suc h as asbestos for ready application to wet surfaces of 30 me i@l objects. One importaiit field for the applicant of suc h:coriipositions is in the case of rail-road cars which ma y be wet from rain or dew as they are brought into rep @L-ir- shops. Practice of my process provides a satisfactpr yl- dumble proiective coating for them with pronounced 35 @a se. An other very important@field for use of my process is for painting metal tanks and other equipment, particularly tho se objects which are frequently or continually wet fro m rain, from cooling tower or other spray or from 40 sw eating." ' The problenis besetting the painter here are to get good adhe ion to th-, wet surface, to have heavy on e-c,oat coverage which goes on, easily, e. g., more than ab out 0. 15 pound p@Dr square foot . to have resistance to wat er spray, rain or the like of i@e appjied coating dur- 45 ing the curin- period so that the uncured material does not wash off, and to have -ood durability after cun,ng. An unsatisfactory painting job on such metal structlires wfl l fail as a rule in less than six months. In accordance with my invention the wet surfares of 50 a variety of metal objects were painted with a plastic c6 mposition of v@hicle and fluer, the vehicle consisting ess e.ntially of an airblown asphalt of a s6ftening point on the order of 180-200' F. Ring and Ball cut back wit h a light distillate thinner to a viscosity within a - range 55 of approximately 45-172 at 122' F. Saybolt Furol and taJ I oil, said filler c(?mprising asbestos, there being 1-5% by weight tall oil, and about 10-38% by weight asbestos fill er in said plastic composition. Excellent bonds were obt ained without any difficulty. The plastic c omposition 60 "lo aded" readily on the surface to give the desirably heavy on e-coat coverage, 'and was cured by evaporation Of the thinner to form adhorent protwtive coating on the sur face of the metal object; such protective coating exhib ited excellent weathering and durability properties. 65 Tal l oil is a product obtained in paper manufacture fro m pine wood. It is a mai6rial of somewhat complex co mpos;tion and includes rosin acids, fatty acids and no n-acid constitueiits including sterols, higher alcohols, an d othei unsaponifiable matter. 70 . - The appliration of the above plastic compositions in the practice of my process can be done in a conventional manner, e. g., painting with a brush or spraying with @a spray gun. In a particular embodiment of my mveniion an otherwise dry or partially ch-k'ibda@e of a metal object is deliberatelk wet wit@ wii@t preparatory to paint .1 ing, and then the plasticodmposition is applied. - This technique permits the painter to woik faster than' if I he left the surface alone, particularly when ising a: biush@ and at the same time he obtains desirably heavy coverage very easily. Preparatory to painting the metal sur-@ face can be cleaned of scale, rust,- and other faulty materiai by conventional scraping and/or sandblastini, then can be protected from -rusting'- with a conve@ntional n3@etal primer such as a zinc chromatecontaining priiiier., This is particularly desirable wh6re a su ' bstantial time interval exists between preparing the object for painting and the actual painting operation. In accordance ivith my invention one can apply,a plastic composition consisting essentially of an airblown asphalt of a softening point on the @ ord.er of 1 SOL-100' F. Ring and Ball etitback with a light distiflate thbin6r to a visrosity within a range of approx'un@tely 45'-, 172 at 122' F. Saybolt Furol, about 10-38% by weight asbesto's filler, and 1-5% @by weight of tafl oil, then curing the applied plastic composition by evaporation of tlie"thinner to form a dark protective coating@' The Wgher,.viscosity cutback- vehicle, e. g., 62-172 Saybolt Fu seconds at 122' F., can be used qpite effectivel :for such. dark cQa Y ing. When ctiring is ov@r, aluminum or other paint can be applied to the dark asphaltid-s@dare 'm' conventio@al manner, if desired. Aluminilm painft is customary ift such instances. A further aspect of my 'mvention is the incorporation of aluminum powder as a fraction of the fiuer contentof the plasticcomposition. -The aluminum ppwder can he incorporated as such or as a paste or conventional (containing s di -&iii@; p.igment ome light petroleum stidate ner as the pigment vehicle) in the manufacture of th6 plastic composition. Tho cutback vehicle in such caso is advantageously a Ettle@less viscous thain when aluminum is not used. Accordingly;. the resultant plastic,comp6d-. tion consists essentially of @ an airblown asphalt of, somning point on the order, of 180-200' F.,-.Ring aiid. Ball cutback vvith a light disfirate thinn ' er to@ a viscosity within a range of approximately 45-70 at 122- F. Saybolt Furol, about 10-38% by weight of asbestos fiuer, about 1-5% by weight of tall oil, and about 10-15% by weight of aluminum powder. Upon curing of this applied plastic composition by evaporation of the thinner an adherent protective coating is formed which is leafed with alufi-Anum (i. e., flakes of alunainum cover the exterior of the'fdm practically completely). In order to assist in obtaining sufficient loading of plastic. on the suffar-e dnd to obtafnadequate leafing of the aluminum powder in the'cun'ng process viscosity of the cutback asphalt used in making the plastic composition should be maintaindd betweeii approximately,45 and 70 at 1221 F. Saybolt Furol. Sub@stantiary below about 10% aluminum powder in the plastic composition results in inadequate leafing roverage of the cured composition; substantiary above about 15% aluminum powder in such composition is not neces-. sary for good leafing and requires considerable agitation to obtain and maintain a substantially uniform dispersioji Gf the metal. Typical aluminum pigments useful in manufacture -of the plastic composition -are standard vamish pigment, wherein a maximum of 0.2% of the powdered aluminum therein is retained on a 100 mesh U. S. Standard sievej, and extra-fine pi.-ment wherein a maximum of 1.0,910 'Ofthe -aluminum powder therein is retained-on a 325 mesh U. S.,Standardsieve, @ Or.dinarily these pigments tontain:, between about-. 30 and - 40%' of 'a Eght petrol6um. distil-@ late v6hicle of: viry -higii Volatility'such@ as benzene foi@
[2]mdrmg thdm in-td d bittid. Iii the manufacture of the pre&ent plastic comp6giti6ft digffef8idift 6f the pagfd ifft6 warmed asphalt or asphalt t-ttback by mechanical agitation readfly evaporates off this light pigment vehicle. A ihorough dispdrsion of alunilnum metal resiilts. Altern@a@vely, d6 atum'mum powder can be incorporated into the cutback or ifie asbestos-containing plastic composition. The propoi-don of asbe8tos filler in the plastic composition is controrc@d to obtain the desirable one-coat loaoing, i. e. above 0.15 pound pet square foot, by using at least 1OVo Asbestos by weight in the composition, advantageously at least about id.5- 12.5%, and preferably at about f8,Yo (e. g., between about _16.5-18.5% using or&;ify plant control prodedure).. The asbestos filler conient shoufd not be substantially above about 38% by weight of the plastic composition in order to mainWn its paintable consistency. By way of ex-ample of the in*ention an airblown aspMt was cutback with naphtha to a viwosity of 172 at 122' V. gaybolt ]Rurol and three mixtures were made with the cutback contafning 1 lo, 3 9o and 5 % (by weight), respectively, of taff oil. -Each of the three compositions was mixed with asbestos in the proportion of 75% ,cutback, 22.5% fine asbestos, and 2.5% coarse asbestos (the percentages being by weighl). Each composition was Applied without dii@aculty to a wet galvam'zed.- iron panel. The panels wete subjected to weatheri.ng- At the eiids of 2i months, the coatings on the panels were still in excellent condition. In additional examples of the invention compositions were prepared containing the following ingredients: Percent Perceut by by weigbt wetght Agohalt A ------ - ------- t2.4 Asphalt B ------------- 40.7 xe 25.7 Naphtha -------------- 36.7 Flz 30 6 Fine Asbestos --------- 18.5 i As --------- @2 Tall OIL -------------- Coarse Asbestos --------- 4.1 Tail Oil ---- ------ &I Asphalt A consisted of a mixture of vacuum residium and vacuum steam stiffed residuum derived from paraffinic asphaltic residua which had been mixed and blown to a Ring and Ball softening point of 185-2000 F. Asphalt B was a 202' F. Ring and Ball asphalt obtained from an asphaltic cyclic residuum by air blowing. The two compogitions were readily applied to wet galvanized iron panels, and after being cured by evaporation of the thinner, were exposed to atmospheric conditions. At the end of 11 months the panel coatings were still in good conditioii. Additional examples of the invention compositions were prepared based on asphalt which was an airblown asphalt of 180' F. Ring and Ball softening point cutbackto a viscosity in the rangt between 45 And 70 Saybolt Fur6l. seconds at 122' F. with a straight run distillate having initial boiling point and end point between about 300' and 400' F. These cor4positions contained 1.11.4% crude tall oil and 10, 16, and 29% fine a sbestos, respectively. The compositions were painted on wet metal panels and cuted. In each cage adhesion to the wet metal was good. The uncured films were sprayed with water to determine their resistance to washing off. 'fhe @fflms from oornpositidng made with 29 % and 16% mbestos had pronounced resistance to the water spray; the film mide from the composition with 10% asbestos was gatitfactory bUt not ag gciod as the other two. in larger scale preparation batches of test plastic composition of the: followiag- t"ical analysis (percentages by weight,) were made up: 18V F. R & B airblown asphalt - 4L95%:to.45%,,, straight run distillate boiling bdtween30011-4000 F..- 39.2%:tD.3.9'6; fme asbestog fibrti-7.5591&--f-G.75%,; itd tall oil-1.3,Yo. Sieve Analysis df the asbestog was as fohows: 2% maximutn on No. 12 screen; 60% maximum passing No. 12 and retained on Nd. 70', 13% fn-dfiffliiifi @a@giig Nb. 70 dfid i6t;iiii6d 6ii No. 200, and 25% maxim@um passing No. 200 screen. Viscosity of the asphalt cutback so made with the above light distihate thinner was in the range from 45-70 Saybolt Futol seconds at 12@' P.41 specific gravity of the finished composition was between 0.995 end 1.025. For one.test application a steel tank was sandblasted and primed with a zinc chromate-containing primer in a 10 C@6n'ventional fashion. Prelimihary to painting the tank a @ainple of the te@@t coniposition was brushed on a piece of metal submerged in water. Complete coverage and good adhesion were obtained. , Paintbrush application of test composition wa made to a dry section of vertical 15 tank surface, and then to a corresponding completely water-wet sectioft of tarik gui-fac@e to obtain one-coat coverage of 2.5 gallons per hundred square feet (0.208-0.214 pound per square foot). It was noted th;it painting on the wetted surface was more rapid and easier than on 20 ttie dry one. Adhesion to the wetted surface was exCeftent, and a continuous protective film which did not wrinkle on curing was obtained. Spray appiication of test composition was then made to a wet surface of the tank to obtain one-coat coverage 25 of @, gallons per hundred square feet (0.249-0.258 pound per square foot). Time required for spray application was about 15 miitites per hundred square feet using conventional paint spraying equipment. A section of the freshly sprayed surface was subjected to a strong stream so of wat6r for 5 minutes; the uncured coating did not wash off. After curing a continuous unwrinkled film resulted. PUrther targe scale test pray applir-ations of the above te@t co lilon were made to various metal tanks, sands' mpos btasted and priined as previously described, and to lines i, loc io s 35 - at n where severe wetting conditions were prevalent, e. g., in the area of spray impingement near water cooling towers. txdehent adhesion and one-coat coveiage was obtained at a loading of 4 gallons of test composition per hundred square feet of surface painted. 40 Over a test period of about two years an agaregate of approximattly 68,000 square feet of such metal surface was painted in accordance with the invention principles. Some of the so-coated tankage was further painted with a:ltiminum paint in the ctistomary manner 30 to 60 days 45 after spraying the composition. Periodically these plastic-coated surfaces were inspected critically and found to be permanently bonded for lasting protection. Several aluminum-coiltaining compositions were formulated for testing in @accordanre with the principles of iny 50 invent.ion. In. the pr@-paration 180' F. R&B airblowji asphalt was cut back with straight run distillate having a boiling range of 360' to 400' F. to obtain viscosity in the range of 45-70 Saybolt Furol seconds at 122' F.; crude tall oil was added to the cutback, then -,ilu@niintim pi5 @) m.ent (65% aluminum-35% highly volatile r-arrier, 99% of the aluminum particles passing a 325 mesh sercen). 'the pigment was dispersed in warmed cutback by mechanical agitation and the pigment carrier a-Ilowed to evaporate in the process; then fine asbestos fibre was 60 added to the mixture. Several exemplary materials were obtained as described in the table below: Ingredient, Weight Percent Composition of Comoosffion 65 A B c D I Asphalt ---- 40.69 39.43 38.93 36.745 Stmight -------------- 38 03 36.83 36.351 34.34 Crude Tlill Oil ------------------------- 1 1'28 1 24 1 @n 1 16 Aluminum Powder ------------------ 10.00 12@ 50 13:9 l@: 75 Asb to Fibre ---------------------- 10.00 10.00 10.00 15.00 7 '@s s Sarnples of each of these compositions were applied to wet galvanized and black iron panels by btush and by spray, It was found that desimbly hebvy films were 75 easy,tg apply and good adhesion was obtiimd in all
[3]5 cases. The films cured to form a heavy protective coating which was well leafed with aluminum. in larger scale testing, spriy application of test composition B, abo-ve, was made to the wet surface of a steel tank usin.- conveiitional plant spraying equipment. No diffictilty was encountered in obtaining a substantially uniform loading above 0.15 pound per square foot. Adhesion was excellent and none of the uncured plastic compositio,-i washed off whed a strong stream of water was played on it immediately after the coating was sprayed on the wet surface on the tank. The freshly-applied coating had a golden sheen; it dried to a bright shiny alun-iintu-n appearance, -@vhich, on periodic critical inspection, has been fciiid to be permanently bonded for lasting protection. Obviously, many n-iodifications and variations of the invention, as hereinbefore set forth, may be made without departing from the spirit and scope thereof, and therefore only such hmitations should be imposed as are indicated in the appended claitns. I
