US2327247A - Method for producing asphalt - Google Patents

Description

'fe'rred in; the roofingindustry;

sitivity test.

Patented Aug. 17; 1943 orat on l .ME'riroDFoR rnonocmensrriarr panels n. can, Los Angeus, an Harold W.

i Ritchey;'Long Beach, Calif., assignorsto Union Oil Company of California, Les a corporation of California Angeles, Qalifi,

. Z No Drawing. Application we is, less. a

Serial No. 279,492 4 a (oi. lea-22y Y '6 Claims.

This invention relates to an improved coating or airblown asphaltandto a process for manufacturing the same. i v V It is well recognized in the art-oi manufacturingair-blown i. e. oxidized or coating type asphalts, that these products may. be prepared by blowing the charging stock, such as asphalt residua producedfrom asphaltmontaining crude oils, with .air or other oxygen-containing gases at-an .elevated temperature. The product resulting from .this'operation will possess, desirable 'low temperature susceptibilities; a higher melting point for a given penetration as compared with un'oxidized asphalts and. a moderately high,

ductility.) Thistype of asphalt is generally pre- 1 In recentyears, attention has been-focused on the light-promoted oxidation of asphalt and as a resultof manyroof failures,,the Minnesota Mining and Manufacturing Company has investigated the effectof-light andjmoisture on asphalt and has devised what is now known as the photosen- They. found that under certaindegrees of exposure to light, all asphalts form a thin jsurface coating of oxidized materials, and that by "immersingthe exposed asphalt in warm water,

the degree'of oxidation can be strikingly shown by a color change. j Sufficiently oxidized surfaces take on a yellow, paint-like appearance, which has been'termed rust. The length of exposure .necessary todevelop this rust is ,takenasan indication of the degree of photosensitivity of'the asphalt.

, The work of the above Minnesota company was mainly concerned with the loss of adhesiveness of the asphaltfor roofing granules in the case of roll roofing or asphalt shinglesiin' which the surfaces are coated with mineral granules which may transmit a certain amount "of light. Sur- 'face oxidation of thelasphalt in the presence of light was assumed by them to correspond to a lo'ss'of binding powervfor the granules. Asphalts which thus show a high degree of photosensitlvity according to the photosensitivity test are regarded as unsuitable 'for'use with their granules.

"However, an aspect of more serious conse- 'quence to the-roofing trade in general is the fact that in the light reaction certain acidic watersoluble substances are formed "which; if not washed completely cit by-rain, tend to concentrate in dew puddles and leave yellow stains, especially in hot, moist climates. This is a frequent' source of complaint in the case of mopped roofs or built-up roofing. It should be noted that this form of stain, whichmayz-il'so effect the color of granules inshingle-coatedroofs, has

nothing whatever; to dowith the-staining due to oil exudation and in fact, is most frequently encountered with certain asphalts which show low stain numbers by the Barber test, which measures the tendency of an asphalt to exude oil.

;'Ihe fact that the water-solubleportion of these oxidation products is'acidic often results rather extensive corrosion of down spouts, galvanized roof gutters, etc.

Also it will be noted that-the photosensitivity phenomenon has no necessary connection with the fundamental weathering behavior of the 'asphalt. Inv fact, some of the asphalts which ohave the longest Weather-Ometer life are the most photosensitive and conversely, some of the poorest asphalts from a Weather-Ometer standjfpointare the best froma photosensitivity standpoint; i. e: are the, least photosensitive. Thus,

some asphalts which are otherwise considered to ,be good: .asphalts and have a long .Weather'- Qm'eter lifehav thedisadvantage ofbeingvery photosensitive. By Weather-Ometer life is meant "thelife of an'asphalt as measured by thetest developed by Dr. stricter fog the U. 3. Bureau of Standards. i

' [Thus, it is an object of invention to produce non-photosensitive asphalts from photosensitive asphalts. f 1 a We have found thatione of the properties of an asphalt mostinfiuencing the photosensitivity test, i. e resulting'in a high photosensitivity, is

the'presence. ofja relatively light oil in'the asphalt.

Our experimentation relating to fractionation of the photosensitive asphalts has shown that the reactive constituents in photosensitive asphalts are confined tothe oils. and are"'concentrated chiefly in the relatively light and medium lubricating oils. "By vacuum topping, it has. been found' possible .to prepare heavy oils from such photosensitive crude oils as Santa Maria Valley (California) crude oil which are relatively, inert to light. Thus, by a suitable'fractionation procedur'e, it is possible to produce from such .photosensitive asphalts, a flux, which, upon air blowing to the desired characteristics, is considerably improved in respect to photosensitivity.

' ,We havealso found it possible to producea flux from a photosensitive asphalt, which, upon "oxidation with air, results inthe productionof a relatively non-photosensitive coating asphalt by subjecting the asphalt or topped asphaltic re- "siduum to extraction with solvents which are capable oiprecipitatingthe asphaltenes and also resins'contained in the asphalt and dissolving the V oil' fractions therein; Wejhave found that the solvent precipitatedasphaltenes and resins are relatively inert with respect to light. By subject,-

' ing the light sensitive solvent soluble fraction to distillation to remove light oils, we have found that the residue consisting of a heavy oil is relatively stable to light, this stability toward light increasing with the boiling range of the heaviest overhead cutrerncved. By blending the heavy oil bottoms with the precipitated asphaltenes and resin in the desired proportions, a composite d asphalt which is stable towards light may be produced and which, if desired, may be air-lblown'to produce an oxidized asphalt which is stable towards light.

The precipitation of the asphaltenes and also resins may be accomplished by extracting the 2 11 with solvents such as the liquefied normally gaseous hydrocarbons, such as ethane, -prqpane, butane and isobutane or mixtures thereof. The separation with these solvents may be effected by simply mixing the asphalt with the solvent e at normal temperatures-or more -elevated temperature er about 103 F; under pressure Sui-ii client-to maintain the solventin the liquidstate at the temperature'em ployed; For example; "in

the case-of propane, approximatelythree tosix volumes of propane -may be -mix'e dwith the asphalt residuurn at a temperature of about 100 -F.- ands pressure ofabout "l'lfi-pounds persquare inch. This mixture is allowed to-remain-in *a quieseent'state until the precipitated asphaltenes and resins havesettledto the bottom'ofthecontainer in -which-the admixture'wasefiected. ,The clear supernatant solution of oil and-propane substantially free from or containing relatively small amountsof 'resins is decanted frorn the s. settled-asphaltenes and resins and ,is subjected to' distlllation 'to remove the propane which-may be recovered by compression'and cooling and re-v turned for yfurthertr'eatment of re iduum, The propane-free oil may thenbe slubjectedto distillation and fra'ctionation in order to separate -thelight;oils contained therein which carry the phctosensii'nve materials; -The bottoms ,are 'then'blendedin the desired'proportion with'the previously precipitated asphaltenes .and resins,

,e, tlculariy .tlie resins of low 7 molecular 'weie'ht,

the'production of air-blown asphalts-which have a relatively low Weather-()mter life; These 7 e i maybe removed bysubjectinetheprwan precip tated asphaltene-iresin mixture to extraction with ,a solvent capable of wdissolving the resins; at least the resins of, low moleculanweight, but not substantial amounts @of .the asphaltene atzthe temperatureemployed. .For thispurpose, relatively j'heavier. solvents may be used such as petroleum (ether. Asian examplathreeorfour .3

volumes ,of petroleum ether may -b.e.mixed with the propane precipitated ,a'sphaltene-resin mixture at a temperature otabout ,175 ,F. .and the mixtureallowedto settle. Ihesolution ofpetrolellmsetber andfresinsis nextdecantedfrom the settled asphaltenes. The latter is then subjiected ..to distillation ttoaremove .any -,petroleum ether mntainea therein. .The asphaltenes may in' he blowing stock are generally responslbleior' u:

distillation in order to distill the oil fractions tracted oil in such proportions as to produce a flux which may be air-blown to the desired melting point-penetration characteristics.

Experimentation has also shown that materials is asphalt which are responsible for high light sensitivity are aromatic ,or unsaturated in nature since they may be removed by extraction of the light or medium lubricating oils with a sective solvent capable of separating the oil into '1 a relatively paraflinic fraction and a relatively non-iparaflinicior aromatic or naphthenic oil fraction. In order to produce the relatively nonphotosensitive asphalt, the asphalt or topped asphaltlclcrude-oil -may be subjected to vacuum from the asphaltenes or the oils may be sepa- 11 ated from the asphaltenes by the'aforementioned precipitation with solvents such as pro- ,Dfine. {The oil is then extracted by known extraction methods with a selective solvent, such asphenol, liquid sulfur dioxide, -furfural andthe 'll-l 'e, to-separate the oil into -a-raffinate phase and an extract phase. The raflinate phase is next stripped of solvent and the rafilin'ateithus "produced is *blended with the aforementioned distillationbottoms, i. e. asphaltenes, or solvent precipitateda-sphaltenes in such desired proportions 'astoprodueeaeompositedasphaltwhich may'be used as composited 'or-which may be subjected to mild ormore severe oxidation "with air or ether oxygen-containing gas. 'If desired, the rafiinateoil may besubjected-to distillation to remove light oils before being ,composited with --the asphaltenes. I'heselight oils, however, are

lthenbe blendediwiththe bottoms-resulting-from the distillation of the previousl :Pmpitlifi @8- generally not sensitive to light since the light sensitive materialshavgbeen removed by the.extraction-prqcess-and remainin the extractphase.

.In order to :still'iurther decrease the photoj sensitivity :or the above produced asphalts, small amounts, ie 025 to 10% by weight of certaln "inhibitors :ofphoto-oxidation may be mixed with theasphalt. =For"this purpose, we have found a large n mber of. ubs ances which may be added to'the asphalt to reduce DhQt'OEQXl-dQ-tiflll. Compounds that are characterized by .pbla character, 1 one hydrocarbon cha.ins terminating in a polar group. .such .as oxygenated smu'p nitro grou s, su phonic mups, halo or aromatic nuclei, have been found to be particularly suitablelas inhihitorslof photoeoxidation. Ihe'nigher straight chainlfatty acidssuch as lauric, tridecoic, myristic, pentadec0ic,rpa1- mitic, margaric, stearic, nondecoic, arachidic, eicosoicor eicosanic, behenic, tricosoic, lignoceric or carnaubic, pentaco'soic, cerotic, ,hexacosoie, carboceric, montanic, acids, and also-the alcohols derived from the above higher straight chain fatty acids such as laury1,.ol.eyl,,stearyl, etc., al- 6 .1015 .havevbeen found to be particu r y acti inhibitors of photosoxidation. Also, the higher straight chainiolefinic acids iundecylinic, myris- .tolenic, ipalmitolin c, .o1eic; petroselie, eruci brassidic, nervonic andlikeolefinic acids-maybe used as inhibitors of photo-. oxidation. Likewise, the alcoholsrderived from these olefinickaeidsare ,good inhibitors of photo-oxidation. Montan-wax,

carnauba wax, hydrogenatedfishoiliacids, acidulated cocoanut oil acids, acidulated shortening oiLaeids, cottonseed oil acids, etc,,;may-a1so;be used. Parafiin wax which-hasbeenpxidimgl gt t vely :low temperatures :under conditionsrfai s ng'fatty acid ratherthan estolide orhydmxy acid-formation has alsobeen ioundt be an :6- aieetive -i-nhibit0r.

1:5 iIhe renewi :sii m tted :as specific sexamples of our invention. These,- however, are

not tobe considered as limiting but merely as illustrative of the invention.

. Emme m A Santa Maria Valley crude oil was topped with steam to produce an asphalt residue having a viscosity of 120 seconds furol at 210F. This residue was then mixed with four" volumes of propane at a temperature of 100 F. under a pressure of 175 lbs.per square inch. The mixture was allowed to remain in a quiescent state at this temperature and pressure in order to permit the precipitated-asphalt to settle below the solution of oil and propane. The latter was decanted from the settled asphalt and the two separated fractions were distilled to remove propanetherefrom. Approximately 53% by weight of propane soluble oil was obtained having a viscosity of 80 seconds Saybolt Universal at 210 F. and low flash point of 250 F. (Cleveland Open Cup). A portion of this oil was then distilled under vacuum to remove as overhead consisting of light and medium lubricating oils. The bottoms representing 60% of the extracted oil had a viscosity of 150 seconds Saybolt Universal at 210 F.

These bottoms were then blended with a vacu urn distilled asphalt produced from the same Santa Maria Valley crude oil having a melting point of 125 F. and a penetration of 40 at 77 F. The blend was effected in the proportions of 60% by weight of the asphalt and 40% by weight of the above bottoms. had a viscosity of 378 seconds furol at 210.F. and a flash point of 530 F. (Cleveland Open Cup);

The blend of asphalt and oil was then oxidized with air'at a temperature of 100- 150 F. for i hours, using 5,cubic feet of air per barrel of charge per minute. The oxidized. charge showed a melting point of 217 F., penetrations of 14 at 32 F., 18 at 77 F. and-33 at 115 F., a ductility of 4.0 at 77 11, a flash point of 520 F. (Cleveland Open Cup) and a Barber stain number of 2.0.

An aluminum panel was coated with this asphalt to a thickness of 0.025 inch and the coated panel was then exposed to the radiation of a 1500 watt lamp at a distance of 6 inches from the lamp. The panel was exposed for 28 hours and was then immersed in warm waterat 140 F. resulting in the formation of a light rust which remained upon drying the panel. No rust was 7 formed on similar panels exposed less than 28 hours.

In order to compare the photosensitivity of the above asphalt with a similar asphalt of 217 F. melting point but which had not been subjected to the process of the above invention, another portion of topped Santa Maria Valley crude oil Example 2 Another portion of the propane extracted oil bottoms having a viscosity of 450 seconds Saybolt Universal at 210 F. of the above example was blendedwitli the propane precipitated asphalt of the above example in the proportions of by weight of the precipitated asphalt and 60% The composited blend An aluminum panel by weight of the oil-bottoms. The blend showed a viscosity of 500 seconds furol at 210 F. and. a flash'point of 560 (Cleveland Open Cup).

This blend was oxidized with air as previously describedto produce an air-blown asphalt having a melting point of 220 K, penetrations of 15 at 32 F., 19 at 77 F. and 31 at 115 F., a ductility of 4.2 and a flash point of 530 F. (Cleveland Open Cup). 'When apanel .coated with this asphalt was subjected to the above photosensitivity test, there was no evidence ofrust formation atYthe end of thirty-two hours exposure to the. lamp.

' Example} The remaining portion of the propaneextracted oil of Example 1. having a viscosityof'80 seconds Saybolt Universal at 210 F. and a flash point of 250 F. was extracted five times at 100 F. with a mixture consisting of 90% phenol and 10% water, using two volumes of selective solvent to one of the oil on each extraction. The raffinate produced by the five extractions had a viscosity of 172 seconds Saybolt Universal at 210 F. and a viscosity gravity constant of 0.836.

The precipitated asphalt of Example 1 which contained resins .was extracted with 350 volume percent of petroleum ether at a temperature of about 175 F. to effect solution of the resins in the petroleum ether. The mixture was allowed to settle and the supernatant solution of resins and petroleum ether was decanted away from the settled asphaltenes. The latter was then stripped of the petroleum ether and was blended with the previously described raflinate in the proportions of 7 by weight of the rafiinate to 40% by weight of the asphaltenes to produce a blended asphalt having a melting point of 220 F. and a penetration of 40 at 77 F. This blend was then tested, as above, for photosensitivity and showed no rust formation at the end of thirty-two hours.

It will be observed that for determining the melting point and penetration, the following methods outlined by the American Society of Testing materials were used:

Melting point (ball and ring method) 13-36-26 Penetration D-5-25 The term viscosity gravity constant hasbeen defined by Hill and Coates in the Journal of Industrial and Engineering Chemistry, of 1928, vol. 20, page 641. This constant is an indication of the parafiinicity or naphthenicity of oil, a high value representing a high degree of naphthenicity, while a low value indicates a relatively greater parafiinicity.

The foregoing description of our invention is not to be construed as limiting but only as illustrative of the invention as many variations may be made within the scope of the following claims.

We claim:

1. A method for producing relatively non-photosensitive asphalt from relatively photosensitive asphalt which comprises mixing said asphalt with a solvent capable of dissolving oil but incapable of dissolving asphaltenes at the temperature employed, separating a solution of oil in said solvent from said asphaltenes, subjecting said separated oil to extraction with a solvent capable of dissolving relatively non-p'araflinic oil fractions but not relatively paraffinic oil fractions, separating said relatively non-parafiinic oil fractions from said relatively paraffinic fractions, distilling said relatively paraflinic fractions to remove light and medium lubricating oils and cornmingling the remaining heavier paraffinic oil fractions with said sepamtetl'aspihaltenmsito produce:arelativelynom photosensitive asphalt, s H

2. A method accnrrlixxg. m claim 1 in which saidrsolventicapablezof dissolving oil but incapable of zdissolvingaaspheltenes at the temperatureemployed'oomprises a liquefied normallygaseous hy- A method according to .claim 1 .in which said :solven't capable *of dissolving-oil but incapable u'f admolving asphaltenes at the tempera iureremployedicomprises propane.

A. :A method according toclaim V1 in which said solvent capable of dissolving relatively n0nparafflnic oil fractions 'biit'not relatively paraffinic :oil :fmctions'icomprises phenol.

5 A,.method accezdingzto'fcla'imi l in which said solvent capable of dissolving oil but; incepable of dissolving asphaltenes at the temperafinic oil fractions comprises phenol.

DONALD E. CARR. HAROLD W. RITCHEY.