Asphalt-Solvent Blends RETARDATION OF VISCOSITY RISE WITH TIME ARNOLD J. HOIBERG Lion Oil Co., El Dorado, Ark. i
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The primary object of the study was to determine theretardation of viscosity rise obtainable when minor amounts of polar compounds are added to cutbacks of blown asphalts. The increase in viscosity of asphalt-solvent blends is especially noticeable with cutbacks of highly air-blown bases. In solvent dilutions of such asphalts, low in content of peptizing resins, the asphaltene fraction apparently can form aggregations which increase in voluminosity with time. The result is to cause an increase in viscosity, which can be expressed by the relation I = kT", where Tis time and k and a are constants for a particular blend. Alkyl amines, alcohols, and organic acids added to such cutbacks in minor amounts had appreciable retarding effect on viscosity increase. Fatty acid amines were especially effective. Some compounds accelerated the increase in viscosity with time.
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pounds is of importance, especially if package stability is required. EXPERIMENTAL
Heated asphalt bases and solvents were admixed with vigorous stirring, and the finished blends were divided into portions and transferred into smaller containers for storage. Compounds to be tested were added directly and the blends were admixed without solvent loss, or were dissolved in a small portion of naphtha and added to the blend in storage containers, an equal amount of naphtha being added to the blank. Initial measurements were determined within 6 to 10 hours after addition of the solvent to the base asphalt, and viscosities or unworked penetrations were determined by A.S.T.M. methods (1,s).
Blend data on the various cutbacks are given in Table I. All bases were air-blown from steam and vacuum distillation residues, the base for cutbacks A, B, and C being a blown penetration asphalt, for cutback D a blown flux of medium oil content, and for cutback E a blown flux of high oil content. Solvents were straight-run untreated naphtha fractions, except for cutback C which also contained C.P. toluene. The 300" to 400" F. boiling range naphtha was negative to copper strip corrosion ( 2 ) ; the 170' to 400' F. naphtha was positive but with insufficient free sulfur compounds resent to be noticed by odor. Aniline cloud points of the naphtias were 126" and 127" F., respectively. The chemicals were of technical erude. the amines and derivatives being described b the manufacther (Armour and Co., Chemical Division) as fofows: AM-1180 C, 84 to 93% monoamine, mean molecular weight of 264. Mixture of technically . pure _ monooctodecyl and monohexadecyl amines. AM-CoCoB mixture of chemically pure amines corresponding in alkyl chain iengths to the fatty acids normally obtainable from coconut oil. Above 98% in purity as monoamine, based on average molecular weight of 200. AMAC-1180, acetate salt of AM-1180 C.
SPHALT-solvent blends are useful for a variety of purposes-as paving cutbacks, waterproofings, roof coatings, dipping blacks, and other paints, and as vehicles to which mineral fillers can be added to prepare various protective coatings such as automobile undercoatings and sound deadeners. A wide variation in composition is possible and is required in the cutbacks as applications vary. Paving cutbacks are usually prepared from steam- and vacuum-reduced asphalt bases and naphtha or kerosene solvents; the selection is dependelit on whether a rapid (RC) or medium (MC) curing type is desired. Protective coatings usually require blown bases and various petroleum solvent fractions, the boiling range of which is selected according to drying time and flash point. The properties specified for such asphalt bases cover a wide range, from those of comparatively low softening point and medium to high penetration to RESULTS highly blown asphalts of low to medium penetrations. The difEFFECT OF VARIATION IN NAPHTHA CONTENTAND TYPEON ferences in character of solvent dispersions are further reflected by VISCOSITY RISE. Increases in viscosity with time of cutbacks A, increases in their viscosity with time. With straight-reduced B, and C of Table I are shown graphically by Figure 1. For combases the increase is negligible in comparison with highly blown parison the increase isexpressed as the percentage of the initial visbases. With the latter, varying with the properties of the blown cosities because of more general significance than the increase in asphalt, viscosity rise can go from negligible to extreme to reach a seconds. The data for cutbacks A and B plot as straight lines on coagulated rubberlike gel state, which is sometimes desired. logarithmic paper; the increase is a t a much more rapid rate for Viscosity rise with time can be related to factors other than cutback B with the lower solvent content. For cutback C the properties of the base, such as solvent properties and the presence irrcrease from 1 to 7 days was more rapid than for A and B; the of inorganic acids or bases. In this study the primary object was rate thereafter decreased to show the same increase as cutback €3 to determine the retardation obtainable with addition of minor amounts of .oolar com.oounds. to cutbacks of blown asphalts which were known to exhibit AND INITIAL VISCOSITIESOF CUTBACKS TABLE I. COMPOSITION fairly high viscosity increases. In practice objectionable visCutback A B C D E cosity rise usually can be overAsphalt base properties come by proper selection of the Softening point (ring and ball) e F. 245 245 245 178 197 Penetration a t 770 F., mm./10' 6 6 6 22 51 asphalt and the solvent. Oc300-400 300-400 75% 300-400 170-400 170-400 Solvent boiling range, F. casionally requirements to be 25% toluene 60 42 60 35 22 Solvent content, % by. wt. Initial viscosity met necessitate combinations 163 ... ... Saybolt Universal a t 77' F., seconds 235 that show more than the Saybolt Furol a t 122O F seconds ... 252 ... 359 desired viscosity increase and Initial penetration a t 770 F., cone, mrn./lO .. ... ... 297 the addition of retarding comO
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T I M E DAVS Figure 1. Increase i n Viscosity w i t h Time of Cutbacks A, B, and C of Table I 42 to 60% solvent content Data of Tahle I
a t 15 days and as A a t 230 days. The viscosities of cutbacks A and B were not determined in the period from 1 to 7 days, and it is possible that the initial slopes of the logarithmic relations would be greater in this period than thereafter. EFFECT O F ADDITIONOF hvIINES, ALCOHOLS, AND ACIDS Yiscosity changes upon addition of amines of high molecular weight are shown in Table 11. Initial viscosities were reduced upon addition of the amine, on an average by 5% with 0.5% amine. Comparisons of viscosity change showed the blended cutbacks with amine to increase on an average less than about one half as much in viscosity as the corresponding blanks. Agreement between average percentage increase of the four blanks of Table I1 and the average values of the total of thirteen blanks of cutback A was excellent, and the over-all average i%used in Figure 2. Similar data on the effect of addition of 0.5% of long-chain alcohols-hexyl, octyl, decyl, and stearyl-are shown in Table 111. The retarding effect of these compounds was less than with the anlines, but appreciable. In comparison with the blanks at 80 to 90 dam, which showed a 39% increase, cutback A with the alcohols increased 24% in viscoiity. Effect of addition of carboxylic acids, capric, palmitic, and tall oil which contains rosin and fatty acids, is shown by Table IV. The decrease, while minor, was consistent, the blank increasing SOYo after 3 months and the blends with an average of 0.6% of ncids increasing by 37% in the same time. lnthranilic acid was found to increase the viscosity rise to nearly double the value found for the blank. RIaleic anhydride,
1% added to cutback A, increased the initial viscosity I,. 10 seconds and caused a sevenfold increase after 1 month. Figure 2 is a logarithmic plot of the percentage increase in viscosity versus time shown by cutback A and after addition
of amines, alcohols, and carboxylic acids. Straight-line relations were found, and the slopes of the lines within experimental error were the same. The equations representing increase in viscosityin per cent, I , for the different cutback:: a w : Cutback X I = 9.3 2 ‘ 0 . 3 6 I 3.7 p . 3 7 A amines -4 alcohols I = 5.0 ~ 0 . 3 8 A acids I = 7.3 where 3’ is time in days. The equations thus represent a I‘ainily of parabolas with ascending convex curves. A comparison of int,ercst is the days required for cutback A and this cutback xith compounds added to increase in viscosity by 50%:
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Blend Cutback .A A amines A alcohols 9 acids
Days 100 900
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T.~RIATIOX WITH CHAINLEIGGIII-I OF A~IISES. The efi’cct of
chain lengths of amines as relat,ed t o reduction of viscosity rise of cutback A is shown by Table V. The ethylamines were found to show no appreciable effect, until aft,er 3 months’ storage, a t which time the viscosity increase was almost double. The butyl and amylamines were almost without action up to 3 months’ storage, a t which time retardation effect t o reduce the increaEe from 54 to about 35% was observed. The longer chain fatty acid amines had appreciable retarding action. The aryl amines-ophenetidine, aniline, and diTABLE 11. EFFECTO F - k \ I I V E S I N RETARDING Tr13C051TY RISE O F c C ! ! B i C K ~henvlamine-causcd a rctardation less than with the amyl Initial % Incredse above Initial after Conon., Viscosity __________ arid fatty acid amines; o-phenea t 77” F., 7-8 25-35 80-90 250-260 365 570 T o . Coiripound S.U.S. day8 days day3 days days days t,idine \vas the most effective of 12 5 26 36 86 .. 1B Sone the three. 24 4.9 13.9 .. .. 1 .4M-1180 C 0:i EFFECTOF CHEMICALSIN 14 7 6 .. 31 .. 2.0 2 &Ai-1180 c 0.5 3 .i AX 13 . O 23 2B None MOREVISCOUS BLEXDS. The 30 .. 5 10 18 3 .4hI-l180 C 0 :6 35 55 .. 9Q 27 3R None viscosity rise of cutback D, 24 32 , . .. 4 hhf-1180 C 0 :2 5 18 21 26 .. .. .. 17 Table VI, was comparatively . i Ahi-1180 c 0.5 21 11 16 .. 33 6 .4M-1180 C 1.0 high, 131% in 3 months, as 44 .. 67 27 28 ,. 2B None 10 .. 15 .. 43 i 4 M CoCoB 0 :6 9 compared to cutback A which h v . values for above 4 blanks 258 20 28 42 (88) increased 46%. Addition of .4v, vslnes for 13 blanks of cutback .4 235 20 30 46 7W 0.57% of amine reduced the 4 ~valnes . with 0.53% of amines 25.5 8 15 21 (30) increase to an average of indicates only 1 or 2 vrtliies available ( 82%) which was about 63Y0aa a Arerage of 4 values much as shown by the blank. ~~
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TABLEV. EFFECTOF CHAIN LENGTHAND TYPEOF AMISES IN
RETARDISG VISCOSITY RISE OF CUTBACK A
(Concentration of compounds, 0.5% by weight) ~ ~ i t i ~ % l Increase in Viscosity above Viscosity Initial after at 77' F. 7-8 25-35 80-90 No. Compound S.U.S. days days days 1 12 None 23 54 13 2 Ethylamine 24 93 Diethylamine 14 19 100 3 20 4 32 34 n-Butylamine 20 n-Amylamine 5 25 37 14 Di-n-Amylamine 6 20 33 27 55 7 35 None 17 AM-1180 C 21 26 8 9 9 None 15 10 9 10 106 AM-COCOB 15 24 11 None 41 64 12 23 Diphenylamine 12 35 7 25 Ani 1in e 13 38 12 +Phenetidine 13 14 20 a 43% after 570 days. OF CUTBACK D TABLEVI. VISCOSITYINCREASE
OF
Initial viscosity, Saybolt Furol a t 122O F., seconds Increase above initial, % 7-8 days 25-35 days 80-90 days
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CHANGES Ih' PENETRATION OF CUTB.4CK E ADDITIONOF AMIXESOR PALMITIC ACID Concn.,
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Cone Penetration a t 77" F., hIm./lO Decrease Decrease 7 days, 25-30 days, Initial % %
high elasticity and the presence of an oily surface caused by free intermicellar liquid. Such differences in behavior of asphalts would necessarily be related to phenomena observed in solvent solutions. The wellknown Oliensis ( 1 0 ) spot test points out such differences by precipitation of flocculated particles from cracked or less stable compositions, either immediately or after a period of storage. Swanson ( 1 1 ) was able to she\% directly by microscopic observation of films the effect of time and concentrationofresinfraction on dispersion of asphaltenes in benzene solution. Clear films were obtained, regardless of age of the blend, with 0.40 gram of solids per ml. of benzene solution when the solids contained 25% of asphaltenes and 75% of resins. With a solids composition of 3370 of asphaltenes and 67% of resins, a clear film was obtained within 45 seconds after dilution with benzene to bring the content minutes after dilution the asphaltenes to 0.30 gram per ml. TFTO were incompletely dispersed and a nonuniform film clearly showed the phenomenon of reassociation of asphaltenes. A 5% solution in benzene of asphaltenes from an asphaltite has been reported to shorn little change in viscosity on aging; a 10% solution doubled in viscosity in 3 months. The viscosities of solutions of resins and oils were found to remain stable irrespective of concentration (18). Rate of diffusion of the stabilizing resin layer to the solvent phase after dilution, proportional to the concentration difference of resins, would be rapid a t first and decrease as equilibrium was approached. With decrease of the concentration of the resin film, molecular forces of the asphaltene molecules would cause agglomeration upon collision to increase their voluminosity or effective concentration, because of spongy or nonspherical structure, and thereby increase the viscosity of the blend. At least two disclosures have been made of the beneficial effects
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of increase of the resin and aromatic contents of solvent solutions of blown asphalts. Knowles and McCoy ( 7 )found that addition of resinous extracts from solvent treatment of lubricating distillates lowered the viscosity of solvent blends at a given content of solids and decreased the viscosity rise. Marc and Greidcr (8) described decrease of the viscosity of blown asphalt solutions beyond the dilution effectexpected, on addition of such compounds as dipentene, wood rosin, and derivatives therefrom. Condensation products from cumene, indene, or similar compounds were found to prevent gelation. With the blonn bases of this study it was found that the percentage increase in viscosity, I , was related t o time, T , by I = k T " ; this can be expressed b y
where Ti is viscosity a t time 1', is initial viscosity, and a and k are eonstants for a given cutback. The presence of certain polar materials was found effectively to retard the viscosity increases. Such compounds are thought to, be adsorbed by the asphaltenes to become orient,ed with the nonpolar end of the molecule out,rard. The longer alkyl groups es'pecially could act as insulants t o decrease the st,rength of forccs tending t o bond colliding asphaltene particles and thereby retard viscosity rise. Ethylamines increased the viscosity rise. Beginning with butylamines, retarding effect was apparent. Three aryl amines, especially o-phenetidine, also were effective in retarding viscosity rise. The most effective of the chemicals tested were fatty acid amines. With basic properties to help in adsorption, their long alkyl chains acted as successful stabilizers. Next in action were: alkyl alcohols, and then long-chain carboxylic acids. Chemicals uhich gave a definite viscosity rise, in addition to the ethylamines, were anthranilic acid and maleic anhydride. Apparently the amine and carboxylic groups of anthranilic acid cannot be absorbed b y asphaltene molecules to orient the benzene ring outward and aggregation forces are increased. Maleic anhydride forms adducts with conjugated dienes and copolymers with compounds as styrene. On heating with asphalts, its action has been found to increase t,heir melting point ( 4 ) . The marked act,ivity of maleic anhydride in increasing viscosity rise of cutback A, 195% in 1month, indicates aggregate formation wibh ccrtain of the asphaltic components. A higher concent,ration of asphalt base increased viscosity rise. Marissens (9) commented that addition of aromatic hydrocarbons prevented gelation, but only when the hydrocarbons constituted 35% or more of the total. I n a concentrated solution the structure of a gel cutback was destroyed by addition of amines. The viscous cutback produced showed an increased tendency t o harden. Rate of hardening of a viscous cutback of this nature f a r from equilibrium conditions would be expected to be greater than with a gel in which the cont'inuous structure would only slowly bc reinforced. Increase of aromaticity of the solvent by addition of toluene was found to cause a rapid initial increase in viscosity, followed by a decrease in rate. With greater solvency shown for the resin film, this would be expected and is in agreement with the rapidity of change noted by Swanson from homogeneous t o nonhomogeneous films within 2 minutes after dilution of a benzene-resin-asphaltene blend. CONCEU STON S
Viscosity rise of solvent blends of asphalts, a function of thc colloidal structure of their bases, can be expressed by the relation I = kl'", where I is the percentage increase, 1' is the time in days, and k and a are constants for a particular blend. Addition of various polar compounds such as carboxylic acids, alcohols, and amines has been found effectively to retard the viscosity rise with
INDUSTRIAL AND ENGINEERING CHEMISTRY
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time. Of these compounds, the most effective were the alkyl amines of molecular weight in the neighborhood of 200 t o 250. The effect Of such compounds is to be due to their adsorption by the asphaltenes t o have the nonpolar portions of the molecules act as stabilizing agents and decrease the rate of aggregation of the particles. ACKNOWLEDGMENT
Appreciation is expressed t o the members of the laboratory staff for carrying out the tests and t o the management of the Lion Oil Go. for permission t o publish results of this study. LITERATURE CITED (1) Am. Soc. Testing Materials, Method D 88-44. (2) Ibid., D 130-50T. (3) Ibid., D 217-48. (4) Bradley, T. F., U.5, Patent 2,347,626 (April 25, 1944).
( 5 ) Eckert, G.
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and Weetman, Bruce, IND. ENQ.CHEM.,39, 1512 (1947)., (6) Fisher, H. C., Ibid., 16,509 (1924). (7) Knowles, E. C., and McCoy, F. C . , U. S. Patent 2,415,697 (Feb. 11, 1947). (8) Marc, Henri, and Greider, H. W., I b d . , 2,188204 (Jan. 23, 1940). (9)Marissens. E., ING. CXIM..29. No. 167. 1-4 (1947). (10) Oliensis, G . L., Proc. An. SOC.Testing MatekaZs, 4 1 , 1108 (1941). (11) Swanson, J. M., J. Phys. Chem., 46, 141 (1942). ENQ. (12) Traxler, R. N., Schweyer, H. E., and Romberg, J. W., IND. CHEM., 36,823 (1944). (13) Uranov, S. A., Orlova, E. N., and Pneva, L. A., BmZZ. O h e m Opyt. Lakokrasoch. Prom., 1939, No. 8 , 22-3. (14) Winterhrn, H. F., and Eckert, G. W., Im. ENG.CHEM., 33, 1286 (1941). RECEIVED October 9, 1950. Presented before the Divisions of Colloid, Gas apd Fuel and Petroleum Chemistry Symposium on the Nature of Bituminous CEEMICAL QocImY, Materida, a t the 118th Meeting of the AMERICAN Chicago, Ill.
Kinetics of the Uncatalyzed Reactions between Resorcinol and Formaldehvde J
R. A. V. RAFF AND B. H. SILVERMAN' Mellon I n s t i t u t e , Pittsburgh, Pa.
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Because resorcinol and particularly its condensation products with formaldehyde have found ever-increasing application in the past few years, a sounder and more scientific basis for these reactions is warranted, and a systematic study of the kinetics of the resorcinol-formaldehyde condensation was undertaken. Experiments are described in which this reaction is studied in dioxane, without a catalyst, at various temperatures, and for different mole ratios of resorcinol to formaldehyde. The apparent first order of the reaction, the energy of activation (around 19 kg.-cal.), and the temperature coefficient (around 2.3/10° C.) were found to remain
constant as the uncatalyzed resorcinol-formaldehydecondensation progresses, and practically independent of the resorcinol-formaldehyderatio. Resorcinol has considerably higher reactivity compared with phenol and alkylated monophenols. As no kinetic data for the very slow, uncatalyzed phenol-formaldehyde reaction are available, and the present study deals with the uncatalyzed resorcinol-formaldehyde reaction only, a comparison between resorcinol and phenol in their kinetica was possible in only a few instances. The data presented should lead to a better understanding of the reaction between phenols, as well as resorcinol and formaldehyde.
THEpr
and again pointed out in 1924 by Zamparo (2%). The formation of colloidal resin suspensions from formaldehyde and resorcinol and their flocculation by ions were described by Engeldinger (10)in 1936. However, apparently the only real kinetic study of the resorcinol-formaldehyde reaction, carried out on a rather limited scale, was reported by Dubrisay and Papault ( 9 ) in 1942 and 1945. These authors condensed resorcinol with formaldehyde in the presence of sodium hydroxide a t 18"and a t 40" C., and determined the viscosity and the amount of free resorcinol in the solution. The results were considered to be in agreement with a reaction mechanism involving the formation of 0- and p-phenol alcohols, their combination to substituted dihydroxydiphenylmethanes, and the condensation of these compounds to networks. No further kinetic study of the reaction of resorcinol with formaldehyde was published until 1949, when Sprung and Gladstone (86) reported that the reaction of 0-methyl01 phenol (saligenin) with resorcinol to trihydroxydiphenylmethane is of second order, regardless of the presence of catalyst (triethanolamine) or diluent (pinacol). The curing reaction of resorcinol-formaldehyde condensation products was the subject of several investigations. Boutaric and Engeldinger (3)in 1938,carried out dilatometric measurements on curing resorcinol-formaldehyde resins, without relating them t o the kinetics of the cross-linking reaction. A most important discovery was made in 1946 when Aero Research, Ltd., in Duxford, England (1) reported that the gelation time on heating a fusible resorcinol-formaldehyde resin with additional formaldehyde is dependent on the p H of the curing mixture
o ~ e 8 8 ewhich ~ take place when phenol reacts with formaldehyde have been thoroughly investigated, and it is now commonly accepted that this reaction takes place in three steps {isogel theory of Houwink (14)J which have been studied and explained qualitatively and structurally (6,16, 33). Kinetic investigations of the phenol-formaldehyde reaction are scarce, although some significant research was reported in recent years, particularly by Nordlander (19), Megson (18),Jones ( l a ) , and Sprung (86,86). In several instances, investigators (7, 11, 26) considered the condensation reaction of phenol itself with formaldehyde as too complex to be understood without preliminary studies on phenols in which some of the three reactive positions (ortho, meta, para) were blocked by substituents, and which would not be capable of such diversified reactions. On the other hand, it is known that the entry of a substituent in meta position to the phenol group, enhances still further the reactivity of the phenol. This is particularly true in the case of resorcinol, where two hydroxyl groups are in meta position to one another, thus possessing three doubly wtivated ring positions as against three singly activated positions in phenol. The complexity of the phenomena involved in the condensation of resorcinol with formaldehyde, where even intermediate phenol-alcohols and resols are, if a t all (8, do), stable only a t temperatures of 5' C. or lower, obviously did not encourage studies of a kinetic nature. The eaae with which resorcinol and formaldehyde react to form condensation products, was described f i s t in 1892 by Caro (4) 1
Present address, Heyden Chemical Corp., Garfield, N. J.
