US2762757A - Asphalt and method of producing the same - Google Patents

Description

Sept- 11, 1956 H. L. BEDELL ET AL 2,762,757

ASPHALT AND METHOD OF PRODUCING THE SAME Filed Deo. 17, 1952 Legg? yoils from the crude.

United States Patent() This invention has to do with asphalts and with a method for producing the same.

In recent years, asphalts possessing a particular combination of properties have been developed for many specialty applications, such as paper saturants in the paper art. These asphalts are characterized by a low viscosity with a large change in viscosity on heating, good thermal stability, and dryness at any given point. 'Ihey are generally referred to as cracked or synthetic, asphalts inasmuch as they are prepared by thermal cracking of gas oil stocks.

So advantageous are these cracked or synthetic asphalts that demand has far exceeded supply. n To meet 4.

this demand, attention has been focused upon other more available hydrocarbon stocks as replacements for the stocks from which synthetic asphalts are usually produced. However, such other stocks as are in supply have not responded to the same thermal cracking operations -to yield the desired products.

It is an object of this invention, therefore, to provide a new method for preparing asphaltshaving the properties of cracked or synthetic asphalts. It is also an object to provide a method for preparing the desired as` ph'alts from hydrocarbon stocks of conventional residual asphalts, which hydrocarbon stocks are in good supply and are relatively inexpensive. Other objects and advantages of the invention will be appa-rent from the following description.

It has now been found that outstanding asphalts, comparable to cracked or synthetic asphalts, can be prepared from straight run asphalts by a particular sequence of operations. A straight run asphalt is blended with a cyclic gas oil of low aniline number, the blend is then subjected to Ia heat treatment or cracking operation and the product thus obtained is thereafter reduced to provide the desired asphalt product. f

As indicated above, the particular sequence of operations which makes possible production of the desired asphalts of this invention is: l

( l) Blending a straight run asphalt with a regulated quantity of a cyclic gas oil of a refractory nature,

a desired asphalt quality, and y (3) Reducing the heat treated or cracked asphalt of desired character.

Ycharge can be, broadly, any petroleum residuum or flux which remains following the separation of the volatile The separation of these volatile oils can be accomplished by `means of vacuumA distillation,

Vsteam distillation or by propane deasphalting. For exblend to an I .(2) Heat treating or cracking the blend, formed in (1) to l 2,762,757 Patented Sept.-1-1, 1956 ample, resid-ua from Penn'sylvanan, Mid-Continental, Californian, Mid-East, Near East, Venezuelan, etc. crudes can be used. Or, in other words, residua from parainic, naphthenic, aromatic, high-sulfur stocks, etc.. are suitable. It will be recognized, of course, that ditte-fences in chargel stocks are reilected in differences in character of the final products contemplated herein. Thefollowing analyses are typical of the asphalt charge stocks found to be advantageous: t

Soft point, ring and ball, F

Speciic gravity 1.01-1.03

Penetra-tion:

@32 F., 200 g., 60 secs 5-13 if @77 F., 100 g., 5 secs 20-50 @115 F., 50 g., 5 secs 70-175 Viscosity, Fu-ro'l, secs.:

@.275l F 30e-80o The gas oils used herein are cyclic in character, and are resistant to thermal cracking. Gas oils of this character are well known in the art as refractory stocks. They are generally prepared by catalytic or thermal cracking processes :such as typified by the Thermofor Catalytic Cracking (TCC) process or thermal cracking processes. Representative cyclic gas oil-s are the following oils designated A and B:

Oil A Oil B Aromatics, Percent by wt 25 Unsaturates, Percent by Wt 59 API Gravity. 7. 0 22. 3 Aniline Number 90 174 Pour Point +80 +85 Flash .F 380 365 Distillation, 5F.:

Sulfur 1. 4

Hydrogen to Carbon Ratio 9. 4 7. 5

Kinematie Viscosity (eentistokes):

@100 F 117. 0 1G. 15 @210 F 11. 4 3.33

`from oil B are not so desirable as asphalts produced from oil A. It will be noted that oil B is less cyclic or aromatic in character than Ais oil A. It is concluded, therefore, that oils having less aromaticity (indicated by higher aniline numbers) than oil B are not suitable in the process of this invention.

'Theproportions of the asphalt charge and gas oil can be varied considerably Within certain limits, depending uponV the source of the asphalt charge and upon the refractory naturerof the gas oil. In general, however, from about 10 to O 'per lcent by weight is made up of the asphalt'charge, with the balance gas oil. By way of illustration, a vacuum reduced straight run asphalt, having a ring and ball soft point of 13G-150 F., is used advantagcously in amounts of 20-30 per cent, by weight, with 80-70 per cent of a gas oil such as the oil identified as A, hereinabove.

As contemplated herein, heat treatment or cracking of the asphalt gas oil blend is conducted in the liquid phase under selected conditions of temperature and time. In general, temperatures of the order of 875 to 900 F. with time intervals of ve to three minutes are used; that is, the lower temperatures generally require the longer time intervals. Under such conditions as the foregoing, the resulting asphalt becomes in nature similar to the synthetic asphalts.

Following the asphalt conversion or cracking operation, the product obtained hereby is reduced at a maximum temperature of about 800 F. This is advantageously accomplished by distillation, with vacuum or with steam. For example, the heat modied or cracked product may be separated into overhead distillate and asphalt residue by vacuum or steam distillation.

The conditions of reduction to asphalt do not have any eiect on the basic properties of the asphalt. The asphalt properties are Xed by the previous heat treatment and the composition of the blend treated. The reduction is merely a means of separating out the asphalt from the other products of the heat treated blend.

A typical operation contemplated herein is illustrated by the ilow sheet shown in the attached drawing. A blend of cyclic gas oil and asphalt charge is pumped from charge blend tank 1 through line 2, by means of pump 3, to preheater 4, through line 5.

The blend is passed through line 6, positioned in the central portion of preheater 4, where the oil is heated to about 750 F,

The heated blend is removed from the prehcater 4 through line 7 and is led into the upper portion of a cracking furnace 8. The blend flows through the furnace (8) via line 9, and leaves the furnace at abou-t 850- 900 F. via line 10. The heat treated or cracked product in line 10 is then led through the pressure relief valve (11). From the pressure relief valve, the product goes through line 10 to conventional vacuum distillation equipment and is thereby separated into overhead distillate and asphalt bottoms.

Oils A and B were each blended with twenty per cent by weight of 140 soft point, straight run asphalt (C) and heat treated as indicated below:

Analysis of the straight run asphalt (C) before processing is recited below:

Soft point, F 144 Sp. Gr. 77/77 1.017 Penetration 100-5-77 28 Xylene equivalent Ductility cm. 77

4 Viscosity (centipoises):

350'F 176 325 F 310 300 F 584 275 F 1210 250 F 2640 Viscosity temperature susceptibility 0.733

From the foregoing results and analysis, it will be -noted that the charge of Oil A and straight run asphalt (C) is converted to an asphalt having properties corresponding to those of synthetic asphalts. The charge of Oil B and (C) is also converted to a modied asphalt. Again, it is emphasized that Oil B has a higher aniline number than Oil A, indicative of lesser aromaticity, and that the greater the aromatic character of the charge oil the more desirable is the final product.

Tabulated below are data obtained by treating two blends of Oil A and the straight -run asphalt (C). The blends were heat treated under similar conditions and then reduced to asphalts of the 140 soft point range.

66.6% Oil Oil A with A With 33.4% 20% Asphalt C Asphalt C Furnace Outlet Temp., F 875 890 Soaking Factor 0. 15 0.19 Analysis of Resulting Asphalt:

Sp. Gr., 77/77 1. 0768 1.1214 Soft Point, F. 142 143 Flash, COC, F... 530 480 Penetration, -5-7 18 9 Xylene Equivalent 75-80 90-95 Solubility CCl4 99. 76 98. 84 Ductility (3l-67 0-196-l- Viscosity (eentipoiscs):

@350 F 66 48 7 85 216 173 355 375 50 F 1,010 918 Viscosity Temperature Susceptibility 0, 841 0. 946

The data tabulated immediately above reveal that the greater the quantity of cyclic gas oil charge, the greater the modiiication of the asphalt charge. However, there is a practical or economical limit to the quantity of gas oil which can be used in the charge, since the larger quantity lof the gas oil increases the quantity of oil processed for the amount of modied asphalt produced.

Additional data is presented below in order to demonstrate the influence of heat treating or cracking conditions upion the iinal product. In each of the Runs given below, a blend comprising two parts of Oil A and one part of the straight run asphalt (C) was used.

Run No 1 2 3 Processing Temp., F 815 875 905 Soaking Factor 0. 0171 0.1514 0. 3192 Analysis of Resulting Asphalt:

Soft Point, F 144 142 144 Penetration, 100-5-77 25 1S 13 Flash, F 530 535 Solubility CCl4 99. 7G 95. 75 Xylene Equivalent 75-80 100+ Ductility, 5 em. 77. 61-67 38-42 S. E. Viscosity (C. P.):

@400 F 60 @375 F 96 @350 F 157 66 68 @325 F- 275 127 108 @300 F- 570 216 215 @275 F 355 700 @250 F 1,010 1, 200 Viscosity Temperature Susceptibility 0. 683 0.841 0.876 oft Point-Penetration Index 05 -L 8 '1. 2 Ductility Coefficient 3. 42 4. 0 4. 22

From the results directly above, it is concluded that the soaking factor maintained in Run l is too mild to provide the desired result. The character of asphalt arcanes? product of Run l is only slightly dilerent from the character of the straight run asphalt of the charge. The asphalt product of Run 2 has desirable properties, thereby indicating that the heat treatment was suitable. In Run 3, the conditions of operation are approaching the upper limit of severity inasmuch as the Solubility CC14 value indicates the presence of some coke-like material in the product.

In general, the products of this invention are characterized by the following properties:

Broad Preferred Range Range Soft Point, 120 to 170 130 to 150 Sp. Gr., 77/77 1. 04 to 1. 20 1.08 to 1.16 Penetration: 100 gms., 5 secs., 77 F 0 to 35 5 to 20 Xylene Equivalent 5 to 100-|- 60 to 100+ Ductilty 77 F 0 to 100+ 40 to 100+ Solubility (C014) 95. 0 to 100 98.0 to 100 Viscosity in Centipoises:

250 F. 600 to 1, 000 275 F 200 to 400 300 F 100 to 200 325: F gotg 1go() 350 F 0 lscosi y empara ure uscep i 1 y V' 't T t S t'bil't (Z50-350 F.) 0.78 to 1. 2 0.9 to 1. 0

Typical uses to which the `asphalt products lof this invention can be put are the following: water-proong of paper; size or coating for insulation board; saturant for panel and molding boards made from Kraft paper; emulsions for briquetting of coal; preparation of molding compounds; saturant or binder for rock wool or liber glass; for compounding with resins, such as vinsol resins.

The gas oils recovered with the asphalt products are also of considerable value. They are used as rubber softeners, saturants for felt and papers, resin plasticizers, etc. and fuels.

We claim:

1. The process for producing a synthetic modified asphalt, characterized by a low viscosity with a large change in viscosity on heating, and good thermal stability which comprises: heat treating at a temperature from about 850 F. to about 900 F. for a period of time from about five minutes to about three minutes, a blend of a straight run asphalt and of a cyclic gas oil, said blend comprising from about ten to about forty weight per cent of said straight run asphalt; and reducing the product obtained by said heat treatment, whereby said modied asphalt is obtained.

2. The process dened by claim 1 wherein the cyclic gas oil contains about twenty-tive per cent by weight of aromatcs.

3. The process defined by claim 1 wherein the straight run asphalt has a ring and ball soft point F.) from about to about 150.

4. The process defined by claim 1 wherein a soaking factor from about 0.1 to about 0.35 is maintained in said heat treatment.

References Cited in the le of this patent UNITED STATES PATENTS 1,881,753 Loebel Oct. 11, 1932 2,542,608 Winkler Feb. 20, 1951 2,658,857 Roediger Nov. 10, 1953 2,662,051 Pelzer Dec. 8, 1953

Claims (1)

1. THE PROCESS FOR PRODUCING A SYNTHETIC MODIFIED ASPHALT, CHARACTERIZED BY A LOW VISCOSITY WITH A LARGE CHANGE IN VISCOSITY ON HEATING, A GOOD THERMAL STABILITY WHICH COMPRISES: HEAT TREATING AT A TEMPERATURE FROM ABOUT 850* F. TO ABOUT 900* F. FOR A PERIOD OF TIME FROM ABOUT FIVE MINUTES TO ABOUT THREE MINUTES, A BLEND OF A STRAIGHT RUN ASPHALT AND OF A CYCLIC GAS OIL, SAID BLEND COMPRISING FROM ABOUT TEN TO ABOUT FORTY WEIGHT PER CENT OF SAID STRAIGHT RUN ASPHALT; AND REDUCING THE PRODUCT OBTAINED BY SAID HEAT TREATMENT, WHEREBY SAID MODIFIED ASPHALT IS OBTAINED.

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