POLYBUTENES Properties and Uses in Petroleum Products R. M. THOMAS, J. C. ZIMMER, L. B. TURNER, R. ROSEN, AND P. K. FROLICH
Esso Laboratories of the Standard Oil Development Company, Elizabeth, N. J.
These higher polymers range in molecular weight by the viscosity method from about 25,000 to 400,000 and higher. Generically all these products are known as polybutenes. Although derived essentially from isobutene, they are p r e pared commercially from isobutene containing varying percentages of the n-butenes.
Hydrocarbon polymers of high molecular weight and varying in appearance from viscous liquids to tough elastic solids are obtained by the polymerization of butenes at low tempera tures. The general properties of these substances, and their use in various petroleum products are described. At ordinary temperatures the polymers are chemically inert and of stable character. In general, they are most readily dissolved in liquid aliphatic hydrocarbons and certain chlorinated hydrocarbons. Dilute solutions of the polymers are employed for the estimation of the average chain length of the molecules by the viscosity method. As addition agents in the production of various petroleum products such as motor oils of high viscosity index, nonleaking textile lubricants, or adhesive grease compositions, concentrated solutions of the polybutenes in mineral oils are employed. In other instances the general properties of products such as asphalt or paraffin wax are modified by the incorporation of the polybutenes directly.
Determination of Molecular Weight The various grades of the polymers may conveniently be classified according to their molecular weight as determined by the Staudinger method. This is based upon the observation that molecules of a threadlike nature increase the viscosity of a solvent, and that this effect is proportional to the molecular length in accordance with the Arrhenius equation:
- loglo qr ~ K c m
where
= qr =
c =
K,,
=
molecular weight relative viscosity (ratio of viscosity of solution t o that of solvent) molar concentration based on fundamental structural unit, in this case isobutene molecular weight-concentration constant (0.77 X for polybutenes)
Typical viscosity-molecular weight curves are given in Figures 1 and 2. The results in Figure 1 are applicable to the lower members of the series, and were obtained from the kinematic viscosity at 20" C. of solutions of different polymers (2.76 per cent by weight) in pure tetrahydronaphthalene. Because of the high concentration of polymer employed, these data are limited to polybutenes of only moderate chain length. For the higher molecular weight homologs of the series, viscosity data are obtained on more dilute solutions of the polymers (1 mg. per cc.) in n-heptane, as given in Figure
HE polymerization of isobutene to liquid products of relatively low molecular weight, using sulfuric acid or boron fluoride as the catalyst, is a familiar reaction; it was described as early as 1873 by Butlerov and Gorianov (1) and more recently by Otto (9). However, the conversion of isobutene into hydrocarbons of decidedly higher molecular weight and different physical properties is a development of comparatively recent date. Polybutenes of moderately high molecular weight and approaching elastic solids in character were first obtained by Otto and Mueller-Cunradi. These products (available commercially as Vistanex Polybutene LM) were described (11) as colorless, sticky, and extremely viscous liquids with molecular weights ranging from about 2000 to 10,000 and higher, determined by the Staudinger viscosity method (13). The production of polybutenes of even higher molecular weight (available commercially as Vistanex Polybutene MM and HM) was the outcome of a research and development program undertaken jointly by the I. G. Farbenindustrie and the Standard Oil Development Company. As described later, this work led to the observation that polybutene hydrocarbons with increasing molecular weight lose the properties of a viscous liquid and acquire those of an elastic solid.
T
2.
The technique of preparing solutions for viscosity measurements has been found important. The higher molecular weight polymers appear to undergo some loss in molecular weight when shaken violently in solution. This effect is shown in Table I ; when a solution of a polymer of approximately 275,000 molecular weight is shaken vigorously, the viscosity is lowered to a value corresponding to a molecular weight of about 150,000. The effect is shown in two different concentrations since it was first thought to have resulted from a condition involving molecular aggregates. Polybutenes of a lower molecular weight failed to show the breakdown under comparable conditions. That the apparent loss in molecular weight by the shaking process is the result of an actual rupture of the hydrocarbon chain rather than to a change in the degree of colloidal dispersion is further indicated by experiment 5 of Table I in which polymer broken down by shaking was recovered under vacuum from solution and redissolved in fresh solvent without shaking. It was not found possible in this manner to reproduce the high viscosity values which were originally observed prior to shaking. The loss in viscosity on shaking 299
INDUSTRIAL AKD ENGIPU’EERING CHEMISTRY
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TABLEI. EFFECT O F SHAKING ON THE VISCOSITY O F POLYBUTENE IN SOLUTIOH Sample
No.
a
b
Description of Sample High mol. wt. polybutene (1 mg./cc.) suspended in n-heptanea Same as 1
Viscosity Apparent a t 20” C . , Mol. Wt., CentiTreatment stokes’ ‘taudinper Method Dissolved by “soaking” 1.425 275,000 in solvent 24 hr.
Dissolved by shakingb 0.936 with air present for 2 hr. at room temp. Same as 1 Dissolved by shakingb in 0.965 atmosphere of N2 for 2 hr. a t room temp. Same as 1 Dissolved same as 1,then 0,900 shaken for 2 hr. in atmosphere of NZat room temp. Samples 2 and 3 com- Dissolved by “soaking” 0.870 in solvent for 24 hr., bined and carefully recovered from soluthen gently mixing tion under vacuum, then suspended in fresh n-heptane Same as 1, but with a Same as 6 0.650 lower concn. of polybutene (0.1 mg./cc.) Same as 6 Dissolved by shaking in 0,625 presence of air for 1.75 hr. a t room temp. Moderately high mol. Dissolved by “soaking” 0.935 wt. polybutene (1 in solvent 24 hr., then gently mixing mg./cc.) suspended in n-heptane Same as 8 Dissolved by shaking in 0.935 presence of air 2 hr. a t room temp. Viscosity at 20° C. of n-heptane used, 0.60 centistokes. Shaken rapidly on a machine with a reciprocating motion.
may be promoted slightly by oxygen from the air, as indicated by the data in Table I, although the difference may be within experimental error. Experiments in which even minute traces of oxygen from the solutions are excluded during shaking have not yet been performed. I n Table I1 molecular weights by the viscosity method are compared with results by the cryoscopic method (7) on two samples of low molecular weight polybutene. These data show good agreement by the two methods, provided small amounts of relatively 300. low molecular weight constituents are removed from p 200. the samples. As would be ,2 expected, t h e viscosity 5 100. $ 80. method is much less sus5 60. ceptible than the cryoscopic b+ 5040 method to the presence of 8 30, low molecular weight fractions. Obviously the situaz 20 > tion would be reversed if the 01 impurities present had a : ;1 molecular weight higher than 6 the average. 5.
140,000 151,000 128,000
116,000
253,600 129,500 140,000
140,000
.
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clear, sticky, and viscous fluids. The high polymers are ordinarily white, tough, and elastic solids, although colorless in a degassed state. On the basis of penetration data, there appears to be a critical change in properties from viscous liquid to elastic solid for polybutenes in the neighborhood of 27.000 moiecular weight (Figure 3). As might be expected from their origin, these polymers have a hydrogen-to-carbon ratio of 2.0. They are odorless and tasteless when pure, and have a specific gravity of approximately 0.90, which is subject to slight variations with changes in molecular weight. In general, the polymers are stable in character. Thus they are more resistant to heat, ultraviolet light, or mechanical working than ordinary rubber. However, under certain conditions they do depolymerize. As data on heating (Table 111) and milling or kneading (Table IV) show, this depolymerization may be greatly retarded by the use of suitable stabilizers. The polybutenes are also resistant to strong acids or alkalies, and are not attacked at ordinary temperatures. At elevated temperatures they are carbonized by concentrated sulfuric acid and are slowly decomposed by concentrated nitric acid with the formation of oily products containing oxygen. Toward oxygen or ozone the polybutenes are also remarkably stable. Details regarding these and other important physical properties such as tensile strength, elongation, cold flow, electric characteristics, etc.; are given in another Paper - - (12). . . Films of the higher molecular weight polymers are impervi&s to water vapor (Table V).
TABLE11. COMPARISON OF MOLECULAR WEIGHTSBY STAUDINGER METHOD WITH CRYOSCOPIC DATA Description of Sample
A, original polybutene A,treated to remove 0.5% by wt. through evaporation
--Mol. WeightCryoscopic Staudinger 1,430 14,000
A , treated t o remove about 10% by wt. through extraction B, original polybutene B, treated to remove about 10% of low mol. wt. material
..
2,800
10,600 1,500
.. 2,500
2,700
5
4
3.
General Properties
2.
0
2OpoO 40,000 60,000
The appearance of the polybutenes varies according FIGURE 1. VISCOSITYMOLECULAR WEIGHTREto their molecular weight. LATION FOR POLYBUTENE Low polymers, such as SOLUTIONS (2.76 PERCENT) dimer or trimer, are liquids. IN TETRAHYDRONAPHTHAIntermediate polymers are LENE
THE
MOLECULAR WEIGHT
MOLECULAR WEIGH7
FIGURE2. VISCOSITY-MOLECULAR WEIGHT RELATIOXFOR POLYBUTENE SOLUTIONS IN
TL-HEPTAXE (1 MG. PER Cc.)
..
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INDUSTRIAL AND ENGINEERING CHEMISTRY
There are many uses for these new Conditions of Examination after products in diversiHeating Heating fied fields, such as the Temp., Time, % loss Mol. Initial Mol. Wt. of Sample c. hr. In wt. wt. incorporation of poly65,000" 100 261 275,000 butenes with rubber 178,000 100 400+ 1D1,OOO 181,000 100 400 + 185,000 to secure composi48,0000 100 232 186,000 t i o n s r e s i s t a n t to 130,000 400 + 100 140,000 38,000 2 150 140,000 ozone, as a coating 33,000 2 150 140.000 125,000 2 150 for high-tension 140,000 + 0 . 1 atabiliser 131,000 2 150 140,000 + 2 . 0 % stabili~er cables, or similar com4 Possibly oontaminated. positions for making articles resistant TABLE IV. EFFECT'OF MILLINGAND KNEADING ON MOLECULAR to corrosive chemiWEIGHTOF POLYBUTBNE cals (14). With reEFFECT OF MILLINQ AT ELEVATED TEMPERATURES gard only to the uses Time of Max. Temp., Mol. Wt. Sample Milling, biin. C. after Milling which h a v e dePolybutene (200,000 mol. wt.) 5 52 163,000 veloped in the petro10 66 158,000 leum industry, the 20 93 156,000 35 115 144,000 following items are of
301
I
I
I
I
I
y 1
I
1 PENNSYLVANIAOILS I
I
I
OF POLYBUTENES TO HEATING TABLE 111. RESISTANCE
O
EFFECT OF PROLONQED KNEADINQ
Sample
Time, Hr.
Polybutene (65,000 mol. wt.) Same 1% atabiliser
12 12
+
Mol. Wt. of Recovered Product
T:mp., C. 125-150 12 5- 150
10,000 65,000
TABLEV. IMPERMEABILITY OF POLYBUTENE TO WATER VAPORa Bottle Containing Water and Sealed with: 0.02-mm. cellophane mem0.02-mm. polybrane isobutene aoatingb
0.04-mm. cellophane membrane Initial wt., grams Final wt., grams
23.70
21.62 -
+
25.03 24.96 ~
Lass, grama 2.08 0.07 0 I n freely circulating air for 120 hours at room temperature. b 150,000 moleadar weight as determined b y the Staudinger method.
All of the polybutenes are soluble a t ordinary temperatures in liquid aliphatic hydrocarbons and have the valuable property of greatly improving the viscosity index of petroleum oils (16). They are likewise dissolved by carbon disulfide and various chlorinated hydrocarbons, such as chloroform or carbon tetrachloride. Except for the high molecular weight products, they are also soluble in aromatics such as toluene or benzene. The reasonably high polymers are insoluble in the common oxygenated solvents such as methyl alcohol, acetone, ethyl acetate, etc. They are not dissolved by ethyl or isomowl ether, but are somewh& soluble in n-propyl and become increasingly soluble with increasing molecular weight of the ether. In general, solutions of the polybutenes are best prepared by the gradual addition of solvent with thorough mixing. Softening of the polymer is deMOLECULAR WEIGHT sirable; it may be assisted FIGURE 3. PEXETRATION- by moderate heating and MOLECULAR WEIGHT RELAparticularly by the use of a TION FOR POLYBUTENES AT kneading machine during 25" C. B Y THE A. 5. T. M. the incorporation of the METHODFOR WAX AND Assolvent. PHALTS
1.0
2.0
3.0
4.0
CONCENTRATION [%)
FIGURE 4. EFFECTOF POLYBUTENE special interest. ON VISCOSITY INDEX Use i n Motor Oils Introduced as a 20% solution of 15,000 molecular weight polybuThe ~ ~ fore motor d tene dissolved in a light mineral oil. oils w i t h a high viscosity index and methods for their production, including a discussion of the polybutenes (referred to as "Exanol") in blends with petroleum oils, were presented by Otto, Miller, Blackwood, and Davis (IO). The addition of the polybutenes to mineral oils as a means of improving viscosity index has since been established on a commercial basis. A concentrate of the low molecular weight polymers dissolved in a light and well refined lubricating oil is available for blending purposes. The effect of this concentrate or "V. I. additive" upon the viscosity indices of different base oils is shown in Figure 4. A typical inspection of the V. I. additive is provided in Table VI. TABLE VI. TYPICAL INSPECTION OF MINERAL OIL CONCENTRATES OF POLYBUTENE Additive= v. 1.
Stringiness Additives
Gravity, "A. P. I. 28.3 30.1 Viscosity, Standard Saybolt units ( S . S. U.) .4t 100' F.(37.8O C.) 55,600 At 210'. F. (98.9' C.) 3,180 14,060 1 2 0 0 Viscosity index 130 Flash point p p e n cup), F. ( " C.) 435 (223.9) 420 '(ii5.6) Pour point, F. ( O C.) +30 ( - 1 . 1 ) Conradson carbon yo 0.04 0.05 Co!of, Tag-Robindon 9-10 10.76 n.n2 Acidity, ma. KOH/eram . ._ 0.02 (1 Containing 20-55% of 15,000 molecular weight polybu.ts:ne, depending upon the base stock employed. b Containing 5% of 73,000 molecular weight polybutene.
....
I n general, for a given amount of polymer, the maximum numerical increase in viscosity index is accomplished with oils of initially low viscosity and viscosity index. Such blended oils have been observed in the laboratory to have slightly lower viscosities under pressure at very high rates of shear than would be expected from calculated values. However, as discussed by Otto et al. there does not appear to be such a deviation in viscosity at the rates of shear normally encountered in lubricating practice. This is in agreement with data from actual performance tests.
Use in Greases and Special Lubricants The higher molecular weight grades of the polybutenes are likewise extensively used in the petroleum industry as concentrated solutions in a selected base oil. Owing to the rubberlike character of these higher polymers, their solutions have a stringy consistency and are highly viscous. Both the
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VOL. 32, NO. 3
A photograph of the apparatus is given in Figure 5. The time required for a string to break is readily obtained with a stop watch started a t the instant the container is dropped from the glass rod and stopped a t the moment the thread breaks. Obviously, the test must he run under controlled conditions of temperature. As given in Tahle VII, measurements of string life made in this manner show that naphthenic oils give the most persistent string. The results are similar to those observed for viscosity effect. A further investigation of the property of stringiness is shown in the following table where string life a t 74" F. (23.3" C.) is reported for blends of &in@ness additive with paraffinic and naphthenic oils of essentially the same original viscosity at 74" F.: % stringiness Additive*
0 1
a
IZIGOEE 5. APPARATUS FOR TEE MEASTTHEMENT OF STR~NG LU'E viscosity and tho stringy character of the product depend upon the type of oil used as a dispersing medium, and upon the molecular weight and concentration of polymer employed. Oils of an initially low viscosity index usually give the most viscous solutions as shown in Table VI1 where the blends are called "stringiness additive". Presumably the effect is a matter of solubility which is governed by the superior solvent characteristics of the paraffinic as compared with the naphthenic hydrocarbons. In all cases the more concentrated solutions are gels of considerable strength. ~
TABLE VII. EFRECT OF VISCOSITY AND VISCOSITYINDEX OF BASE 011 ON VISCOSITY AND %'RINQ LIFE OF STRINGINESS ADDITIVE , Bass Oil . -Stringiness AdditivesType
Paraffia P*rai6n P.SSi60
viaeosity at 210' F.. 8 . 5 . U. 45.0
86.5
50.0 47.5
visoositr index 90.0
92.0 97.0
ViRCoeitY at
21O0 F., 6 . S. U. 1480 SO50 1550 2000
19.0 Naobthene a Containing 5% of 73.000 molecular weight polybutene.
stringliie
.. 618
14.3
Tahle VI1 also shows the effect of the viscosity of the base oil upon the viscosity of the final blend. Of two base oils with nearly the same initial viscosity'index, one increases in viscosity upon the addition of polymer to a much larger extent than the other. The results on "string" life (Table VII) were determined by a special test devised to measure the stringy character of the various blends. Essentially the test consists of producing a vertical thread or string of the sample, then measuring the time required for the column to break. Tho string is produced by immersing a glass rod into a 2-ounce container holding the sample and supported inside a glass cylinder so as to permit the container to fall away from the rod a t a given instant.
Parsilinio Oil 0 4.4
-
-6trinp Life Naphthenic oil
0 5.3
2 5.0 7.5 5 7.5 9.8 Contsidng 5% of 73,000rnoleoulai wsight polybutene.
These data further support the conclusion that naphthenic type oils give t,he highest degree of stringiness. That the effect is not due to viscosity alone has been demonstrated by blending an oil to the same viscosity with polybutenes of different molecular weight. The polybutenes of less than 30,000 molecular weight in all cases give a string life of zero; the polymers of better than 30,000 molecular weight all give positive values. The critical molecular weight range for producing string closely parallels that determined for the resistance of thc polybutenes to deformation or penetration as previously shown in Figure 3. The solutions are of particular value as additives to greases (17) and special lubricants (16). For many years rubber (as a solution in mineral oils or more recently in the form of latex) has been added to gi-eascs to impart string and adhesiveness. Owing to the susceptibility of rubber to oxidation, with consequent loss in molecular weight, the ruthcr-compounded greases soon lose this stringy characteristic. Bccanse of their marked chemical stability, the polybutenes are superior to rubber in this respect. In addition to its use in greases the application of stringiness additive to lubricating oils for sleeve or other open-type bearings has been found advantageous since the string imparted by this means often reduces oil leakage and consumption in the bearing without increasing power consumption or frictional drag. Applications of this type include textile lubricants, mine car lubricants, castor machine oils, and special luhricating oils for the food industry where drippage and excessive oil consumption must be avoided. Also the polybutenes of medium or higher molecular weight range are finding an o u t let in oils used in making paper-impregnated insulation for electric cables (4). The main advantage is a reduction in the migration of the oil which is brought about by the large increase in viscosity.
Blends of P o l y b u t e n e s with Asphalts Many of the commonly measured physical properties of asphalts, such as softening point, penetration, or susceptibility factor appear to be closely associated with their viscosity under differentconditions of temperature. It is not surprising, therefore, that the polybutenes which have already been shown to be useful in modifying the viscosity-temperature relation of petroleum oils, should he capable of modifying the various properties of different asphalts (Table VIII). In general, the addition of polybutenes above a certain quantity to asphalts primarily results in higher values for softening point, accompanied by an increase in penetration, so that the softening point-penetration reletion is improved. Values for ductility are generally somewhat lowered.
(a,
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TABLEVIII. PHYSICAL PROP~RT~ES OF ASPHALT-POLYBUTENE BLENDS POiY.
butene Added
Asphalt Base
% Oxidised aolur+bian asphslt 180-20W F. (82.2-93.3' C.) aofteoing poult
same
0 0.5 1.0 2.0 5.0 10.0 20.0 0
0.5 1.0
2.0
3.0
10.0 "
...
1.0
F. (71.1-76.7°
C.1
Asphalt. 1109 F. (43.3* C.1 softening point
5.0 10.0 0 0.5
1.0
a.0 6.0
a
Ball and ring method.
a RSUO of pemrstion
tlt
1,500
1,500 1500
1:SOa
1,500
is.660 15,000 15.000 15000 15:noo 4iO& 40 000
....
1.n
1n.o
190 (81.8) 190 (87.81 190 (67.8) 191 (88.31 191 (88.81 193 ( 8 9 . 4 ) 209 (98.31 190 (87.81 211 (99.41 209 (98.3) 207 (97.2) 219(103.9) 251 (121.7) 190 187.8) 204 (95.6)
1,500
20.0 0
0.5
Point'F. PC.1
....
40:000
2.0
Soitenins
Polybutene
?.a
0.0 10.0
Steem-r?duced asphsit,, 160-170' .aftenLng point
Mol. Wt. of
215(101.7)
214!101.1j 234 (112.21
40.000 40,000 40.000
265 (129.41 285 (140.6) 171 ( 7 7 . 2 ) 176 (801 176 1801 179 (81.7)
1.500 1.500 1,600 1.500 1,500
166 (74.4)
164 (74.41 108 (42.21 112 (44.4) 109 (42.S) 112 (44.11 11s (48.3)
...,
40 OM) 40:000 40,000 40.000 40,non
I56 (68.91
-Penetration3Z0 F. 77- F. 115' F. (0- C.1 (25'C.l (46.1* 62.1 -0.1 mm.I5 23 38 16 23 3s 16 23 3s 16 23 39 21 23 41
28 32 44
44 48 60
15
23 21 22 24 30 20
38 35 36
3s
6
23 24 23 26 25 20 34 12 15 IS 14
8 11
20
fil
99 92 89 79 86
3no+
15
16 16 22
23
15
16 15
22
16
27
32
*5
6
15 10
30 37 44 37
19
65
3s 47
39 40
58 44 41 30 46
37 41
43 39
55
3w+ ma+ 300+ 3wc 208
A. S. T. M. Duotility (77- F.1
Sueoeptibility Fmtorb
em. 2.5 2.5
2 2.75 2.75 2.5 1.5
1.53
1.44 1.44 1.44 1.33
1.38 1.07
..._ .... ..., .... ...,
1.53 1.40 1.38
2.5 2.75 2.5
1.53 1.50
2.5
3.5 I 0
I
2.5
....
.... ..._ .... 1 1W+ lO0f
loof 97 82 54
1.50 1.36
1.26
1.53 1.18 1.68
0.74
1.w 3.0 3.0 3.0 2.67 2.38
1.82
6.6 9.2 2.96
2.14 1.88 1.75
77' to that at 320 F.
The various blends shown in Table VI11 were prepared in akneading machine a t an elevated temperature by the gradual addition of asphalt to polybutene. The solubility of polybutenes in asphalts is difficult to determine accurately. Approximations of their compatibility were obtained by a standardized method for visual examination-viz., cooling the hot blend to room temperature, allowing i t to starld for one week, and then observing whether the surface of the sample was bright and homogeneous or dull and heterogeneous. Tho limiting values for compatibility in this sense are illustrated in Figure 6. I n general, the extent to which the polybutenes are compatible ~vitliasphalts is a function of both the molecular weight of the polymer and the origin of the asphalt. Y I preliminary On the basis results, of
free of cracks. An additional test involving the coating of an exposed 10-inch (25.4-cm.) pipe line with twenty-four different samples of various asphalts, inchiding several blends with the polybutenes, is now in progress.
Blends of Polybutenes with ParaBn Wax The propertics of crystallinc or amorphous paraffin wax are changed considerably by the addition of polybutenes. Their viscosity is increased by an amount depending upon the concentration and molecular weight of the polybutene added (Figure 8). This increase in the viscosity of wax is of value as a means of reducing "strike-through" or the tendency of the wax to penetrate a surface to which it is applied. This is encountered in the preparation of coated goods where the wax is desircd as a film on the outer surface of the article only. Compositions of low viscosity are applied using conventional waxers. The more viscous mixes require "hot melt" machines for satisfactory application. The low-temperature Bexibility of para& wax is likewise modified by the addition of polybutenes. For composi-
i*:m
E
4
the effect of polybutenes upon the $ O O lop00 m m a,- "9ow sopm aging characteris8 MMLCULAR WEIGHT of POLYBUTENE tics asnha,ts is -- -FruuaE 6. COMPATIBILITY OF POLYof considerable inBUTENES WITR COLUXBIAN ASPHALT terest. Figure 7 OF 160-170" F. SOFTENING POINT shows the appearance of two metal surfaces protected with a quarter-inch (6.35.mm.) layer of asphalt and an asphalt-polybutene blend respectively, and then exposed to general outdoor weathering conditions for 208 days. The surface coated with straight asphalt rusted badly, whereas the surface coated with asphalt containing 5 per cent of a 1500 molecular weight poiybutene was not appreciably affected. A second experiment w&s conducted in which a blend of asphalt with 10 per cent of 15,000 molecular weight poIybutene was applied in a rather thin coat to the roof of a building, one portion of which waa similarly coated with the original nnblended asphalt to serve as a blank. After 21O-day exposure to general weathering conditions, the 1W per cent asphalt surface showed cracking, whereas the asphslt-polybutene-coated section of the roof remained soft, pliable, and
e
I
Protected by straight saphalt
Protected by asphslt containing 5 per Fent of 1500 molecular weight pdybutene
FIGURE 7. APPEAWCE O F METALSURFACES AFTER 2 0 8 - D ~ ~ EXPOSURE TO ATMOSPHERICWEATHERING CONnrTtoNs
304
INDUSTRIAL AND ENGINEERING CHEMISTRY
tions of 135" F. (57.2"C.) melting point wax containing 1 per cent of 15,000 molecular weight polybutenes, tests on brittleness have shown that there is very little if any tendency toward chipping and cracking at temperatures below 0°F. (-17.8"C.). When polybutenes 5 10 ;, of somewhat lower % POLYSUTENE molecular weight FIGURE8. EFFECTOF POLYBUTENES (e. g., 10,000) are OF DIFFERENT MOLECULAR WEIGHT d d e d to W a x in UPON THE VISCOSITYOF PARAFFIN c o n c e n t r a t i o ns WAX higher than about 5 per cent, they lead to soft tacky products which are subject to "blocking". This is the term applied when wax-coated sheets laid one upon the other tend to stick together under their own weight on standing. In many cases it is desired to obtain a satisfactory bond between two waxed surfaces or between a waxed and an unwaxed surface. Straight wax has little or no bond strength. Polybutenes of more than 10,000 molecular weight added to wax in different concentrations produce bonds of considerable strength after heat sealing. Similar compositions have also
VOL. 32, NO. 3
shown good adhesion in laminations and an improved impermeability to water vapor.
Miscellaneous Uses
A number of other applications in the petroleum field have been investigated. These include the use of polybutenes in motor fuels (6),shock absorbing liquids (8), cosmetics and medicinal preparations (a), compositions for impregnating leather (S), and many others which lend themselves best to separate discussion. Acknowledgment The writers wish to acknowledge the active participation of their associates in obtaining the large amount of information from which this paper is abstracted.
Literature Cited Butlerov and Gorianov, Ann., 169, 146 (1873). Byrne, P. J., Jr., U. 8. Patent 2,085,693(1937). Frolich, P.K., Ibid., 2,093,431(1937). Haslam, R. T.,Ibid., 2,145,350(1939). Holmes, Collins, and Child, IND. ENG. CHEM.,Anal. Ed., 8 100-4 (1938). Howard, F. A,, U. 9. Patent 2,049,062(1936). Kraus, C. A., personal communication. Matheson, G. L., U. S. Patent 2,058,899(1936). Otto, Brenneto.tW"-em., 8,321-36 (1937). Otto, Miller, Blackwood, and Davis, Oil Gas J.,33, No. 26, 98 (1934). Otto and Mueller-Cunradi, U. 9. Patent 2,130,507(1938). Sparks, Lightbown, Turner, Frolich, and Klebsattel, IND.ENG. CHEM., t o be published. Staudinger, "Die hochmolekularen organischen Verbindungen" (1932). Wiezevich, P. J., U. S. Patent 2,138,895 (1938). Wulff, Moll, and Breuers, Ibid., 1,998,350(1930). Zimmer and Carlson, Ibid., 2,074,039(1937) Zimmer and Morway, Ibid., 2,062,346(1936).
PRODUCTION OF PETROLEUM RESINS S.
c. FULTON AND A. H. GLEASON
T
HE subject of resins from petroleum is old and at the same time very limited if we confine ourselves to the naturally occurring petroleum resins which are asphaltlike in nature. On the other hand, a wide variety of resins of the highest quality can be synthesized from petroleum products or by-products when one considers the possibilities with pure olefins, diolefins, ketones, alcohols, etc. Between these two extremes is a field in which certain by-products or even crude products of a more or less complex nature may be treated or condensed to form resins of undetermined structure. I n addition to the asphaltlike substances present in petroleum, there are many high-molecular-weight compounds which are only one step removed from the resin stage and may easily be converted to the latter by heating, such as in distillation or cracking operations or by some simple chemical treatment such as oxidation, sulfurization, or mild polymerization. By simple we mean that the mechanics of the operation may be rudimentary; chemically, the reaction may be complex. In general, the resins prepared directly from petroleum fractions are poor in color, and so far little success has been had in attempting to utilize these resins.
Standard Oil Development Company, Elizabeth, N . J.
The purpose of this paper is t o present certain aspects in the recovery of naturally occurring resins and those formed during certain processing operations, and to suggest a few possibilities in the field of resin synthesis as applied t o various petroleum distillates.
Naturally Occurring Resins Most crudes contain resinous constituents frequently referred to as asphaltic resins. These materials are complex mixtures of hydrocarbons with relatively low hydrogen content which frequently contain sulfur and sometimes traces of oxygen. They are probably polycyclic compounds as evidenced by the ease with which they react with nitric and sulfuric acids. Asphaltic resins have been separated from pitches and asphalts by methods involving combinations of selective solvents and adsorbents but are not well defined, the properties being largely dependent upon the particular combinations used. This is due in part to the close relation between asphaltenes (defined as petroleum-ether-insoluble) and oily constituents with which the resins are associated. Asphaltenes have been substantially reduced to resins by
