November, 1933
I N D U STR I A L A N D E N GINEE R IN G C H EM I STR Y
Germany covering a number of years has amply confirmpd these claims. The variety of forms available and the relatively low cost of the finished material suggest its wide use in American chemical plants. Tanks, reaction vessels, dye vats, pickling tanks, vacuum drier trays, pipe and fittings, filter press plates and frames, agitators, and numerous other standard forms are available, and special forms and shapes are readily fabricated. For most applications the natural strength of the material itself is sufficient but where special requirements demand it, the resinous cement may be successfully applied to steel members with which it forms a strong bond. For abrasion resistance, blocks of abrasion-resistant material may be built into equipment where needed. Where it is desirable to alter connections to a unit already installed, holes can be easily drilled in the material and threaded to take pipe of a similar composition, or larger pieces may be sawed out of the walls when necessary to e3ect alterations. Superstructures of any of the ordinary plant materials may be firmly bolted in place by drilling and threading holes in the walls. Indeed, although the material is much harder and more resistant than wood, it may be handled for in-
1219
stallation and operating purposes in much the same way as a very hard wood might be. Several patents have been issued covering various phases of the manufacture of this equipment,' and other applications are pending. It must, homever, be emphasized that the skill of the artisans mho perform the actual operations of building equipment and the special equipment used in the molding, hardening, and finishing operations are probably more important in the success of the product than any patentable phases of the methods employed.
ACKNOWLEDGMENT The thanks of the author for information on this subject and for many courtesies must be given L. W. Tarr of the Haveg Corporation and Hans Lebach of the Saeureschutz Gesellschaft m. b. H. RECEIVED March 28, 1933 Wirth and Haimberger, U. S. Patent, 1,582,563 (April 27, 1926); Wirth K.,U. S. Patents 1,582,586 (April 27, 1926); 1,747,964 (Feb. 18, 1930);
I
J.
1,767,421 (June 24, 1930); 1,789,642 (Jan. 20, 1931); 1,867,960 (July 19, 1932).
Effect of Oils and Chemicals on DuPrene Compounds 0. M. HAYDEN AND E. H. KRISMANN, E. I. du Pont de Nemours & Company, Wilmington, Del. Consequently, one cannot speak UPREh-E is the t r a d e A typical oil-resisting naiural-rubber siock is of the oil resistance or any other name for a s y n t h e t i c compared with a DuPrene compound containing property of DuPrene except in rubber obtained by the the same fillers in the same volume relationship. the most general terms. Specific polymerization of chloroprene, Both compounds are immersed in various animal, information must always relate which was first d e s c r i b e d by vegetable, and mineral oils, and synthetic organic to a certain DuPrene compound Carothers, K i l l i a m s , Collins, vulcanized under certain conand Kirby.' These authors desolvents which swell rubber f o r periods ranging ditions. Likewise, if one wishes scribed the synthesis of chlorof r o m a f e w hours to several weeks. The effect of t o compare the oil resistance or prene, the conditions of polyimmersing (1 pure gum DuPrene compound in other properties of a particular merization and the properties of kerosene f o r two years is also shown. The aroDuPrene compound with rubber, chloroprene polymers, pointing matic hydrocarbons and chlorinated compounds the rubber compound must be out particularly that, this syndescribed in equal detail; otherthetic rubber is much more resistaffect DuPrene and rubber about equally, but pracwise the comparison will be of no ant than natural rubber to most tically all of the other swelling agents have much value. chemicals, especially o i I s a n d less effect on DuPrene than on rubber, the greatThe formula for a typical oilsolvents. The purpose of this est differencm being shown by tests conducted at resisting natural rubber stock paper is to present further data elevated temperatures. The effect of hot and cold and for a comparable DuPrene with reference to the effect of compound containing the same various oils and chemicals on acids and alkalies is reported i n terms of reducfillers in the same volume relaDuPrene compounds. tion in tensile strength during immersion. tionship is as follows: Unvulcanized DuPrene is a plastic material somewhat simiCOM- COMcox- C O M lar to crude rubber. When masticated on a rubber mill it POUND POUND P O U N D POUND R-1 D-1 R-1 D-1 becomes quite plastic and may then be compounded with . . . 100. . Cottqnseed oil 1 2 DuPrene vulcanizing agents, regnforcing pigments, coloring ingredients, Smoked 100 Stearic acjd 1 ... sheets 85 Wood rosin . 5 Soft whiting (40 vol.) 112 softeners, fillers, etc. 38 28.5 Neozone D (phenylGastex" (20 vol.) DuPrene compounds that contain, in addition to DuPrene, Glue (10 vol.) 16 11.6 6-na~hthvlamine) 2 2 oxide IO 10 Sulfur6 1.5 only such added ingredients as are essential for vulcanization Zinc Light calcined magnesia . . . 10 D u Pont Accelerator 808 (butvrhave physical properties similar to pure gum rubber; but aldehyde- ahifor most commercial purposes DuPrene is compounded with a line) 1 .. large proportion of fillers and other ingredients, the nature a Trade name for a special variety of carbon black. and amount of the added ingredients being dependent upon the conditions of service to which the article is to be subjected. Table I shows the physical properties of these two compounds over a wide range of cures. The DuPrene stock has 1 J . A m . Chem. Soc., 53, 4203 (1931).
D
'
'
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INDUSTRIAL AND ENGINEERIKG CHEMISTRY
VOl. 23, No. 11
TABLEI. PHYSICAL TESTSON COMPODSDS D-1 ASD R-1 CUREAT 287'iF. (141.7' C.)
D-1 (DUPRENE) Tensile Lb./ (Kg./ 8q. in. sq. c n . )
ZOO'% modulus Lb:/ (KO./ an. sq. cm.) No cure 225 ( 1 5 . 8 ) 325 ( 2 2 . 8 ) 375 ( 2 6 . 4 ) 500 ( 3 5 . 1 ) 625 ( 4 3 . 9 ) 650 (45.7) 725 ( 5 1 . 0 )
Min.
sq.
3 5 7 10 15 30 45 60
Elongation
%
...
1225 1525 1600 1725 1750 1750 1775
...
(S6.'1j (107.2) (112.5) (121.2) (123.0) (123.0) (124.8)
550 560 530 510 430 420 420
higher tensile strength, much higher elongation, better tear resistance, about six points lower hardness a t all cures, and a more rubbery feel than the corresponding natural rubber stock. It is characteristic of DuPrene that it will take up considerably larger volumes of pigment than rubber without becoming stiff and boardy. DuPrene compounds have higher elongation than similarly compounded natural rubber stocks, and they maintain desirable physical properties over a much wider range of cure.
EFFECTOF KEROSENE Table I1 shows the effect of immersing these two compounds, cured 15,30,45, and GO minutes a t 287" F. (141.7" C.) in kerosene a t room temperature and a t 212" F. (100" '2.). TABLE11. EFFECT OF KEROSEXE o s COMPOUSDS D-1 AND R-1
'
CURE
INCREASE IN VOL.
AT
287' F,. AT 82' F . (2S0 C.) (141.7 COM- 24 3 7 C.) POUND hours days days
%
Min. 15 30 45 60
D-1 R-1 D-1
R-1
D-1 R-1 D-1 R-1
15.2 80.8 15.6 71.4 14.2 73.5 16.8 76.7
% 22.0 83.6 23.8 74.5 22.8 77.9 22.0 78.8
%
INCREASE I N VOLUMEA T 212' F. 3.5 hours
%
24 hours
%
(1000 C . )
4 days
6 days
8 days
%
%
%
22.0 36.2 41.7 42.0 40.7 43.1 8 3 . 6 107.2 167 317.0 Disintegrated 23.8 31.9 40.4 40.4 39.0 39.4 7 4 . 5 100.2 1 5 3 . 0 2 7 0 . 0 Disintegrated 3 2 . 1 36.2 22.8 35.8 36.5 37.8 77.9 9 5 . 3 142.3 254.0 Disintegrated 22.0 30.6 3 7 . 0 36.7 37.0 37:2 78.8 9 4 . 2 1 4 4 . 0 2 5 4 . 0 3 5 0 . 0 Disintegrated
All swelling tests reported were conducted on molded samples 1 X 2 X 0.080 inch thick. Samples were weighed before immersion and, after removal from the solution, were immediately wiped dry with absorbent paper and weighed within a minute or two. The percentage increase in weight was determined and percentage increase in volume calculated according to the formula: % increase in weight x sp. gr. of sample % increase in vol. = sp. gr. of s~ellingmedium The data of Table I1 indicate that the slyelling effect of kerosene on the DuPrene compound a t room temperatures is independent of the state of cure within the range tested. However, the 15-minute cure on the rubber compound swells more than the longer cures. At 212" F. the 45- and 60minute cures of both the DuPrene and the rubber compound swell less than the shorter cures. The most striking difference between the two compounds in this test is not the fact that the DuPrene compound swells only about 30 per cent as much as the rubber compound in cold kerosene and about 15 per cent as much as the rubber compound in hot kerosene, but that the rubber compound becomes very tender and in hot kerosene it completely disintegrates and goes into solution, whereas the DuPrene compound retains a large portion of its original strength and tear resistance even under conditions which cause the rubber compound to dissolve completely.
EFFECTO F OILS OTHER THAN PETROLEUM DERIVATIVES Table I11 shows the effect of immersing compounds D-1 and R-1 in a variety of oils and solvents for 1, 3, and 7 days
200% modulus Lb:/ W g . / s q . an. sq. em.) 375 ( 2 6 . 4 ) 575 ( 4 0 . 4 ) 650 ( 4 5 . 7 ) 700 ( 4 9 . 2 ) 800 ( 5 6 . 2 ) 950 ( 6 6 . 8 ) 950 ( 6 6 . 8 ) 950 ( 6 6 . 8 )
R-1 (RUBBER) Tensile Lb:/ (Kg./ sq. an. sq. em.) 1350 (94.9) 1650 (116.0) 1600 (112.5) 1650 ( 1 1 6 . 0 ) 1550 (109.0) 1325 (93.1) 1275 (89.6) 1275 (89.6)
Elongation
% 470 420 400 380 330 260 260 260
a t 82" F. (28" C.). Samples for this test were all cured 45 niinuteb a t 287" F. Cottonseed, linseed, and olive oils were taken as representative types of vegetable oils. In all cases the DuPrene compound swelled less than the rubber compound, and, what is more important, the physical properties of the DuPrene compound were affected hardly a t all whereas the rubber compound became definitely more tender. The same is true of a typical animal oil, lard oil. Oleic acid swelled the DuPrene and the rubber compound to about the same extent, but again the DuPrene compound retained most of its original toughness and tear resistance whereas the rubber compound became very tender. I n turpentine the rubber compound showed a tendency toward sloughing off, a phenomenon which has not been observed with respect to DuPrene compounds in any of the swelling tests carried out in this laboratory. TABLE111. EFFECT O F ONP PETROLEUM SwELL1X.CAGENTS IMXERSED IN:
[At 82' F. (28' C.)] INCREASE IN VOLU.\IE COhfPouNDa 24 hours 3 days 7 days
% Cottonseed oil
D-1 0 R-1 5.8 Lard oil D-1 2.4 R- 1 5.4 Linseed oil D-1 0.9 R- 1 2.2 Oleic acid D-1 20.4 R- 1 15.9 Olive oil D-1 0 R-1 5.0 Turpentine D-1 50 R-1 113 Carbon tetrachloride D-1 164 R- 1 160 Benzene D-1 168 R-1 113 Creosote D-1 85.5 R-1 42.8 5 .&I1 cures 45 minutes a t 287' F. (141.7' C.).
%
%
1.0 7.9 3.6 7.1 2.8 3.7 33.7 29.2 0 7.3 67 116 166 165 172 114 157 67.2
2.5 14.6 5.4 12.3 3.7 6.8 47.0 56.7 0 13.2 88 135 176 172 174 122 232 81.6
In carbon tetrachloride the DuPrene compound swelled as much as the rubber compound, and in benzene and creosote the DuPrene compound swelled more. However, even these aromatic solvents, which have a marked swelling effect and cause some tendering of DuPrene, do not affect the physical properties of DuPrene compounds to the same extent as they affect rubber. These tm-o stocks were also tested in a variety of swelling media not shown in the tables. Toluene, xylene, and solvent naphtha caused almost exactly the same amount of swelling as benzene, both in the case of the DuPrene and the rubber compound. Other chlorinated solvents such as trichloroethylene and tetrachloroethane have approximately the same effect as carbon tetrachloride. Other vegetable oils have an effect similar to that of cottonseed oil and linseed oil. Olive oil is an exception t o the rule in that it causes practically no swelling of DuPrene compounds Swelling tests were also made a t 212" F. in the oils shown in Table I11 together n-ith a variety of other nonpetroleum swelling agents. Detailed results are not reported here in order to conserve space. At this high temperature, oleic acid, butter, lard, olive oil, coconut oil, turpentine, etc., all caused pronounced swelling of the DuPrene stock but in no
November, 1933
I N D U ST R I A L Ah-D E N G I N E E R 1N G C H E M I ST R Y
case w:ts there any sign of sloughing off or incipimt disintegration. These same swelling agents a t 212" F. caused the rubber compound to disintegrate and slough off on the surface. Tests were likewise conducted on methyl, ethyl, butyl, and amyl aicohols, on glycerol and ethylene glycol, castor oil and triethanolamine. These compounds are all alcohols in the sense that they contain hydroxy groups. Eone of these compounds has a n appreciable swelling effect on either DuPrene or rubber.
EFFECTOF CRUDEASD REFINEDPETROLELX Table I V shows the effect of immersing the 45-minute cure of compounds D-1 and E-1 in various types of crude oil and refined petroleum products a t room temperature. The Pennsylvania crude which consists largely of saturated aliphatic hydrocarbons caused the DuPrene stock to sxell much less than the Midcontinent and Coastal crudes. The same is true of the spindle oils derived from Pennsylvania, hfidcontinent, and Coastal crudes. The hlidcontirient crudes are someTThat unsaturated; the Coastal crudes art' still more unsaturated and composed largely of aromatic (naphthenic) hydrocarbons. This is in accordance with the general observation that DuPrene stands up best in saturated straightchain hydrocarbons, is affected to a greater extent by unsaturated compounds, and is especially sensitive t o aromatic hydrocarbons. TABLE IV. EFFECTOF PETROLEUM SWELLING AGENTS [At 82' F (28' C ) I IMMERSED IN:
%
%
%
D-1 R-1 D-1 R-1 D-1 R-1
2.2 46.5 6.3 39.2 6.6 15.5
7.0 55.0 11.2 55.4 9.3 31.6
9.6 58.7 20.2 61.3 18.1 54.2
D-1
1.3 11.1 ' 4.2 17.6 4.7 17.0
3.6 20.2 5.9 29.2 10.1 29.6
5.7 33.4 9.2 46.1 13.9 51.7
D-1 1.0 R-1 4.5 Sun No. 30 D-1 1.8 R-1 5.7 Atlantic KO.30 D-1 0.9 R- 1 4.2 Motor gasoline (Sunocc) D-1 29.2 R-1 84.0 Casing-head gasoline D-1 8.9 R- 1 53.0 All cures, 45 minutes a t 287' F. (141 7' (2.).
1.4 6.9 2.2 10.2 0.9 6.4 29.2 84.0 8.9 56.5
1.4 11.0 3.1 15.5 0.9 10.7 33.0 88.5 8.9 58.0
Crude oil: Pennsylvania Midcontinent Gulf Coast Spindle oil: F r o m P a . crude From lfidcontinent crude From Coastal crude Motor oil. Essolube
0
I N C R E A S E I N VOLUME COMPOUNDQ 24 hours 3 d a y 7 days
R- 1 D-1
R- 1 D-1 R- 1
Essolube was chosen as one of the motor oils to be tested because the authors are informed that it consists of hfidcontinent, Coastal, or other unsaturated crudes that are saturated by hydrogenation. Definite information as to the source of the crudes from which the Sunoco and Atlantic motor oils are made is lacking, but examination indicates that they consist largely of' saturated hydrocarbons, presumably from Pennsylvania crudes. It is noteworthy that the hydrogenated oil has but little effect on DuPrene, as would be expected from a saturated hydrocarbon, in spite of the fact that it is derived from crudes which experience indicates have a more harmful effect. Tests were conducted on eight popular motor gasolines, and very little difference was found between any of them. Only Sunoco is reported here. This gasoline, in common with most other high-grade gasolines, is made by a cracking process and hence contains a large percentage of unsaturated hydrocarbons which affect DuPrene much more than the
1221
straight-chain saturated hydrocarbons in casing-head gasoline. Table V shows the results of swelling tests a t 212" F. in the same group of crude and refined petroleum products. Petrolatum was included in the 212" F. tests but the gasolines were omitted because of their volatility. The results of the 212" F. tests may be summarized by the statement that the advantage of DuPrene over rubber is much more pronounced a t high than a t low temperatures. The tremendous difference in the swelling of the DuPrene and the rubber compounds in the saturated motor oil (Essolube) and in petrolatum is especially noteworthy. There was no indication of disintegration or sloughing off of the DuPrene stock in any of these tests, whereas the rubber stock in all cases showed a tendency toward sloughing off during the first few days and in many cases disintegrated and completely dissolved before the test was completed. TABLEV. EFFECTOF PETROLEUM SWELLING AGEXTS [ A t 212" F (100' C ) I COM-
IMMERSED IN. POUND^ Crude oil: Pennsylvania Midcontinent Gulf coast
D-1 R-1 D-1 R-1 D-1 R-1
r
3 5 hr.
INCREASE I N V O L U M E - - - - - - 24 hr. 4 days 6 days 8 days
%
%
%
17.6 68.4 26.2 64.7 25 58.3
21.7 110.0 52.7 130 59.2 151
20.7 261 70 214 91 342
20.7 20.7 Disinteerated 74.2 75.6 Disintegrated 101 102.6 478 Disintegrated
20.4
22.6 22.6 Disintegrated 49.2 49.2 Disintegrated 86.0 98.5 Disintegrated
Spindle oil: 8.5 20.4 From P a . crude D-1 R-1 45.2 96.0 From Midcon- D-1 15.1 36.4 46.0 tinent crude R-1 112.0 FromCoastal D-1 28.4 63.7 crude R-1 54.4 127.2 Motor oil: Essolube D-1 0.5 3.7 R-1 18.4 56.8 Sun No. 30 D-1 9.6 26.2 R-1 32.3 90.4 Atlantic No. 30 D-1 1.3 6.2 R-1 20.2 53.0 Petrolatum D-1 2.2 8.9 R-1 24.3 63.5 a All curee, 45 minutes a t 287' F. (141.7' (2.).
44.3 349.0 78.0 410.0 8.4 107.7 39.1 199.3 10.7 90.3 15.4 114.2
%
9.9 131.3 41.5 260.0 12.3 116.2 17.6 149.2
%
9.9 156.8 44.7 398.0 13.3 140.3 17.6 178.3
EFFECTOF VARIOUSCONPOUKDIXG IXGREDIESTS hlost DuPrene compounds contain small amounts of zinc oxide, magnesia, and rosin which play an essential part in the vulcanization of DuPrene. The following table shows the formulas for four DuPrene compounds, one of which (842) contains only these vulcanizing ingredients and a plasticizer: 84
DuPrene type D Zinc oxide Light calcined magnesia Medium process oil Wood rosin Glue Sulfur Soft whiting Brown factice Cottonseed oil
lUU
10 10 5 5
CONPOCND 818 820 100 100 10 10 10 10 5 5 10 10 1
8
88 .1 .~
100 10 10 5 5 40 1 110 20
10
Compound 818 is designed to show the effect of adding a small percentage of glue. Compound 820 was run to show the effect of sulfur in addition to glue, and 881 is a commercial stock containing a high percentage of glue and other diluents as well. These compounds were all mold-cured 60 minutes a t 287" F. and immersed for 2 weeks in various solvents, in water a t room temperature, and in v,-ater that was kept boiling continuously by blon-ing steam through it. The percentage increase in volume is shown in Table VI. The most important conclusion is that glue, either alone or in combination with sulfur, has a relatively slight effect on the resistance to kerosene, but a much greater effect on the resistance to benzene and carbon tetrachloride. The com-
1222
INDUSTRIAL AND EXGINEERING CHEMISTRY
mercial compound 881, which contains a fairly high percentage of fillers is, as might be expected, considerably better than any of 6he others in its resistance to organic solvents but absorbs a great deal more water. The effect of glue on absorption is especially pronounced in the boiling water test. TABLEVI.
EFFECTOF SOLVENTS O X DTJPRENECOMPOUNDED WITH VARIOCSINGREDIENTS
Vol. 25, No. 11
The following formula illustrates the effect of using a high proportion of P-33 carbon black: '-33 black
114.0
Figure 1 shows the percentage increase in volume of this compound, cured 60 minutes a t 287' F., when immersed for SOLVENT 842 279 days in a number of active swelling media. The time of % immersion is plotted on a logarithmic scale. This compound Benzene 378 Carbon tetrachloride 363 has slightly poorer resistance to oils and solvents than comKerosene 47.7 Water (68" F. or 20' C.) 7.7 pound D-1. The information given by Figure 1 is of parWater (212' F. or 100' C.) 28.8 ticular value because it shows the effect of prolonged imAll cures, 60 minutes at 287' F. (141.7O C,), mersion of a DuPrene compound in the solvents. Gasoline Channel carbon black increases the oil resistance of DU- and ether had practically no effect after the first day; benPrene compounds more than any other pigment, comparisons zene, carbon tetrachloride, and carbon disulfide had so nearly being made on equal volume loading. The same is true of the same effect that it is impossible to show the differences rubber compounds. However, carbon black has a greater between them on Figure 1. These solvents, together with stiffening effect than any other pigment, and, since the hard- turpentine, caused a continuous increase in volume of the ness of an oil-resistant stock is usually strictly limited by the DuPrene, although the rate of change after the first week was conditions of service, it is not feasible to use carbon black in as very slight. Medium process oil, on the other hand, was large proportions as other pigments. The semi-reenforcing continuously absorbed by the DuPrene a t a very slow rate. blacks, such as Gastex, P-33, and Fumonex, can be used in This test has now been in progress for more than a year and much larger proportions and are therefore generally preferred the sample in medium process oil is still increasing in volume to channel carbon black. Nonreenforcing fillers, such as although the rate of increase becomes continually less. whiting, can be used in even larger proportions although they produce compounds having poorer physical properties than EFFECT OF PROLONGED IMMERSION the semi-reenforcing blacks. Clay is not an entirely satisfacThe effect of prolonged immersion of DuPrene compounds tory filler because DuPrene compounds containing it have an excessively high permanent set. The effect of the use of in kerosene is illustrated by tests that have been in progress other pigments, including barytes, asbestine, zinc oxide, and for more than two years on the following compound (No. blanc fixe, have also been studied. Space does not permit 841-15) : presentation of detailed results of these tests, but it suffices to DuPrene 100.0 Neozpne D 0.5 Stearic acid 1.0 Benildine 0.5 state that no advantage is found by using any pigments Zinc oxide 10.0 other than whiting, glue, and the various grades of carbon This stock was mixed in February, 1931. A sample cured black. Glue is a particularly desirable ingredient for stocks that 30 minutes a t 287' F. was immersed in kerosene a t room temperature on the day followmust resist benzene or other ing curing and has been conaromatic hydrocarbons. It is tinuously kept under kerosene desirable in any heavily loaded since that time. Table VII stock because it is molten a t shows the results of this test. mixing, calendering, and tubThe s w o l l e n s a m p l e was ing temperatures, and consebroken for tensile strength after q u e n t l y makes more readily 146 days of immersion when workable stocks than other reit appeared that the degree of enforcing pigments. swelling had reached the maxiThe use of channel carbon mum. There was no change in black seems to be d e s i r a b l e volume between 146 and 232 only in case service conditions days, but thereafter the volume require an oil-resisting stock declined quite rapidly until a t having also a high a b r a s i o n the end of 730 days the Duresistance. The semi-reenforcPrene was actually swollen less ing blacks m e n t i o n e d above than a t the end of the first day. s h o u 1d be used when an oilT h i s phenomenon h a s been resistant stock of moderately noted in a g r e a t many Duhigh t e n s i l e s t r e n g t h and Prene swelling tests although a b r a s i o n r e s i s t a n c e is reit is more marked in this case quired. Whiting s h o u 1d be than in any o t h e r , presumused as the principal filler when I 2 4 8 6 32 6 4 I Z 8 2 5 ably because none of the other the conditions of service are DAYS IMMER5lOfl AT 82°F. DuPrene swelling tests covers such as not to require a comp o u n d h a v i n g high tensile FIGURE1. INCREASE IN VOLUMEOF P-33 STOCKAT 82' F . so long a period. At no time (28' C . ) during the test has this Dustrength or abrasion resistance, Prene comwound shown anv but merely the best possible oil resistance a t the lowest possible cost. The soft blacks, tendency toward sloughing off. It iswe1lk;lown that any purk such as Thermax, are but little better than whiting, and it gum rubber compound would completely disintegrate in keroseems that the results with this type of black can be obtained sene in a relatively short period. The value of this test is more cheaply with a combination of whiting and one of the somewhat decreased by the fact that the type of DuPrene that was available in February, 1931, was far inferior to present semi-reenforcing blacks. VOLUME
0
ISCREA0E OF C0.\rPO12NDa 818 820 881 % 5% 5% 313 230 i7i 301 224 171 41.2 39.2 18.3 8.5 7.9 22.7 108 130 243
I N D U S T R I A L A N I) E N G 1 N E E It I N G C II E M I S T H Y
November. 1933
1223
ox COMPOUND 841-15 TABLEVII. I:IIBECT OF KEROSENE PmcsnTAoe 0.5
1
5.7
8.2
H"",
