Tall Oil Esters as Plasticizers for GR-S W.I. HARBER AND C. S. YOFU" Witco Chemical Company, Chicago, I l l .
Tall oil is a rich source of resin and fatty acids. Previous work has shown that this material exerts a plasticizing effect on GR-S. The structure of tall oil was modiiled by esterification with alcohols. Most interesting were those esters derived from hydroxy compounds related to GR-S
unit structure. They were superior to tall oil in rate of incorporation into the GR-S and general plasticizing action. For a comprehensive picture of the propertiesof tall oil esters, data are also given for esters of aliphatic, phenolic, cycloaliphatic, and polyhydroxy alcohols.
T
aliphatic residues of the fatty acids and the phenanthrene residue of the resinic acids continue to be of major importance. While those esters of tall oil which are related to the structure of GR-S are of more importance, it was considered of interest to prepare esters of other classes in order to present a complete picture of the value of tall oil esters in plasticizing GR-S. The following basic formula for tire tread stock was used in comparing the properties of the tall oil esters with tall oil and commercial plasticizers:
ALL oil is a by-product of the pine wood paper industry. It consists of approximately equal amounts of fatty and resin acids plus 6-10% of unsaponifiable matter. It would be expected to have the general properties of resin and fatty acids; tests made in these laboratories indicated that tall oil exerted a plasticizing action in GR-S. However, when added to GR-S on the laboratory mill it produced greasiness and incorporated into the mix rather slowly. Furthermore, the tall oil tended to bleed out of the stock on curing, and the stock was sticky when hot. It seemed desirable, therefore, to seek ways of improving the properties of this material. The simplest chemhal modification which was considered practical was to convert the tall oil to its esters. I n this manner the chemical constitution of the material could be brought closer to that of GR-S. In the following formulas R represents the aliphatic-phenanthrene residue of tall oil: Tall oil:
The esters wcre prepared either by direct reaction of the tall oil and the hydroxy compound, or by conversion of the tall oil to its acid chlorides and reaction of these with the hydroxy compounds. ESTER PREPARATION AND RUBBER TESTING
Ry-bH
d
1
(2)
Tall oil esters: R-(3-0
II
C!" I
~ p h ; q d ( ~ ~ , u n iless t
R - C - O - - C H 2 ~ b e n z y l (GR-S unit less groups 2-6)
)!I
R-C-O--CHz
b
C H i O p - p h e n y l ethyl (GR-S unit less groups 2,4,5,6)
R-C-0-CH--methyl
b
DH8
R-C4-CHZ-CHSH-
ti
phenyl carbinyl (GR-S unit less groups 3-6)
c3
cinnamyl (GR-S unit less groups 1-3)
Effecting this change should result in greater solubility of the tall oil in GR-Sand, consequently, more rapid incorporation and enhanced plasticizing action. These effects a t best would be produced only moderately because whatever the change in the carboxyl group of the tall oil, the contribution of the long-chain 1 Present
addreal, Brown Rubber Company, Lalayette, Ind.
POLYHYDROXY ALCOHOLESTERSOF TALLOIL.The preparation of the glycerol ester illustrates the procedure: A &liter three-necked flask was equipped with a glass inlet tube, thermometer, and air-cooled reflux condenser a t the top of which was a water-cooled take-off condenser and receiver. In the flask were placed 879 grams (3 moles) of Indusoil (distilled tall oil), 110 grams (1.2 moles) of glycerol, and 0.5 gram of litharge catalyst. The flask was heated in a graphite bath while nitrogen was bubbled through the reaction mix. Heating was continued a t 250" C. for 4 hours a t which time the acid number of the product dropped to 2.1. During heating, the water of reaction passed through the air condenser and was collected in the receiver. At the end of the reaction time the temperature of the flask was raised above the boiling point of the glycerol to remove any unreacted material. The yield was quantitative. ESTERSOF OTHERCLASSES. Esters other than those of polyhydroxy alcohols were prepared from the tall oil acid chlorides and the hydroxy compound. The preparation of the cresyl esters illustratks the procedure: A 1-liter Claisen flask was equipped with a dropping funnel, and through the other neck was placed a short air condenser which was, in turn, connected to a hydrochloric acid-water trap. The distilling tube of the flask was plugged with a glass rod. I n the flask were placed 104 grams (0.5 mole) of phosphorus pentachloride. Through the dropping funnel were added slowly 145 grams (0.5 mole) of Indusoil. After the initial vigorous reaction had subsided, the reaction was brought to completion by warming on the steam bath for 30 minutes. The flask was then equipped for vacuum distillation (water pump) and heated in an oil bath, and the phosphorus oxychloride was removed. As soon as decomposition was noted in the flask (around 110' C.), heating was stopped. The flask was 953
Vol. 37, No. 10
INDUSTRIAL A N D ENGINEERING CHEMISTRY
954
TABLE 1. PROPERTIES OF PLASTICIaED GR-S STOCKS Plsllticiaer
Boftener Control (no #oftener)
fi"oc%z; Beo. None
Tall oil (Indusoil)
276
Benzyl alcohol
225
&Phenyl ethyl alcohol
186
Meth 1 phenyl oar&nol
130
Cirnamio aloohol
126
Willisma Plaatidty Cure st s t 70' C., 307O F., Cm. Min. 0.473
0.368
60 80 100 120 60
80
100 120
Tensile Strength,
Modulm
st 300%
ki:f,9' 2740 2810
'646 2666 2500 2790 2830 2820
1660 1840 1970 1970 630 740 800 860
Elonpatfon st Break,
%
410 490
Tear Re-
eistancsa, Lb./In. Thickneed 249
860
360 670 680 630 610
a30
Hardness (Rhore) 30Inatantaneoru seo.
# 68
69 60 61 62 61
62
e4
66 66
66 66 67 68
Rebound (Bashore)
26oc.1000 c. 31 42 42 31 41 30 30 41 26 37 26 37 27 37 28 38
Flex Crackm at 2b0 C.0 Kilocyold per Cm. 156
436
E S T ~OF S AROMATIC-ALIPKAT&C ALCOHOLS 0.366
0.340
0.368
0.363
60 80 100 120 60 80 100 120 00
80
100 120 60 80 100 120
2200 2730 2930 2830 2300 2320 2670 2650 2260 2320 2400 2420 1990 2090 2220 2100
620 780 870 930 480
b70 600 630 620 600 660 710 380 390 420 440
700 660 640
600 770 690 700 660 710 690 640 640 800 790 760 700
339
68
304
66 68 68 62 62 64 64
240
80 60
61
26 26 27
36 35 34 34 32 33 34 34 31 32 a2 31 30 31 31 32
66 67 67 67
49 49 60 62
31 31 29 29 27 2s 28 27 29 30 29 29 29 29 28 28
36 36 34 34 36 37 38 37 38 38 37 37 34 34 33 33
28 28 28 28 28 29 29 29 29 29 29 28 26 26 26 26 26 26 27 27 24
33 33 33 34 a4 34
60 60
60 307
66
61 63
62 65
66
66 60
61 62 62
66 65 60 68 61
64 67
31 31 30 30 27 27 28 28 27 28 2s 27
26
316
744
1039
1888
ESTBRS OF ALIPEATIC ALCOHOL^ Methyl alcohol
200
b o ro yl s?co~ol
226
Butyl aloohol
226
Allyl sloohol
276
0.391
60
80
0,363
100 120 60 80 100 120 60
0.320
100 120 60
0.341
80
80
100 120
Ethylene glyool
Diethylene drool Tetraethylens lKbco1
...
... ...
0.318
60
80
100 120 0.336
0.341
60
80 100 120 60
80
100
120
Nonaethylens glycol Qlyoerol
226
0.381
60
80
100 120 I..
0 3Z8 I
60 80
100 120
Pentaergthritol
Phenol
e..
*..
0.332
60
T b ~ d
0.8M
886
0.888
WK)
2260
2280
60
2310 2520 2800
2460 2630
460
490
610 630 640 040 720 770 630
600
760 820 600 610 670 720
390 410 420 440 630 760 810 a20 860 880
920 020 860 860 930 930 420 680 620 620 400 480 660 670
690 670
280
060
660 720 690 660 640 710 620 020 600 670 690
287
293
847
660 660
730 070 660 600 670 640
286
262
610
610 000 600
248
680 620 600
239
690
660 660
730 660 620 600 770 700 700 660
267
66
67 67 68
66
69 60 60 69 60 60 61
66 67 69 69 66 67 68 68 66 66 66
67 66 67 69 67 66
69 60
60
314
65 69
IO
62
62
b8
60 64 66 66 55
6b 56 66
61
62
64 66 60 62 64 63 61 63 63 66 64
66 66
66
60
64 66 65 00 63
26
60
66 M
25 24
66 68 69
61 56
28 29
61
68
67 68 89 70 69
80
29 30 29 29 28 28 28 28 29 29 29 29 a0 20 27 28
60
294
468
468
...
..,
...
34
36 36 36
364
36 34 34
117
36
35
34
31
32 32 33 32 33 33 32
...
..
ESTBXSOF PKBNOLS 0.330
200
226
2430 2300 2360 1620 2480 2610 2610 2620 2630 2820 2780 2730 2860 2850 2610 2660 2060 2170 2160 1820
80 100 120
80
100 120
pchlorophol
1930 2230 2320 2660 2310 2600 2800 2660 2320 2260 2630 2690 1930 2280 2410 2370
0.374
0.851
60
80 100 120 60
80 1 00 120 60 80 100 120 80 80 100
120
2600 2840
2880 2800 2780 2130 2700 2830 2860 2130 2460 2820 2780 2060 2600 2440 a870
610 720 790 860 670 820 970 1020 620 700 760 890
620
640 800
880 460 020 760
624
070 660 050 610
868
640
980
640 600 570 700 690 660 620 070
650
804.
61
814
ea0
600 090 680 610
ea0
60
8M
60 67 67 60
80 67
80 00
61
66
01 62 68 64 66 66 66 63 62 I6 66
63 €86
67
68
30
as
33 34 35 35 37 36 35 35 22
as
32 33 34 34 34 34 35 31
838
31
44b
133
420
646
380
999
I N D U S T R I A L A N D E N G I N E E R I N G CIFEMISTRY '
October, 1945
TABUI. PROPEETIBIS OF PLASTICUIBD GR-S STOCKS (Contiwedl Cure at
807O
Softener ZChlord-tmb amylphenol
280
pPbenylpheno1
160
#-Naphthol
0.868
0.848
226
0.801
F.,
Min. Bo 80 100 120 Bo 80
100 120 00 80
100 120
lbnaile Btrength,
Lb
Bp:
E:
Modul~m Elongation at Break,
at 800%.
%
680 800
a060 2440 2400
660
aao
040
490 600 680 720 400
at00 2450
2790
2800 2410 2610 2760 2920
600
600
060
710 070 620 620 740 890
TeareiatanceO, Lb./In. Thicknsss 803
380
800
Bo
01
01 62
690 080
730 780 710
60 60 01 Bo
824
Bo
01
08 64
26 20 20 20 24 24 25 25 24 26 26 26
62 66 66
w
63
60 MI 68
64
66
67 60
82 82
880
82 82
...
82
aa
84 84 29 80
20.'
ao
80
Eezmae OF CPOLOALIPEATIO ALOOHOLL. Cyalohelsnol
Borneol
0.820
176
226
0.820
00
80 100 120 Bo
80 100 I20
Witco MR No. 8s
Bardd
Witao No. 20 Wit00 sa
0.874
. 226
Bo
80
100
120
26
0.888
0.803
a76
0.880
200
0.826
60
Bo
80 100 120 60 80 100
120 60 80 Ing I20
80
80
10
Pine tar
200
0.419
Turpum
I26
0.864
Avenge of four curd..
b
120 00 80 100 120 60 80 100 120
640 750 770 010 880 760 780
2360 1900 2250 a880 2810
Eema Tetrahydrofurfuryl elcoho1
'*
2040 2890
3400
2790 2910 2910 2790 2690 2810
2p40
2960 2200
aiw 2300
2200 2810 2540 2800 2960 2am 2510 2780 2860 2070 1950 2060 2440 1810 2880 2710 2860
OF
660
670
824
800 830
000 680 670
283
670 620 090 760
740 720 700 090
82 1
890 000
620
265
000
020 730 780 620 690 660 780 410 870 480 640
280 410 480
so0
610 490 490 710 080
00 81 01 02 Bo
299
65 66
66 88
27 27 27 27
55
26 26 26 26 29 29 28 28 27 28 27 27 20 26 20 26 22 28 24 24 29 29 80 80
69 00
66
643 60
2sa
290
66 67 69
298
64 64
60 67 67 66
67 67 69 66
sa
Bo Bo 00
01 01 01 00
29 29 29 28 27 28 28 29
64
66 65 56
60 Bo 61 Bo 80
Bo Bo
690 090
760 090 090 670 810 740 720 780 860 800 790 770
60 68 Bo
Bo Bo
MISOmLLA~mOUSALOOEOL 680 720 808 080 080 800 080 ai0 630
1010 990
89 Bo
80
640
66
w
111
62 68 60
60 51 62 62 67 66 60
68 69 69
68
..
84 86 36 80 34 35 35
...
a6
82
246
ai
498
82 81 a2
82 82
ai
89 39 88 38 82
182
...
aa
83
88
88 83
'
. . I
34 86
ai
. . I
82 88
88 80
87
...
88
88
Based on optimum owe.
again equipped as at first, and to the crude acid chlorides were added slowly 54 gram (0.5 mole) of U.S.P. cresol. The flask was warmed on the steam bath until hydrogen chloride evolution ceased. This required about 2 h o w . The product was cooled to room temperature, taken up in ether, wwhed with 600 ml. of 5% sodium hydroxide, then washed twice with saturated salt mlution. The ether solution waa dried over ealaum chloride. After removal of solvent, a dark brown liquid (acid number 6.2) remained. The yield waa 170 grams (89%). RUBBERTIXITINO M.IUTHODS.Stress-strain measurements were made by A.S.T.M. Method D412-41. The cures were 60, 80, 100,and 120 minutes at 3M"F. Tear rmistance was determined by A.S.T.M. Method D624-41T. Hardness waa determined with a Shore type A durometer; 30-second d n g was obtained after the durometer had m t e d on the teat piece with a !& pound weight for that length of time. Flex cracking waa determined by making an initial nick in the sample and noting the number of kilocycles of flexing needed to extend a crack to a width of 1 crn. The following waa devined aa a combination of the eserential features of the tsst methods reported by Vila (4),Carlton and Reinbold (S),and Breckley (1): A standard De Mattia test sample aa provided in A.S.T.M. Method D430-40B was mounted in a National &tubber Machinery flexing machine, model D.
An initial nick 0.2 cm. long w a made, ~ and the sample was flexed at 460 cycles per minute from 0' to 90' until a crack of 1.2 am. waa obtained (8). BEHAVIOR OF ESTERS IN GR-S
The G R S tread stock waa highly loaded (16 pa-) with the plasticisem under investigation 80 that their effects on physical properties would be more easily noted. Hence the properties of the stocks listed in Table I are not intended for compariaon with commercial tread stocks. They are of value only in comparison with obe another. The esters in Table I which are directly related to the GRS unit structure -CH,-CH-CH-CH~H~ I
dlH,
I
fall into the class of aromatio-eliphaticalcohol esters sincethe GR-8 unit is aromatic-aliphatic. When aromatio-aliphatic alcohols were attached to the tall oil carboxylp u p , marked changes occurred in the vulcanizatea. The time required t o incorporate these estsre waa the lowest of any of the classes studied. The more rapid
,
INDUSTRIAL AND ENGINEERING CHEMISTRY
956
dispersion of these plasticizers may be attributed to their similarity in structure to the GR-S unit. The esters of the aromaticaliphatic alcohols had the same order of plasticity for the uncured stocks as had tall oil, but the moduli of the cured stocks were lower than the cured tall oil stocks. This was especially outstanding with the cinnamyl ester which produced a cured stock having half the modulus of the tall oil stock, The aromaticaliphatic esters gave higher ultimate elongations than the tall oil stocks. These observations indicated a generally greater softening of the cured stocks. The marked superiority of the aromaticaliphatic esters in flex-crack resistance may have indicated that the esters most closely related to the GR-S unit have the property of reducing the tendency for cracking under dynamic flex. However, it may be argued that stocks plasticized with esters of aromatic-aliphatic alcohols showed greater resistance to flex cracking because these stocks had low moduli. Hence the work done per flexing cycle on each test piece was less for these lowermodulus stocks, This argument does not appear to apply in the case where the methyl phenyl carbinyl ester is compared with Witco MR No. 38, for here the moduli of the stocks are of the same order yet the ester is superior in flex crack resistance. While the lowering in modulus of the aromatic-aliphatic esters on the cured stocks was greater than tall oil, these stocks retained their hardness and did not lose their resilience. I n tensile strength and tear resistance the aromatic-aliphatic esters gave poorer re-
Val. 3!7, No. 10
sults than tall oil but still compared favorably with some of the commercial types of plasticizers. With respect to the other classes of esters in Table I the aliphatic esters were found to be about as greasy on the mill as tall oil. There was some decrease in plasticizer incorporation time. I n general there was no significant improvement in the physical properties of the stocks. These remarks apply about as well for the esters of polyhydroxy alcohols. Attaching phenolic types to the tall oil molecules did tend to improve the plasticizing action of this material. In general they were less greasy on the mill and easier to incorporate. Otherwise the physical properties of the stocks were of the same order as tall oil. The physical properties of the cycloaliphatic esters were of the same order as the phenols. ACKNOWLEDGMENT
The authors wish to thank H. F. Schwarz and H. R. Spielman for their help in obtaining the data on the physical properties of the stocks. LITERATURE CITED
(1) Breokley, J., Rubber Age (N. Y.), 53,331 (1943). (2) Carlton, 6. A., and Reinbold, E. B., India Rubber World, 108, 141 (1943). (3) Schwarz, H.F., Zbid., 110,412 (1944). (4) Vila, G.R., IND. ENO.CREM.,34, 1275 (1942).
Two-Component Equilibrium Curves for Multicomponent Fractionation FRANK J. JENNY ~ ~ MICHAEL 1 3 J. CICALESE Hydrocarbon Research, Znc., New York, N . Y .
A
GRAPHICAL method for the solution of multicomponent fractionation problems was presented in an earlier paper (9). A modification of the graphical solution using a two-component structure is presented whereby equilibrium curves are drawn which simulate the McCabe-Thiele structure for twocomponent systems. Figures 1 and 2 show the new form of equilibrium curve for multicomponent problems which is based on plotting the mole fraction of the light key component and lighter in the vapor phase, y, against the mole fraction of the light key component and lighter in the liquid phase, x. Figure 1 shows the equilibrium curve and operating lines for the theoretical minimum reflux ratio of example 1, for which a detailed algebraic solution is available (9). Figure 2 presents equilibrium curves for reflux ratios varying from the theoretical minimum to total or infinite reflux. METHOD OF CONSTRUCTION
To illustrate the method used in constructing two-component equilibrium curves, the example given in the previous paper is reviewed briefly. The material balance on the column follows: Feed, Molee/Hr. CHa CaHs CaHa NC4Hs NCrHa NCaHu _.
Dist Gau MoledHr.’
26 9 25 17 11 12
26 9 24.6 0.3
100
59.9
-
.... .... -
Bottoms
MO~W/H;.
.... ....
0.4 16.7 11.0 12.0
-
40.1
The light key component in this separation is CaHs and the heavy key component is NCIHXO. “Light key component and lighter” is defined here as the summation of CHI, CzHs, and C3H8. A complete solution of the problem a t a reflux ratio of 1.5 to 1 gave the following equilibrium values for the concentrations of the light key component and lighter throughout the column: Light Ke Component and lighter X
Stripping section Reboiler Tray B-1 Tray B-2 Tray B-3 Tray B-4 Tray B-5 Tray B-6 Tray below feed tray Feed tray Fractionating seation Tray above teed tray 2nd tray above feed tray Tray A-4 Tray A-3 Tray A-2 Tray A-1 Condenser
1/
0.0274 0.0516 0.0865 0.135 0.195 0.268 0.350 0.480 0.555 0.418 0.518 0.886 0.792 0.873 0.931 0.968
0.707 0.772 0.872 0.924 0.957 0.979 0.995
These values me plotted as curve b of Figure 2. The values in the region of the feed tray are slightly different from those presented in the original paper because the feed tray temperature has been changed from 205’ to 210”F.in order to obtain a more optimum feed tray location. Figure 1shows that a t the theoretical minimum reflux ratio the operating lines touch the equilibrium curve at two distinct points, one in the fractionating or enriching section, point A , and the
