I N D U S T R I A L A N D E N G I N E E R I N G CHEMISTRY
1592
ployed. A low polymerization rate resulted but the unmodified polymer of 32% conversion (8 days) showed good breakdown characteristics when given 10 passes through a cold tight mill (Table X I I ) . Table XII.
Breakdown Characteristics of Low Temperature Polj-mer 70
Raw 10 passes
32.2 1.45
swelling Williams' Plasticity Index Y3 Rec. 103 L30 2.30 121
3.08
0.44
intrinsic Viscosity 4.68
POLYM
equivalent solution utilizing forniarnide as antifreeze had a viscosity of only 26 centipoises. hIoreover, formamide would have an advantage over methanol, the commonly used antifreeze; at extremely low temperatures, where high concentrations are required, formamide is largely immiscible with monomers, whereas methanol t,ends t o blend monomers with the continuous medium. It is expected that improvement, in the rat,e of polymerization 111 low temperature aqueous-formamide recipes can 'ne accomplished by further changes in the recipe.
Literature Cited
2.49
A great viscosity advantage in ion. temperature recipes is given by the use of formamide as antifreeze as compared with glycerol. For example, a n aqueous solution containing' sufficient glycerol t o prevent freezing a t -40" C. had a high viscosity of 1600 centipoises a t -35" c. (Brookfield viscometer), whereas an
VOl, 41, NQ. 8
(1) Bacon, Trans. Faraday Soc.. 12, 140 (1946). ( 2 ) Carothera. U. S.Patent, 2,080,558 (1937). (3) Frye and Peyne, 6.Am. Chem. Soc., 53, 1973-90 I 19:31) (4) Hatcher and Holden, Trans. Rog. SOC.Can,, 20, 395-8 \ atoi PH
70
C o n i eision/lIour
Use of Inyert Sugar Parts
$& Conversion in 17 Houis
1 .o 1.0
2,36
1.0 1.0
2.89
1.97
2.81
Suggested X-478-Kalex Recipe
Butadiene Styrene hIT11-4 Water Dreainate 214 Daxad 11 K C1 KOH 3TEDT or R b U T Dextrose FeS04.711zO
CHP
Parts 72 28
0.24 180.0
4.7
0.1 0.5 0.00 0.10 1.0 0.028 0.1
These are very distinct process advantages. The final recipe suggested for X-478-Kalex would be that in Table XXXV. Variations using sodium nitrilo triacetate were tried in order to improve the rate of conversion using this material which potentially at least is a. cheaper chemical. Unfort,unately as the data in Table XXXVI indicate, little success was acliieved although a practical rate was attained at times. The complex of sodium nitrilo triacetate and ferrous iron is reportedly iiisoluble and the use of potaesium nitrilo triacetate v-as tried without improvement,. Likewise, the complexes with sodium nit,r.ilotriacetate arc more stable a t elevated temperatures and so forming the complcx at higher temperatures was tried with moderate success. I t x-ould seem that, sodium nitrilo triacetate would likely be suitable foy a higher temperature redox system were such required. In general loner concentrations of sodium nitrilo triacetate and higher of ferrous sulfat,eheptahgdrate ivere better. Even a small amount of sodium riitrilo triacetate in a mixed activator m-ith pyrophosphate drast,ically reduced the rate of conversion. The fen- other metals t,ried were not as effective as ferrous sulfate heptahydrate. Thus it was concluded that a greater change in forniulation viould be required in order t,o use sodium nitrilo triacetate.
Discussion The formulas described do not differ fuiidaiiieritally from other 41 ’F. recipes but merely operate with novel arid more coiivenient activators and reducing agents. Obviously the recipes niay be altered as to monomer content, modifier, catalyst, wat,er, pH, bu€fer, electrolyte, emulsifier, dispersing agents, etc., in the usual manner. Also the recipes may use any source of “enediol” material according to German ( 7 ) concepts. The usual inethod is t o add digested dextrose solution but undigested ascorbic acid, dihydroxyacetone, or invert sugar may be uaed with equal success. These results are in contrast nit>hthe data of Johnson and Bebb (6) but in line x-it,hthe results of Marvel et al. (8, 9) who used low iron recipes. -4complete discussion of the iron complexes must await publication of the results on the forniation and stability of metal complexes (2%)and the interact,ion of these materials with peroxides
Vol. 41, No. 8
( 3 ) . However, a qualitative description would be helpful. It must be realized that the rat’esof conversion were det’ermined : ~ f ter a definite time period so that there is no way of knowing ~ whether it has gone rapidly whether a reaction has been s l o or and then slowed. This latter is undoubtedly true in sovrral cases. Also, when comparing various complexes of iron or otiicr. metals, the amounts should be tuned for optimal results. Severtheless it is possible to correlate the effectiveness of the materials with known concepts of complex stability. Most suitable complexes are formed with two nit,rogeri atoms joined by a bridge containing two carbon atoms. Such materials are ethylene dinitrilo tetraacetic acid, o-phenanthrolirie, and CY>CY’bipyridyl. In the first-mentioned the iron also forms a salt in which the ferrous ion replaces two of the sodium or potassium ions. The ferric salt’is formed similarly and the third valency seems to hc hydroxyl. The complrx is blood red in color and catalytically active. The structure of the complexes 734th et8hylenedinitrilo tetraacetic acid is believed t’obe in the form of an octagonal structure surrounding the iron (22-26). If the bridge between the nitrogen atonis is broken as in the case of the complex with two molecules of nitrilo triacetic acid the complex is less stable and less suitable. The second type of activators is the alpha-keto1 or enediol type. Citrate is the best in this case and the act’ivity is reduced if the bridge between the ester groups is broken as in the case of lactate or salicylate or shortened as in the case of the tartrate. Removal of the hydroxyl group next to the CO group still further reduces the activity as indicated by phthalate and oxalate. Gluconate seems to be as unstable in alkaline medium as ferrous sulfate. The inorganic complex with thiosulfate is reasonably good. The ferric salt may be used in its preparation. The arsenite Xvitli ferrous sul€ate and ferrocyanide Tvitliout, ferrous sulfate were not effective activators. The tannate was inefTeet,ive,indeed pIobably an inhibitor. The oil-soluble iron complexes as a group were poor activators under these condit,ions falling rather into the class of materials studied by Kern ( 7 ) . Ferrous phthalocyaninc, hemin, and the compler with I~-N’-disalicylidine ethylenediamine [CY,.”-( ethylpnc r1initrilo)di-o-cresol ] as well as the copper phthalocyanines (Monastral dyes) yielded very poor rates of conversion in the present system. T h e effect of the met,allic portion of the activator is more difficult to discuss because it behaves in way? other than just related
Table XXXVI. Gse of Sodium Nitrilo T r i a c e t a t e in X-478 D?O X N T , FeSOd. 7H20, Conversion Part Part i n 17 Hours 0.53 0.53 0.53 0.40 0.268 0.13
0.14
Tariation in Activator
0.28 0.28 0.28
9.4 19.4 13.9 4.1 2.1 10.1
pII pH PH pH pH
0.53 0.53
0.14 0.14
28.8 14.6
0 . 4 dextrose digest 10 iniri a t 8 3 O C. 0 . 4 dextrose: digest 50 inin: a t 85. C.
0.53 0.53 0.53 0.53 0.53
0.28 0.14
0
38.2 12.2 19.7 6,5 3.0
0 . 4 dextrose, digest 10 iriin. 0 . 5 dextrose, digest 10 min. 0 . 5 dextrose, digesr. 10 rriin. 0 . 5 dextrose, digest 10 min.
0.53 0.636 0.74
0.28
25.6
0.28
16.3
0.53 0.371 0.268 0.106
0.14 0.14
31.7 31.7 35.7 38.8
0.28 0.28
19.4 5.0
KKT (3.63 0.83 0.53 0.53 0.53
0.25 0.28
0.11
0.08 0.28 0.14 0.14
0.395
0.336 0.06
12.8 10.6 10.9 7.4 12.0
15.2
2.7 0.9 0.0
0.035 KiPzOi 0.0825 KaP107 0.123 K4P20~ B’eSOh.7Hr0 F‘e(N€I1)~(SOa)~,61120
hls(SOi)a.l6IirO CaO
at at at at
8 5 O C.
8 5 O C. 8 5 l C. 8.j0 C.
August 1949
I N D U S T R I A L A N D E N G I N E E R I N G CHEMIS,TRY
to the structure and stability of the complex and the solubility of the complex in the two phases of the polymerization medium. Differences in the stability of the complexes of various metals with ethylene dinitrilo tetraacetic acid or with nitrilo triacetic acid are possible ( I , 2, 12-21), I n addition i t is likely that the optimal concentration required for any metal other than iron may be far different than t h a t used, in agreement with the data of Marvel et aE. ( 8 ,9 ) . Kern ( 7 )reports an effectivity series for various metals. T h e authors' data agree with his concepts which seem t o be explained by a somewhat more complex system than proposed by Wall and Swoboda ( 2 4 ) . The activating effect of the tertiary nitrogen groups cannot be neglected since ethylene dinitrilo tetraacetic acid itself is a potent activator and might be rendered more effective by a metal not itself catalytically active. It was noted that silver was deposited from the silver complex.
Acknowledgments The authors wish t o thank Polymer Corporation Limited for permission t o publish this investigation; the technical assistance of A. A. Johnston, G. C. Vincent, and E. R. McCrie is acknowledged. Samples of Kalex-K, Kalex-Sa, and Kalex-TCN were generously supplied by E. I. Birnbaum of H a r t Products Company of Canada Limited. The last two were specially prepared for this study.
Literature Cited rintzmann, H., and Hesse, E., 2. anorg. u. allgem. chew., 249, 113, 299 (1944). (2) Flood, H., and Lor& V., Tids. fiemi, Bergwesen Met., 4, 35 (1944); Ibid., 5 , 35 (1944); Ibid., 6,83 (1945).
1599
(3) Fordham, J. W. L., and Williams, H. L., unpublished data. (4) Harrison, S. A., and Meincke, E. R., Anal. Chem., 20,47 (1948). ( 5 ) Houston, R. J., I b i d . , 49. (6) Johnson, P. H., and Bebb, R. L., J.Polymer Sci., 3,389 (1948). (7) Kern, W., iMalzromol. Chem., 1, 199, 209, 229,249 (1948). (8) Marvel, C.
S.,Deanin, R., Kuhn, B. A M . , and Landes, G. B., J . Polymer Sci., 3, 433 (1948). Marvel, C. S., Deanin, R., Overherger, C. G., and Kuhn, B. M., I b i d . , 128. Mitchell, J. M . , Fordham, J. W. L., Spolsky, R., Yeager, J. J., Bercov, B., Coulthard, H. K., and Williams, H. L., unpub-
lished data. Mitchell, J. M., Windsor,H., and Williams, H. L., I b i d . Pfeiffer, P., Angew. Chem., 53,93 (1940). Pfeiffer, P., Be?., 77A, 59 (1944). Pfeiffer, P., and Offerman, Ibid., 75B,1 (1942). Pfeiffer, P., and Simons, H., I b i d . , 76B,347 (1943). Pfeiffer. P.. Thielert, H., and Glaser. H.. J . vrakt. Chem., 152, 145 (1939). Schwaizmbach, G.. Helw. Chim. Acta, 29, 1388 (1946). Schwarzenbach, G., and Ackermann, H., Ibid., 30, 1798 (1947); 31, 1029 (1948). Schwarzenbach. G.. and Biedermann. W..Zbid., 31. 331. 456, 459 (1948). Schwarzenbach, G., Kampitsch, E., and Steiner, R., I b i d . , 28, 828, 1133 (1945); 29, 364 (1946). Schwarzenbach, G., Willi, A,, and Bach, R. O., Ibid., 30, 1303 (1947). Spolsky, R., and Williams, H. L., unpublished data. Vandenberg, E. J., and Hulse, G. E., IND.ENC.CHEM.,40, 932 (1948). (24) Wall, F. T . , and Swoboda, T. J., J . Am. Chem. Soc., 71, 919 (1949). \
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I
RECEIVED May 26, 1949.
LOW TEMPERATUBE POLYMERIZATIONS Emulsifiers of Alkyl Aromatic Sulfonate Type W. A. Sohnlze, C. M. Tuoker, and W. W. Crouch Phillips Petroleunt Company, Bartlesuille, Okla. Butadiene-styrene copolymers have been made using sodium alkyl aryl sulfonates as emulsifiers in redox polymerization recipes at 41' F. With sulfonates specially treated to remove sodium sulfate and unsulfonated oils, very satisfactory reactions were obtained in both laboratory and pilot plant tests. Fluid latices of excellent stability were prepared. In properly adjusted polymerieation recipes, the sulfonates are effective at much lower concentrations than those at which other emulsifiers have been employed. The vulcanizates are similar to those of comparable polymers at 41' F. with other emulsifiers in that they are characterized by high tensiles a t both normal and elevated temperatures, high flex life, and excellent resilience.
I
N THE development of commercial processes for the production of synthetic rubber of the butadiene-styrene type a t temperatures of 41 O F. and below (?', 9 ) , considerable emphasis has been required on the selection of emulsifiers for the polymerization reaction. The special grade of sodium tallow soap used in the standard GR-S process is not applicable because of the tendency of its solutions to gel a t low temperatures. Potassium soaps and sodium or potassium salts of certain purified fatty acids ( 8 ) have been used with some success, but the emulsifiers employed
most frequently have been sodium or potassium salts of disproportionated rosin acids ( 3 ) . With all the low temperature recipes developed heretofore, however, relatively high concentrations of the emulsifiers have been required t o promote a satisfactory rate of reaction and provide stable latices; consequently, after brineacid coagulation the polymers contain fatty or rosin acids in quantities t h a t may be considerably in excess of the amount required for optimum physical properties. It is usually desirable to include in these recipes a small amount of a synthetic surface-active agent such as Daxad 11 t o improve the stability of the latex, but some difficulty in t h a t respect still may be encountered, particularly if any fermentation of the latex is allowed t o occur. Recently there has been observed a spectacular increase i n the production of synthetic surface-active agents of various types. Of these, the products now manufactured i n greatest volume, and among the lowest in cost, are the sodium alkyl aryl sulfonates. They are prepared commercially by alkylating an aromatic hydrocarbon, usually benzene, with a long-chain olefin or alkyl chloride, recovering the alkyl aromatic hydrocarbon, sulfonating the latter with concentrated sulfuric acid, and neutralizing with sodium hydroxide t o provide a mixture of the sodium alkyl aryl sulfonate and sodium sulfate. I n connection with experimental work in t h e preparation and utilization of these products, the authors have investigated their use t o replace rosin or fatty acid soaps in the
