September, 1944
INDUSTRIAL AND ENGINEERING CHEMISTRY
per unit volume of solid appears t o be a function only of particle shape. For different preparations of emery the indicated quantities were 20 and 28% of the volume of solid. Several lines of evidence are presented to show that this liquid is not adsorbed by the particles. Apparently it is simply liquid that has remained stagnant at angularities in the particles. Flocculation of concentrated suspensions of the same emery powders that were tested in the nonflocculated state materially reduced the rates of sedimentation. However, the same rate equation could be applied with fair success when modified only by a n increase in wd which, for the nonflocculated suspensions, corrects for the liquid that is assumed to be stagnant. It is concluded that in highly concentrated flocculated suspensions there is no opportunity for liquid to by-pass floc structure in escaping from the mass during sedimentation, but that in general this liquid must flow past the individual particles in much the same way as in a nonflocculated suspension. Two possibilities are seen for the increase in wr: (1) The quantity of stagnant liquid may be increased by reason of interparticle contacts caused by flocculation. (2) There may be isolated pockets of liquid distributed through the mass, pockets whose dimensions are materially greater than those of the meshes in the floc structure itself. How such pockets can produce an increase in wi has been Hhown. The possibility that structural (nonviscous) resistance produced by the flocculation may have been a factor in decreasing the rates of settlement was investigated by determining hydrostatic pressures in flocculated suspensions of various powders, but principally in aqueous pastes of portland cement. It was found that there is no appreciable structural resistance during the initial stage of the sedimentation when the constant rate is established. ACKNOWLEDGMENT
The writer was assisted by Richard G. Brusch and Herbert We Schulta in the experimental work reported in this artiole.
847
NOMENCLATURE
Q = initial rate of settlement of top surface of a suspension, cm. /sec.
V . = rate of fall of a n isolated sphere as given by Stokes law, cm./sec.; used also to represent rate of fall of a n isolated particle when Reynolds number is such tzat a
-
sphere would fall in accordance with Stokea law dimensionless constant used by Powers (14) tu, = dimensionless constant analogous t o wi a = dimensionless constant denoting volume of fluid per unit volume of solid, that a pears to remain with angular particles during their e = proportion of total volume of suspension occupied by liquid (analogous to porosity in beds of particles)
w,
fa8
LITERATURE CITED
Bastow, S. H., and Bowden, F. P., Proc. Roy. SOC.(London), A151, 220-33 (1935). Bulkley, R.. Bur. Standards J. Research, 6,89-112 (1931). Carman, P.C.,J. Agr. Sci., 29, Pt. 2,262-73 (1939). Carman, P.C., J. SOC.Chem. I d . , 57, 225-34T (1938). Carman, P. C . , Trans. Inst. Chem. Engrs. (London), 16, 1138-88 (1938). Egolf, C . B., and McCabe, W.L., Trans. Am. Inst. C h .Engra., 33,620-42 (1937). Fair, G . M., and Hatch, L. P., J. Am. Water Worlcs Assoc., 25, 1551-65 (1933). Oaudin, A. M., “Principles of Mineral Dressing”, 1st d.. Chap. 8,New York, McGraw-Hill Book Co., 1939. Johansen, F. C., Proc. Roy. Soc. (London), A126, 231-45 (1930). Kermack, W. O., M’Kendrick, A. G., and Ponder, Eric, Proc. Roy. SOC.Edinburgh, 49,170-97 (1929). Koaeny, Josef, Kulturtechnilcer, 35,478-86 (1932). Kozeny, Josef, Sitzbe-r. A h a . Wiss.Vien, IIa, 136,271-306(1927). Lea, F. M.,and Nurse, R. W., J . Soo. Chem. Id.,58,277-83T (1939). Powers, T. C . , Research Lab., Portland Cement Aasoo., Bull. 2 (1939). Steinour, H. H., IND.ENQ.C H ~ M36, . , 618-24 (1944). Wagner, L. A., Proc. Am. SOC.Testing Materialrr, 33, Pt. 11, 553-70 (1933). Ward, H. T.,a;nd Kammermeyer, Karl, IND.ENO.CHBY.,32, 62243 (1940). Work, L. T.,and KoNer, A. S., Tbid., 3.2,1329-34 (1940).
PRINTING INKS from Colloidal Dispersions of SOYBEAN PROTEIN
ALFRED F. SCHMUTZLER AND DONALD F. OTHMER Polytechnic Institute, Brooklyn, N. Y.
P
ROTEIN dispersions in diethylene glycol a previous article (98). Printing inks ma persions are nondrying on the printing press, but when printed films of the inks are exposed t o steam, they harden immediately. They are not sufficiently water resistant for universal use. To eliminate this defect, reactions designed t o lower the water absorption of proteins were investigated. I n aqueous dispersions, soybean protein will not precipitate or gel when reacted with formaldehyde (95). Plastics made from it have relatively high water absorption (1-4). I n contrast to soybean protein, casein and blood albumin gel almost immediately upon the addition of even small amounts of aldehydes t o their aqueous dispersions, a n indication that the behavior of the former differs considerably from that of the latter. Nevertheless it,
was found that some features of the hardening of casein could be applied to soybean protein. I n order to improve the hardness and durability of casein fibers (artificial wool, lanital), in some instances)small amounts of salts of heavy metals are added to the spinning solution (10, 13, 1.9, 1.6, 20); in others the .dispersed casein is reacted with isocyanates (6, 16, 17, 18),isothiocyanates ( 1 1 , 16),and carbon disulfide (6). Although isocyanates may undergo side reactions in the presence of hydroxyl groups, isothiocyanates and carbon disulfide combine solely with amino and amide groups. The initial step is the formation of thiourea derivatives, followed by condensation reactions with aldehydes, with the formation of modified thiourea resins (9, 10, $4). I n the reaction of proteins with carbon disulfide, hydrogen sulfide is liberated and can combine with aldehydes, with the formation of thioaldehydes, which are much more reactive than the aldehydes from which
&18
INDUSTRIAL AND ENGINEERING CHEMISTRY
Printing inks which harden immediately by exposure to steam were made with colloidal dispersions of aldehydereacted soybean protein in diethylene glycol. The "hardened" protein has a relatively high water absorption. This disadvantage was eliminated by reacting the dispersed protein in the presence of catalysts such as aluminum chloride and zinc nitrate, and of protein-precipitating reagents such as phenyl isothiocyanate and phenolic resins. The results indicate that materials so formed may be useful in other fields.
they are derived; these thioaldehydes are also subject to spontaneous condensation with themselves (9). Although the mechanism of the hardening of casein and other proteins with aldehydes is unknown, reactions of urea ( 7 , 8, 82) and melamine (16) with formaldehyde suggest that the amino groups may form monomethylolamines, dimethylolamines, or methylene linkages. The gelling of casein suggests the formation of a larger complex, with adjacent polypeptide chains supposedly joined together by methylene linkages. EXPERIMENTAL PROCEDURE
Yol. 36, No. 9
The tests for hardness and water resistance were made with printing inks consisting of 30 grams of Litho1 red and 70 grams of dispersion. The two were mixed uniformly and milled on a threeroller laboratory paint mill. Printing was done on a Vandercook proofing press (KO. 219) equipped with split rollers, so that two inks could be printed simultaneously for comparative testing The prints were passed over steam issuing from a steam bath in order to set the ink to a hard film. The relative hardness of the printed films were determined OD the scratch tester (Figure 1) designed by J. G. Curado for the research laboratories of General Printing Ink Corporation. .4 bead of Pyrex, ~ / I B inch in diameter, is attached to the lower end of a vertical rod; a t the other end is a small platform for holding weights. By means of a counter-balancing spring attachment, the bead exerts practically no pressure upon the print when the platform is not weighed down. Two rollers, whose rate of rotation can be adjusted by a rheostat, pull the printed sheet from underneath the bead, which scratches the printed film if it is weighed down sufficiently. Thus the appearance of the scratched surface indicates the relative hardness of the film; but if the film is so hard that sufficient weight may not be used n'ithout tearing the paper, the bead will usually pick up some pigment from the print and deposit it on the unprinted part of the sheet; this also serves as a means of visual comparison of the relative hardness of several inks. The water resistance of the dry ink films was tested by pulling a wet piece of filter paper over the dry print. Whatman filter paper No. 1, 3 inches in diameter, wab soaked in water, and the excess water was allowed to drain off. The reaction of the printed proof to this test was regarded as a measure of its relative resistancp to water.
The object of these experiments was to obtain dispersions of aldehyde-reacted proteins in diethylene glycol, suitable for hard-drying and water-resistant printing inks, The dispersions (Table I) and additions were heated in an Erlenmeyer flask under a reflux condenser. The contents were shaken vigorously a t 10minute intervals in order to duplicate occasional stirring, customary in the preparation of varnishes. After completion of the reaction and cooling, 2 grams of the mixture were diluted with PRECIPITATE FRORl WATER DlLUTIQh 100 cc. of distilled water. The dilution was allowed to settle for 24 hours and filtered through a tared Gooch crucible; the It was found that the amount of precipitate obtained b; bottom of the crucible was covered with a small circular piece diluting the protkin dispersions with n-ater was a measure of the of acid-washed filter paper. The collected precipitate was dried relative water resistance of the binder in the printing ink. hca t 90" C. for 20 hours. The amount of precipitate obtained cording to Figure 2 , the maximum amount of precipitate in bot11 was accepted as a measure of the degree of water resistance of c the binder in the printing ink vehicle. To define the consistency of the dispersions, the relative viscosity was determined in a Stormer viscometer; the readings in seconds were converted to poises by a calibration chart (23). These values differ considerably from those of the viscosities of oils and varnishes; their importance depends upon the fact that, with the same concentration of the same pigment, the lowviscosity dispersions give softer inks than the more viscous dispersions. As a general rule, the weight of the plummet for the Stormer viscometer depended upon the consistency of the dispersione.g., plummet of 100 grams, up to 5 poises; 200 grams, up to 15 poises; 500 grams, up to 60 poises; and 1000 grams, above 60 poises. The pH was read on a Beckman meter, to define whether the dispersions were acid or alkaline with respect to diethylene glycol (pH 6.86). The readings on colloidal dispersions of proteins in diethylene glycol do not show the true hydrogen-ion concentration; small additions of either guanidine carbonate or acetic acid to diethylene glycol cause greater deviations from the pH Figure 1. Curado Scratch Tester of 6.86 than the same amounts cause from a pH of 7.0 in doubledistilled water. Color and appearance depend upon pigments, while hardness and water TABLE I. SOYBE.4N P R O T E I S DISPERSIONS resistance of the printed films are imparted by the binder; in this inSoybean Guanidine DicyanPhthalic Diethylene Reaction Relative Beckmdi stance, they are due to the aldehydeExyt. a-Protein, Carbonate, diamide, Anhydride, Glycol, Temp., Viscosity, pH C. Poises Reading Grams No.
reacted protein, which occludes the pigment and precipitates from its colloidal dispersions upon exposure of the printed film to steam.
172(88)
gi : 286
Grams Po 20 20 20
Grams 6 6 6 3
Grams
Grams 3 70
3
..
74 00 70 30 68 00 74 00
135 135 135 140
18 9 25 5 28 o 21 3
10 4 8 7 11 4 9 8
INDUSTRIAL AND ENGINEERING CHEMISTRY
September, 1944
TABLE 11. ACTIONOF PARAFORMALDEHYDE ON ALKALINE DISPERSION172
(100 grams of dispersion 172 and varying amounts of paraformaldehyde heated 2 hours a t 110’ C. under reflux condenser) Printing Inksb Dispersions Red imParaformRelative Av. “waterpression Expt. aldehyde, visqosity, insol.”, g./g. Ink with load No. Grams man) poise@ of sample no. in grams 172 0 10.4 18.9 0 43.7 202 3.00 8.9 5 10 203 4.00 8.9 55.7 20 5.00 50.4 204 8.4 42.6 20 205 8.2 6.00 40.3 10 206 7.00 8.0 36.8 8.0 5 8.00 207 0 208 31.6 8.0 9.00 30.9 10.00 0 209 8.0 210 53.7 3.50 8.8 10 5 With 500-gram plummet. b Buttery appearance, poor water resistance.
(&%-
TABLE111. ACTION OF PARAFORMALDEHYDE ON ALKALINE DISPERSION 216
(100 grams of dispersion 216 and varying amounts of paraformaldehyde, heated for 2 hours a t l l O o C. under reflux) ParaformRelative Av. Expt. aldehyde, PH Viscosity, “Water-Insol.”, No. Grams (Beckman) Poises5 G./G. of Sample 0 8.7 25.5 3.00 7.8 36.7 4.26 7.4 38.8 5.50 38.9 7.3 7.2 39.0 6.60 7.1 39.6 6.80 7.20 7.1 31.6 7.60 7.0 29.3 28.1 8.00 7.0 a With 500-gram plummet.
TABLE IV. ACTIONOF PARAFORMALDEHYDE ON ACID DISPERSION225 (94 g r a m of dispersion 225 and 6 grams of glacial acetic acid heated for 2 hours) ParaformAnhyRelative “WpterExpt. aldehyde, drous AlCla, pH Viscosity, Insol GJG. NO. Grams Gram (Beckman) Poises of Simple 2258 226 227 228 229 230 231
0
4.0
5.0 5.8 6.8 4.5 5.3
Reacted at l l O o C. 0 6.0 0 6.0 0 5.9 0 6.0 0 6.0 0 6.0 0 5.9
27.0 16.9 15.8 16.4 18.1 16.6 16.0
0.0418 0.0485 0 0503 0.0452 0.0440 0.0493 0.0477
.
849
alkaline and acid dispersions is obtainable when between ‘4.5 and 5 grams of paraformaldehyde had been reacted with 100 grams of 20% soybean protein dispersion; with either more or less paraformaldehyde the amount of precipitate is less. Tables 11,111,and I V show that it is somewhat greater in acid than in alkaline dispersions but relatively low with respect to total solids in the dispersions, even in the presence of protein-precipitating aluminum chloride and zinc nitrate. According to Table V, a larger amount is obtainable from dispersions in which the protein is reacted with carbon disulfide before the reaction with paraformaldehyde, but the disagreeable odor freed during the reaction forbids its use in printing inks. Ammonium nitrate slightly improves the odor but not sufficiently. It shifts the maximum amount of precipitate toward the 6-gram range on Figure 2. Table VI shows t h a t relatively large amounts of precipitate are obtainable in experiments made with dispersion 286, in which a mixture of dicyandiamide and guanidine carbonate served as the peptizing agents for soybean protein. I n contrast to the other dispersions of Table I, which foam profusely during acidification, dispersion 286 foams but slightly during the addition of acetic acid. After reaction with paraformaldehyde in the presence of phenyl isothiocyanate, i t yields large quantities of precipitate on dilution with water; still larger amounts are obtainable when the reaction with paraformaldehyde is carried out in the presence of a small percentage of phenolic resin Amberlite K6S. This resin was selected from several diethylene-glycolsoluble phenolic compounds listed in Table VII. Tables VI and VI1 demonstrate the relation between the amount of precipitate from water dilutions of the protein dispersions and the hardness and water resistance of the printed films made with corresponding printing inks. TESTS ON PRINTING INKS
I n Table I1 dispersions 204 and 205 yield the greatest amount of precipitate; the corresponding inks, 204R and 205R, gave the
Reacted at 130° C. 232 4.5 0 6.0 16 8 0 0499 233 5 0 0 5.9 16.4 0.0512 234 5 3 0 6.0 16.7 0 0501 235 5.6 0 6 0 16 9 0 0485 236“ 4.5 1.0 5.8 19 5 0.1076 237n 5 0 1 0 5 7 19 8 0,0998 2385 5.3 1.0 5.7 20.1 0.0576 5 A small amount of scum which formed was removed, and tests for waterinsoluble substances were carried out with t h e clear dispersion.
TABLE V. ACTIONOF CARBON DISULFIDEAND PARAFORAMLDEHYDE ON
DISPERSION 225
Additions t o 94 Grams of Dispersion 225, Grams “WaterDiethylH Relative Inaol.” Expt. ene Acetic Zn(Na0)n. Paraform(8eck- Viscosity, G./G. 0; No. glycol aoid NH4NOa 6HpO CSs aldehyde man) Poises Sample 0 10 0 7.4 31.6 1 10 5 6.7 17.1 3 10 5~ 6.5 12.2 4 5 10 6.4 17.6 5 5 10 6.1 17.0 3 ... 5 10 6.5 21.2 0 10 5 7.3 46.3 1 10 5 6.5 41.8 2 10 6 6.5 37.3 fi 5 8 6.27 4.7 6 8 8 4.7 5.92 6 11 8 4.7 5.77 6 . . * 15 8 4.8 5.63 5.5 0.5 5 8 4.8 9.31 .. 5 1 5 8 4.7 10.15 2 5 8 4.7 12.90 .. 8C 5 8 4.9 17.73 2 5 8 4.7 12.90 2 5 5 5.0 10.72 .. 2 5 6 4.9 9.30 .. 2 5 7 4.8 16.63 .. 5 2 19.22 4.7 a CSz, acid, and dispersion 225 reacted for 1 hour at 40° C.; remainder of items reacted for 2 hours a t 130’ C. b All items mixed and heated for 1 hour at 40° C., followed by 2 hours a t 130’ C. 0 A small amount of scum formed.
.. .. .. .. .. .. .. ..
.. .. ..
.. .. ..
... ... ... ... ... ... ...
...
... ... ...
... ... ... ... ... ... ... ...
2 4 6 8 IO Addition of Poroformoldehyde to 2 0 9 . Protein i n Dispersion
0
Figure 2. Effect of Paraformaldehyde (Grams Added) on Water Insolubility of Soybean Protein in Diethylene Glycol Dispersion Weight of water-insoluble main formed in 50 ml. of water per gram nample of din ernion. Numbers refer to experiments limted in tab7ea. Asterink indicates effeect of shift of maximum point by aotion of carbon dinuliide.
INDUSTRIAL AND ENGINEERING CHEMISTRY
850
T.4BLE
VI. ACTIONO F PARAFORMALDEHYDE
ON
Vol. 36, No. 9
DTSPERSION 286
Printing Inks “WaterRed imRelative insol.”, pression Expt. pH viscqsity, & / g . of Ink Behavior w i t h load Water So. (Beckman) poises sample no. Appearance on press i n grams resistance 0 286 .. 9.8 21.3 0.0069 286R‘ ’ 5 Poor .. 6 6 287 c 6.2 32.3 0.0704 287R 10 Poor .. 5 5 28SC 6.2 0.0895 39.5 288R Slightly Fair 20 Poor .. 4 6 289 6.2 38.0 0.0948 289R tacky .20 Poor 29OC 5 ~. 4.5 6.2 46.4 0,1002 290R 20 Poor .. .. 5.5 291c 5 6.1 38.1 0.0872 291R 20 Poor .. 7 5 292 0 6.1 37.6 0.0488 292R, 10 Poor 293d 4.4 5 3 111.0 0.1206 7.0 293R ‘30 Fair 294d 4.7 5 3 0.1226 115.1 6.7 294R ’ Moderately Fair Fair .. 5 5 295d 3 111.6 0.1172 6.7 245R tacky Fair .. 4.2 5 296: 3 6.7 112.0 0.1198 296R Fair .. 4 5 14 297 6.5 98.5 0 . I864 297R’ Good ’50 Good 5 .. 14 5 298 157.2 6.4 0.1858 298R, Very tacky below 4d% 50 Good 5 14 5.5 299 * 6.5 272.0 0.1874 299R humidity 50 Good 14 6 5 6.2 .. 0,1990 275,O 300Rl 30OC 50 Good a Consisting of 50% zinc nitrate hexahydrate and 50% glacial acetic acid by weight. b Consisting of 60 grama Amberlite K66 and 80 grams diethylene glycol. 0 Items mixed and heated for 2 hours a t 130’ C. Phenyl isothiocyanate and dispersion 286 mixed and heated a t 130’ C. €or 10 mintues: zinc nitrate solution and paraformaldehyde added, and mixture heated for 2 hours a t 130’ C. Additions t o 100 Grams of Dispersion -___ 286, Grams Zn Phenyl Amherlite nitrate isothioK6Sh Paraformsoh.“ cyanate soln. aldehyde
Dispersions
_ _ I
..
..
r ABLE 1’11.
~
ACTIOX O F P A R A F O R X A L D E H Y D E AND P H E N O L S ON
DISPERSION 22P
Relative Viscosity, Poises 17.6 125.1
“Water-Insol.” Expt. pH Phenolic Compound (Beckman) G./G. of Sampld No. 6.2 0,0948 276 U. S. P. phenol 6.0 0.1806 277 Amberlite K6S 278 Super-Beckacite 3000b 6.1 ... .... 36.9 Nevillac hardQ 6.1 0.1626 279 ‘1 3Iixture: 94 grams of dispersion 2 1 5 , 6 oi diethylene glvcol, 6 of glsrial acetic acid, 8 of par&formaldeli).de, nnd 8 of pllcnolic eoriipou::d. Resin dissolved i t i diethylene glycol; reinaiiidcr of i t e m added. n:ixed. and heatcd for 2 hours at 130’ C . 1, Resulting product unstable: resinous mixture separated from dispersion. 0 .4 modified coumarone-indene resin with several phenolio hydroxyl groups (ti).
hardest printed films, an indication of the importance of the maximum range of paraformaldehyde additions of Figure 2. The decrease of the precipitate with an excess of paraformaldehyde may be explained by the rule formulated for the solubility of organic compounds; Le., greater structural similarity between solute and solvent is accompanied by greater solubility (19). It is assumed that with a n excess of paraformaldehyde many methylal groups are formed and thus cau-e relatively greater solubility of the aldehyde-reacted protein in water; conversely, such a protein binder retains larger proportions of diethylene glycol after “steam-setting’’ of the printed films. The diqpersions of Table V I give the most satisfactory printing inks. Phenyl isothiocyanate imparts good water resistance and hardness; still greater hardness and water resi5tance are obtainable with the phenolic resin Amberlite K6S. The inks made with di3pcrsions containing this resin are sensitive to humidity above 45%; a t high humidity the ink fails t o distribute on the printing press. Upon the addition of small amounts of diethylene glycol monophthalate, these inks can be used a t a humidity greater than 45%. I N K VEHICLES FROM MIXTURES O F TWO DISPERSIONS
Dispersions of casein and blood albumin in diethylene glycol turn t o gel-like masses on intimate contact with paraformaldehyde. When either of these gelled dispersions is mixed with a n equal amount of a liquid dispersion of aldehyde-reacted soybean protein or corn protein, liquefaction of the gel takes place. The resulting mixtures are suitable printing ink vehicles, as illustrated by one example:
EXPERIMEXT 324. One hundred grams of 20% casein dispersion in diethylene glycol, with a relative vi,co-ity of 25 poises (23) was reacted with 3 grams of paraformaldehyde at 100” C. It gelled; the gel was mixed with 103 grams of dispersion 290 (Table VI) and stirred for 5 minutes until the mixture became liquid and homogeneouq. It had a relative viricoaity of 129 poises and a Beckman pH meter reading of 6.7. Its precipitate on dilution with water was 0.144 gram per gram of sample.
The behavior on the printing press of ink 324R made from this vehicle was good up to 70% humidity. Scratch tests showed impressions with a load of 60 grams, and the water resistance was almost as good as that of inks 297R to 30012. This example indicates the possibilities in the application of soybean protein dispersions to inks also containing dispersions of other prot,eins. CONCLUSION
I n the preparation of printing ink vehicles, best results can be obtained when an optimum amount of paraformaldehyde is reacted with the dispersed soybeBn protein in diethylene glycol. According to the types of dispersions used, the optimum amount lies within the range 4.5 to 5 grams of paraformaldehyde per 100 grams of 20% dispersions. The characteristics of these dispersions suggest a variety of other applications, such as specialty paints, paper sizin and artificial fibers. I t might be necessary to change to lower-foiling alcohols, such as ethylene glycol, but the capacity of the dispersions of aldehyde-reacted soybean protein and corn protein to liquefy casein-formaldehyde gels, appears to be of varied industrial importance. LITERATURE CITED (1)
Arnold, L. K., and Quackenbush, A. D., P r o c . Ioua
41cad. &:i.,
47, 231-4 (1940). (2)
Beckel, A. C., Brother, G. R., and McKinney, L. L., XND. ENG.
(3) (4)
Brother, G. H., and McKinney, L. L., Ibid., 31, 84-7 Brother, G. H., and McKinney, L. L., U. S. Patent
CHEM., 30, 1236-40 (1938).
(1939). 2,262,422
(1942). (5) Dickson, J. P., Brit. Patent 523,759 (1940). (6) Dpnagemma, Giusseppe, Ibid.,505,756 (1939). (7) Einhorn, A., A m . , 343, 207 (1906). (8) Einhorn, A., and Hamburger, A., Ber., 41, 24 (1908). (9) Ellis, Carleton, “Chemistry of SynLhetic Resins”, New York. Reinhold Publishing Corp., 1936. (10) Elod, Egon, and Schmitt, Gustav, Kolloid-Z., 92, 106-12 (1940). (11) Esselmann, Paul, and Dusing, Josef, U. S. Patent 2,220,441 (1940). (12) (13) (14) (15) (16)
Ferreti, Antonio, Brit. Patent 483,731 (1938). Gohda, Tadashi, French Patent 767,874 (1934). Gould, S.P., and Whittier, E. O., Ibid., 841,603 (1939). Groves, W. W., Brit. Patent 509,852 (1939). Hodgins, T. S., I-Iovey, A. G., Hewett, S., Barrett, W. R., and Meeske, J. C., IND.ENG.CHEM.,33, 767-79 (1941). I. G. Farbenindustrie, A.-G., French Patent 840,773 (1939).
(17) (18) Ibid., 844,289 (1939). (19) Kamm, Oliver, “Qualitative Organic Analysis”, New York. John Wiley & Sons, 1932. (20) LeRoy, M. C. A., B d . SOC. iad. Rouen, 60, 25 (1932). (21) Rivkin, Joseph, and Sheehan, W. E., IND. ENG.CHEM.,30, 1228-39 (1938). (22) Scheibler, H., Trostler, P., and Scholz, E., 2. angew. Chem., 41, 1305-6 (1928). (23) Schmutzier, A. F., and Othmer, D. F., IKD. ENG.CHEM.,35, 1196- I202 (1943). (24) Shriver, R. L., and Fuson, R. C., “Systematic Identification of Organic Compounds”, New York, John Wiley & Sons, 1940. (25) Smith, A. K., and Max, 13. J., IND.ENG.CHIM., 32, 411-16 (1940).
