Effect of Nonvolatile Material on Solvent Balance JOHN B. DORSCH AND JAMES K. STEWART Anderson-Prichard Oil Corporation, Chicago, Ill.
be hydrocarbons other than aromatics. For a petroleum diluent, Troluoil was used. Its aromatic content, as indicated by analysis, was 3 per cent. The data obtained with solvents of the quality described may not be strictly comparable to data that might be obtained with solvents of commercial grade.
Samples of the solvent-diluent mixture were used to make up nitrocellulose and nitrocellulose resin solutions. The composition of the solutions was determined at various stages of evaporation (from 0-95 per cent). The data indicated the following relations between mixtures containing no nonvolatile material and mixtures containing nonvolatile material such as nitrocellulose or resin: (1) During the first 50 per cent of evaporation the composition of the solvent-diluent mixture was apparently unaffected by the nonvolatile material. (2) I n the last 5 per cent of unevaporated liquid mixture apparently no hydrocarbons were present. (3) Apparently in solvent-diluent mixtures containing only nitrocellulose as the nonvolatile material, the last few per cent of hydrocarbons evaporate at a relatively slower rate. (4) If ester gum was also present, butyl alcohol was held back more than the last few per cent of hydrocarbons. Apparently the ingredient held back least by the nonvolatile material was butylacetate.
TABLEI. NONVOLATILE MATERIAL DISSOLVED IN 100 Cc. OF MIXTURE B Sample No. 9 (mixt. B) 20
30 40
50
Nonvolatile Materia '/z-sec. dittrocellulose z-sec. nitrocellulose ster gum I/z-sec. nitrocellulose Ester gum (R7) l/z-sec. nitrocellulose Hardened ester gum (RP)
x
Weight of Ingredient
Total Weight
Grams
Grama
..
..
6
1.5
4.5 6
6
6
18
24
18
24
6
The solvent-diluent mixture B (toluene 20 per cent by volume, 93 per cent butyl acetate 33, butyl alcohol 12, and Troluoil35) as described in the previous paper was used (IO).
Methods of Analysis The compositions of the solutions were determined at various stages of evaporation. The nitrocellulose solutions, as well as those containing resin, were evaporated according to the procedure previously described (9). The evaporations were carried out under such atmospheric conditions that water did not condense in the evaporating solutions. It was found that greatly divergent results were obtained if water condensed in these solutions, especially in the later stages of evaporation. I n order to separate the volatile portion from the solids, the method described by Metzinger was used ( 7 ) . Instead of tricresyl phosphate, however, dibutyl phthalate was used as the very high-boiling solvent. I n distilling the solvent-diluent mixture from the solid material, a slight loss was encountered-namely, that introduced by the wetting of the apparatus walls. I n this case the loss was found to be a constant quantity of 4 cc., regardless of the fact that the distillate volume varied between 90 and 280 cc. The individual constituents were then determined as previously described (9). I n addition, the aromatic hydrocarbons were determined from a sample of the total hydrocarbons according to the method proposed by Hess (6) and modified by Faragher, Morrell, and Levine (6). The analytical data are shown in Table 11. The values represent the actual percentages of each constituent present. The values for the aromatic hydrocarbons include the aromatic hydrocarbons present in Troluoil. Similarly the values of butyl alcohol include the butyl alcohol present in the butyl acetate used in this work.
I
N PREVIOUS work on solvent balance, the effect of nonvolatile material was not studied ( 1 , 3 ,8,9). The object of this paper, therefore, was to outline some of the possible effects of solid material. The types and concentrations of the nonvolatile material were chosen so that there would be a t least a rough correlation between the data obtained and previous data of the authors (9). These are shown in Table I. Doolittle (4) showed the importance of knowing the ester content of ester solvents. For the present work butyl acetate of commercial grade (88-92 per cent ester, A. s. T. M. specification D303-33) was distilled twice through a 12-inch Widmer fractionating column. The ester content of this material after purification was found to be approximately 93 per cent as determined by saponification. The 7 per cent impurities were assumed to be butyl alcohol. Butyl alcohol of commercial grade was distilled twice through a 12-inch Widmer column. Toluene of A. C. S. grade was used. The aromatic hydrocarbon content, as indicated by analysis, was 97.5 per cent. The 2.5 per cent impurities were assumed to 325
INDUSTRIAL AND ENGINEERING CHEMISTRY
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VOL. 30, NO. 3
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OBTAINED TABLE 11. AXALYSISOF VOLATILECONSTITUENTS FROM VARIOUSSAMPLES % RemainHydrocarbons -Butyling % AroAce- AlooEvapo- after tate hol rated Evapn. Total matics A . Mixture B after Evaporation 100.0 65.5 22.8 29.7 14.8 0 40.0 19.2 38.6 21.4 64.0 36.0 44.5 25.0 13.5 46.3 28.7 55.5 36.4 16.0 8.7 49.9 34.1 63.6 33.0 12.5 6.7 51.4 36.1 67.0 4.0 1.0 53.7 42.3 28.0 72.0 59.1 41.0 .. 8.0 92.0 ,. . . 54.1 46.9 3.7 96.4
..
8.
o
Sample 20
Thinner used in making sample 20 100.0 55.0 21.5 30.3 14.7
Thinner obtained from evaporated sample 20 100.0 65.0 21.2 29.7 15.3 0 24.2 75.8 46.8 20.6 34.8 18.4 74.1 44.5 20.3 36.5 19.0 25.9 53.5 46.5 27.1 13.7 46.6 26.3 56.0 44.0 24.9 12.6 48.0 27.1 30.4 15.6 7.6 53.3 31.2 69.6 29.7 14.8 7.3 53.6 31.6 70.3 9.2 4.3 56.7 34.1 21.3 78.7 8.1 4.4 56.4 36.6 21.1 78.9 3.0 1.3 56.8 40.2 lG.4 83.6
C. 0
Sample 30
Thinner used in sample 30 100.0 65.5 22.8 29.7
14.8
Thinner obtained from evaporated sample 30 79.1 47.0 21.8 34.6 18.4 20.9 76.5 45.2 20.1 35.8 19.1 23.5 43.2 24.5 13.0 48.1 27.4 56.8 41.7 23.9 12.9 48.2 28.1 58.3 33.7 10.5 5.0 53.3 36.2 66.3 3.0 1.3 55.6 41.4 75.2 24.8 15.0 0.6 0.2 59.5 40.0 85.0 60.3 39.7 13.1 0.1 86.9 40.5 11.5 * . 59.5 88.5 60.0 40.0 11.0 *. 89.0 58.4 41.6 5.3 * . 94.7
.. .. ..
% Re-
marning E V R ~ O -after rated Evapn.
To
Hydrocarbons -ButylAroAce- AlooTotal matics tate hol
D. Sample 40 Thinner ueed in sample 40 0
100.0
55.0 21.5
30.3 14.7
Thinner obtained from evaporated sample 40 100.0 55.2 22.4 30.0 14.9 0 25.4 74.6 44.9 20.0 36.1 19.0 30.2 69.8 42.3 19.7 37.6 20.2 60.0 40.0 23.6 12.7 39.7 23.6 12.4 49:O 2?:5 60.3 36.0 23.6 10.7 48.2 28.2 64.0 70.3 29.7 21.5 11.0 50.2 28.3 70.9 29.1 21.1 10.8 48.8 30.1 79.9 20.1 19.9 9.4 49.6 30.5 80.4 19.6 19.5 9.2 50.1 30.4
E. Sample 50 0
Thinner used in sample 50 100.0 55.0 21.5 30.3 14.7
Thinner obtained from evaporated sample 80 54.9 21.7 30.0 15.0 0 0 74.3 45.0 20.9 25.7 36.5 18.5 73.5 44.7 20.5 36.5 18.8 26.5 51.0 36.7 17.3 40.7 22.6 49.0 47.5 34.5 16.3 42.2 23.4 52.5 63.1 36.9 30.0 14.6 44.3 25.8 44.3 25.8 65.0 35.0 30.0 14.1 80.1 19.9 30.5 12.1 43.3 26.2
..
Effect of Nonvolatile Material Curves were obtained by plotting the composition of the samples a t various stages of evaporation. The curves for sample 9 (solvent-diluent mixture B) are shown in Figure 1, plotted from the data of Table 11.4. The curves for sample 20, a solution of nitrocellulose in sample 9 (mixture B), are shown in Figure 2. These curves are plotted from the data of Table IIB. Comparison of the curves shows that they are identical to roughly the halfway point in the evaporation. Beyond that point, the curves for sample 20 diverge. This indicates that the hydrocarbons were retained to some extent by the nitrocellulose. Comparison of the curves at the point which represents 25 per cent of the samples unevaporated brings out the following relation: The hydrocarbon content in sample 20 a t this point was roughly double the hydrocarbon content in sample 9. I n a study of drying lacquer films, Bogin and Wampner (2) concluded “that as much as 20-25 per cent of the original solvents are present when flow stops.” Apparently a small percentage of hydrocarbona might be present in a film from sample 20 a t this stage of drying. The curves for sample 30, a solution of nitrocellulose and ester gum in sample 9, are shown in Figure 3 (from the data of Table IIC). Superimposing Figures 1, 2, and 3 would show that the curves are identical for the first halfi. e., to the point where 50 per cent of the solvent-diluent mixture was unevaporated. Superimposing Figures 1 and 3 would indicate that the curves for sample 30 agree within experimental error, almost to the end. Comparison of the curves a t the point which
represents 25 per cent of the samples unevaporated b r i n g s o u t the following relation: The hydrocarbon content of sample 30 at this point was roughly the same as the hydrocarbon content in sample 9. Apparently the presence of ester gum and nitrocellulose of this concentration would have little effect on the hydrocarbon content that might be in a film “when flow stops”
(f4.
FIGURES 1 TO 3. COMPOSITIONS OF SAMPLESAT VARIOUS STAQESOF EVAPORATION
Effect of Nonvolatile Concentration Curves for sample 40, the more concentrated solution of nitrocellulose and ester gum, are shown in Figure 4 (plotted
MARCH, 1938
INDUSTRIAL AND ENGINEERING CHEMISTRY
from the data of T a b l e 110). If Figure 4 were placed on Figure 3, the curves would again be identical to the h a l f w a y point. B e y o n d this point the curves for sample 40 diverge. Comp a r i s o n of t h e curves a t the point which represents 25 per cent of the solvent-diluent mixture unevaporated b r i n g s o u t the following relation: The hydrocarbon content of sample 40 a t this point was six to seven t i m e u t h a t of sample 9 or 30 a t the same p o i n t . Apparently t h e concentration of the nitrocellulose and e s t e r g u m mixtures is a factor in the hydrocarbon retention by the solids in solvent-diluent m i x t u r e B. In Figure 5, Figure 4 has been superFIGURES 4 TO 6. COMPOSITIONS OF SAMPLESAT VARIOUSSTAGESOF imposed on FigEVAPORATION ure 1 (mixture B). The divergence of the curves for sample 40 takes place a t the point which represents approximately 45 per cent of the thinner remaining. The solids content, in per cent by weight, a t this point was calculated to be slightly less than 40 per cent. Curves for
327
sample 50, a concentrated solution of nitrocellulose and a h a r d e n e d e s t e r g u m , are shown in Figure 6 (Table IIE). Superimposing Figure 6 on the other curves would show t h a t it is d i f f e r e n t from them. Curves m i g h t be drawn through the points in Figure 6 so that roughly a third of the curves would coincide with the o t h e r s . In the case of sample 50 t h e hydrocarbon retention appears considerably greater than for sample 40, of similar concentration. Comparison of the curves a t the point which represents 25 per cent of the solvent-diluent mixture unevaporated brings out the following relation: The hydrocarbon content of sample 50, containing hardened ester gum, was 50 per cent greater than the hydrocarbon content of sample 40, containing ester gum. The relative change in volume of each ingredient may be visualized from Figure 7. If unit depth is imagined for Figure 6, then the areas occupied by each ingredient would represent volumes. As evaporation progresses, the top part of the figure is progressively cut off.
Conclusions 1. The solvent balance of thinner B may be affected by the presence of nonvolatile material. 2. The type of the nonvolatile material may be a factor. 3. The concentration of the nonvolatile material may be a factor. 4. The change introduced in the solvent balance of the thinner is due primarily to the retention of hydrocarbons.
Acknowledgment Grateful acknowledgment is due some of the leading lacquer chemists for helpful suggestions. The authors are glad to acknowledge the assistance of G. C. Hook in checking some of the calculations. I n addition, various members of the staff of this laboratory rendered valuable help and sssistance in the work.
Literature Cited (1) Bent, F.A., and Wik, S. N., IND.ENG.CEIEM., 28, 312 (1936). (2) Bogin, C.,and Wampner, H. L., Ibid., 29, 1012 (1937). (3) Brown, B. K., and Bogin, C., Ibid., 19, 968 (1927). (4) Doolittle, A. K., Ibid., 30, 189 (1938). (5) Faragher, W.F., Morrell, J. C., and Levine, I. M., IND.ENG, CHEM., Anal. Ed., 2, 18 (1930). (6) Hess, ErdisE u. Teer, 2, 779 (1926). (7) Metainger, E.F., P a i n t OiE Chem. Rev., 98,No. 10, 18 (1936). (8) Ibid., 99, No. 10, 9 (1937). (9) Stewart, J. K.,Dorsoh, J. B., and Hopper, C. B., IND.ENO. CHEM.,29, 899 (1937). R ~ C B I V FSeptember JD 23, 1937. Presented before the Division of Paint and Varnish Chemistry at the 94th Meeting of the American Chemiaal Society, Rochester, N. Y . , Reptember 6 to 10, 1937.
