INDUSTRIAL AND ENGISEERING CHEMISTRY
1210
With a pigment of definite hydrophilic properties, the relative hydrophilic and organophilic tendencies with respect to the water and oil phases may be so balanced by manipulation of the wetting properties of the latter phase as t o produce varying degrees of thixotropy in the system. The water is usually introduced into these paints in the form of a dilute solution of a soap or electrolyte. Although the presence of the soap or electrolyte no doubt has some influence on the tendency of the water phase to replace the oil a t the pigment interface, the main function of these agents appears to be merely to aid in distributing the water more uniformly through the system by means of the emulsifying action.
General Discussion An attempt has been made to point out the nature of thixotropy as it exists in paints with special reference to the flat wall type. Because of the marked influence these thixotropic characteristics have on certain paint properties, they should be given consideration in the formulation of paints not only of the heavier bodied, flat wall type but in other classes as well. With the development of pigments of widely different properties and with the increase in the types of vehicles used, oil absorption values give no indication of the type of consistency produced and can be taken as only a very general measure of the relative consistencies two pigments may produce in a given vehicle. Also, the rheological properties of paints are somewhat complex, and more detailed consideration must be given them if a complete understanding of the influence which they have on other paint properties is to be had. The control of these properties is, to a large extent, a matter of the formulator's art,
but a better understanding not only of the factors determining the rheological characteristics of a paint but also of the influences these factors have on other paint properties will certainly lead to greater latitude in paint formulation.
Acknowledgment The author wishes to acknowledge the assistance of L. D. Grady, Jr., in the preparation of this paper, and the criticisms of other members of the Research Division of the New Jersey Zinc Company. He is indebted to Victor Bachman who made the rheological measurements.
Literature Cited (1) Booge, Bingham, and Bruce, Proc. Am. SOC.Tevfzng Materiala, 22,Pt. 11,420 (1922). (2) Cunningham, J . Phys. Chem., 35, 796 (1930). (3) DeWaele and Lewis, Kolloid-Z., 54, 175 (1931). (4) Green, I N D . E N G . CHEII., 15, 122 (1923). ( 5 ) Green and Haslam, Ibid., 17, 726 (1925). (ti) McMillen, Ibid., 23,676 (1931). (7) McMillen, J. Rheol., 3,Nos. 1 and 2 (1932). (8) Peek and hlclean, Ibid., 2, 370 (1931). (9) Pryce-Jones, J . Oil Colour Chem. Issoc., 17,305 (1934) (10) Reiner, Kolloid-Z., 54, 175 (1931). (11) Rhodes and Jebens, J . Phys. Chem., 35,383 (1931j. (12) Ryan, Harkins, and Gans, IKD.EKG.CHEM., 24, 1288 (1932). (13) Waring, J . Rheol., 2,No.3 (1931). (14) Werthan, S.,Oficial Digest Fed. Paint &. Varnish Production Clubs, March, 1936; Am. Paint J.,20, 18 (March 16, 1936). (15) Williamson, IND.ENG.CHEx., 21, 1108 (1929). (16) Williamson, Patterson, and Hunt.,Ibid., 21, 1111 (1929). (17) Wolff and Zeidler, Farben-Ztg., 38, 1495-7 (1933). R E C E I V ~April D 21, 1936. Presented before the Division of Paint and Varnish Chemistry at the 91st Meeting of t h e American Chemical Society, Kansas City, hlo., .4pril 13 t o 17, 1936.
DISTILLATION EFFICIENCY IN 3-AND 6-MM. FRACTIONATING ARTHUR ROSE The Pennsylvania State College, State College, Pa.
@T
HE experiments described here consisted in the determination of the number of theoretical plates in glass columns, 3 and 6 mm. in diameter and 30.3 em. (one foot) high, a t all vapor velocities from nearly flooding to as low as possible, when the columns were both empty and packed. Figure 1 indicates the construction of the columns. The mixture used was benzene-carbon tetrachloride, and analyses were made by refractive index. The number of theoretical plates was obtained by reference to the vapor-liquid equilibrium diagram for the system (1, 2 ) . One bheoretical plate was subtracted to correct for the fact that samples were taken from the still rather than the bottom of the column. The rate of flow of liquid down the column was determined sometimes by counting the drops per minute falling from the calibrated tip a t the bottom of the column, and sometimes by the heat input. In the latter case it was necessary t o correct for heat loss from the still. Samples from the still were withdrawn by applying a slight vacuum to the still take-off line until liquid was drawn above the side arm on thib line. The vacuum was then re-
VOL. 28, NO. 10
leased, and the few drops of liquid t r a p p e d in the side arm were taken off and analyzed. Samples from the top of t h e c o l u m n w e r e withdrawn simply by opening slightly the stopcock on the side arm there. No g r e a s e was used on any of the stopcocks, and the first two drops of a sample were d i s c a r d e d to avoid possibility of contamination. The rate of taking a sample was sometimes d e t e r m i n e d , not by the position of the stopcock plug in its socket, but by the slope of the take-off line and the rate of flow of l i q u i d p a s s i n g the side arm. The rate of taking a sample was always so slow that the reflux ratio was greater than 70 t o 1.
INDUSTRIAL AND ENGINEERING CHENISTHY
OCTOBER. 1936
6UM. @2UMN
INSULATED BY SILVERED V.icuv~ TABLE I. DATAO N COLCMNB (10-8 MM.) JACKET ,-.._
6-3lm. Column--Equivalent no. theoLiquid retical Packing velocity platesa Cc./miid.
--3-Mrn.
~
Spiral Helice.:
Carding teeth
1 5 5 1.5 1
6.5 4.0 8.0 9.3 11.0
3 6 3 2 1.4 0 7 0.6
3.3 3 3 3 0 3 4 6 0 6.0
1211
F / G 2 . IVWUTED
BY SILVERED WCUUM JICKET
Cnluiiin---Equivalent no. theoLiquid retical velocity plates5
Packing
Cc./min.
1.1 1.0 0.8 Spiral
0.6 2.20
5 6 7 9 8
1.6 1.0 0.7 0.6
6 5 6 8
I
00
I
2
FIG. 3.
J
4
5
I
e
7
6
CMIIUUISON OF JMM AND 6MN MlUUNS IUSUUTED ai SILVERED VACUUM JACUET
IO
9
a 7
6
Per foot (30.3 cm.) of column.
s 5
TABLE 11. -So
Liquid velocity
C'c./min. 0.6 0.8 1.0 3.0 5.0 a
3-
COMP.4RISOS OF WITH
-4ND
6-MM.
J
VACUUMJACKET
Packing-Equivalent no. t h o retical plates5
S-mm.
f
6 1 Floods
-Spiral Liquid velocity
6-mm.
9-mm.
0.6 1.0 2.20
..
5 8 Floods
5
1
2
PackingEquivalent no. theoretical platesa
Cc./min.
No liquid a t top of column 8
1
6-mm. No liquid a t top of column 6.5
...
4.0
Per foot (30.3 cm.) of column.
TABLE111. EFFECTO F
I
o.,
6.0 6.0
{
N o liquid a t top of column 5.5 5.1 4,s
... 1 0 ... 1.1 . . 1 . :3 3.4 4 0 1.4 ... 3.0 1 8 3.0 3 .0 2.0 3.3 3.0 3.0 3.3 3.0 3.6 3.0 4 Per foot (3~1.3om.) of column.
...
TABLEIv. EFFECTO F ----Spiral
--
Cc./min.
Cc.linin.
0.6
6-MM. COLCMN No Packing Equivalent KO.Theoretical Platesa Vacuum Vacuum jacket jacket only and heater
INSTJLlTION O N
-Carding-Tooth Packing---Equivalent No. Theoretical Plates= Liquid Vacuum Air Liquid velocity jacket jacket velocity
a
2 4
COLCYX INSULATED
Liquid velocity C'c./niin 2.20 8 0 2.00 8.0 0 0 1.80 8.0 5.0 6.0 1.60 3.0 1.30 1.00 1 K O liquid 5.0 0.70 4 a t top 6 0 0.60 [ of column J 8 4 Per foot (30.3 cm.) of column.
1
6.2 5.0 2.5 1.9 1.4 0.9 0.8 0.45 0.22 0.17
-No
0.5 0.5 1 0 1.0 2 0
0.5 1.0
...
{
...
2.0 5.0
1
LiluIpd does not reach top of column J
ISSULATION ON
Packing-Equivalent X o . Theoretical Plates= .lir Vacuum jacket jacket
...
... . .
8.0
3-MM.
3.0 4.0 6.0 13.0 17.5
COLGMS
PackingEquivalent No. Theoretical Platea" Air Vacuum jacket jacket
Liquid velocity Cc./min. 3.00 1.3 2.00 1.5 1.60 2.2 1.30 4.0 1.00 7.0 0.80 No liquid a t 0 56 ( t o p of column]
JMM COLUMN
17
FiG.5, EFFECT OF INSULATlON
6MM CDLUMN
,6
FIG. 4. EFFECT
OF INSULATION
12 1I
10 9
1.0 2 0
8
4 0 3 0 6.0 7 0 9 5
7
6
5
AIR JACKET &DING 0
7EETd VACUUM JACKET (CAPDING 7EETH)
4
2
Results Table I and Figure 2 give the results of the experiments with the 6-mm. column (a) empty, (b) packed with a continuous spiral of KO. 26 nickel wire of pitch 2.1 turns per cm. (5.3 turns per inch) which fitted snugly into the column, (c) packed with single-turn helices of 3.18-mm. diameter (1 8-inch size) and of S o . 26 nickel wire ( I ) , ( d ) packed with bent carding teeth (1) (7.94 mm. or 5/16 inch in size). Each
/
2 1
t 0
1
2
3
4
5
6
7
THROUGH PUT AT &IS€ OF COLUMN IN C C OF LIQUID DER MINUTE
8
1212
VOL. 28, NO. 10
INDUSTRIAL AND ENGINEERING CHEMISTRY
throughput at high efficiencies is small. The efficiency of the unpacked columns drops off rapidly as the rate of boiling increases. 2. The single-turn, So. 26 wire helices ( 1 ) result in high efficiency (eight plates) even a t relatively high rates of boiling. This type of packing gives higher efficiencies than any other studied. 3. The continuous spiral packing used in the 6-mm. column is not as efficient as the single-turn helices. At low rates of boiling the unpacked column is a little more efficient than the spiral packed. 4. rlt the same rate of boiling, the empty 3-mm. column is no more efficient than the 6-mm. column. The 3-mm. column, however, does give higher efficiencies a t very low rates of boiling-i. e., conditions under which the larger column cannot be satisfactorily operated. 5. The effect of insulation is as follows: At high rates of boiling the effectiveness of the insulation seems to make but little difference in efficiency. At somewhat lower rates of boiling the better insulated column has the lower efficiency. However, the better insulated columns can be operated at velocities below those possible with poorly insulated columns, and under such conditions the better insulated columns have greatest efficiency, 6. The results with qpiral packing in the 3-mm. column re-
quire further investigation because of the unusual way in which efficiency varies with rate of boiling.
Experience in operating the columns leads t'o the following conclusions : 1. Operation of the columns becomes more and more dificult as the rate of boiling becomes very low because the slightest variation in the insulation of the column or heat input to the pot destroys the equilibrium in the column. For successful operation at very low rates of boiling the columns should be insulated almost as well as a calorimeter. Under such conditions efficiencies as high as thirty plates per foot seem possible. 2 . The 3-mm. column is so difficult to operate smoothly that its further use is probably undesirable unless further work with packed rolumns shows substantial advantages over the 6-mm. column.
Literature Cited 1) l ~ v u d k eQuiggle. , and Tongberg, ISD. Exo. CHEK, 24, 410 (1932).
2 ) hlcCahe and Thiele, Ibid.. 17, 605 (1925). RECEIVED July 16, 1936. Presented before the Division of Petroleum Chemietry at the 92nd Meeting of the American Chemical Society, Pittaburgh. Pa . Yeptember 7 t o 11, 1926.
ANIMAL AND VEGETABLE OILS Viscosity-Temperature Characteristics Viscosities in centistokes at 100" and 210" F. were determined for some thirty animal and vegetable oils of various types. Other properties of the samples are listed. In general these products show high viscosity indices and low gravity indices. LTHOGGH >tattered data expressed in various units at many different temperatures exist for the yiscosities of animal and vegetable oils, apparently no coinparatiye collection has been made. I n the present investigation, viscosities at 100" and 210" F. (37.78" and 98.89' C.) have been found in fundamental units for about thirty common animal and vegetable oils possessing other physical and chemical characteristics as listed. From the combined data, viscosity indices, gravity indices, and viscosity-gravity constants were found. The oils are classified in groups according to the scheme used by Mitchell (9).
Oil Specimens The oils used were obtained from several sources and are believed t o be true samples. The olive oil, the second castor oil, and the second lard oil obtained from the Department of' Agricultural and Biological Chemistry had been tested for the addition of foreign substances. Although the other samples were not so examined, specimens from different sources were found in each case to be remarkably uniform in their properties. The last three rosin oils listed are certain cuts from the fractionation of the commercial rosin oil whose properties are not included in this report.
A. R. RESCORLA A N D F. L. CARNAHAN The Pennsylvania State College, State College, Pa.
Methods and Apparatus Seutralization and saponification numbers were obtained by methods much the same as the A. S. T. hl. procedures (1). Specific gravities at 20" C. (68" F.) relative t o water at 4" C. 39.2' F.) were found by pycnometers; division of these values by the factor 0.999 gave specific gravity a t 60" F. 15.6" C.) This factor was derived from the experimental Yalues shown in Table I and represents the ratio between -pecific gravity a t 68" and a t 60" F. for eight oils of different classes. The corresponding value for petroleum oils is 0.9968 '3'). Refractive indices a t 68", loo', and 130" F. (20', 37.78', .tnd 54.44' C.) were evaluated by an Abb6 refractometer. TABLE
1. VARIATION O F SPECIFIC GR.4vrr.i WITH TEMPER.~TURE FOR SOMEFIXED OILS
Ratio Sp. Gr. 6S0/ Sp. Gr., Chtnge in Sp. G I 15.6'/4' C . Sp. Gr. mi 1 O o / 4 O C . 37.78'/4O C. Per C. Per ' F. (Calod.) 60' F. Almond 0.9188 0.9141 0.00026 0.00015 0,9200 0.998; Rape0.00037 0.00021 0.9023 0.9990 seed 11.9114 0.9078
-
-Sp,
R e f i n d.__
Gr. -
--
perilla 0.9329 Castor 0.9619
0.9294 0.9580
0,00019 0.00022
0 00011 0.00012
0.9338 0.9629
0.9990
kernel U.9190 Yeat'sfoot 0.9158 3ardine 0.9384 Sperm 0.5829
0.9154
0,00020
0.00011
0.9198
0,9990
0.9105 0.9351 0.8800
0..00029 0,00018 0.00016
0.00016 0.00010 0.00009
0.9171 0.9392 0.8536
0.9986 0,9991 0.9992
Pllrn -
0.9990
Kinematic viscosities at 100" and 210" F. (37.78" and 98.89" C.) in centistokes were determined by the use of modified Ostwald pipets (4, 11). Viscosity-temperature change is expressed in terms of the kinematic viscosity index #$), The Saybolt viscosities were obtained from a conversion table (8). From the Saybolt viscosity at 100" F. and the specific gravity a t 60" F., the gravity index ( 7 ) may be found ilr +he viscosity-gravity constant (6) calculated.
