INDUSTRIAL A N D ENQINEERIPG CHEMISTRY
June, 1930
603
is extremcly important to prevent any considerable tempera-. ture drop in t,he air filters or in the conveyor leading to the packaging departnieiit, since the slightest condensation of water from the moist air canses the powder to stick and ball up. Tbe walls of the spray chaniber are accordingly insnlated with a iialf-inch layer of asbestos, and the filter units, hopper, and coiiveyor are also ~uellinsnlated. Figure 5 shows two of t,he air filter nnits as now insulated, while tlic insnlat,cd hopper bottoni and the end of tlic screw conveyor lionsing are evidmt to the tipper rigbt of Fignre 1. As a rrsult, of the prPcautions t,akPn in tlir inattcr of insulation, tlic opcratcs witiiout difficulty. T i i e product is do temperatiire olapproxiiiiately 65" C. (150- P.) with anioisture erated without any preconcapacity of li00 to 1800 how. The spray chamber lave been in operation for one year. I n the second unit now under constrnction there will he a rex, minor changes. In addition t.o t,he w e of nickel in the milk lilies to the drier, the screw conveyor will be elimin a k d by locating the sifting and packaging .equipment directly beneath t,hc hopper of the spray chamber. This arrangement was not, possible with the present installation beenuse of the existing plant layout. Figure 5-Two
of the
Twelve Air-Filter Unitci Mounted
on the Spray Chamber
Acknowledgment
atid t.lie resistance to air f l i i v through the filters. IJnder nornial operating conditions the pressure drop through the filters is 5 inches of water. Recorders also indirate the temperature in the body of the spray chamber, which runs very close to 7 i " C. (170' P.). It
Acknowledgment is dun to the Laboratory Products Company and t o the Dust Recovering arid Conveying Company, both of Cleveland, Ohio, for couperation in tbc preparation of this article.
Preservation of Highly Polished Surfaces' A. C. Hanson ROCX ISLAND ARSBNAL LABORATORY, Roc=
HE corrosion grobleni of tlic Ordnance Ikpartnient of the Anny consists of preserving a highly polished sur-
1 s ~ ~ h - ILL. n.
During the test the minimum temperatrrn: was approximately 21" C. For this rcason the first set did not show rust
face for ten or fifteeu years wit.h an easily removable coating. The fact. that. no perfect rust-preventive compound has yet been found for this porpose was thought to be due partly to applying tire rust preventive udiile t,iiere was a t,hin film of moisture on tlic metal, thus entrapping tbe nioisture and allowing corrosion to begin. To stndy t.be effect of humidity, a cabinet was constructed of moue1 metal, containing a hygrorrieter and Iialders for stoppers of bottles so made that the stoppers could be placed in the bottles withont opening tbe cabinet. A beaker containing solutions of salts to give tbe required humidity was placed in a hole in the bottom of tho cabinet and heated when necessary. When the correct humidity was obtained, the temperature was kept constant for 1 bonr, afier n-bich the bottles containing the steel samples were stoppered, removed, and sealed with wax. There were three bottles containing samples in each of eight sets representing various humidities. S41
Am TBIP.
fluM~DxTY
Daw PumT
WT. OF Ha0
'C.
I
Perrrnf ' C . 30.5 54 20.5
Mi. 1.328
I1 111
25.8 29.4
22.2
1.535
SI
92
27.8
2.124
Received January 2. 1930.
RBSULTS
Placed in refrigerator after 74 days, showed rust in 4 days Traces of rust after 104 days Rust in 5 d a y r
Humidify Cabinet A-Eeaker with humidifying solution B-Rottler with steel specimenr C-HygrOmeter D-Holders for stoppers
604
I S D USTRIAL AND ENGINEERI-VG CHEMISTRY
until placed in the refrigerator. The last set showed rust when examined after 5 days. It probably rusted the first night, when the temperature fell below the dew point. The second set did not show rust for some time because the tests were conducted during the summer months and therefore the dew point was not reached until the latter part of the summer. The traces of rust as found under the microscope were identified by placing a small drop of a solution of am-
Vol. 22, s o . 6
monium sulfocyanate in a 10 per cent solution of hydrochloric acid, on the supposed rust. A red color in the solution proved the presence of rust. From the results as shown in the accompanying table it seems that high humidity does not necessarily mean corrosion. Unless the moisture is precipitated on the metal, there will be no corrosion. Therefore, it is a matter of dew point and not humidity.
Use of Ethylene Dichloride in Lacquer Formulation' R. B. Frazier and E. W. Reid MELLOXINSTITUTE OF
INDUSTRIAL
RESEARCH, CNIVERSITY OF PITTSBCRGH, PITTSBURGH, PA.
velopment of a number of new solvents that adequately meet the requirements of the lacquer industry. On the other hand, the lacquer diluents have been limited to the aromatic and petroleum hydrocarbons, which have certain disadvantages but because of their low cost and availability have found universal use. Recently the attention of the industry has been directed to ethylene dichloride as a combined diluent and solvent. This product is a colorless liquid of characteristic odor, boiling a t 83.5' C. It is a n excellent solvent for resins and oils and in combination with alcohol becomes a solvent for nitrocellulose and cellulose acetate. It is available a t a low price and permits the use of minimum amounts of the more expensive lacquer solvents. There is a very definite prejudice against the use of a chlorinated compound by the lacquer industry. This i\ probably due to the tendency of the solvents. heretofore available to hydrolyze in the presence of moisture with the accompanying corrosion of the containers and discoloration of the lacquer. Ethylene dichloride, on the other hand, may he safely handled in the presence of water a t boiling temperature, in iron or other metal vessels without danger of corrosion. Sitrocellulose and cellulose acetate lacquers containing large quantities of ethylene dichloride have been prepared and stored in metal containers for two years with no indication of corrosion of the metal or diwoloration of the lacquer. Under identical conditions the more commonly known chlorinated solvents hydrolyzed readily, corroded the metal cans, and discolored the lacquer within a few days. The Iom flammability of ethylene dichloride is a distinct advantage. This compound is on the border line between the fire-extinguishing hydrocarbons and the combustible d v e n t s . Under the normal conditions of use this compound may be ignited by a flame, but when this flame is removed the draft from the combustion will extinguish the solvent flame. Being heavier than water, its flame is easily extinguished by water in contradistinction to the usual solvents and diluents, which will float and burn on the surface of the water and can be extinguished only by chemical means. Inhalation of the vapor of ethylene dichloride is not dangerous, although, as in the case of any organic solvent, it is to Presented before the Division of Paint 1 Received April 15, 1930. and Varnish Chemistry at the 79th Meeting of the Amerlcan Chemical Society, Atlanta, Ga , April 7 t o 11. 1930
line (1). Solvent Action
Among the most important considerations in the use of ethylene dichloride as a diluent is its solvent action on the non-volatile constituents of the lacquer in the presence of and in conjunction with the usual lacquer solvents and diluents. The solubility of nitrocellulose and cellulose acetate was determined in several three-component solvent mixtures. These data are graphically expressed by means of triangular coordinate charts and indicate the percentage volume composition of solvent mixtures that would dissolve 8 per cent by weight of the cellulose ester. With 1/2-second R. S. nitrocellulose these data show: that the active solvents tolerate a larger amount of an ethylene dichloride-alcohol mixture than of either component alone; that the optimuni ethylene dichloride-alcohol mixture, indicated by the maximum tolerance, consists of from 60 to 80 per cent ethylene dichloride to 40 to 20 per cent alcohol; that the optimum mixture of ethylene dichloride and denatured ethyl alcohol requires but 1 per cent of an active solvent to give a complete sol ut io11. Table I-Solubility of Some G u m s a n d Resins 807, ETHYLEHE 80% ETHYLENE DICHLORIDE DICHLORIDE 20% DE2 0 7 ~DE-
ETHYLENEN A T U R E D
SCBST.ANCE DICHLORIDE .ILCOHOL Bodied linseed S oil S S Blown castor oil S S S Amberol S Albertol S S Bakelite S S S Cumar S S Camphor PS S Dammar S ss Elemi S S Ester gum Guaiac
Gliionite S = soluble soluble
ss
ETHYLENE NATCRED
SUBST.ANCE DICHLORIDE .%LCOHOI, Kauri I S Manila S Manila ester ss Mastic S Rosin S Glyptal I Sarpee SS Sandarac SS Shellac X'inylite A S l-inylite 80 S
S
S s 5 S = slightly soluble
PS = partly soluble
I = Ln
This indicates that a mixture of 80 per cent ethylene dichloride and 20 per cent ethyl or methyl alcohol is practically a solvent for nitrocellulose, requiring only the addition of a very small amount of an active solvent to effect solution. Attempts to determine the dilution ratio of the 80-20 per cent mixture by the usual means were not successful, a- no precipitation of the nitrocotton occurred.
