I N D U S T R I A L A N D ENGINEERING CHEMISTRY
326
Vol. 22. No. 4
Nitrocellulose of Low Viscosity' M. G. Milliken HERCULBS POWDER COMPANY, WILMINGTON, DEL.
38
ORIGINAL VIXOSITY APPRO%. 500 5EC.,Nzx12.25Y.
3s 34
VISCOSITY DROP AND NITROGEN REDUCTION VS.TlML OF DIGL5TDN.
k 3L
5 30
366 X)LVENT=ETHYL ACETATE 20. ETHYL ALCOHOL 2 5 , TOLUOL S I PARTS BY WEICHT.
320
326 2R 24
-Z
Z *O ;le
3'" $14
ucts of denitration are not removed when reduction in viscosity is accomplished in solution. Some other methods of reduction in viscosity give greater denitration-for example, the use of pyridine. This reagent has never come into use because it discolors the nitrocellulose badly and the last traces cannot conveniently be removed, so that the viscosity of the finished nitrocellulose is likely t o continue to fall in storage. The commercial practicability of the preparation of nitrocellulose of low viscosity by heating in autoclaves with water having been established in semi-plant units, events then moved rapidly to factory production, using a brick-lined digester containing 1000 pounds of nitrocellulose and 12,000 pounds of water per charge. The next step was the use of welded steel, brick-lined digesters holding 4000 pounds of nitrocellulose and 60,000 pounds of water per charge. As many as ten of these were in operation at one time. As the size of the digesters was increased, more difficulty was experienced in providing adequate removal of the gases arising from the slight denitration of the nitrocellulose. The oxides were entrained by the fibrous nitrocellulose, causing false water levels in the digesters. I t was probably this entrainment of gases that caused dry spots in the digesters and the serious accidents experienced by some users of batch digestion.
2 0
1
9
3
4
IO
HOURS D16ESTlON AT 132. C.
incorporated in such lacquers, and sufficient nitrocellulose could not be put in to produce a thick film, because in doing so the solution became too viscous to apply. There was a distinct field for nitrocellulose of low viscosity, which would allow the preparation of a lacquer containing relatively large amounts of nitrocellulose and pigment and still be of such a fluidity as to permit application by brush or spray gun. Development of Process
The first nitrocellulose of low viscosity made in this country by this company was prepared by heating a mixture of nitrocellulose and water in a small hospital sterilizer behind a boiler-plate shield. Since promising results were obtained, the next step was the use of small autoclaves, in 15 hich temperatures and pressures were controlled, studied, and correlated with viscosity reduction and degree of denitration. The data obtained are shown in the accompanying graph. In all methods of viscosity reduction some loss of nitrogen content is encountered, no matter whether the reduction is carried out in an aqueous suspension or in solution in a solvent. For example, in pressure digestion in aqueous suspension a viscosity reduction from 500 to second is accompanied by a drop in nitrogen content from 12.25 to 12.05 per cent. This is a relatively slight denitration, and the products thereof pass into the aqueous suspension and are removed in the washing operation which follows. Such prod1
Received March 5, 1930.
Tower Supporting Back-Pressure Standpipe
It was realized from the very start that a prime necessity for safe operation was the maintenance of a submerged state of each and every particle of nitrocellulose by thorough circulation. However, in spite of all precautions, high pressures developed in several digesters. I n no case was there the slightest evidence of detonation. Indications of the recording pressure gages showed sudden rises in pressure. No
1:ontinuou*
uigestrr coils
crnfrlfuyal Pumps Connected in Series
tkiorc innrkctiirg i,lie prcalimt of (,mtiiIiiuw digestioii i t quaiitities, at a great uiiiformity, aiid with a iriiiiiiirum of tested w r y tliuroughly as to propertics a i d tho proper- labor. The t,otal qiinritity of nitrocellulose in the continuous ties of pmrliicts coiitairiii,g it,. It was fourid to be in 110 way digester at any tiine is 601) poimds. No operator is in thc iiiferior, and in soinc respects sularior, tu t,lie i1itrocellulovc coil rooin during operation. Property damage in case of a inatic by bat,oh digestkrn, altliough of a surnewliat deeper burst coil u~ouldbe relatively small, because of the inlierent color. This drrprr color was foinid to bc in no wa,y detri- design and because the ainouiit of water in the system, which mmit,nl to ilre production uf e v r i i t,lie irrost deiicatciy tiirt,t.il coiild possibly flash into stenni, is only about 13,000 Iioiulds lacquers, and the discoloration of lacquers on agiiig was i i i as compiircd t o W,OOO pouiids in the former digester. Since ironiirg out, tlie starting-up difliculties, a coinsrieri:ial . iio way worse t.liari iii tlie batch product. uutput of over 6 sriillioii poiinds testifies to tlie surcess of Advantages of Continuous Process tlie equiprnent.. Patents have i)eeii obtaiiied or applied for in the Knited In C O ~ I I I ~ I O I I~ i t , i rmost contiriuoos operatiusis, the (witSbatcs and foreign i:ouiitries. tiiiiiws digeatcr makes limsilile the inaiiufactiire of large WBS
Fumigation with Ethylene Oxide' J. M. Russ. Jr. CAXlliOS
&
C A R B O N CIIIBMIC*I.S C"YP".*TI
I1E probleiiis of pest control are of such imlmrtnirw that iriuch inuriey and effort have beeii spent by E'rrlcral and State Govcriiments and by various industries 011 roh in the >rarious phases uf the subject. Iris C ~ I S of C their iiiany varieties and forms, have been Llie in, ilifficiilt pcsbs to combat. The most effective IlleRllS irating tliem, where the operation can he carried out, i n a gas-tight e~iclosurc,is by fumigat,iirir.
T
Previous Studies on Ethylene Oxide as B Fumigant
1)iiriiig an exhanstirc stiiiiy of clwmical coiripouiids, t of tlic Yoitetl States Ihpartineiit i l i i r i cthylenc uxiclc possesacs rem ( 2 ) . Etliylriie uxidc is a wlorlcss liquid wliicli h i s at 10.5" C. '~hcrcir~re Etlrj-Ieiic midi! hiis vi{, of 0.887 :tt i"i-1' :ii1:1r w ~ i ~ lofi t34.031, arid :I liowxl that it is not rlangeroualy toaii: t,si liiiiiiaii b?iii$w. JVVhen iiiiialed i i i suliicieirt c o i i c e i i t m t i w s it prdiiccs it kind of cyanosis, wliiali is i:ouriterac~~d t i y c::irl~uii dioxide gas. It wiis fouiid that, ill aii air-tight vault a climgc of 1 pi)uiid i~tliyleiieoxide per 1000 cuiriic feet uf vault space gives in 20 110ursa 100 per cent kill of the elotlx:s iiiotii, Tiricolu 6i~e11ic1l~z; of nri,,iis
1
Received February 14, l%U.
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thc carpet bectles, .4tl(i,gmi~.~ pireus aird . I d h r e r ~ u s ciiruz; the rice weeril, Sitophiliis oryzu; tire Isidiasi m e a l motti, t,lie san-toot,lied graiii beetle, Orwiethe rcil-k!gged liairi beetle, X c m i l i k rli$pi'~; and tlie flour bectle, Triholiiini ~~iJ:o11J't~sUffl.. It was reeniirrriciided that i n oonimercial fiiinigation a dosage of 2 pounds per 1000 cubic feet be ii I':xperirncrita with various foodst.isli's siiorvoil that 110 residual tastes or ni1or.s t m I d t ivitli iuaterinls which have bee11 in contact writli the v a p r s rii etliyleiie oxide during fuinigation. It, was also foiuid that t,lic vqiors of vthyieile oxide cxliit,it imi~siilcra,l~k p o w r s of penctratioii iiito dense inatrrials srioii as wlieat flour. Addition of Carbon Dioxide to Ethylene Oxide iitly ilie 13ureaii OF EiitiiinuhiKy has ifeloririiiicd t h t jii,t, iisr uf carboii dioxide perinits of rlcr:rcnsi tire tiirie of expimire iicc iliisngw d etliyleiie oxid
s (,j), Tlris is ascribed actio11 of irisocts whicli is car~sed lig tire 1.arlioii dioxide. A dnaagr of 1 p;,isrrd eilivlerie oxidc i ~ i i d7 pourids carbon dioxide mill give t.iie saisie results in 16 hours that 2 poiinda etliyleiie oxide alone rvill give in 20 hOllrs.
A mixture of 7.5 parts carbon dioxide aiid 1 part etlryleiie oxide is noli-iiiflammable in airy proportion in air ( 3 ) . Since
