April 1, 1921 



THE INDIA RUBBER WORLD 



489 



mixed with an equal volume of gasoline to form a clear liquid, 

 boiling between 115 and 160 degrees C. It may be that a use 

 for t^his solvent will be found either as a thinner for the varnishes 

 used on rubber-coated fabrics, or as a thinner for the sulphur 

 chloride used in the manufacture of dipped goods. The use of 

 butyl alcohol as a primary material in the manufacture of syn- 

 thetic rubber from starch was proposed several years ago. 



Fusel Oil. In the manufacture of ethyl alcoli&l from grain and 

 potatoes, a certain amount of fusel oil is formed. This is a mi.\- 

 ture of propyl alcohol, iso-butyl alcohol and amyl alcohol. Its 

 boiling point, therefore, ranges through those of its constituent 

 alcohols, and is higher than that of grain alcohol (79 degrees C). 

 Kusel oil mi.xe.-i with an equal volume of gasoline. 



Acetone. The material known to chemists as di-methyl ketone 

 is interesting to rubber goods manufacturers because of its pecu- 

 liar property of dissolving resins contained in crude rubber. Com- 

 mercial samples show a boiling point of about S7 degrees C, with 

 about 90 per ci.'nt boiling below 58 degrees C. (137 degrees F.). 

 It first came mto notice shortly before 1900 when experiments 

 were conducted on deresinating crude dry Pontianak or jelutong. 

 It was found in the laboratory that the resins of rubber could be 

 dissolved in acetone, and this observation was carried over into 

 factory practise. Accordingly, large deresinating plants for the 

 treatment of the jelutong were erected in Akron as well as at 

 Goebilt on the island of Borneo. This process becomes costly when 

 acetone sells at 93 cents per gallon and refined Hevea rubber sells 

 in New York at approximately 20 cents per pound. 



One other consideration, however, enters into the question and 

 -that is the peculiar properties of the jelutong resin which is thus 

 obtained from crude Pontianak. This resin is probably related 

 to iso-cholesterol and the nnsaponihable matter in wool grease. 

 It melts at about 160 degrees C. 



Acetone and grain alcohol are unique among volatile solvents 

 in that they both mix readily witli water, and both have a boiling 

 point far below that of water. 



In a recent article published by Andrew H. King in Chemical 

 and Metallurgical Engineering, mention was made of the fact that 

 the solvent used on an industrial scale for deresinating guayule 

 and Pontianak was composed of 53 gallons of 98 per cent acetone, 

 mixed with 47 gallons of gasoline. The acetone had a specific 

 gravity of 0.8041 at 16 degrees C. (60 degrees F.), while the gaso- 

 line showed a specific gravity of 0.7000 and contained practically 

 no residues boiling above 130 degrees C. (266 degrees F.). It 

 was shown that acetone and gasoline, when mixed in the per- 

 centages mentioned, will mix without any trouble at all. King 

 has also prepared tables showing the specific gravity of 100 per 

 cent pure acetone to be 0.794<5. while 90 per cent acetone (10 per 

 cent water) shows 0.8340 gravity. 



The deresination of 1,200 pounds of guayule requires 3,200 gal- 

 lons of mixed solvent, and the loss of solvent is about 44 gallons 

 of gasoline and 15 gallons of acetone. 



NON-INFLAMMABLE SOLVENTS 



We now come to the consideration of a group of materials 

 which are of exceptional technical importance because they are, 

 .as it were, "fire-resisting." They are, all of them, compounds con- 

 taining chlorine, and all of them are much heavier than water. 

 ■Carbon tetrachloride (or tetra-chlor methane), tetrachlor-cthane 

 and tri-chlor-ethylene are the volatile organic liquids to which I 

 have reference. 



Carbon TetrachiiOriue. Since about 1905 more and more at- 

 tention has been given to the production and use of this material 

 in the i)rocesses of the rubber industry. Its agreeable odor quick- 

 ly made it a favorite over the disagreeable-smelling carbon bisul- 

 ■phide, and the fact that it had a definite boiling point {77 degrees 

 C.) and was not acted on chemically by sulphur chloride, de- 

 manded the interest of many in the rulibcr trade. The price of 

 $1.63 per gallon, however, is prohibitive for its general use as a 



tliinncr in cements and doughs. The speed of evaporation is an- 

 other point which is sometimes left out of consideration in the 

 choice of a solvent. For example, the cement used for painting 

 the inner tube of fire hose should dry in IS or at most 30 min- 

 utes, but this would be impossible if a high-boiling, slow-evaporat- 

 ing solvent were used. 



Tri-chlor-ethylene. The "chlorine solvents" were introduced 

 over ten years ago, and one of the earliest makers of these prod- 

 ucts was the Bosnische Electricitaets Actien Gesellschaft in 

 Vienna, Austria. Like tetra-chlor-methane (carbon tetrachloride), 

 this solvent has a fixed boiling point below that of water, and a 

 specific gravity almost one and one-half times that of water. Its 

 current price of approximately $1.83 per gallon, including drums, 

 has interfered somewhat with its wider application, but at the 

 same time it should be recalled that these "non-flam" solvents can 

 be added to gasoline in definite pro|)ortions, and the result will 

 be a liquid which will not take fire. The fact that the vapors of 

 carbon tetrachloride will quench the flame of gasoline has been 

 put into practical use in the modern auto fire extinguishers. 



Tetrachlor Ethane. This solvent has a specific gravity of 

 1.600, sells at about $2.12 per gallon, boils at 147 degrees C, and 

 like the two previously mentioned chlorine derivatives, it is not 

 ignited by sparks of static electricity. For this reason, our indus- 

 trial chemists look forward with pleasure to the day when the 

 price of these solvents will make possible a wider use of them. 

 The spreader room fire is a bugaboo, and the fire hazard in the 

 cement churn room is also an item to be reckoned with. Were 

 the "chlorine solvents" now available at SO or even 75 cents per 

 gallon, it is safe to assume that many of our larger rubber goods 

 factories would rapidly consider their wider use. 



LABORATORY TESTS 



Speed of Evai'ORATIo.v. < Ine (jf the properties of volatile sol- 

 vents which determines their usefulness to a considerable extent 

 is that known as : "Speed of Evaporation." No standard methods 

 for determining this value have -been agreed upon but for the 

 practical purposes of the rubber goods manufacturer the follow- 

 ing method is satisfactory. 



Secure ten of the flat glass dishes technically known as "Petri 

 dishes" used for bacteria cultures. Weigh the dish. Weigh into 

 it ten or even twenty grams of the solvent. Expose the dish to 

 a temperature the same as the temperature which will be used 

 to drive off the solvent, when in actual use. After a certain num- 

 ber of minutes, place the cover on the dish, and weigh the residue. 

 It will be found that an exposure of 30 or of 60 minutes will give 

 interesting results. 



In a test such as this it will be found that petroleum gasoline of 

 low and undesirable grade will leave a residue of high boiling 

 oil, and this will interfere with its use as a wiping fluid in cases 

 where the surface of the rubber must be quite clean before a 

 second layer of rubber is applied. 



Action of Sulphur Chloride. In cases where a solvent is to 

 be mixed with sulphur chloride, a preliminary test should be car- 

 ried out to determine what chemical action, if any, the sulphur 

 chloride will have on the solvent. 



IMPROVED BURRS FOR RUBBER HEELS 



.\ new line of rubber heel burrs, so constructed as to be guar- 

 anteed perfectly centered, has been added to the products of a 

 manufacturer of high-grade metal specialties. The great dif- 

 ficulty in rubber heel burrs has been that the hole has not been 

 centered and the edges have been ragged, causing them to catch 

 in the mold pins and thereby inconvenience the pressmen and 

 hold up production. This new line of rubber heel burrs is a 

 clean-cut article, perfectly centered, made from high-quality cold 

 rolled steel. — Independent Nail & Packing Co., Bridgewater, 

 Massachusetts. 



