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THE INDIA RUBBER WORLD 



Tl-LY 1, 19J1 



Carbons and Hydrocarbons Used in the Rubber Industry 



A Study of Carbon Blacks. Oils, Fats and Waxes of Mineral Origin 



By Frederic Dannerth, Ph.D. 



THE materials used for imparting a black color to rubber com- 1. What influence does it exert on the tensile strength, elasticity, 

 pounds are either pitches or carbon pigments. The former elongation before rupture, permanent set, and life, of a rubber 

 class includes the pitch obtained from coal-tar; blown or compound? 

 oxidized petroleum pitch; asphalt pitches; gilsonite products, wood 2. How does it influence the density and toughness of the corn- 

 pitch and stearin pitch. The carbon pigments include graphite, pound, and its resistance to abrasion? 

 powdered bituminous coal, hone black, lampblack, and gas black. 3. Does it "fly" in the mixing room and is it injurious to the 



The pitches, or "hydrocarlwns" as they are called in the factory, health of the workmen? 



are valuable chiefly because they render the compound oil-resistant 4; q^„ jj be used to advantage to replace rubber? 



and steam-resistant. .\t the same time they impart a good black 5 yj^^^^ advantage has this material over zinc oxide? 



color to the finished product, especially when used m conjunction g ^^,,^^j .^ ^^^ maximum amount which can be used for every 



with lead compounds. Their prmc.pal value, however, lies m the ^^ ^^^^^^^ ^^ ^^^^^^ .^ ^ ^^^^^^ compound? 



fact that compounds containing 3 and even 10 per cent of these hy- _ , .... . ^ ... , , ^ 



, ,' . • T .1. J *u ^- vVhat is the maximum percentage which can be used to 

 drocarbons show a great resistance to aging. In other words, the 



material, because of its wax-like character, has mixed with the t> -r, .u r l- v. , • j , • ■ -li 



, ■ , r ^t. ^ J • u ii . II ™„^» o- JJoes the use of this black in a compound make it impossible 



other materials of the compound in such a way that all or most '^ ' 



, , . , . , , T^, ,. • ,, . 41 to use anv other materials ? 



of the minute pores have become sealed. The result is that the r, , ', ■ , , , , • , , , 



, , . ^ »i 1 .,1. 1,1, - ij „»i,„,..,:c„ K= ='• i" which rubber compounds can it be used to best advantage? 



oxygen of the air cannot attack the rubber as would otherwise be ' ,,,,., ■ ,- 



, TL i-j- /: ^1. J ■ 1 1 I .u„ i.,.-f !"• i" which rubber compounds should it be omitted.' 



the case. The life of the compound is prolonged, and the product , • , j • • , , , , . . , , 



J ,.,. , f. ■. u 1 £. tu _ i,K„, „^^A„ 11- f" what phvsical condition should this material be when it 



maintains its good qualities long after it has left the rubber goods ..:,,. . -. 



, is delivered to the rubber manutacturer ? 

 lactorv 



pj^.j. J YHE CARBONS '-• How should it be prepared at the rubber factory in order 



_, , , . ^ ..■ J I, i. .• 1 ij ko to incorporate it properly with the dough in rubber compounding? 



Of the carbon pigments mentioned above, attention should be ,,,,,, c •,,,,, , •, • • . 



,, , , , , J J u-» _,• „i „ „ „„^ „„j;„„ 1^- vVhat specincation should a black meet if it is to be used to 



called to the value of powdered bituminous coal as a compounding , , , 



mineral filler especially adapted for steam packings. For this best advantage. ^ ., ^ . 



^ . , c I » onn „u I „„f..,^ki„ ''*■ flow much mineral matter, carbon, and oil does it contain? 



purpose It must be of a fineness equal to 200-mesh and preferably , . ' , , , , 



,,^ , , ... ., k ui 1 u u„„„ .,^^A (^, -, l3- VVhat advantage does it offer over lampblack, or over pow- 



SOO-mesh. Lampblack or oil carbon black has been used for a .^ ^ h . e 



considerable period in compounds of all descriptions and uses, ^^^ ^°^ '1 • , , r ,, 



. / .L £ r •.. •■ ' ,j »!,„ i,i,..i. „^1„, ,.,v,,vv, lo- vVhat IS the volume cost of a rubber compound containing 

 because of the fineness of its particies and the black color which , . , . ., , , , 

 . . , , .^ » tu A^^^^A on^f ^r^^„/-orl this material as compared with a similar rubber compound con- 

 it imparts. -■Xs a rule it represents the condensed soot producea . . ,.,,.. . , . 

 ,.,,.,. -1 <■ i 1 J 1 ... „_ k., ,„<..! taming an equal weight of zinc oxide? 

 when high boiling oils of petroleum and coal-tar are burned. = . . , . -.i • • .l r • • ■ l 



_ , ., , I... • J k k • . .,1 ^ ;„ o„^v. o I'- What defects will arise in the process of mixing or in the 



Gas carbon blacks are obtained by burning natural gas in such a , , .. .,. . . , ,. ° 



, ^, ■ rp, !,„,.„ .,1.,^ koor, process of vulcanizing, if it is improperly prepared.' 



way as to cause separation of the carbon. They have also been *^ ,„ ,,., . , , •„ ■ ■ . 1 .. , 



.,1k..-- »i™ _...:.i„o.. ;„ v,«t 18. What defects will arise in the use of a rubber product con- 

 produced experimentally bv atomizing petroleum residues in hot . . .,.,.. , . , -, , 

 : T .1 • ..L 1- -J - .J :„» „ «.,o „..„. taming this material, if it is not properlv incorporated with the 

 iron retorts. In this wav the liquid is converted into a gas very * , . , ,, , , - 



. ■ . t , L J- "ik .k 1 - Tk., „„„„:(;„ „,.,„;*„ compound in the rubber tactorv .' 



rich in hvdrocarbons of the ethylene series. The specific gravity ,„ ^ , • , , , , J r 1 1 - , j 



of this m'aterial, after complete exhaustion of the air, was found . 19. Is this black acted on by any of the oUier materials used 



to be 1.7290 Owing to its peculiar method of manufacture carbon '" ^"^ber compounding? 



produced from natural gas is practically free from oily matter VOLUME COST 



and its particles are in an extremely fine state of sub-division. Although rubber and the various compounding materials are 



The melting point of carbon is above 6500 degrees F. This latter purchased and sold by the pound, it will be realized on close 



fact in itself makes it a material of preeminent importance in cases examination that the majority of rubber products are sold on 



where the finished rubber product is exposed to high temperatures. (j^g j^^^jg ^f volume. For that reason, the oMer method of calju^ 



Graphite, artificially produced, has recently been considered as x^^^^g costs of compounds has now been supplemented by the 

 a compounding ingredient for the rubber industry. It was dis- determination of the volume cost of the compound. As a stand- 

 covered some time ago that graphite can be obtained by suitable ^^^ ^f comparison one may choose one cubic foot and note the 

 decomposition of a carbide. This artificial graphite cannot be „umbcr of pounds of the material required to fill that volume, 

 produced by mere heating of pure carbon. The industrial process p^j. example : 



consists in using anthracite, with about 10 per cent of ash, as a Specific r- One Cubic Foot ^ 



furnace charge. The anthracite coal may be converted into Gravity Weighs, Pounds Costs 



graphite while in powdered form. .\ furnace 13 feet long will Water 1.00 62.5 @ ... 



consume 1000 h.p. in this operation. Kuhler 0.93 58.0 @$0.25 $14.50 



Zinc oxide 5.75 360.0 @ .10 36.00 



VALUATION OF A COMPOUNDING INGREDIENT Gas carbon black 1.75 109.4 @ .20 21.90 



The questions which arise in connection witli the use of carbons ^^ ^^.^^ ^ ^^^^^^^ ^^^^ ^^^ ^^^^ ^^ ^^^^.^^ ^^^^^^ ^^^ ^^^^.^ ^^^^ 



in rubber compounding natural y vary from one case to another, .^ ^^^^ ^^^^ ^^^^ ^^ ^^^ ^^.^^ ,^^^ ^^.^^ magnesium oxide, iron 



depending upon the use to which the fimshed rubber product is ^_^^ ^^^^^^^ 

 to be put. There are, however, certain points which apply in 



many instances, and in the case of a carbon black used for rubber METHODS FOR INCORPORATING BLACK PIGMENTS 

 compounding a complete investigation should furnish answers to xhe methods for incorporating gas black in rubber compounds 

 the following questions which refer only to carbon black: depend upon the preparation of a "master-mix" for the purpose 

 of removing the air from the black fluffy powder. William Geer 



1 This article may not be reprinted without permission of the .luthor, ^.^j j|^g g p Qoodrich Company in 1917 obtained a United States 

 who reserves all publication rights. 



