July 1, 1921 



THE INDIA RUBBER WORLD 



743 



patent" for the use of kerosene in connection with gas blacks. 

 The materials which can , be used to advantage in preparing a 

 masterrmix are : 



1. Pine rosin 4. Cylinder oil 



2. Petrolatum 5. Paraffine wax 



3. Washed and dried rubber 6. Reclaimed rubber 



Other reasons for preparing these master-mixes in advance of 

 the actual rubber compounding operation are : to reduce the time 

 required to incorporate the powder ; keep the main factory mixing 

 room in clean condition; and insure uniform distribution of the 

 gas black in the batch. 



The use of gas black produces tire compounds having a 

 relatively low specific gravity ; high tensile stren.gth ; high elon- 

 gation; low permanent set; and high speed of vulcanization. 



PROPORTIONS TO BE USED 



In compounding rubber for auto tire treads certain carbon blacks 

 have been used in quantities as high as 20 per cent of the total 

 batch, but 15, 10 and 5 per cent are the quantities used in most 

 instances for tread stocks. Five per cent in this case would mean, 

 for example, live pounds of carbon black in a total batch of 100 

 pounds. In the manufacture of high-grade black steam packings 

 it can be used to advantage in amounts up to IS per cent. In 

 other types of mechanical rubber goods such as railroad steam 

 hose, belting for power transmission, and conveyor belting, blacks 

 can likewise be used to advantage in replacing fillers of high 

 specific gravity. 



Speci.\l Mixtures. One of the more interesting experiments, 

 for example, carried out in connection with the present investiga- 

 tion of carbon blacks had for its aim the preparation of a com- 

 pound which could serve several purposes at one and the same 

 time. It was, for example, found possible to produce a mixture 

 which was quite tacky and at the same time possessed good lubri- 

 cating qualities. 



ANALYTICAL DATA 



The laboratory information which is of interest and importance 

 when deciding on the use of these materials for rubber com- 

 pounding includes figures on : 



1. Hygroscopicity. 



2. Moisture content of the materia! as delivered. 



3. Non-volatile mineral matter. 



4. Acetone-soluble matter. 



5. Fineness of the particles under microscope. 



6. Specific gravity. 



7. Cost of the material per cubic foot, based on its 



specific gravity. 



8. Tinting strength or coloring power. 



EXPERIMENTAL DATA 



In order to determine the inllucnce of gas black on the physical 

 properties of rubber several compounds were prepared, vulcanized 

 and tested. The results of these experiments are recorded below : 



Experiment 1. A compound was prepared containing — 



Rubber (plantation smoked sheets) 90. 



Carbon black 1.0 



Sulphur 9.0 



Vulcanize at 287 degrees F. for 165 minutes. 

 Tensile strength of compound, 2725 pounds. 

 Elongation, from 1 to 9.1 inches. 

 Permanent set, 1 to 1.10 inches. 



Experiment 2. A compound was prepared containing — 



Rubber 85.5 



Gas black 6.0 



Sulphur 8.5 



Vulcanize at 287 degrees F. for 180 minutes. 

 Tensile strength of compound, 2900 pounds. 

 Elongation, from 1 to 8.3 inches. 

 Permanent set, 1 to 1.14 inches. 



Experiment 3. A compound was prepared containing — 

 Rubber 77.5 



"Uniied States patent No. 1.245,700. 



Gas black 15 q 



Sulphur ] ' 7 J 



Vulcanize at 287 degrees F. for isO minutes. 



Tensile strength of compound, 3260 pounds. 

 Elongation, from 1 to 7.6 inches. 

 Permanent set, 1 to 1.22 inches. 



Experiment 4. A compound was prepared containing— 



^"''•'7 •, 61.0 



Gas l^'ack 33.0 



Sulphur gQ 



Vulcanize at 287 degrees F. for 165 minutes. 

 1 ensile strength of compound, 3750 pounds. 

 Elongation, from 1 to 5.5 inches. 

 Permanent set, 1 to 1.4 inches. 



This compound showed a greater tensile strength than all other 

 mixtures which were tested. Almost equal results were obtained 

 with a mixture containing 200 ounces of rubber plus 100 ounces 

 of gas black. 



Experiment 5. When zinc oxide was used in place of gas black, 

 the greatest tensile was observed in a compound containing— 



^."''bcr, 56.0 



Zinc oxide 37 q 



Sulphur 5 Q 



Tensile strength of compound, 3300 pounds. 



Elongation, from 1 to 7.0 inches. 



REFERENCES 



The following articles published in The Indi.v Rubber World 

 and pertaining to carbon blacks and colloid chemistry, are inter- 

 esting for collateral reading: W. B. Wiegand, October 1 

 1920, page 21; H. F. Schippel, January 1, 1920, page 208;' 

 E. B. Spear, September 1, 1920, page 809; G. L. Cabot 

 September 1, 1920, page 810. 



In the Journal of Industrial and Engineering Chemistry: G. 

 S. Perrott and R. Thiessen, April 1, 1920, page 324, contributed 

 from the United States Bureau of Mines, Pittsburgh, Pennsyl- 

 vania, 



PART 2. THE REFINED HYDROCARBONS 



Mineral Oils, Fats and Waxes. These materials are charac- 

 terized by the fact that they are all "unsaponifiable" because they 

 are derived or prepared from petroleum and other mineral prod- 

 ucts. In geiieral it may be said that a "parafiine base" petroleum 

 will yield solid hydrocarbons of the paraffine series, and the 

 "asphalt base" oils are rich in asphalt, but contain no solid paraf- 

 fines. Hydrocarbons of the define series are present in petroleums 

 in small amounts. 



Lubricating Oils. When the original crude oil is distilled there 

 is a residue of about 12 per cent, which is known as tar. It has 

 a specific gravity of about 0.9250 and contains lubricating oil as 

 well as wax. The oil is separated from the wax by refrigeration, 

 and purified by washing and distillation. Finally an oil of about 

 "28 Baume" is obtained. With a specific gravity of 0.886 this is 

 also a low-viscosity lubricating oil. Cylinder oil and spindle oil 

 are much heavier in body and have a high "fire test," flash 260 to 

 320 degrees C, high viscosity (100 to 230 seconds at lOO degrees 

 C), and low "cold test," because of the way in which they are for 

 the most part employed. 



Petrolatum is a substance resembling in a measure the greases 

 obtained from plants. It is made from selected crude oils by 

 careful reduction and finally, filtration through fullers' earth or 

 bone black. Reduced oils are obtained by driving oflf or distilling 

 ofif the light fractions of the crude petroleum without cracking. 

 Instead of heating them by direct fire they are distilled by the 

 aid of a vacuum and by superheated steam. Petrolatum or vase-, 

 line has been used in rubber works for softening certain gums. 

 For example, when Pontianak is washed and dried and then 

 cooled, it appears as a rather brittle mass, but the last parts of 

 the water are removed with some difficulty when treating large 

 quantities. The conversion of the ponti into a plastic mass which 

 can be weighed off conveniently in the compounding room, is the 

 most desired thing. To this end it is mi.xed with a fixed per- 



