May 1, 1921' 



THE INDIA RUBBER WORLD 



565 



pass oxygen along from the air to the oil. The result is that the 

 oil finally becomes permanently hard and the surface of the 

 wood is protected. For 100 kilograms of oil, the manufacturer 

 of varnish would use not more than one kilogram of the drier. 

 This is equal to one per cent. In fact 1/10 of one per cent in 

 many cases is quite sufficient to induce drying. 



The accelerators used in the rubber industry, are generally 

 recognized as catalytic agents, used for the purpose of carrying 

 sulphur to the rubber, and helping these two substances to com- 

 bine chemically. Charles Goodyear in his early experiments dis- 

 covered that raw rubber could be converted into a useful sub- 

 stance by mixing it with a certain amount of sulphur, and heat- 

 ing thi» mixture while it was under compression. 



Later it was found that the addition of litharge hastened the 

 process of vulcanization, and so this substance was recorded as 

 an accelerator, or as now termed a catalyst or "carrier." In this 

 particular instance the litharge is a carrier of sulphur, but there 

 are other substances which, being similar to litharge in chemical 

 behavior, act in the same manner. These are the oxide of cal- 

 cium (lime) and the oxide of magnesium (magnesia). 



TECHNICAL PROPERTIES OF METALLIC SOAPS 



If rubber has been properly vulcanized its physical properties 

 of tensile strength and elasticity increase to a marked degree. If 

 a varnish has been properly dried, we will note a similar change. 

 This, and many other observations make clear why the rubber 

 industry has much in common with the other industries which 

 use plastic masses. Thus we find that several mineral soaps ; 

 the oleates and stearates of lead, and magnesium and calcium, 

 have been applied successfully to the rubber-sulphur compound 

 for the purpose of hastening vulcanization. Besides those just 

 named, aluminium oleate, stearate, and resinate, and zinc oleate, 

 stearate and resinate deserve attention as possible compounding 

 ingredients which will give to the rubber mixture some property 

 hitherto unknown. 



LEAD OLEATE 



The properties of lead oleate which commend it to the con- 

 sideration of chemists and compounders in the rubber industry 

 may be summed up thus : 



1. It is possible to use as much as five pounds of lead oleate for 

 each 100 pounds of rubber used. 



2. The oleate ran be incorporated without having the batch 

 become soft and sticky. 



3. If more tlian five per cent is used, the batch will not become 

 soft or sticky, or difficult to work on the rolls. 



4. Five pounds of oleate appear to be equivalent in action as 

 a catalyzer to three pounds of litharge. 



>Pb 



5. The molecular weight of lead oleate is 487 equal to the 

 formula : 



C^HaaCOO 



Q,H„COO 



It contains 42.5 per cent of lead by weight, and has a specific 

 gravity of 1.50. 



6. Owing to its oleaginous nature, lead oleate is easily mixed 

 with the rubber, and more uniformly distributed in a shorter 

 time, than is the case with litharge. The amount of lead in 

 litharge or lead oxide is 93.0 per cent. 



7. Lead oleate is preferable to aniline as an accelerator in those 

 cases where poisonous vapors are objected to. 



8. Oleate assists cohesion of the ingredients and helps the com- 

 pound to stick together. 



9. Oleate prevents blooming of the sulphur in the finished rubber 

 product. 



10. Oleate costs $29 per cubic foot, weighing 93.6 pounds. 



11. When litharge is used, there is danger of burning the 

 compound on the mill or calender, but if oleate is used this 

 danger disappears. 



12. Lead oleate can be used with impunity in the same com- 

 pound with bone glue. 



CHEMICAL FORMULAS 



Oleic .acid is a derivative of the olcfiiic hydrocarbons and is a 

 liquid at ordinary room temperatures, whereas stearic acid is a 

 derivative of the methane hydrocarbons, and is a solid waxy 

 substance at ordinary temperatures. The molecular weights are 

 given below : 



Oleic acid Stearic acid Resinic acid 

 Molecular Molecular Molecular 



Weight = 282 Weight = 284 Weight = 656 ? 

 CH, CH, (C,H,) 



I I I 



(CH,): (CHO„ (QHO 



I I I 



C CH= (COOH), 



I! I 



C COOH 



I 

 (CH,), 



I 

 COOH 



M.\GNESiuM Oleate is the product obtained by heating magnesia 

 with oleic acid and is a plastic mass much softer than lead oleate. 

 It can be used in compounds both for its lubricating properties 

 as well as its ability to accelerate the cure. 



Materials 



Oleic acid... 

 r.i]mitic acid. 

 Stearic acid . . 

 Peanut oil . . . 



Soya oil 



Corn oil 



Rape oil 



Cotton oil. . . . 



Tung oil 



Linseed oil. . . 



Perilla oil 



MenV."»d':n oil 



Physical Properties of Some Oils, Fats, Waxes and Resins 



Specific MeltinR Specific 

 Gravity Saponification Point Materials Gravity 



at 15° C. Value Degrees C. at 15° C. 



.898 ... 14 Hog lard oil .916 



.853 ... 62 Palm fat 9^5 



■*^' ••• 69 Tapan fat. '.'.V.'.'.'.' .'.'.'.'.'.'.'.'.'.' ! .970 



.920 191 tj Coconut fat .911 



.925 193 Cottonseed stearin .920 



■'?' }?? « Candelila wax .983 



ill j" Carnauba wax 995 



■'-2 19* c Beeswax 960 



.936 193 i: Wcol wax ,973 



932 194 f- 1 . 



gin \ho £ Gu,iyule rcsin 



•9^'^ "" t Pine resin 1.080 



.930 191 _: Jelutong resin 



Melting 

 Saponification Point 



Value Degrees C. 



193 Under 20 

 190 — 205 30 — 42 



220—240 50—55 



245—260 20—25 



195 40 



65 67 



JO— 85 84 



90—96 60—65 



98—102 40 — 42 



<20 



130 



160 



Rl'le to Determine the Volume Cost of Materials 

 One cubic fo<.t of water at 16.5 degrees C. wcichs 62. ,^55 pounds. The specific gravitv of water is l.OOO. A substance having a specific 

 gravity of 0.963 will weigh: 62.355 X 0.963 = 60.05 pounds per cubic foot. If this material is quoted at 12 cents per pound, it will cost: 

 12 X 60.05 = $7.20 per cubic foot. Therefore: 62.355 X specific gravity X price in cents per pound is equal to the price of the material 

 per cubic fr>ot. 



