November 1, 1915.] 



THE INDIA RUBBER- WORLD 



63 



What the Rubber Chemists Are Doing. 



S1)I,L' I li )XI':n fabrics ii^cil in Imildiiig aiUcinidliiK- tirt- casings 

 may lie injured Ijy action (if sulphurous or sulphuric acid 

 formed during the vulcanization process. Protection against 

 tliis possibility may be secured by impregnating the fabric, pre- 

 vious to sohitioning, with such salts as the double sulphates of 

 zinc and ammonium, magnesium and ammonium, or acetate or 

 carbonate of ammonium. The amount of these salts should 

 vary from live to thirty per cent, of the rubber employed in the 

 tire, and if desired may be added to the rubber solution as a 

 compounding ingredient. 



V. Cayla, in a recent issue of "Le Caoutchouc & la Gutta- 

 percha," writes on the use of sodium bisulphite in the prepara- 

 tion of plantation rubber. 



The object of using bisulphite of soda is to preserve the light 

 color of plantation rubber by retarding oxidation. The matter, 

 therefore, does not concern smoked sheets, biscuits or fine hard 

 Para, which are always dark in color. 



Without the use of bisulphite, plantation varieties, after being 

 prepared, frequently show grayish in color, more or less dark, 

 sometimes with dark stripes on a lighter ground. This colora- 

 tion is not due to the incorporation of impurities in the crude 

 sum but to chemical modification. It is a much discussed point 

 whether this modification has any efTect on the rubber from the 

 manufacturer's standpoint. It is a fact that lack of uniformity in 

 appearance substantially depreciates the value of the rubber 

 with purchasers, practically irrespective of other more important 

 qualities. 



The cause of this loss and inconvenience to plantation rubber 

 producers was first overcome in the Federated Malay States by 

 the addition of bisulphite of sodium to the rubber late.x. Prac- 

 tically all the pale crepe is now so prepared. Plantation practice 

 varies with circumstances, .-^n authority, Mr. BarrowcIifT, makes 

 the following statement regarding the proportions of bisulphite 

 employed : The minimum proportion of bisulphite that produces 

 any eflfect on the color of the rubber is one part of bisulphite to 

 6.500 parts of latex. This amount gives fine crepe and sheet 

 rubber. It corresponds with the addition of one half ounce per 

 gallon of latex, of five per cent, bisulphite solution in water. 

 Thin sheets with a strong tendency to oxidize and intended for 

 smoking, and undiluted latex especially rich in rubber require 

 an ounce of five per cent, solution to 3,250 of latex. BarrowclifF 

 recommends, for the preparation of pale crepe, the use of one 

 part of bisulphite solution in l.fOO of latex, although one part to 

 400 of latex may be used for the thinnest crepe. The presence of 

 bisulphite in rubber impedes its drying; consequently in the 

 pieparation of thick stock small proportions only are employed. 



B. J. Eaton prescribes two ounces of bisulphite to ten gallons of 

 latex containing IS pounds of rubber. 



Vulcanization tests made in the Federated Malay States have 

 shown bisulphite-treated rubl)er to be equal, not to say superior 

 to that untreated. Manufacturers have, however, declared that 

 rubber so treated loses quality and has a tendency to become 

 brittle. These conclusions of the manufacturers are quite con- 

 trary to those published by BarrowclifT in 1912, who stated that 

 bisulphite needed to be used only in small <|uantities and that it 

 was entirely eliminated from the rubber. 



Clayton Beadle, H. P. Stevens and Sydney Morgan, in lluir 

 study of the eflfect of bisulphite in preparing ruliber from late.x, 

 compared the properties of bisulphite-treated and untreated 

 samples of rubber under identical conditions. They found very 

 little diflFerence between these samples, but proved that those 

 treated with l)isulphite were slightly superior to the others and 

 c.onch'ded that bisulphite is excellent in its effect in obtaining 

 uniformly pale rubber. 



1 he uiconveinence of using bisulphite is that the ire;ited rubber 

 dries rather slowly, requiring from two to three ilays extra. It 

 is also more difficult to smoke. For this reason the proportion 

 of bisulphite must be adjusted to the amount required to stop 

 oxidation, and at the same time not substantially retard the 

 drying of the rubber. Otherwise the formation of mildew will 

 be facilitated, which means spotted rubber and other undesirable 

 conditions. Therefore, each planter must experiment for him- 

 self to determine the quantity of bisulphite to add to his par- 

 ticular quality of latex. 



BarrowclifT mentions that excessive use of bisulphite may 

 cause formation of sulphuric acid, causing detrimental eflfects. 

 This is not supported by the results of Beadle, Stevens and Mor- 

 gan, who state that traces of sulphite are often found in rubber 

 not prepared with bisulphite. They have also preserved rubber 

 prepared with sulphuric acid for five years without noting any 

 alteration, thus proving that the presence of sulphuric acid is 

 not injurious to rubber. Bisulphite-treated rubber is unques- 

 tionably good and satisfies the demand for the lightest-colored 

 rubber for specific uses. Color is not an indication either .li 

 quality or lack of quality. 



NEW PROCESSES IN RUBBER MANUFACTURE. 



Method of Proofing Fabrks.— United States patent No. 1,154.- 

 875, James Meade. First a light coating which is partially drie<l. 

 and then a heavy coating on which second layer of fabric is 

 liressed. The machine is described in this issue. 



M.AKiNG Rubber Bands.— United States patent No. l,15S,32.i. 

 Thomas W. Miller, assignor to The Faultless Rubber Co. Rub- 

 ber is molded in the form of a tube and vulcanized and then cut 

 into bands. 



Making Spongy Rubber.— United States patent No. 1,156,184. 

 P. Schidrowitz and H. -^. Goldsborough. (See The India Rub- 

 ber World, July, 1915.) Coagulating rubber latex under condi- 

 tions producing a porous or spongy coagulum and fixing the 

 pores by vulcanization. 



Insulating Composition. — United States patent No. l,lS6.4.i_'. 

 L. H. Baekeland, assignor to (leneral Bakelite Co. 



Rubber Preservative Composition. — United States patent No. 

 1,156,561, Samuel T. Smith. 



ViiLCANiziNG AND ATTACHING RuBBER. — United States patent 

 1,157,572, Frederick Moench. This process consists in applying a 

 preliminary coating of rubber dissolved in a mixture of chloro- 

 form and gasolene, allowing the coating to dry. scratching the 

 dried coating thoroughly into the face of the material and apply- 

 ing over it an unvulcanized rubber sheet coating ; l.ually heating 

 the rubber-coated article for an hour at .320 degree-- F. for vul- 

 canization. 



Manufacture of a Seamless Rubber (;lo\e with I,inin(. oi 

 Exposed Elastic F"abric and Intermedl\te Laikk uk Adiu sivi 

 Material.— United States patent 1,157,646. Thos \\ . .Miller .is- 

 signor to The Faultless Rubber Co. 



Substitute for Lampblack. — United States patent \o. I,156.- 

 742. Blardone, Nichols & Brugiere. CJround burned rice hulls. 



Tubular Cords.— British patent No. 12,629 (1914), J. D. Tew. 

 Akron. Ohio. .\ number of strands impregnated with rubber are 

 luisted together in tubular form. (See August issue.) 



Impregnating Textile Fabrks with Rubber Solution.— 

 British patent No. 17,097 (1914); (;. W. Beldam and A. U. B. 

 Ryall. The fabric on a roller is immersed in rubber solution 

 and is wound oflf on another roller, also immersed in the 

 solution, passing on its way, across the surface of one or more 

 perforated, revolving rollers or between two plane-surfaced, per- 

 forated boxes, to the interior of which rubber solution is sup- 



