THE INDIA RUBBER WORLD 



■29 





Iready ailopted partially or 



icn and with what results. 



n the cornpetitor's knowledge, in any 



s, or has been the subject of any 



I \ person, or is in any way 



country. 



{€) Wliether the suggestion 



wholly and by whom and 

 (/) Whether the suggestion i 



way covered by |).itciit laws, or 



application for l<-ti. : , i 



affected by any kI^ 



6. The decision of the n 

 competitors and will be cor.'' 



7. In the even', of the ' 

 be cf equal merit, or in the event . f a il 

 power is reserved to divide the prizes. 



8. Suggestions must be accompanied 

 cutside the notn de pivmc or number, and i 

 of the competitor. Names of prize winner 



9. All competitors shall he bound by 

 competition. 



10. The closing date for receiving suggestions from competitors \i 

 Decemtcr 31. 1920. Envelopes will not be opened before this date. 



U. Suggestions should be addressed to: The Rubber Growers' Associa 

 tion Prize Competition, care of Messrs. Fitzpatrick, Graham & Co., 

 Chartered Accountants, 9.Sa. Chancery I.ane, London, W. C. 2. 



N. B. — All inquiries in ronncclion with the competition (other than the 

 competitive suggestions) fhould he addressed to The Rubber Growers' 

 .Association (Dept. C), 38, Eastcheap, London, E. C. 3. 



be final and binding on a 

 all the competitors. 

 :wo or more suggestions t 

 ■ ween the judge: 



by a sealed envelope bear! 

 nside the real name and addr 

 i only will be published, 

 the conditions governing t 



T 



PEACHEY'S NEW VULCANIZATION PROCESS.' 



By S. J. Prachey. .1/. Sc. Tech. F. 1. C. 

 LC.ANiZATiON of rubber is effected at the present time 



by one of two methods, the hot cure, which v-- extensively 

 empUiyed in the production of the great majority of rubber 

 goods, and the cold cure, which finds application mainly in the 

 manufacture of thin sheet rubber goods, dipped articles and rub- 

 ber proofed fabrics. 



The first method consists in mixing the rubber with a certain 

 proportion of sulphur, and heating the compound to a temper- 

 ature of 130 to 150 degrees C. for a period of time, which varies 

 with the amount of sulphur employed, and averages perhaps one 

 to three hours. 



The second process was discovered by Parkes. Its apphca- 

 tion in the industry is limited by the fact that it produces a mere 

 surface vulcanization, and can therefore be employed only for 

 thm rubber sheets or surfaces. 



From the time of Parkes' discovery of the sulphur chloride 

 process in 1846— three-quarters of a century ago— nothing in the 

 nature of a chemically new method of vulcanization had been 

 brought forward until the year 1918. when the process forming 

 the subject matter of British Patent No. 129,826 was discovered 

 by the writer, as the result of an investigation on the behavior of 

 rubber towards the various allotropic forms of sulphur. 



Briefly the new process consists in exposing rubber, alone or 

 in admixture with practically any useful filling agent or pig- 

 ment, successively to the action of two gases, sulphur dioxide and 

 hydrogen sulphide. The gases diffuse into the rubber and there 

 interacting produce a particularly active form of sulphur, which 

 is capable of combining with and vulcanizing the rubber, even 

 at the ordinary temperature. The reaction presumably takes 

 place according to the equation : 



2H,S -f SO, = 2H,0 + 3S. 



Unlike the Parkes process, which yields an addition product 

 containing both sulphur and chlorine, the new process leads to 

 the formation, without the aid of the heat, of a sulphur addition 

 product, comparable in every way with that produced by the 

 hot vulcanization process. 



The process is applicable not only to rubber in its ordinary 

 form, that is to say, as an elastic or plastic solid, but also to 

 dissolved rubber. The treatment of a rubber solution alternately 

 with the two gases mentioned above brings about complete pec- 

 tization of the solution to a jelly consisting of vulcanized rub- 

 ber distributed through the solvent. On expelling the latter 

 by evaporation a fully vulcanized rubber of excellent quality is 

 obtained. 



The new process, eliminating as it does the use of heat and 

 of sulphur chloride, renders it possible to introduce into the 

 rubber a large selection of coal tar dyestuflfs and lakes, and even 

 natural coloring matters such as chlorophyll, and to produce 



19. 1920, pages 



vulcanized rubbers possessing pure and delicate shades of color 

 quite unobtainable under the old conditions. Further, organic 

 filling agents, such as leather waste, sawdust, wood meal, and 

 the like, which are decomposed or partly decomposed at the 

 temperature employed in the hot vulcanization process, or by the 

 action of sulphur chloride in Parkes' process, can be introduced 

 by the new method into rubber mixings, yielding cheap vul- 

 canized products possessing new properties and a high degree 

 of durability. 



In this manner, for example, employing wood meal and a 

 small proportion of rubber, it becomes possible to produce a 

 new and very cheap class of material to replace linoleum and 

 other floor coverings, with distinctly superior qualities as re- 

 gards color, durability and flexibility. Similarly, by incorporat- 

 ing leather waste (buffings or shavings) with a comparatively 

 small amount of rubber, and vulcanizing by the new process, it 

 becomes a simple matter to manufacture a reformed leather 

 closely resembling the real article in appearance and character, 

 and possessing even greater durability. The process lends itself 

 to the manufacture, not only of hard-wearing leathers suitable 

 for boot and shoe manufacture, but also of delicately tinted and 

 grained leathers for upholstery and artistic work. Further, by 

 the application of the new solution process, the reformed leather 

 may be built up into any desired article, the seams united by 

 vulcanization, and stitching and riveting wholly dispensed with. 

 In regard to cost, the new process compares very favorably with 

 the existing processes, in that it dispenses with the use of steam 

 and of mechanical pressure, and employs in the place of sulphur 

 and sulphur chloride two gases which can be prepared and 

 manipulated on a large scale at a very cheap rate. The main 

 drawback is the objectionable smell of the gases, but the writer 

 is assured by expert rubber engineers that this presents no 

 difficulty in the application ..f tin- pr.ici-s. 



Is Practiced on the Goodyear 20,000 Ac 

 Sumatra. A Native Tree Surgeon Is Here 

 Operating on a Hevea Brasiliensis. 



The "EverReady" Products— EverRe.\dy soud woven asbestos 

 brake lining and EverReady solid woven asbestos clutch fac- 

 ings are claimed to be especially satisfactory, due to the care 

 bestowed upon their manufacture under the direction of ex- 

 perts. (Kelso Manufacturing Co., Trenton, New Jersey.) 



