January 1, 1917.] 



THE INDIA RUBBER WORLD 



191 



pheres — 42 pounds — while without the accelerator 2 hours would 

 be required), whereas 90 parts Para, 9 parts sulphur, and 1 part 

 lime require 85 minutes at the same pressure for a cure. 



Quaternary ammonium bases: These are covered by Bayer & 

 Co., patents of 1914 together with aldehyde ammonia, para- 

 phenylenediamine, sodium amide, benzylamine, and naphthylene- 

 diamine, all rapid accelerators. 



• AMINO COMPOUNDS. 



Accelerene : This widely used English catalyzer is among, the 

 most powerful known accelerators. When used in the propor- 

 tion of 5^ to ^ of 1 per cent it reduces the required period of 

 vulcanization to one-third normal with highly satisfactory re- 

 sults; and in conjunction with certain other familiar substances 

 in quick repair compounds reduces the period of cure to one- 

 eighth normal. Cheap mixings containing considerable reclaim 

 or waste, particularly if golden antimony sulphide be present 

 but no free sulphur, do not respond so readily as medium and 

 high-class mixings. In such cases sufficient free sulphur must 

 be added and the proportion of antimony sulphide may be re- 

 duced to that needed to give the desired color, after which the 

 usual acceleration will be attained. In the manufacture of vul- 

 canite the addition of J4 of 1 per cent of accelerene to a mixture 

 consisting of 100 parts rubber and 40 parts sulphur reduced the 

 period of vulcanization from 6 to 2 hours, yielding a hard and 

 very durable product. 



Essentially paranitroso dimethylaniline, and wholly different 

 from the German type of accelerators, accelerene owes its activity 

 to the presence of the nitroso group, and not to feeble basic prop- 

 erties. Aside from its high acceleration it possesses several 

 characteristics in use that are of great value. Goods vulcanized 

 in its presence show somewhat greater tensile strength, probably 

 due to the diminished degree of depolymerization possible in so 

 short a period of heating. Vulcanization stops when the goods 

 are taken from the pan or press, so they suffer little deterioration 

 in storage, tests of this now covering a period of two years. Sul- 

 phuring-up may also be entirely prevented by its use, though at 

 the sacrifice of acceleration. "The quantity of sulphur may be 

 reduced to 3 or 3^ per cent, Yz per cent of accelerene is then 

 added and the mixing cured in the ordinary manner. As em- 

 ployed for this purpose the catalyzer facilitates a complete com- 

 bination of rubber and sulphur, with the result that little or 

 none of the latter remains in the rubber. 



NH.. 

 A 

 V 

 NH, 

 poisonous catalyzer melts at 140 degrees C, sublimes without 

 decomposition at 267 degrees C, is readily soluble in alcohol 

 and ether, and moderately so in water. In Bayer & Co.'s Ger- 

 man patent No. 280,198, January 1, 1914. it is stated that this 

 accelerator gives good satisfaction with synthetic rubber, 100 

 parts isoprene rubber having been cured compjetely upon being 

 mixed with 10 parts sulphur, 2 parts paraphenylenediamine and 

 being heated in a press for IS minutes at 45 pounds steam 

 pressure. 



Tctramethyh-ncdiaminc: NH. fCH;), NH~ Known also as 

 putrescine, this is a natural product of protein decomposition 

 formed during the putrefaction of animal matter such as fish. It 

 is produced chemically by Bayer & Co. 



Hrxainrthylrnc-tclranunc: Known also as H exameihyleneamine 

 and Fnrmin. 



Miscellaneous Amines: Other amino compounds cited by King 

 as of lesser importance yet having some accelerating power in- 

 clude: sodium amide, Na NH, (rapid acceleration according 

 to Ditmar) ; naphthylenediamine, C,„He (NH.), (rapid accelera- 

 tion according to Ditmar); trimethyleneamine (CHjIj N; ben- 

 zylamine, C„H-. CH,. NH,. (rapid acceleration according to Dit- 

 mar) ;^/J dimethyl A trimethyk-ncimine ; and nitrosodimethyl- 

 aniline. 



Para-fhenylciicdiamine: CoH, (NH,), 



This very 



PIPERIDINE .\ND DERIVWTIVES. 



Piperidine or Aminopentane: C5H10NH. A liquid miscible in 

 water in all proportions, having a specific gravity of .881 at 

 degrees C, boiling at 105.7 degrees C, and smelling like pepper 

 and ammonia. This, the prototype of the more recently dis- 

 covered organic catalyzers, was brought out and patented by 

 Bayer & Co. in 1912 for use in the itianufacture of synthetic 

 rubber, but its extraordinary value as an accelerator in connec- 

 tion with natural rubber for both hard and soft rubber articles 

 soon overshadowed its original purpose. A mixture of 100 parts 

 Para and 10 parts sulphur that requires an hour to cure at 53 

 pounds, steam pressure may be cured perfectly with only IS 

 minutes' heating by the addition of Yi part piperidine. The 

 product obtained from this compound contains about 3.5 per cent 

 of combined sulphur. Piperidine may also be used for producing 

 hard rubber by adding 25 per cent sulphur. (German patent 

 266,618.) 



Methyl piperidine: CsH,„ (CH3). This active catalyzer boils 

 at 107 degrees C. 



QUIXOLTNE AND DERIVATIVES. 



CH • CH 

 Quinoline: CoH4< ' While this is a good acceler- 



N =:CH 



ator, its derivatives, the sulphate and quinosol, are more fre- 

 quently used because of the ease of mixing. Quinoline has a 

 specific gravity of 1.0947 at 20 degrees C. ; it boils at 240 degrees 

 C. ; and is soluble in alcohol and ether, but only sparingly so in 

 water. Its odor is disagreeable and penetrating; its taste, bitter 

 and acrid ; and on exposure to moist air is converted to the 

 hydrate. As an accelerator the amount used is 2 or 3 per cent. 

 Quinoline does not appear to enjoy accelerating power, accord- 

 ing to Ditmar. 



Quinoline sulphate: Also known as quinoline sulphonic acid. 

 Kn excellent accelerator yielding good-looking, well-vulcanized 

 rubber. King suggests that the potassium salt of this acid might 

 give better results. 



Hydroxy quinoline: This derivative, which ought to prove a 

 valuable accelerator, takes the form of prismatic needles melting 

 at 76 degrees C. and boiling at 266.6 degrees C. under 752 mm. 

 pressure. Although readily soluble in alcohol and volatile with 

 steam it is only sparingly soluble in cold water. 



Quinosol: This accelerator takes the form of sulphur yellow 

 needles soluble in both alcohol and water. It is manufactured 

 by Frisch, of Hamburg, Germany, and mixes easily with rubber 

 compounds before vulcanization. In a mixture of Peruvian rub- 

 ber, 12 kilograms; white substitute, 19 kilograms; Kaolin (China 

 clay), 2 kilograms; chalk, 5 kilograms; and sulphur, 4.5 kilo- 

 grams, the accelerating effect, according to Ditmar, is not great, 

 Inil quinosol acts quite differently when mixed with litharge and 

 crude rubber free of substitute, the combined effect being greater 

 than the sum of the effects of each employed alone This fact is 

 of great importance to rubber footwear manufacturers who use 

 mixtures containing litharge exclusively, as they can cut the 

 period of vulcanization in half by using 2 to 3 per cent of quinosol. 



O.viquinoline: Cited by Ditmar. 



Oxiquinoline Sulphonic Acid: Gives good acceleration but very 

 porous rubber, according to Ditmar. 



Oxiquinoline sulphide: This is a satisfactory but too active 

 accelerator. It can be used with all sorts of compounds because 

 it answers all the needs of the industry. In tests conducted by 

 Ditmar in collaboration with the Japanese chemist Nawa-Naami, 

 a mixture containing Peruvian rubber, 40 kilograms ; brown rub- 

 ber substitute, 10 kilograms ; paraffin, 5 kilograms ; chalk, 41 

 kilograms; and sulphur, 4 kilograms, required 2 hours' heating 

 at a pressure of 4 atmospheres (56 pounds). With oxiquinoline 

 sulphide the mixture was vulcanized in 50 minutes. With qiirnn- 

 line sulphate 75 minutes was required. Tests of accelerated and 



