T h e r u b b e r industry is getting set to meet this shortage a n d polyisoprene is the best candidate at the moment. This January, Goodyear p u t on stream a large pilot plant to make Natsyn, its brand of polyisoprene, a n d will soon start to engineer a full scale Natsyn plant with 25,000 to 30,000 tons a n n u a l capacity. Firestone also m a d e news by exp a n d i n g its pilot plant which makes Coral b r a n d polyisoprene. Price is still a problem. Goodyear says that the cost of polyisoprene, at present, is m u c h too high to guarantee its use in a normal peacetime economy. Goodrich says that in large scale production its product, Ameripol SN, could be marketed at a price which would be competitive with the prices that prevailed for crude rubber during 1955. But that year, natural r u b b e r climbed to over 50 cents a pound. T h e present price for natural is m u c h lower, though a shortage could change the price picture rather quickly.
Compel Route*'·"
; i f,ciniormo*o"
Gentlem·^
d'i«9as to 9''""
hu,e,
1 t £ •— ·'""
pos'it' 0 "-
1 ^r^W^^ lor dry pulverizing j : of materials to micron-size \ T , V ^ e •" Jet powders...
Pulverizer
Ziegler or Lithium
Synthetic natural r u b b e r is one of several " m i r a c l e " polymers that have been m a d e possible by the advent of stereospccific catalyst systems. Goodrich, which in late 1954 was first to announce a high cis content polyisoprene, uses a Ziegler-type system to duplicate natural rubber. Firestone's Coral rubber, on the other h a n d , is produced with a lithium catalyst. And Goodyear is still evaluating both systems. It's too early to say which type of system is better, as the r u b b e r companies haven't disclosed m u c h process information. I n fact, the question of whether lithium has a n edge over Ziegler types or vice versa is the subject of some debate (C&EN, M a r c h 10, page 43). Work by Goodyear and Firestone shows that lithium catalysts m a y be able to produce higher molecular weights t h a n either n a t u r a l rubber or polyisoprene m a d e with Ziegler-type systems. But on the other h a n d , Goodyear says there is still some doubt as to whether a lithium system gives as high a proportion of consecutive cis units. But any discrepancies in structure probably aren't too important, since all three
8 CUSTOM MADE SIZES
MILL DIAMETERS
FROM 2" to 36"
•
Grinds to finer particle size range than any other fluid energy mill (5 microns to less than 0.5 micron).
• • •
No aUritional heat developed with air as energy source. Highest efficiency — negligible maintenance — lowest cost. No moving parts.
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Easily replaceable parts and liners.
Since 1946, Jet Pulverizers has served a wide range of leading companies in -paint, cosmetic, pharmaceutical, petroleum and industrial chemical fields in the United States and throughout the world.
THE JET PULVERIZER COMPANY !'.·
VOL. 50, NO. 5
•
MAY 1958
31 A
