CHEMICALS Freon Marks Quarter of a Century Plays major role in bringing refrigeration industry to $ 2 billion class; spurs aerosol packaging and flammability, like other properties, might be periodic, Midgley noticed that flammability decreased as h e went from left to right. Going u p the column, he observed that toxicity decreased. The element where the lines met was fluorine. Starting with Qve 1-ounce bottles of antimony trifluoride, the team prepared dichlorodifluoromethane. A test using a guinea pig and some drops of the compound under a bell jar proved its nontoxicity. It also met their other conditions: it was noncombustible, nonflammable, and boiled at —29.8° C. Du Pont undertook the manufacturing process and began marketing Freon-12 in 1931. The first batch of Freon cost $50 a pound to produce; its developers gambled successfully and offered it on Jan. 13, 1931, at $1.00 a pound. The basic price of Freon-12 is now about 25 cents per pound, and i t takes about a pound to meet requirements of an average 19 cubic foot reîngerator. Freon-12 was only the beginning of a whole family of fluorinated hydrocarbons. Six commercial Freon compounds can now supply practically all temperature requirements from t h e moderate demands of air conditioning to the very low temperatures of some industrial processes. M o i n Aerosol Bandwagon. The most phenomenal growth pattern for Fréons has been in the aerosol propellant applications. First used in t h e early 1940's as propellants in the armed forces' "bug bombs," fluorinated hydrocarbons are today used as the propellants for approximately 100 household, personal, pharmaceutical, and industrial products. The family of Fréons continues to increase as new compounds must be developed to meet needs o f various containers and contents. For example, Freon-12 may be used as the propellant, producing a pressure of 70 pounds gage at 70° F. Freon-11 (monochlorotrifluoromethane) used a s a diluent reduces pressure to less than 40 pounds gage in order to meet shipping requirements and to enable use o f low-cost, expendable containers. D u Pont uses an infrared spectro- Freon-22 and Freon-114 (monochlorophotometer to keep a careful check on difluoromethane and dichlorotetraamount of moisture in its Freon re* fluoroethane, respectively) are used t o frigerants and propellants solubilize certain ingredients in the pro-
JLx 1928 the refrigeration industry was looking for a nontoxic, nonflammable refrigerant. T h e then available refrigerants, either difficult to use, flammable or toxic, were retarding the industry's progress. Thomas Midgley, Jr., working with Albert L . Henne and a group of General Motors and Du Pont chemists, engineers, physicists, and toxicologists started a search. What they came up with, dichlorodifluoromethane (Freon-12), had its 25th birthday this month and has helped in a major way to transform the refrigeration business from a $1 million one to a multibillion dollar business. Looking for a substance that was nontoxic, nonflammable, and. which boiled between 0° and —40° C , the scientists found carbon tetrafluoride listed in the International Critical Tables as boiling at —15° C. This was an error; it boils at —128° C , but Midgley and his associates riad their interest in fluorine aroused. The element was toxic, but what about its compounds? Midgley went to the Periodic Table, eliminating all elements whose compounds were known to be too unstable or toxic to fill the bill. One of the eight remaining elements was fluorine. Deducing that volatility
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pellant and to produce certain desired effects. Last year the aerosol industry reached a retail sales level of about $200 to $250 million. D u Pont states that Freon compounds used as aerosol propellants already account for about one third of their over-all production. With the boom on aerosols, the company feels it is entirely possible that the volume going into aerosols may surpass the volume going into refrigeration within the next two or three years. Fluorinated hydrocarbons have found many other uses than a s refrigerants or propellants. Freon-22 is a n important intermediate in the manufacture of Teflon tetrafluoroethylene resins. Freon-12B2 ( dibromodifluoromethane ) is used in fire protection systems in piston-driven aircraft. Lockheed first used the system on its super Connies; all four air-cooled reciprocating engines were protected with a total charge of 76 pounds of the compound. Stored as liquid under pressure of 600 pounds of nitrogen in four spherical containers, dibromodifluoromethane delivers a high volume of low toxicity, flame-smothering vapor at all flight temperatures. An additional advantage—negligible effect on metals. Solutions composed of Fréons or certain compounds alone are solvents used in degreasing operations. Low toxicity, nonflammability, and nonexplosive properties suit them to this application. Chlorotrifluoroethylene, a cousin of the family, is a monomer building block for polyfluoroethylene resins (Fluorothene and Ke!«F) used in chemically resistant plastics materials, films, and coating materials. The Freon family boasts many members: the methane series has 10 fully saturated compounds; the ethane series 4 5 , both symmetrical and asymmetrical arrangements. With an increase i n carbon atoms, the complexity and number of possible combinations rapidly increases into the thousands; each compound has some property which fits it more peculiarly to a specific use. Up to the present there have been t w o producers: D u Pont's Kinetic Chemicals Division and Allied Chemical and Dye's General Chemicals Division (whose fluorinated hydrocarbons are trade-marked Genetron) . Pennsylvania Salt will start production of its fluorinated hydrocarbons (Isotrons) sometime in late 1956 at its Calvert City, Ky., location. D u Pont believes the market is only barely tapped—a surv e y made last year showed that over 89% of the nation's homes were without some form of man-made cooling at the present time. This represents a virtually untapped market for the air conditioning industry, for example.
D u Pont now has a sprawling 18-acre plant for Fréon production at Carney's Point, Ν. Y. T w o other plants are lo cated at East Chicago, Ind., and Louis ville, Ky., and a fourth is under con struction at Antioch, Calif. A fifth
plant, operated by Du Pont of Canada, Ltd., is at Maitland, Ont. Allied Chemical and Dye's General Chemicals Division has two Genetron plants in operation, one at Baton Rouge, La.; the other at Danville, 111.
Less Polishing Needed New automotive finishes offer many advantages among them, a shinier car with lots less effort L E S S ELBOW WORK will b e necessary to
keep certain 1956 model cars in tip-top appearance. The reason—two automo bile paints that eliminate car waxing for at least 1 8 months under normal conditions of service. Developed by Du Pont and trade-marked Lucite and Dulux 100, the finishes are being used to a limited extent by several car manu facturers on 1956 models. Dulux 10O is a synthetic resin enamel, now in production at D u Pont's Philadelphia, Toledo, and San Fran cisco plants. Several other of its plants are expected soon to start manufacture. Dulux 100 is said to come out of the baking oven as hard a s present-day enamels after several months' aging. Marring and scratching are minimized on production line and outstanding oven-bake discoloration is prevented, says company. In addition to being highly blister-resistant, Dulux 1 0 0 can be buffed to remove minor scratches and abrasions, eliminating spotting in. The Lucite acrylic lacquer is based on the same chemicals as D u Pont's Lucite acrylic resin. Before volume production begins, Du Pont says a multimillion dollar plant investment will be necessary. Ease of maintenance i s claimed for the Lucite lacquer. Additionally, it
will make possible dramatic new glam our colors and color effects. A blend ing of metallic powder and pigment (Pontiac has used aluminum with the plastic lacquer but has other metals under consideration) in combinations never successfully used before is possi ble, says company. Viewed from vari ous angles, t h e colors change hue as light is reflected from metallic particles imbedded in the coating. Exposure tests under Florida condi tions and road tests throughout the country show that the finishes retain their original luster three times longer than conventional car paints. Also company says both compounds -will greatly reduce the car owner's trouble from oil or grease staining. In 1923 D u Pont introduced its ni trocellulose lacquer; in 1926 the Dulux synthetic resin enamel. Company offi cials say the new finishes are the most significant advances in automotive fin ishes technology since that time. CS 1
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Pontiac's 1956 Star Chief Custom Catalina coupes and sedans in Sun Beige and Sandalwood two-tone colors u s e Lucite Acrylic Lacquer. Pontiac engineers say completely n e w fields in color treatment will open with lacquer's use
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