INDUSTRIAL FLUOROCHEMICALS JAMES 0. HENDRICKS Central Research D e p a r t m e n t , Minnesota Mining a n d Manufacturing Co., S t . Paul, M i n n .
I
NDUSTRIAL fluorochemicals, collectively speaking, are new and in their infancy, I n fact, the whole field of organofluorine chemistry is just beginning t o unfold. A firm foundation on which the structure can grow has been laid by the fluorine pioneers. I n 1886 Moissan ( 4 6 ) prepared elementary fluorine by electrolysis and in 1890 (45) reported on some fluorocarbons. Swarts was an early, brilliant investigator and made many important contributions. While this paper is principally a review of industrial Auorochemicals and the work of industrial laboratories, credit should be given t o many universities for their numerous contributions t o the field of fluorine chemistry. REFRIGERANTS AND PROPELLENTS
Midgley and Henne ( 4 1 ) developed a number of chlorofluorocarbons specifically for use as refrigerants; however, they are also widely used today as propellents. Freon 12, dichlorodifluoromethane, is t h e most important member of this group. It is used both as a refrigerant and a propellent. It is nontoxic, nonflammable, and has thermodynamic properties (6) suitable for use in the field of refrigeration. Large scale production has brought the price t o a low figure-approximately 25 cents a pound. Freon 12 is produced by a modified Swarts reaction by treatment of carbon tetrachloride with hydrogen fluoride in the presence of antimony trichloride and antimony pentachloride. An interesting fact is t h a t Swarts ( 6 1 ) &st reported the compound over 40 years ago. A number of patents cover commercial processes for making Freon 12 (14, 16, 42,4S), Freon 113, and Freon 114 (16,27). Freon 11 has a small volume use as a diluent in certain propellent compositions. Freon 114 was formerly employed as a refrigerant by Frigidaire, but it is of only minor importance at present. Genetron 100 (9),1,l-difluoroethane, and Genetron 101 (IO), 1-chloro-1,l-difluoroethane,are products of the General Chemical Division of Allied Chemical and Dye Corp. The Genetrons
Electrofluorination Cell (Prior to Assembly) for the Production of Highly Fluorinated Materials
also are used in the refrigeration and propellent fields.
Carrene
7, a Carrier Corp. refrigerant, is a blend of Genetron 100 and Freon 12. The various reactions used in the commercial production of the Freons and Genetrons are presented herewith. Bromotrifluoromethane (63, 6 4 ) is now. being introduced as a low temperature refrigerant by Eston Chemicals, Inc., under t h e trade name of Kulene 131.
Chlorofluorocarbons
+ +
CCI, 2HF HF CCl, CHC13 + 2 H F CC13CC13 3HF CC13CCh 4 H F
+ +
HC=CH+2HF CHF2CH8
+ Clz
:Lz;:
-*
* Ultraviolet
+ light
+++ +
2HC1 CClzFz HCI CC13F 2HC1 CHClFz 3HCl f CClzFCClFz 4HC1 CCIFSCIF,
FLUORINATED PLASTICS
Genetron 100
CHF2CH3 CClFzCHa
Freon 12 11 22 113 114
+ HCl
Freon 22 and Freon 113 are intermediates in the manufacture of tetrafluoroethylene and chlorotrifluoroethylene, monomers of the two principal commercial types of fluorine plastics. Tetrafluoroethylene is prepared by passage of Freon 22, chlorodifluoromethane, through a hot tube (18).
101
99
INDUSTRIAL AND ENGINEERING CHEMISTRY
100
Vol. 45, No. 1
TABLEI. PROPERTIES OF FLUORIXATED ETHYLENE POLYXIERS
Polymer Kel-F
Sp. Gr.
n g5
2 1
1 43
Tensile Strength, Lb./Sq. I n .
Brittleness Temp., F.
5700
Outdoor Aging
2 2-2 3
1 30 (approx.)
1500-2500 15,000
S o change, 1 year
2 8-2 3 ( 2 5 0 C.)
< - 100
4 5 X 10-6 (-80' t o 20' C ) 7 x 10-6 (20' t o 150' C.)
S o detectable
18 X 10-6 (80' to 260' C.)
2-2 05
change, 4 r e a r s
(oriented)
2CHC1Fz Hot tube CLFl (Freon 2 2 ) Uncatalyzed
+
2HCI
Zn ---f
CzClFI
+ ZnClp
TABLE 11. hIECHANICAL PROPERTIES O F FLUORIXATED ETHYLENE POLYMERS
Teflon
Service Temperature, C. 175-200
225-250
Solid Phase Transition Resilience Temp., ' C. RIoldabiiity Does not retain 180' to 315' C . permanent set Coatings from dispersion are fused a t 240-250' C.
....
Slow to recover from compression; recovers by raising temperature
327
0 010 -+ 0 027 -+ 0 008 + 0 004
