INDUSTRIAL AND ENGINEERING CHEMISTRY
lune 1953
pending installation of additional equipment. scheduled to be resumed in the near future.
Operations are
SUMMARY
-
I n the proper environment, the lower polyethylene polyamines, diethylenetriamine and triethylenetetramine, can be successfully employed as activators for all-rosin soap-emulsified 41’ F. polymerizations. At 0” F., reasonable polymerization rates were obtained in a system emulsified with 85% disproportionated rosin soap and 15% fatty acid soap when the freezing point depressant consisted of a mixture of methanol and ethylene glycol in a ratio of 3 t o 1, 25% of the water having been replaced with the antifreeze. D a t a showing the effect on polymer quality, of methanol when employed as an antifreeze agent in polymeriza, tion, indicate that i t may cause a slight deterioration in tensile strength, flex crack resistance, and abrasion resistance of tread vulcanizates. A method for shortstopping of 41 O F. polymerizations with hydroquinone is described. A study of the dithiocarbamate shortstops in cold polymerizations indicated that the potassium salt of dimethyldithiocarbamic acid is superior t o the sodium salt from the point of view of precoagulum formation tendency. Successful pilot plant polymerizations were conducted in 3 to 5 hours’ reaction time, using reactors equipped with a latex circulating pump and an external heat exchanger. A successful continuous polymerization was also conducted using a platetype heat exchanger as the reactor and a residence time of less than 0.5 hour. ACKNOWLEDGMENT
The authors wish t o acknowledge the assistance of W. H. Leukhardt and C. V. Bawn who conducted the experimental work, and the work of R. W. Brown and J. A. Reynolds of the research staff who made valuable contributions to the development work reported herein.
1311
The various projects were carried out under the sponsorship of the Reconstruction Finance Gorp., Office of Synthetic Rubber, as part of the government synthetic rubber program. Thanks me due to that organization for permission t o publish this paper. LITERATURE CITED
Brown, R. W., U. S. Rubber Co., unpublished work. Corrin, M. L., Klevens, H. B., and Harkins, W. D., J. Chem. Phys., 14, 480-6 (August 1946). Embree, W. H., Spolsky, Roman, and Williams, H. L., IND. ENG.CHEM.,43, 2553-9 (1951). Goodrich Chemical Co., B. F., private communication to RFC, Office of Rubber Reserve, 1950. Hart, E. J., and Meyer, A. W., J. Am. Chem. SOC.,71, 1980-5 (1949). Howland, L. H., Messer, W. E., Neklutin, V. C., and Chambers, V. S., Rubber Age ( N . Y . ) ,64, 459-64 (1949). Kirkpatrick, S. D., Chem. Eng., 58,148-52 (November 1951). McCleary, C. D. (to U. S. Rubber Co.), U. S. Patent 2,457,701 (Dec. 28, 1948). Neklutin, V. C., Westerhoff, C. B., and Howland, L. H., IND. ENG.CHEM.,43, 1246-52 (1951). Phillips Chemical Co., private communication to RFC, Office of Rubber Reserve, 1951. Provost, R. L. (to U. S. Rubber Co.), U. S. Patent 2,560,741 (July 17, 1951),2,577,432 (Dec. 4, 1951). Reynolds, J. A., U.S. Rubber Co., unpublished work. Smith, H. S,, Werner, H. G., Madigan, J. C., and Howland, L. H., IND. ENG.CHEM.,41, 1584-7 (1949). Smith, H. S., Werner, H. G., Westerhoff, C. B., and Howland, L. H., Ibid., 43, 212-16 (1951). U. S. Rubber Co., private communication to RFC, Office of Rubber Reserve, 1948. U. S. Rubber Co., private communication to RFC, Office of Rubber Reserve, 1951. Whitby, G. S., Wellman, N., Floutz, V. W., and Stephens, H. L., IND. ENG.CHBM.,42,445-52 (1950). RECEIVED for review October 24, 1952. ACCEPTED February 2, 1953. Presented before the Division of Rubber Chemistry a t the 123rd Meeting of the AMERICAN CHEMICAL SOCIETY, Los Angeles, Calif.
Reaction Times for
Polvmerization of Cold GR-S J
B. C. PRYOR, E. W. HARRINGTON, AND DONALD DRUESEDOW B. F. Goodrich Chemical Co., Cleveland, Ohio
T
HE improved quality of finished rubber products made from cold GR-S, polymerized at 41” F. instead of the 122’ F.
A
temperature used for regular G R S , has resulted in constantly increasing customer demand. Plant modernization in 1952 increased cold rubber production capacity t o about 75% of the total. A typical comparison between “cold” GR-S and regular “hot” QR-S illustrates the improvement.
Wltimate tensile lb /s inch ultimate elongstioh 300% modulus, lb./sq. inch Rebound % De Matt;& flex resistance (flexurest o failure) T r e a d wem index, passenger tires
2
Typical Tire Tread Compound Regular OR-8 Cold GR-S 3300 4250 630 710 1040 910 33 38 100,000 320,000 100 115-120
More detailed comparisons of hot and cold GR-S may be found i n the literature (3, 8). Production of cold GR-S started on a small commercial scale in 1948, and larger scale production was under way in 1949 in
several plants. This paper discusses the progress made in improving capacity for cold rubber production a t the RFC-owned OR-S plant a t Port Neches, Tex., operated by the B. F. Goodrich Chemical Co. Cold rubber production was made possible by the discovery of redox initiation, which permits practical polymerization rates at low temperatures. Redox polymerization can be described as the chemically controlled production of free radicals in the presence of the monomers by action between a reducing agent and a n oxidizing agent. Most present production processes utilize a n organic hydroperoxide, which is decomposed by a ferrous iron complex, producing free radicals and ferric iron. The free radicals initiate chain polymerization of the butadiene and styrene. Reducing sugars or certain other reducing agents may be used to regenerate the ferrous iron. Production of cold GR-S X-542 started a t the Port Neches plant in August 1949 using the polymerization formula known as the low-sugar recipe (9).
INDUSTRIAL AND ENGINEERING CHEMISTRY
1312
LOW-SUGAR RECIPE Butadiene Styrene teTt-Dodecyl mercaptan Potassium rosin soap Trisodium phosphate. 12Hz0 Tamol N
71 29 0.175 4.5 0.5
Temperature, F. Conversion of monomers, % Reaction time, hours
40-43
Vol. 45, No. 6
and slow and variable reaction rates were obtained. Therefore, the following rigorous measures were taken in the production plant startup to reduce the possibility of contamination with air: Charge nater was deaerated. Soap and activator storage tanks were designed with slow agitation, so that there would be no vortex to draw in air. Liquid transfer pump packing glands were kept tight. Oxygen in the fresh and recycle butadiene was carefully controlled by periodic removal of vapors from the storage tanks. Maximum oxygen content in the vapor space above the butadiene was maintained as follows:
60 18 2 batchwise charging 22 7 continuous charging
Recycle storage tanks, 0 47, oxygen Blend tanks, 0 2% oxygen
Charge surge tanks, 0 1% oxygen An average reaction time of 18.2 hours was obtained when reactors were charged batchwise, or individually, and each was empAir leakage was eliminated in the vacuum recovery system for tied a t the end of the cycle. recycle butadiene and styrene. I n regular GR-S, continuous polymerization had found general commercial acceptance for improving uniformity and plant caThese precautions resulted in a smooth startup with relatively uniform reaction times. It is estimated that reaction times would pacity ( 8 ) . The reactants are charged continuously t o the first have been 4 to 12 hours longer without oxygen control. Furreactor of a line of twelve connected in overflow series from one to the next, and the finished latex is discharged from the final ther improvements from the original reaction times of 18.2-hour batch and 22.7-hour continuous would have been less effective reactor. I n October 1949 continuous polymerization was begun without these measures. on cold GR-S a t Port Keches ( 5 ) . Reaction time to 60y0 was ACTIVATORQUALITY. The quality of the iron pyrophosphate22.7 hours, which was over 4 hours longer than by the batch dextrose activator suspension is one of the most important factors process. This slower rate had been predicted from experimental in cold GR-S reaction rate and uniformity. The activator is work a t the Government Laboratories and the B. F. Goodrich prepared by a special procedure. A dextrose-potassium pyroChemical Co. pilot plant ( 7 ) and is attributed to retardation phosphate solution is heated, aged a short time, and partially due to a seeding effect, resulting in larger latex particle size ( 1 ) cooled, ferrous sulfate solution is mixed in, and the mixture is and consequent slower over-all rates. I n spite of the slower polyagain aged and finally cooled. However, the exact temperatures merization rate, production capacity was increased about 3.5% and times of heating, aging, and cooling, and the turbulence durby continuous polymerization, and a more uniform product was ing mixing proved t o be very critical with respect to activator obtained a t a lower cost. The elimination of reactor charging activity, as judged by early development rvork. It was apparent and blowdown cycles and the use of 100% of the reactor volume that these conditions could be most readily controlled to exact (as compared to only 90% for batch operation) explain the inspecifications in equipment for continuous activator preparation. creased capacity. Pilot plant work resulted in the installation of such a system as With large scale production of cold GR-S under way in the part of the original cold GR-S equipment installed a t Port Neches. fall of 1949, it was apparent that in all plants the principal bottleThis equipment is diagrammed in Figure 1. neck in production was the relatively slow polymerization rate. Original conditions were as follows: Concentration by development and plant technical groups on this problem during the following years resulted in a demonstrated Dissolve dextrose and potassium pyrophosphate in 10 parts of reduction in minimum continuous polymerization time from 22.7 water a t about 90" F. hours to 9 hours. Polymerization capacity then for the first Dissolve ferrous sulfate in 1 part of water adjusted to pH 3.0 time was in excess of the capacity of the other processing equipwith sulfuric acid. ment in the plant, such as pumps, monomer recovery units, and dryers. ERROUS DEXTROSE
PYROPHOSPHATE S O L 3 WATER 10.0 P y T s K4P207 0.2 DEXTROSE 0.75 "
IMPROVEMESTS IR PRODUCTION
The various improvements which made this possible are discussed below. Although many of the factors are interrelated, the contribution of each is estimated. OXYGEN ELIMINATION. It had long been recognized that oxygen was a powerful retarder for emulsion polymerization. Early in the development of cold GR-S it was realized that oxygen was a more powerful retarder for this system than for regular GR-S. When oxygen was not carefully excluded from the reactor, long and variable induction periods n-ere experienced
4 MlNUTE AGEING TANK
? 1
SULFATE SOLN. WATER 1.0 PARTS FeS047%0 0.14 "
I GPM.
STEAM 1 . :
ICOOLER TO NO'
COOLINGNG WATER MIXER FORMATION FERROUS PYRO COMPLEX
PROPORTIONING PUMP COOLER TO 85'F: ACTlVATOR STORAGE
Figure 1.
Flow Sheet of Continuous A4ctivatorMake-Up
INDUSTRIAL AND ENGINEERING CHEMISTRY
June 1953
- POTASSIUM
1313
mental run a t the Port Neches plant in November 1949. Diisopropylbenzene ACTIVATOR SUSPENSION,16" PIPE AIR VENT monohydroperoxide gave, TO COOLER in direct comparison with cumene hydroperoxide, a NOZZLE 316 SS 3.5-hour reduction in polymerization time, and startPYRO. S0LN.ing in December 1949 i t was used in all production of X-542 cold GR-S at Port Neches. With raw maFERROUS S U L ~ A T E terials of normal purity, a SOLN. 4-hour reaction rate advanc tage was obtained. ACTIVATOR Another very important SUSPENSION advantage was discovered. 6" SCH. 80 PIPE With cumene hydroperoxide FERROUS SULFATE initiator, a reduction in the charge purity of the blended fresh and recycle butadiene PYRO. SOLN. materially slows down the I ~ T Y P E 347ss TUBING I$SS TUBING reaction r a t e f o r example, when the butadiene purity Figure 2. Diagram of Mixer was reduced from 95.5 to Above. Original activator complex mixer 93.5%, a necessary costBelow. Improved mixer saving production practice, the polymerization time was . Pump dextrose-pyrophosphate solution t o continuous heat exlengthened 4 hours. However, when diisopropylbenzene monohychanger, heating t o 220" F. in about 1. minute. droperoxide was used as the initiator, the use of butadiene of Age dextrose-pyrophosphate solution in continuous holdup lower purity did not slow the polymerization. Under these contank 4 minutes a t 220" F. ditions reaction times of up to 26 hours could be reduced by Cool t o 140" F. in continuous heat exchanger. Add ferrous sulfate solution stream in continuous mixer. 8 hours or more using diisopropylbenzene monohydroperoxide, Cool activator suspension to room temperature in continuous and more uniform rates were obtained. heat exchanger and run to storage tank. s-CH-CH3 CHa Plant technical personnel began experimentation with these C CH conditions, constantly improving them during a period of about 6 [C8 \ CH /\ H,C CH, months. It was found t h a t improvement could be made if the dextrose-pyrophosphate solution was aged a t a lower temperature for a longer time. T h e following changes were made: FERROUS
SULFATE
--
PYROPHOSPHATE
--
-
*
The dextrose-pyrophosphate solution was batch-aged 2 hours
at 155" F.
This solution was then heated continuously to only 190" F. instead of 220" F. The solution was then mixed with the ferrous sulfate solution at 110" F. instead of 140" F. Storage tanks were completely emptied before fresh activator was add>d.
I(
I
CHa-C-CHa
I
OOH Cumene hydroperoxide (CHP)
I
CHa-C-CHa
I
OOH Diisopropylbenzene monohydroperoxide (DIP)
\
CH3-C-CHa
I
OOH p-Menthane hydroperoxide (PMH)
I n March 1951 p-menthane hydroperoxide ( P M H ) was introThese improvements in activator make-up resulted in 2 t o 3 duced at Port Neches as a replacement for diisopropylbenzene hours' shorter polymerization time with better uniformity. hydroperoxide, which was in short supply. pillenthane hydroA further improvement in activator quality was made by a peroxide gave slightly faster reaction rates, and, because of its minor change in the activator mixer. Soon after cold GR-S prolower molecular weight, could be used a t lower concentrations duction started i t was noticed that the activator suspension in the cold GR-S formula. It soon became the preferred initiator. from the plant equipment was lighter in color and more opaque Careful testing of the quality of the cold GR-S made with the than activator from the pilot plant continuous installation. new hydroperoxide showed that physical properties and tire tread It was found that the turbulence a t the point of formation of the wear were not changed. ferrous pyrophosphate complex in the production activator mixer FIRSTREACTORTEMPERATURE (CONTINUOUS POLYMERIZAwas undesirably high, and the mixer was redesigned to give TION). When continuous cold GR-S polymerization was started lower turbulence a t this point. This resulted in better plant aca t Port Neches, the first reactor in the chain of twelve was run a t tivator quality and cut polymerization reaction time by 1.5 43" F. and the remaining reactors were run a t 41" to 42" F., as it hours. The change in mixer design is shown in Figure 2. was felt that higher temperature in the first reactor would give INTRODUCTION OF MOREACTIVEHYDROPEROXIDE INITIATORS. the reaction a "kick" and tend t o overcome any possible inducIn initial production of cold GR-S in 1948 and 1949 cumene hytion period. Experimental work in the continuous polymerizadroperoxide (CHP) was used as the initiator (IO). Wicklatz tion pilot plant a t the Government Laboratories ( 7 )unexpectedly et al. ( 1 1 ) and Fryling and Follett ( 1 ) found that certain hydroshowed slower polymerization rates a t successively higher temperoxides which were less soluble in water were more active and peratures up to 60' C. in the first reactor. When this concept gave more rapid reactions. With the cooperation of the Herwas applied to the production reactors a t Port Neches in October cules Powder Co., one such initiator, diisopropylbenzene mono1950, a reduction in the polymerization temperature in the first hydroperoxide (DIP), x-as tried in a short production experi-
INDUSTRIAL AND ENGINEERING CHEMISTRY
1314
Vol. 45, No. 6
L i n e of 3700-Gallon Cold SR-Reactors, Continuous S y s t e m reactor from 43" to 41' F. resulted in 0.5-hour faster reaction time, proved by side-by-side operation of two continuous reactor lines :
PORTNECHES,TEX., GR-S PLAUT X-5717, OC'TOBER 21-23, 1950 S o . 1 Reactoi Temperature O
DA reactor series DB reactor series
F
Time t o 60%
Conveifiion, Hours
41 43
14.4 14 9
Reduction in the first reactoi teniperatuie to 39 5" F nnd lower gave no furthei improvement. The 41" F trmperatuie for the first reactor n a s adopted as standard. ELECTROLYTE CHANGES.Most cold GR-S recipes include at least 0.5 part of electrolyte for 100 parts of monomers, in order t o maintain the particle size and fluiditv of the latex. Without electrolyte the latex would gel badly as it approached 60% conversion, and agitation and heat transfer would be severely reduced. Soon after cold GR-S production \>as started using 0.5 part of trisodium phosphate, increased amounts of electrolyte and replacement with potassium chloride viere tried. Both measures increased latex fluidity and improved temperature control. As potassium chloride replaced trisodium phosphate, reaction rates increased.
PORTKECHES,Tcx., GR-S PLAAT. COLDGR-S X-577 Electrolyte, Part 0 . 6 NaaPOa.12HsO 0.3 NasPOcl2HzO f 0 . 3 KC1 0 . 6 KC1
Reaction Time to 60% Conversion, Hours 15.0 14.0 13.0
INTERNAL COOLING COILSI N REACTORS.The improvements in polymerization recipes and plant operating techniques had by the start of 1951 made possible polymerization rates of standard cold GR-S as fast as 12 hours with continuous polymerization, or down to 8 or 9 hours batchwise. These fast reaction rates evolved heat of polymerization so rapidly that it could not all be removed through the reactor walls into the refrigerant in the jackets. T h e reactors therefore overheated. Much work was done to improve latex fluidity further and therefore improve the heat transfer coefficient on the inner surface of thc reactor. Higher elec-
trolyte concentrations were partially successful. Additional cooling surface inside the reactor was an obvious answer. At t,he start of GR-S production in 1942 all reactors had been equipped with cooling coils installed in the vapor space in the top of the react'ors, but these had been abandoned as unnecessary and ineffective for regular GR-S. The Phillips Petroleum Co. ( 4 )adopted the principle for cold GR-S with a workable modification. A bundle of C-shaped tubes was inst,alled inside the reactor, so that it would be immersed in the latex, and refrigerant was circulated through these tubes. The added capacity for heat removal \\-as sufficient to allow good polynierizat,ioii temperature control at rates as fast as 7 to 8 hours. These tube bundles were quickly approved for installation in the Port Xeches plant in the last six reactors of each continuous 12-reactor chain. This removed heat transfer capacity as an immediate bottleneck in polymerization capacity. INTRODUCTION OF METALC o i w L E x I s G AGENTS. In 1951 another important principle in speeding cold GR-S polymerization rate mas introduced commercially a t the GR-S plant a t Port Keches. I t was found that, the addition of "very small" amounts of metal sequestering or complexing agents to the formula, added with the water, reduced the reaction t,ime by as much as 4 hours. ,4 typical complexing agent which proved effective was Versene (Bersworth Chemical Go.), the tetrasodium salt of ethylenediaminetetraacetic acid. Other eff ertive agents were Seque,streiie AA and Chel (Alrose Chemical Co.). Continuous reaction times as fast as 9 hours to 60% conversion were experienced using only 0.02 part of sequestering agent per 100 parts of monomers. Smaller amounts gave proportionately smaller increases in polymerization rate. In addition, initiator and activator concentrations could be reduced by 25 to 30% without affecting the increased reaction rate obtained. Process and quality control was improved remarkably because reaction rate from day to day became much more uniform. A typical polymerization formula giving a 9-hour continuous reaction time is shown on page 1315. The quality of cold GR-S made by this 9-hour formula was normal. Polymerization capacity with a 9-hour reaction rate, for the first time, exceeded the capacity of the latex processing and drying equipment.
INDUSTRIAL A N D E N G I N E E R I N G C H E M I S T R Y
June 1953
H HOUR GR-S 100 RECIPE Butadiene Styrene tert-Dodecyl mercaptan Potassium rosin soap Trisodium phosphate. 12Hz0 Versene Fe-3 Diisopropylbenzene monohydroperoxide Dextrose Potassium pyrophosphate Ferrous sulfate.7HzO Water Temperature, f. Reaction time for 60% conversion, hours
u
75.0 25.0 0.200 4.50 0.80 0.02 0.085 0.563 0.150 0.105 190.0 41 9
A possible explanation for this important rate improvement is t h a t the sequestering agent complexes and inactivates traces of calcium and magnesium ions which are known to be present in the chemicals and water used in the formula. The severe retarding effect of traces of calcium and magnesium and the corrective effect of the sequestering agent are shown in Table I.
A
TABLE I. EFFECT OF SEQUESTERING AGENT Materials Added t o Standard Cold GR-S Recipe Versene, pert/100‘ Mg++, CS++, monomers p.p.m. on water p.p.m. on water
4 4
8 8 16 16 None None None None None None
None None None None None None 4 4 R 8 16 16
0.025 None 0.025 None 0.025 None 0.025 None 0.025 None 0.025 None
Reaction Time to 60% Conversion, Hours
10.4 12.0 10.4 13.0 11.7 13.7 9.9 15.5 12.2 Died Died Died
SUGAR-FREE FORMULA. Recently all cold GR-S production has converted t o what is known as the “sugar-free” formula (6)’ which is very similar t o the low-sugar recipes described above. With only a slight increase in ferrous sulfate and potassium pyrophosphate, dextrose can be eliminated entirely from t h e recipe. Reaction rates equivalent to those prevailing for the low-sugar recipes are obtained. T h e activator is slightly lower in cost and is simpler t o prepare. T h e sugar-free recipe is more sensitive t o oxygen inhibition.
by the continuous polymerization process and 18 hours by a batch process. Comparable reaction rates were being experienced in the other cold GR-S plants. Technological advances in the succeeding 2 years more than doubled polymerization capacity. Reaction times were reduced t o 9 hours (continuous) and a potential 5 to 6 hours (batchwise). Polymerization capacity now, for the first time, exceeds the capacity of other processing equipment in the cold GR-S plant. Rubber quality remained excellent. This was accomplished by: Careful exclusion of oxygen from the reactors, giving a smooth startup and a sound basis for further improvement. Improved activator preparation techniques-3.5 to 4 hours’ improvement. Introduction of more active hydroperoxide initiators-4 to 5 hours’ improvement, Improved electrolyte-1.0 to 2.0 hours’ improvement. Lower first reactor temperature-O.5 hour’s improvement. Use of metal complexing agents-4.0 hours’ improvement. Total improvement-13 to 15 hours. I n order t o take advantage of the faster reaction rates, improved methods of polymerization heat removal were utilized to maintain the reaction temperature a t 41 O F. Research and development work shows that still further increases in polymerization rate are attainable when they are needed. LITERATURE CITED
(1) Fryling, C. F., and Follett, A. E., J. Polumer Sci., 6 , 59 (1951). (2) Gracia, A.J., Chem. Met. Eng., 52,186 (May 1945).
(3) Howland, E. H., Messer, W. E., Neklutin, V. C., and Chambers, V . S., Rubber Age, 64, 459 (1949). (4) Kirkpatrick, S. D., Chem. Eng., 58, 148 (November 1951). ( 5 ) Larson, M. W., Chem. Eng. Progr., 47, 270 (1951). (6) Neklutin, V. C., Westerhoff, C. B., and Howland, L. H., IND. ENQ.CHEM.,43, 1246 (1951). (7) Reconstruction Finance Corp., Office of Synthetic Rubber, pri-
vate communication. (8) Schulze, W. A , , Reynolds, W. B., Fryling, C. F., Sperberg, L. R., and Troyan, J. E., India Rubber World, 117, 739 (1948). (9) Troyan, 3. E., and Tucker, C. M., Ibid., 121,67 (1949). (10) Vandenberg, E, J., and Hulse, G. E., IND. ENG.CREM.,40, 932 (1948). (11) Wicklatz, J. E., Kennedy, T. J., andReynolds, W. B., J. Polymer Sci., 6 , 45 (1951). RECEIVED for review October 2, 1952.
LOOKING T O THE FUTURE
If still faster reaction rates are needed in present cold GR-S plants or in new plants to be built in the future, they will be attainable-for example, the use of fatty acid soap in place of rosin soap will reduce reaction time by at least another 2 hours. An extreme in fast recipes is the following one, run in the laboratory. It is characterized by high soap and activator concentrations and runs to 60% conversion in only 11 minutes. RAPID41’ F. RECIPE 1
Butadiene Styrene tert-Cn mercaptan Potassium laurate Potassium myristate Potassium chloride Tarnal N Versene Fe-3 Water Phenylcyclohexane hydroperoxide Ferrous aulfate.7HzO Sodium pyrophosphate Temperature F. Time t o con;ersion, min.
75.0 25.0 0.1 7.0 7.0 0.4 0.2 0.1 860.0 0.61 1.11 1.06 41 eo%, 1 1 83%, 15
SUMMARY
When large scale cold GR-S production was started a t the plant operated by the B. F. Goodrich Chemical Co. at Port Neches, Tex., in 1949, polymerization reaction times were about 23 hours
1315
-
E
ACCEPTED February 24, 1953.
