PRODUCT AND PROCESS DEVELOPMENT Hoffmann, U., and Jacobi, B., U. S. Patent 1,992,615 (Feb. 26, 1935).
Horner, L., and Schwenk, E., Angew. Chem., 61, 411 (1949); Ann., 566, 69 (1950); K a u t s c h u k u. Gummi, 3, 21 (1950). Klevens, H. B., Chem. Reus., 47, 1 (1950). KIevens, H. B., J . Am. Chem. Soc., 72, 3581 (1950). Kolthoff, I. M., and Meehan, E. J., J . Polymer Sci., 9, 343 (1952). Ibid., p. 433. Kolthoff, I . M., and Miller, I. K., J . Am. Chem. Soc., 73, 3055 (1951). Ibid., p.’5118. Kolthoff, I. M., and Stricks, W., J . Phys. and Colloid Chem., 52, 915 (1948). Kolthoff, I. M., h!Ieehan, E. J., and Carr, C. W., Ibid., 6 , 73 (1951). McBain, J. W., and Huff, H. M., J . Colloid Sci., 4, 383 (1949). McBain, J. W., and Johnson, K. E . , J. Am. Chem. SOC.,66, 9 (1944). h,IcBain, J. W., and Merrill, R. C., Jr., IXD.ENG.CHEM.,34, 915 (1942). McCutcheon, J. W., Chem. I n d . , 61, 811 (1947).
(19) Marvel, C. S., Deanin, R., Claus, C. J., Wyld, M. B., and Seitz, R. L.. J . Polvmer Sci.. 3. 350 (1948). (20) Mitchell, J. M:, Spolsky, R., agd Williams, H. L., IND. ENG. CHEM.,41, 1592 (1949). (21) Monsanto Chemical Co., Monsanto Tech. Bull. P-123 (1948). (22) Morton, M., Salatiello, P. P., and Landfield. H., IND. ENG. CHEM.,44, 739 (1952); J . Polymer Sci., 8, 111 (1951). (23) Orr, R. J., and Williams, H. L., J . Am. Chem. Soc., 76, 3321 (1954). (24) Ibid., 77, 3715 (1955). (25) Orr, R. J., and Williams, H. L., J . Phys. Chem., 57, 925 (1953). (26) Spolsky, R., and Williams, H. L., IXD.ENG.CHEX.,42, 1847 (1950). (27) Whitby, G. S., Wellman, V., Floutz, V. W., &ndStephens, H. L., Ibid.. 42. 445 (1950). (28) Wiedeman; 0. F:, and Montgomery, W.H., J . Am. Chem. SOC., 67, 1994 (1945). (29) Winsor, P. A., Trans.‘Faraday SOC., 44,463 (1948). RECEIVED for review September 16, 1954. ACCEPTEDMarch 18, 1955. Presented before the Division of Rubber Chemistry at the 126th Meeting of the AMERICAN CHEMICAL S O C I ~ T New Y , York, N. P., 1954..
CoDolvmerization of Butadiene and Stvrene -
- 1
-
I - - - ---
-- -
-
.
~
--
-
--I--
EFFECTS O F IMPURITIES IN COMMERCIAL LOW TEMPERATURE RECIPES CARL A. URANECK AND ARCHIE E. FOLLETT Phillips Petroleum Co., Phillips, rex.
GEORGE J. KOSTAS The General Tire & Rubber Co., Boyfown, rex.
T
HE influence of contaminants in “polymerization grade”
butadiene (98.5%) on the emulsion copolymerization of butadiene and styrene has been of concern t o the synthetic rubber industry ever since the inception of the synthetic rubber program. The trace amounts of various impurities have been suspected as one cause of process control irregularities in plant production of GR-S at 50’ C. using the so-called Mutual recipe. The effects that possible impurities in butadiene and styrene have on the Mutual recipe have been extensively studied ( 3 , 6, 7 , IS, 18, 20). The results of these studies indicate t h a t the compounds with the most objectionable effects on polymerization a t 50’ C. are 1,4-pentadiene, vinylacetylene, vinylcyclohexene, acetaldehyde, and ammonia. K7ith the advent of low temperature polymerization systems, the effect of impurities in monomers on polymerization characteristics of these new redox systems was of increasing importance since it is generally believed t h a t low temperature recipes are more sensitive t o impurities than the high temperature recipes. S s a consequence the Office of Synthetic Rubber, Federal Facilities Corp., assigned the investigation of the influence of butadiene contaminants in low temperature recipes t o Phillips Petroleum Co. and t o The General Tire & Rubber Co. of Baytown, Tex., participants in the government sponsored rubber research program. This report is a composite summary of the cooperative study. The butadiene contaminants studied by the two groups were 4vinyl-1-cyclohexene, acetaldehyde, vinylacetylene, 1-butene, 2butene, 1-butyne, 2-butyne, propyne, acetone, and ammonia. The effect of the impurities was studied in three commercial recipes, GR-S-100, GR-S-IO1 (currently GR-S-1500), and x - 6 3 6 , representing, respectively, the iron-pyrophosphate-sugar, the ironpyrophosphate-sugar-free, and amine recipes currently employed t o produce a major proportion of low temperature rubber.
1724
Oxygen was not included in this study as i t h a d been investigate previously (9) in low temperature redox systems. I n the cooperative study every effort was made t o eliminate as many variables between the groups as possible. Each critical ingredient examined by both investigating groups was obtained from the same sample lot. Each group adjusted the amounts of ingredients in the control recipes so that the rate of polymerization was constant for 65 t o 70a/, conversion, and 6001, conversion was attained in 8 t o 10 hours. Information concerning polymerization techniques and recipe work was exchanged between the groups until satisfactory duplicability was achieved. The following ingredients were divided between the two groups. Butadiene: Phillips Petroleum Co. special purity monomer, 99.65 mole %, .was distilled through a short packed column equipped for reflux to remove inhibitor and accumulated dimers. Total acetylene content found by the silver nitrate method was 0.008 %.
Styrene: Dow Chemical Co. polymerization grade, 9 9 . 6 % pure, was either distilled at approximately 10-mm. pressure t o remove inhibitors or caustic washed before use. This difference in the purifying treatment is not considered significant. Dresinate 214: Hercules Powder Co. disproportionated rosin soap was supplied as a concentrated aqueous paste of the partially neutralized soap with an acid number of 8.8 and total solids of 79.2%. Potash Soap (K-OSR): Swift and Co. potassium soap flakes met specifications of. the Office of Synthetic Rubber, FFC. Daxad 11: Dewey and Almy Chemical Co. commercial grade sodium salt of a formaldehyde-naphthalenesulfonic acid condensation product. M T M and Sulfole: Phillips Petroleum Co. mixed tertiary mercaptans (MTM) and tdodecyl mercaptan (Sulfole) met specifications of the Office of Synthetic Rubber, FFC.
INDUSTRIAL AND ENGINEERING CHEMISTRY
Vol. 47, No. 9
PRODUCT AND PROCESS DEVELOPMENT Cumene Hydroperoxide (CHP): Hercules Powder Co. 73% material met specifications of the Office of Synthetic Rubber, FFC. Diisopropylbenzene Hydroperoxide ( D I P ) : Hercules Powder Co. 52% material met specifications of the Office of Synthetic Rubber, FFC. Cerelose: Corn Products Refining Co. commercial dextrose. Versene Fe-3: Bersworth Chemical Co. 34y0 solution of the sodium salt of ethylenediaminetetraacetic acid. Triethylenetetramine (TETA): Carbide and Carbon Chemicals Corp. polyamine. Common Chemicals and Distilled Water: These materials used throughout the study were obtained by the individual groups. Sodium hydroxide, potassium chloride, ferrous sulfate heptahydrate (FeS04.7Hz0), potassium pyrophosphate (KdPPOI) trisodium phosphate (-UasPOd.12HZO), and sodium sulfite (h'azSO,) all C.P. grade were obtained from J. T. Baker Chemical Co. The following chemicals were divided between the two groups and were analyzed in various Phillips Petroleum Co. laboratories by chemical, cryoscopic, optical, and mass spectrographic methods. Butadiene Dimer (4-vinyl-1-cyclohexene): Phillips Petroleum Co. pure grade, 99.0 mole yominimum purity. Acetaldehyde: The Matheson Co. research grade chemical with a boiling point of 20' t o 22' C. contained 93.8y0acetaldehyde. Vinylacetylene: D u Pont Co. 50% solution of monovinylacetylene in xylene. Vinylacetylene was isolated in accordance with instructions furnished with the sample. 1-Butene: Phillips Petroleum Co. pure grade material had the composition Mole 1-Butene %Butene low boiling %Butene: high boiling
Yo
99.3 0.3 0.1
2-Butene: Phillips Petroleum Co. pure grade material had the composition Mole 3 '% 2-Butene, low boiling 2-Butene, high boiling +Butene 1,c-Butadiene 1-Butene Isobutane Isobutylene
47.7 49.2 1.0 0.0 1.0 0.1 1.0
I I
I in m a n u f a c t u r i n g /ow t e m p e r a t u r e GR-s I FOR IMPROVED PLANT OPERATION
. . .this report shows that concentration of
impurities in the monomers should be kept at a minimum and constant level
sugar solution was prepared by dissolving 7.5 grams of Cerelose in distilled water in a 100-ml. volumetric flask and adding 4 ml. of I N potassium hydroxide solution. This mixture was heated in a water bath until the solution became amber colored; i t was then cooled and made up to volume. The proper amount of this solution was added to the polymerization bottle. 3. The styrene solution which contained the mercaptan and hydroperoxide was added by volume. 4. The polymerization bottle was balanced against a tare and a weight equivalent to the amount of butadiene was added. About 0.5-gram excess butadiene was added, the cap placed on top of the bottle, and the excess butadiene was allowed to evaporate. The cap was then crimped on. 5 . The system was pressured to 20 lb. per sq. inch with prepurified nitrogen and the bottle rotated in the polymerization bath 15 to 20 minutes. 6. The addition of the impurity was dictated by the nature of the comDound. The butadiene dimer was added after the stvrene solition. The acetaldehyde was prepared as a 10% solution in distilled water and injected after the butadiene had been added and the bottle capped. The other gaseous impurities were injected from a cooled syringe after the butadiene had been added and the bottle capped. When 0.5 gram or more of impurity was added, the amount injected mas checked by carefully weighing the bottle before and after the addition. 7. The ferrous pyrophosphate activator solution was used when the sugar solution was prepared separately. The ferrous sulfate heptahydrate (FeSOa.7HzO) was dissolved in a small amount of distilled water in a 100-ml. volumetric flask and to it was added a solution of potassium pyrophosphate (K4PzO7)in distilled water. The mixture was made up to volume, blanketed with nitrogen, and stoppered lightly by a ground glass stopper. The flask was heated in a 60' C. circulating air oven for 40 minutes. The activator solution containing sugar was prepared by dissolving the potassium pyrophosphate (KlP207) in 90% of the activator water, adding sugar, and heating at 100" C.
1-Butyne: Farchan Research Laboratories product analyzed 98.4 mole yo,and mass spectrometer scanning of this material indicated that paraffins and olefins were absent. 2-Butyne: Farchan Research Laboratories product analyzed 91.4 mole %, and analysis by the silver nitrate method indicated that 6.7% of the material reacted as a primary acetylene. Propyne: Farchan Research Laboratories product analyzed 90 mole %, and mass spectrometer scanning on this material indicated that paraffins and olefins were absent. Ammonium Hydroxide and Acetone: J. T. Baker Chemical Co. c. P. grade chemicals., Polymerizations were conducted in bottles provided with crown caps which were fitted with a self-sealing gasket assembly. The bottles placed in a constant temperature mater bath maintained a t 5" C. were rotated end-over-end a t a speed of 27 r.p.m. The ingredients employed in each of the three polymerization systems developed by the two groups are presented in Table I. The charging procedure for GR-S-100 is as follows:
Table 1. Control Recipes Developed by Two Groups for GR-S-100, GR-S-101, and X-636 Systems
1. The emulsifier solution was prepared by dissolving Dresinate 214, Daxad 11, and trisodium phosphate (NaaPO4 12Hz0) in 170 parts of distilled water. The solution was brought to a boil, cooled, and distilled mater added to compensate for evaporation losses, the p H measured, and the requisite amount of solution charged t o the polymerization bottle by weight. The p H of the emulsifier solution was 11.1 to 11.3. 2. The sugar solution was prepared either as a separate solution or was included in the preparation of the activator. The
mine FeS04.7HzO K~P~OT NanSOa Shortstop Sodium dimethyldithiocarbamate Dresinate 214 Polyamine H Special
September 1955
Butadiene, 100% Styrene, 100% Water Dresinate 214, 100% Potassium OSR NaOH Daxad 11 KC1 iYaaPOa.12Hz0 Cerelose Versene Fe-3
MTM
Sulfole
(Temperature 5' C.) GR-S-100 GR-S- 101 ' A B A B 75 75 75 75 25 190
4.5
... ,..
0.10
25 190
190
190
...
01045
0.10
...
...
... ...
...
25
190 4.5
...
0.50 0.75
25
75 25
4.5
...
0,50 0.75
X-636
A
0.10 0.50
...
...
... 0.25
4.5
... ,
.
,
0.10
.., 0.50 ...
2.93 1.57
... 0.10 ... 0.50 ...
, . .
0.01.
0.28
.
.,
0.21
...
..
0.10
...
0.10
...
... ...
0.10
... ...
0.09
0.11
...
0.09
0.20
0.17 0.20
...
0.10
0.15
...
...
0.05
0.10
.., ...
0.05
0.05
INDUSTRIAL AND ENGINEERING CHEMISTRY
0.17 0.20
,
0.14 0.18
...
...
0.05
0.10 0.05
...
0.21
B 75 25 190 2.93 1.57
... 0.10 ... 0.50
...
0.01
..,
0.20 . . I
0.10
0.08
...
...
0.29
0.35
...
0.05
...
...
O,l5
0.05
0.05
1725
PRODUCT AND PROCESS DEVELOPMENT for 15 minutes. The digested sugar solution was cooled t o between 60" and 49' C.; the iron salt dissolved in the remaining 10% of water was added slowly; and the resulting solution was cooled t o 32' C.immediately. The proper amount of the activator solution which had been cooled t o room temperature and shaken was injected in the polymerization bottle. The charging procedure for GR-S-101 was as follows: 1. TKe emulsifier solution was prepared by dissolving Dresinate 214, Daxad 11, electrolyte, and sodium hydroxide i n 180 parts of distilled water. The solution was brought t o a boil, cooled to room temperature, distil.led water added to compensate for evaporation losses, and the requisite amount of solution charged t o the polymerization bottle by weight. The p H of the emulsifier solution was 10.4 t o 10.6 2. The remainder of the steps in the charging procedure was the same as the preceding steps 3 t o 7 .
140
P -I 2 I20
g
u
100
'
5 0 0 2
80
60 40
, .
1.3
Figure 1.
1.7
2.1 2.5 INHERENT VISCOSITY
____--
2.9
3.3
Mooney viscosity versus inherent viscosity
Polymer plasticity was determined
Since i t is extremely difficult in the laboratory t o shortstop all polymerizations a t exactly 60% conversion, it was necessary t o employ some method of correcting all Mooney data t o a common conversion level. Throughout the study by the groups two methods were employed. I n one method the polymerization was stopped close t o 60% conversion, the polymer isolated, and from a predetermined conversion-Mooney relationship, t h e Mooney value was correct,ed t o 60% conversion or t o an average conversion level for a set of experiments. The correction factor obtained from the predetermined conversion-Mooney relationship was one Mooney point per unit conversion. These factors are sometime used in pilot and plant operation for process control. Each pilot plant has determined a conversion-Mooney relationship, and the factor is generally 1t o 2 Nooney points per conversion unit. I n the second method, t h e Mooney viscosity was determined from inherent viscosity measurements rather than from measurements of the Mooney viscosity on copolymer shortstopped at or near 60% conversion. Experimentally, a sample of latex was withdrawn when the conversion was about 50%, again when the conversion was greater than 60%, and inherent viscosity of the two samples was measured. The Mooney viscosity versus inherent viscosity was plotted for all t h e samples on which these properties were measured during this study; the most representative line was drawn through these points. This plot is shown in Figure 1. The next step was t o plot the two conversion versus inherent viscosity values for a given sample. The inherent viscosity value a t 60% conversion was interpolated from the curve. The Mooney viscosity was then taken from the Mooney viscosityinherent viscosity correlation. On the basis of other studies ( 1 ) and the data presented in this report, this procedure for determining Mooney viscosities is reliable. Boyer points out that the shape of the curve in Figure 1 is qualitatively similar t o a curve predictable from a relationship between Mooney and intrinsic viscosity (2).
The charging procedure for X-636 was as follows: 1. The emulsifier solution was prepared by dissolving Dresinate 214, K-OSR soap, Daxad 11, trisodium phosphate (Na3P04. 12HzO), and Versene Fe-3 in 180 parts of distilled water. The solution was brought t o a boil, cooled t o room temperature, distilled water added t o compensate for evaporation losses, and the requisite amount of solution charged to the polymerization bottle by weight. T h e pH of the emulsifier solution was 11.2 to 11.4. 2. The remainder of the charging procedure was the same as preceding steps 3 to 7 for GR-S-100 except t h a t the activator solution was prepared by dissolving sodium sulfite (NanSOI) in a small amount of distilled water in a 100-ml. volumetric flask, and a solution of triethylenetetramine in distilled water was added. The solution was made up to volume and, without prior heating, the proper amount of the solution was injected directly into the polymerization bottle.
Sampling. The course of the reaction was followed by means of the hypodermic syringe-sampling technique described by Houston (10)and Harrison and Meincke ( 8 ) . Just prior t o withdrawing the first sample for the determination of total solids, the system was re-pressured t o 20 lb. per sq. inch with pre-purified nitrogen. Samples for Mooney viscosity were coagulated by the brine-acid or the brine-alcohol method. The coagulation procedure dmployed depended on the amount of latex available. The polymer was washed thoroughly with water and dried in a forced air oven at 88" C. For inherent viscosity measurements the latex was injected into an isopropyl alcohol solution which contained 0.5% shortstop (sodium dimethyldithiocarbamate) and 0.5y0 antioxidant (phenyl-B-naphthylamine). The rubber, squeezed free of excess isopropyl alcohol, was dried in a vacuum oven for one hour at 80" C. Relative viscosities of benzene solutions of copolymers, measured in an Ostwald-type viscometer, ti-ere used in calculating inherent viscosities according to the recommendation of Cragg ( 4 ) .
1726
Reproducibility of control experiments was esfablished
The rate of reaction and modifier requirements were adjusted for each of the polymerization systems so that t h e influence of the impurities could be compared. The concentration of the ingredients in the initiating system was adjusted so that a conversion of 6OY0 was obtained in 8 t o 10 hours. The concentration of mercaptan was adjusted so that a Mooney viscosity (ML-4) of 60 was obtained for the brine-alcohol coagulated polymers or of 50 for the brine-acid coagulated polymers a t a conversion of 60%. The test recipes developed by the two groups are shown in Table I. These formulations were used throughout the investigation except for variations in kind and amount of added impurities. The recipes developed by the two groups differ mostly in the initiator systems. However, these differences are within the specifications set by the Office of Synthetic Rubber, FFC. The reproducibility obtained for control sets of 6 bottles for each of the recipes is shown in Table 11,and the reproducibility for the individual controls conducted with some of the impurity ex-
Table II. Reproducibility of a Series of 6OyO Conversion GR-S-100, GR-S-101, and X-636 Controls GR-S-100 Hours ML-4 10.0 10.0 9.85 9.7 9.7 10.0
Average Standarddeviation
9.88
O,l5
55 55 53 52 52 53
53.3 1.35
I N D U S T R I A L A N D E N G I N E E R I N G CHEMISTRY
GR-S-101 Hours ML-4 7.9 67 7.8 65 7.8 65 7.8 65 7.6 62
...
...
7.8 0.11
64.8 1.86
X-636 Hours 8.3 8.2 8.4 8.1 8.2 8.3 8.25 0.10
ML-4
56
52 54 49
55
54 53.3 2.50
Vol. 47, No. 9
PRODUCT AND PROCESS DEVELOPMENT of the amounts of various impurit'ies that could be tolerated by the different systems, and t o GR-S-100 GR-S-101 X-636 measure one specific effect of AML-4B AHoursg A ML-4 B AHoUr& A M L -B~ the possible impurities on t h e AHoUrs13 polymerization systems. Al9.8 59 47 9.4 9.8 53 47 7.9 8.8 59 46 10.0 58 8.3 9.8 8.8 48 54 8.7 9.3 51 7.9 56 56 though it is evident that all of 47 8.4 11.6 50 48 8.1 8 . 3 60 47 10.0 8.3 44 9.9 10.0 60 51 8.5 9.6 53 46 7.8 7.9 55 50 * the contaminants would affect 57 9.8 49 8 5 10.0 53 8.1 8.8 61 42 1 0 . 1 48 the three systems if present in 51 8.6 53 7.3 55 48 9.9 10.0 60 9.1 54 7.8 45 8.6 8.3 50 8.0 10.0 8.0 47 54 8.4 63 46 sufficient concentration, this 43 9.0 9.8 55 45 8.0 10.0 9.9 47 9.9 63 42 51 8.5 10 5 64 42 8.0 10.3 11.7 55 9.6 66 52 study was limited t o impurity 48 10.5 11.0 9.3 9.5 53 56 55 7.6 8.3 63 53 concentrations below 5% since 48.6 8.75 10.02 9.76 5 2 . 4 9 . 7 5 54.2 49.9 48.2 7.96 8 . 5 2 60.1 Average it is unlikely t h a t contamina1.14 6.20 3.27 0.36 0.87 3.78 Standard deviation 0.22 5 . 2 6 0 . 2 0 0.79 3.61 4.59 tion of plant material would exceed this level. .4ny rigid c I a s s i f i c a t i o n periments is shown in Table 111. The reproducibility for the get of compounds as inhibitors and retarders is arbitrary, since of control bottles for a recipe is significant in t h a t the influence of the differences in behavior is one of degree. I n different SYSincreasing amounts of a n impurity in a formulation was detertems under various conditions, oxygen, for example, is known mined b y comparing the results with the control for the series. t o function in the role of inhibitor, retarder, comonomer, or The data for the sets of controls, Table 11,indicate that a variainitiator. The assignment of a specific chemical reaction t o tion greater than 10% in reaction time for a n experimental system an impurity in a polymerization is complicated unless the t o reach 60% conversion is outside the limits of error and can be necessary kinetic data and identification of resultant products attributed t o the impurity; likewise a lo-point change in the are obtained. I n view of these complications a certain amount Mooney viscosity is significant. Variations of this order in plant of arbitrariness has been used in describing the behavior of the operation are considered process control irregularities. impurities in the polymerization systems for the sake of brevity. Although reproducibility is good for a single set of controls conducted at one time, the reproducibility for the controls conducted a t different times and by different technicians ie only fair aa data in Table I11 indicate. Nonetheless, in view of the Table IV. Impurity Effects on 60% Conversion GR-S-100, great number of variables involved in conducting emulsion polyGR-S- 101, and X-636 Systems merization experiments, the agreement between groups is satisfactory. D a t a in Table I11 illustrate that the order of decreasing GR-S-100 GR-S-IO1 X-636 pa~~&~oo reproducibility in both reaction rate and Mooney viscosity is Monomer Hours BIL-4 Hours ML-4 Hours ML-4 X-636, GR-S-101, and GR-S-100. Butadiene dimer 0.00 10.0 59 9.4 53 7.9 59
Table 111. Reaction Time and Mooney Viscosity Reproducibility for 60% Conversion GR-S- 100, GR-S- 1 0 1, and X-636 Controls for Separate Impurity Experiments
All impurities caused an increase in reaction time but their effect on viscosity varied
The various trace impurities possibly present in commercial butadiene were added in known amounts t o the GR-S-100, GR-S-101, and X-636 polymerization systems t o determine their influence on the rate of reaction and Mooney viscosity. The experimental results are listed in Table IV. These values are a composite of the best values of the two groups. The criteria used t o select the data were the consistency of a set of data, whether the control polymerization fell within the 6.0 t o 7.5% conversion per hour rate, and whether Mooney of the control polymer was within experimental error. I n Table V are listed the impurity concentrations which increased by 10% t h e time required for the polymerization t o attain 60% conversion. I n Table VI are listed the impurity concentrations which changed the Mooney viscosity b y 10 points. All the impurities when present in high enough concentration produced a n increase in reaction time; however, the effect of these same compounds on the viscosity of the polymers varied. Some caused an increase, some a decrease, and a few did not influence Mooney viscosity.
Vinylacetylene
1-Butene
2-Butene
1-Butyne
2-Butyne
Propyne
Amounts of impurities that could be tolerated by the various systems were quantitatively measured
Acetone
The impurities can be placed in three groups based on possible effects in the polymerization system. The impurity may react with free radicals, or with initiators, or may function as a neutral diluent. The effects caused by these reactions result in either an increase or decrease in the rate of reaction or hlooney viscosity. The object of this study was to obtain some quantitative measure
Ammonia
September 1955
Q
0.10 0.25 0.50 1.0 2.5
9.7 10.4 10.6 13.1 17.4
57 49 44 51
9.7 10.3 4.9 10 8
42
a
0.0 0.1 0.5 1.0
10.0 10.4 10.3 10.6
44 73 111
0.0 0.5 2.0 5.0 0.0 0.5 2.0 5.0 0.0 0.5 2.0 5.0 0.0 0.5 2.0 5.0 0.0 0.5 2.0 5.0 0.0 0.4 2.0 10.0 0.00 0.05 0.10 0.50 1.00 2.50
9 9 10.3 11.0 12.0 9.8 10.2 10.9 11.4
>111
8.4 8.2 8.6 9.65 %!
56 48 47 45
50 69 100 >lo0 53 54 53 53 47 51 56 54
9.9 12.0 9.5 10.1 10.3 13.6
9.9 9.7 11.3 13.0 10.0 10.2 11.4 12.4
60 49 49 48 49 49 48
8.6 8.6 9.6 11.6 8.6 8.6 9.8 9.9
10.0 10.6 11.2 11.7 10.3 10.3 10.3 12.75
47 48 49 46 55 58 45 38
9.0 9.4 10.5 11.0 8.5 8.6 9.0 11.6
55 60
. .56.
9.3 10.2 11;9
.. .. ..
a
12.7 9.9 10.1 11;s a
49 42
a
55 53 43 54
...
...
56 48 48 47 48 44
60
8.1 8.5 14;2 10.4
8.1 8.2 8.6 9.65 7.8 8.2 10.0 13.0 8.1 8.1 8.6 10.0
60 91 >91 >91 55 53 49 49 61 58 57 63
54 f;
7.8
55 55
50 54 53 51 58
11.3 8.0 8.0 8.9 9.5
50 63 66 69 51
8.0
63 59 63 55 66 58 54 44
gi
8.0 8.0 12.4
64 60 58 51
8.0 8.1 8.5 14.1
42 39 40
7.9 9.0 8.4 9.7 8.4 8.9
... ... ...
49
41
47 42 41
...
Reaction terminated.
INDUSTRIAL AND ENGINEERING CHEMISTRY
1727
PRODUCT AND PROCESS DEVELOPMENT ~~~
Table V. Estimated Impurity Concentration to increase Time 10% for 60% Polymerization Conversion Impurity/100 Parts Monomer GR-S-100 Butadiene dimer Acetaldehyde Vinylacetylene 1-Butene 2-Butene I-Butyne 2-Butyne Propyne Acetone Ammonia
Table VI.
0.4 0.4 >1.0 2.0 2.0 1.4 2.0 1.8 5.4 0.4
.
GR-53-101
X-636
0.2 1.0 >l.O 1.2 2.2 1.8 1.8 1.2 3.2 0.05
0.3 1 . 0 (0) > 1 . 0 (0) 0.04 (+) 0 . 0 3 +) 0 > 5 . 0 (0) 4 '. 01 35 (+) (-) >5.0 i-1 > 5 . 0 10) >5.0 (-) > 5 . 0 10) 2.1 i-j > 5 . 0 (oj >5.0 (-) >5.0 (0) >5.0 (0) >5.0 ( 0 ) >5.0 2 . 0 (-) 4.2 (-) 1 . 5 (-) 0 . 4 (--) >o. 10 (0) 1 . 0 (0)
13)
The accuracy of the quantitative values listed in the summary Tables V and VI is unknown. However, additional information on impurities in reports t o the Office of Synthetic Rubber and in literature is available. Vinylacetylene in butadiene has been widely suspected of influencing adversely free radical polymerization systems. In one study (14) a sample of butadiene containing approximately 0.10% acetylene of which 0.06% was vinylacetylene was scrubbed with silver nitrate until free of acetylenes. The scrubbed and unscrubbed butadiene gave identical rates of reaction in a GR-S-100type formulation a t 5' C. and in the GR-S Mutual recipe at 50" C. The influence of acetylenes in butadiene on polymer viscosity was also studied by another group ( 1 6 ) . Synthetic mixtures of propyne, 1-butyne, and vinylacetylene in butadiene were prepared, and the concentrations were determined by infrared analysis. These samples were polymerized in 12-ounce bottles according t o the GR-S-101 formulation. The polymerization results showed that 0.57 part of propyne in the monomers or 1.65 parts 1-butyne had no effect on either the polymer viscosity or rates of reaction. However 0.075 part of vinylacetylene increased the Mooney viscosity between 15 and 20 points but had little effect on the rate of reaction. The addition of vinylacetylene t o a polyamine system similar t o X-636 indicated that the polymer viscosity was increased t o about the same extent as for the GR-S system, but the contaminant exerted a mild retarding effect on this polyamine system. I n another study (15) t o prepare highly branched polymers, butadiene was polymerized in the presence of 5 parts of vinylacetylene in a recipe similar t o that of the GR-S-100 formulation. The result from this study also indicated that vinylacetylene was not a serious rate retarder. This perhaps was to be expected since a derivative of dimethylvinylethynylcarbinol, copolymerizes vinylacetylene, rapidly with butadiene. Consideration of all this polymerization information on vinylacetylene indicates that this contaminant is not an effective retarder, but that it is a very effective cross-linking agent. A concentration of 0.1 yo in a 7 5 :25 butadiene-styrene monomer charge causes an increase in Mooney viscosity of 20 t o 30 points. On the basis of these results, process control will become irregular if the vinylacetylene in the monomers fluctuates &0.015%. Butadiene dimer has long been recognized as a retarder in polymerization systems. The data in Table V and VI indicate
1728
~
that 0.2 t o 0.4 part of dimer in the monomers will lower the rate of the three systems significantly, and 0.5 part will decrease the Mooney viscosity approximately 10 points. Recycle butadiene may contain considerable quantities of butadiene dimer, especially when stored a t high temperatures. The dimer should not be a serious problem in plant operations, however, because its low rate of formation ( 1 7 ) and the high boiling point (127' C.) relative t o that of butadiene simplifies removal if it is present. Acetaldehyde is only a mild retarder or modifier in the GR-S100 and -101 systems based on ferrous pyrophosphate complex as the reductant, but is extremely harmful t o the X-636, polyamine system. The inertness of the aldehyde in the two iron systems indicated little interference with the free radical propagation step or the initiating redox couple, but in the polyamine system the aldehyde probably reacts with the amine t o form a powerful retarder or a nonreducing product which is incapable of entering the initiation reaction. The formation of retarder is indicated since the Mooney viscosity of the polymer was markedly lowered. Because of the extreme sensitivity of the polyamine system t o trace amounts of acetaldehyde, i t seems advisable t o check the aldehyde concentration of the various ingredients used whenever the polyamine-type recipe is t o be employed. Ammonia varying over a great concentration range has been investigated in emulsion polymerizations systems. Trace amounts have been reported (13)t o exert a profound and characteristic retardation in polymerizations conducted at 50" C., when the combination of persulfate, disproportionated rosin soap, and tertiary mercaptan was employed. However, the various redox recipes, developed for polymerization a t low temperature, are much less susceptible to retardation by ammonium ion than the persulfate system. Large amounts of ammonium chloride were used as an antifreeze agent for a subzero polymerization system employing a ferrous pyrophosphate complex reductant (19), and other recipes, such as diazothioether ferricyanide (1%')and hydroperoxide-polyamine (21) systems, were unaffected by the ammonium ion present. Successful polymerizations have also been conducted a t -18" C. with polyamine systems containing 18% ammonia in the aqueous phase (11). These experiments establish that the ammonium ion is not an inhibitor. The retardation encountered in the persulfate system was attributed t o a possible interference with the initiation step ( I S ) , and this retardation could be suppressed by use of mixtures of normal and tertiary mercaptans and by an increase in the hydroxide ion concentration. The retardation by ammonia encountered in the three commercial recipes used in the present investigation also appears t o affect the initiation step. The retardation by ammonia in emulsion polymerization systems is apparently complex and more experimentation will be required before the mechanism can be elucidated. Butenes and simple acetylenes are relatively inert contaminants in the three polymerization systems studied. Butenes constitute the greatest proportion of impurity, varying from 50 t o 84Oj,, of the impurity fraction of butadiene, The Mooney viscosity data in Table VI show that sufficiently great fluctuations of the concentrations of these impurities in recycle butadiene will not occur under normal plant operation t o cause any difficulty in Mooney control. Hovever, if the purity of the butadiene charged t o the reactors of a copolymer plant fluctuates between 95 and 98.5oJ, or more, some rate control irregularities in copolymer plants could be assigned t o the butene fraction variation. On the other hand butadiene and styrene have been copolymerized a t -10' C. in the presence of 40 parts of 1-butene, and rates of 3 t o 401, per hour were attained; the polymers had normal plasticity (6). Therefore, butenes can be considered t o be rather mild retarders. Acetone was the least harmful of the impurities investigated. One series of polymerizations was conducted to determine the influence of a mixture of 0.10 part of vinylacetylene and 0.5 part of butadiene dimer in the GR-S-101 system. This mixture in-
INDUSTRIAL AND ENGINEERING CHEMISTRY
Vol. 47, No. 9
PRODUCT AND PROCESS DEVELOPMENT creased the time t o attain 60% conversion by 15% and the Mooney viscosity was increased by 8 points. These results verify a prediction that could be made from the data in Tables V . and VI. None of the contaminants studied influenced the stability of the latex as judged by visual examination. Vinylacetylene and butadiene dimer seriously interfered with GR-S-100, GR-S-101, and X-636 polymerization; acetaldehyde retarded the X-636 system
Of the ten impurities studied, vinylacetylene and butadiene dimer seriously affected polymerization in the GR-S-100, GR-S101, and X-636 systems and acetaldehyde was a powerful retarder in the x-636 system. The amounts of these impurities that caused either a 10% increase in time t o attain 60% conversion or a 10-point variation in Mooney viscosity were so small that large enough fluctuations in the concentrations of these contaminants might conceivably occur in the manufacturing or in the recycling step of the monomer t o cause production of off-specification rubber. The information presented should prove useful in explaining and preventing some polymerization reaction anomalies experienced by copolymer plants. Compensating for the contaminants present in the butadiene is not a practical means of process control. A uniform supply of butadiene charged t o the reactors and containing minimum quantities of objectionable contaminants is the best safeguard against polymerization difficulties from impurities. Acknowledgment
The work discussed herein was performed as a part of the research project sponsored by the Federal Facilities Corp., Office of Synthetic Rubber, in connection with the Government Synthetic Rubber Program. A. L. Hollis of the Office of Synthetic Rubber and W. B. Reynolds of Phillips Petroleum Co. participated in outlining the program and the methods of investigation. T. J. Kennedy of Phillips Chemical Co., Copolymer Section, supervised the additional experimental work with acetylenes cited in the body of the report. G. D. Hanson,
J. L. Hutson, and R. D. Barnett, 111, of The General Tire & Rubber Co., Baytown, plant supervised the experimental work performed a t Baytown. literature cited
(1) Back, A. L., IND.ENG.CHEM.,39, 1339 (1947). (2) Boyer, T. W., Kentucky Synthetic Rubber Corp., Progress Rept. Federal Facilities Corp. for period ending Sept. 30, 1953, CD-3055. (3) . , Burke, 0. W.. Starr, C. E . . and Tuemmler, F. D., “Light Hydrocarbon Analysis,” p. 18, Reinhold, New York, 1951. (4) Cram. L. H.. Rubber Chem. and Technol.. 19. 1092 (1946). (55 Frani, R. L., Blegen, J. R., Inskeep, G. E:, and Smith, P. V., IND.ENG.CHEM.,39, 893 (1947). (6) Fryling, C. F., and Mitchell, L. A., Phillips Petroleum Co., private Oommunication to Federal Facilities Corp., Office of Synthetic Rubber, Dec. 18, 1845, CR-955. (7) Fryling, C. F., and Pritchard, J. E., Phillips Petroleum Co., private communication to Federal Facilities Corp., Office of Synthetic Rubber, Oct. 24, 1950, CR-2495. (8) Harrison, S. A., and Meincke, E . R., And. Chem., 20, 47 (1948) (9) Hobson, R. W., and D’Ianni, J. D., IND.ENG.CHEM.,42, 1572 (1950). (10) Houston. R. J.. Anal. Chern.. 2 0 . 4 9 (1948). (llj Howland, L. H., Reynolds, J. A‘., and Brown, R. W., IND.ENG. CHEM.,45, 2738 (1953). (12) Kolthoff, I. M., and Dale, W. J., J . Polymer Sci., 3, 400 (1948). (13) Kostas, G. J., and Faull, J. H., The General Tire & Rubber Co., private communication to Federal Facilities Corp., Office of Synthetic Rubber; McCleary, D. C., U. S. Rubber Co., private communication to Federal Facilities Corp.; Fryling, C. F., IND. ENQ.CHEM.,40, 928 (1948). (14) Phillips Petroleum Co., progress rept. to Federal Facilities Corp., Office of Synthetic Rubber, December 1950, CD-2010. (15) Ibid., Jan. 31, 1953, CR-3212. (16) Phillips Chemical Co., Copolymer Section, unpublished data, January 1950. (17) Robey, R. F., Wiese, H. K., and Morrell, C. E., IND.ENG. CHEM.,36, 3 (1944). (18) Schiller, J. C., and Seyfried, W. D., “Product Quality Studies of Butadiene,” RUR SRlO and RUR SR99 (Technical Reoort. Humble Oil and Refining Co.). Seotember‘l9. 1944. (19) St. John, W. M., Uraneck,C. A:, and Fryling, C. F., J . Polymer Sci., 7, 159 (1951). (20) Whitby, G. S., “Synthetic Rubber,” pp. 260 and 683-4, Wiley, New York, 1954. (21) Whitby, G. S., Wellman, X., Flouts, V. W., and Stephens, H. L., ~ N D ENG. . CHEM.,42, 445 (1950). I
RECEIVED for review October 14, 1954.
ACCEPTED April 27, 1955.
END OF PRODUCT AND PROCESS DEVELOPMENT SECTION
Dimensional Stabilization of Textile Fabrics N. A. MATLIN AND A. C. NUESSLE Textile Applications Laboratory, R o h m & Haas Co., Philadelphia 37, Pa.
HE most important end use of textile fabrics is in the manufacture of clothing. Only a few decades ago i t was common practice t o buy garments several sizes too large, in the hope that after a few washings they would shrink t o an approximate fit. Today, however, both common sense and fashion decree a reasonable immediate fit. One of the first major advances in the dimensional stabilization of textiles was Sanforizing, a mechanical preshrinking process in which cotton fabrics are compressed in the warp direction t o such a degree t h a t on subsequent washing they shrink little or not a t all. The utility of the process was so evident that “Sanforized” is now a household word. More recently, chemical September 1955
processes have been developed which extend the range of fiber and fabric types t h a t can be stabilized. Most of these treatments minimize t h e tendency of the fabric to stretch as well aa t o shrink. This dual resistance is termed dimensional stability. The present discussion centers almost entirely on chemical processes that impart such stability to fabrics. The primary emphasis throughout, however, is on the control of shrinkage. The mechanics of shrinkage will vary with the type of fabric, and especially of t h e fiber. Cotton and rayon shrink because of fiber swelling, wool because of felting, the hydrophobic synthetics because of thermal disorganization and mechanical distortion. All fabrics shrink when strains developed in manufacturing are
INDUSTRIAL AND ENGINEERING CHEMISTRY
1729
