Alkarvlsulfonates as Conditioners in Wet-Twisting Cotton Tire Cord J
J . C. AI\IBEL..ING, J. A. SHOTTON, G. W. GOTTSCHALK, H. P. STEVENS, AND G. E. P. SMITH, JR. Chemical and Physical Research Laboratories, The Firestone Tire and Rubber Co., Akron, Ohio
T
HE use of wetting and sizing agents in the wet twisting of cotton tire cord has long been common practice, since these materials are known to improve mill operations and frequently Pesult in improved tensile strength. Rosin soaps are regarded by Buckwalter (3’) as deplasticizing, wax-peptizing agents which increase the strength of the cord by repressing the lubricating action of the natural waxes on the cotton fibers. The same reference points out t h a t wetting action alone does not account for the increase in strength as numerous wetting agents have either no effect or a deleterious effect on the cord strength. I n the present work, however, it has been found that appropriately constituted wetting agents are quite as effective as rosin soap in increasing strength and in improving the performance of the cord. Heretofore the relation between molecular structure of alkyl aromatic sulfonates and their effect on cotton cord has not been made clear in the literature. The present investigation generally confirms Buckwalter’s results with numerous commercial wetting agents, including some of the alkarylsulfonate type, whose use in twisting (does not result in significant improvement in cord strength. On the ather hand, certain synthetic alkarylsulfonates of sufficiently high molecular weight are in a class by themselves in t h a t they are effectiye in lower concentrations than is a rosin soap and impart more desirable properties t o the cord-softer hand, ease of handling in the mill, and longer service.
ring twister. A comparison of the data in Table I shows that the standard deviation in breaking load of the cord was close to 1 pound in all cases. A significant difference between the means of 40 breaks was calculated to be close to one-haIf pound, This figure was arrived a t by application of Student’s t test (IO). The standard deviation in values for elongation at a 10-pound load i s not shown because representative histograms showed thaO the elongations did not always follow the Gaussian distribution curve, apparently being affected strongly by the tension in drying or destretching. The general trend seemed to be towzrd greater variation a t higher elongations. SYNTHESIS OF SULFONATED WETTING AGENTS
The alkylnaphthalene, prepared as indicated beIow, was dissolved in a n equal weight of carbon tetrachloride and sulfonated with chlorosulfonic acid, 1.5 to 2.0 moles per mole of hydrocarbon. The acid was allowed to drop in as the mixture was stirred mechanically. The stirring was usually continued for 1 t o 2 hours after addition of the chlorosulfonic acid. The mixture was then made alkaline with 5001, sodium hydroxide and extracted with. hot methanol. The cooled extract was filtered from the separated salt and concentrated t o about 50% solids. For analysis t,he solution was evaporated t o dryness in the oven. The residue mas extracted, usually with 2-propanol, to
. I
APPLICATION OF WETTING AGEVTS TO TIRE CORD
LABORATORY SCREENING TESTS. Tire cord twisted without the aid of water or wetting agent solutions was reeled into skeins of four or five turns. The skeins were dipped for 30 seconds into a solution of the experimental cord conditioner and dried under tension for 1 hour a t 230’ F. The initial drying tension mas usually about 0.3 pound per cord and was most easily accomplished in a standard cord-conditioning rack, Four skeins of five
TABLEI. STANDARD DEVIATIOSS AND SIGNIFICANT DIFFERENCES OF TESTIKG PROCEDURES~
turns, sufficient cord for ten breaks in each skein, were taken t o permit distribution of the samples and hence greater replicability of cord for t h e different wetting agents under test. An alternative drying procedure was t o dry the skeins individually in a vertical oven which permitted a weight to be hung on the lower end of the skein. Constant and higher tensions were possible by this second procedure, though more labor was involved in obtaining a large enough number of cord samples. CORDTWISTING TEST. The wetting agents were added t o the water used t o wet the plies before cable twisting on standard 5inch rings on a Whitin laboratory machine. The plies, which had been wet twisted with water only, were usually passed over brass rolls partly immersed in the test solution before being led to the traveler for cable twisting. A single lot of NO. 10 count ply yarn was used in all tests and a 10/4/2 tire cord was produced by the experimental twisting operation. All cords were then “destretched” while still wet before tensile determinations. The destretching refers to the process of stretching the cord in a wet condition, a known procedure for reducing the elongation and increasing the strength of cotton cord (8). TWO COMPAEISOX OF RESULTS OF TESTING PROCEDURES. wetting agents and a control were tested in both laboratory screening procedures and twice in cord twisting on the experimental 204
Cord-twisting test (Whitin laboratory machine), wetting agent added i n twisting, destretching 10/4/2 cord, 40 samples Sodium sulfonate of triamylnsghthalene Proprietary h Water Significant did ., 95% probability Repetition of cord-twisting teSt Bodium sulfonate of triamylnaphthalene Proprietary -4 Water Significant diff., 95% probability Laboratorv screenine test, (Drocedure I). skeins alternatezon cord conditiongg racks, hand dipped in wetting agent solution, 11/4/2 dry-twieted cord, 40 samples Sodium polyamylnaphthalenesulfonate Proprietary A Dry cord, untreated Signifioant diff., 95% probability Laboratorv screening test (Drocedure 11). skeins“ alternate& dipp’ed singly and dried under constant tension of 7.5 lb./cord, 10/4/2 dry-twisted cord, 20 samples Sodium polyamylnaphthalenesulfonate Proprietary A Water Significant diff., 95% probability a On oven-dried samples.
Breaking Load, ~ l Lb. tion at Stand. 10-Lb. deviaLoad, Mean tion Mean % ,”
20.56 19.22 17.47 0.49
0.98 1.03 1.14
4.7
...
...
20.32 19.95 17.48 0.50
1.07 1.01 1.14
5,0
,.,
...
16.88 15 83 14.09
0.78 1.04 1.28
10.4 9.7 8.7
052
...
...
19.39 18.47 18.08 0.70
0.98 0.88
6.2
...
...
1.34
5.3 5.1
4,4 4.3
6.5
6.6
~
January 1953
INDUSTRIAL AND ENGINEERING CHEMISTRY
205
side of Russia, in whose publications most of the references Chlorn. were found (W, 4, 7, 11, 18). The nature of the alkylating agents and t h e procedure would be expected to lead to a mixture of isomers, which was 5 1.5 10.89 8.65 7.84 6.21 Amyl 1.39 70 High thought to be acceptable in this 9 10 1.5 8.95 10.71 6.72 7.68 Diamyl 1.33 7 1.28 8 15 2.0 7.42 7.28 5.80 5.22 Triamyl 8 study. In the Friedel-Crafts 6 High 1.51 1.5 10.79 10.54 7.12 7.66 45 Hexyl 12 8.05 6.02 6 6 Dihexyl 1.49 1.5 9.00 5.78 alkylation experiments it was 7 1.5 9.54 9.77 7.12 14 68 Heptyl 1.34 7.01 found that the dialkyl deriva8 14 1.5 6.80 7.52 5.78 5.40 1.18 7 Diheptyl 2.0 9.30 9.37 1.23 46 8 10 7.54 6.72 Octyl tives were formed in relatively 16 5.94 1.5 7.25 7.05 6 1.22 3 5.06 Dioctyl 9.00 9 7.64 10.77 10 27 1.41 2.0 6.48 Nonyl small yields even when a large 6.65 53 1.41 18 2.0 5.74 4.82 Dinonyl 8.11 23 excess of alkylating agent was 12 9.10 8.05 16 2.0 .88 5.78 Dodecyl .. .. ... ... ... 6... ... 1.32 12 204 Dibutyla present. For this reason a Obtained by courtesy of C. S. Marvel from the Noyes Chemical Laboratory, University of Illinois, Urbana, moderately high temperatures Ill. (f)* and active catalysts-e.g., a 1u m i n u m c h 1o r ide-w e r e used to increase the vield of separate the sulfonate from the sodium sulfate. The extract dialkylate. Also the most readily available and practicable alkywas then evaporated t o dryness and the residue dried t o conlating agents in this country are the alkenes. The Russian workers stant weight in a n Abderhalden dryer. seemed to prefer alkyl halides and worked at low temperatures. The same procedure was followed in sulfonating alkylbenaenes Under their conditions monoalkylnaphthalenes were probably and alkylphenols. Since the lower alkylphenolsulfonates apobtained in a purer state and with less isomerization. This difpeared t o have low thermal stability, the samples of concenference in operating conditions possibly accounts for differences trates were dried in vacuo with little or no heating above room between their physical constants and those given in Table 111. temperature. Available commercial or pilot plant alkylbeneenes A typical preparation is as follows: and alkylphenols were employed as starting materials in place For the preparation of dioctylnaphthalene 4 moles of naphof the laboratory preparations of alkylnaphthalenes used in the thalene (512 grams) were stirred under reflux with 10 moles of preparations of the alkylnaphthalenesulfonates. The analyses diisobutylene (1120 grams), while 1 mole (133 grams) of aluminum chloride was added slowly. The temperature rose and of the alkylnaphthalenesulfonates reported in Table I1 require was held a t 70" C. for 3 hours. The mixture was then poured some explanation. The theoretical sulfur-sodium ratio in a onto ice and the oily layer was washed with 10% sodium hysodium sulfonate of any hydrocarbon is 1.39. The high sulfurdroxide and water and dried over anhydrous magnesium sulfate. to-sodium ratio in the sulfonation products of hexyl- and dihexylThe dried oil was fractionated under reduced pressure and t h e following data were obtained: naphthalene suggests the presence of sulfone. A low sulfur-tosodium ratio is more difficult t o explain unless oxidation is nsB.P., c., Yield, sumed. This could lead either t o a carboxyl group or to a pheFraotion a t 1 Mm. Grams n -V 110 ... nolic group as in the alkali fusion of sulfonates. The high values 175 for both sulfur and sodium observed when certain hydrocarbons 140 1.'5468 250 1.5415 were sulfonated suggests the occasional introduction of two sul232 1.5354 fonic acid groups into some of the molecules. However, the forAI Below 180a 17 mation on the average of a monosulfonate of a mixture of posiAI1 185-190n 180-185a 125 1.'i434 AI11 tion isomers containing the correct number of alkyl group8 at106 1.5406 a At 5 mm. tached t o the aromatic nucleus is indicated and assumed in dnch case. Fraction IV-AI11 was assumed t o be di-tertoctylnaphthalene. PREPARATION OF ALKYLNAPHTHALENES. The hexyl, heptyl, Analyses of molecular weight (cryoscopic) gave values of 345 and 359, average 352; the calculated molecular weight for and octyl naphthalenes apparently have been little studied Gut-
TABLE 11. PREPARATION OF SODIUM ALKYLNAPHTHALENESULFONATES
...
O
TABLE 111. PREPAFUTION AND PROPERTIES OF ALKYLATED NAPHTHALEKES Alkyl Groups Amyl Diamyl Triamyl Hexyl
12:f&
Mixed Aniline pt.a, Density 0 C. -G./cc. C'.
Boilitg pt
Molecu$r Molecular Wt. Refraction Carbon, % Hydrogen, % 760 Mm. Calcd. Found Found Calcd.d Calcd. Found Calcd. Found
o
c.'.;
n&' Source Commerci: : (Sharples) 1.5724 9.5 0.960 22 279-310' 198 C o m m c r r d Sharples) 1.5518 29 0.932 22 329-361' 268 Laboratory ($harplee) 1.5404 45.5 0.920 22 382-388' 338 . . 308-322 212 Pre from commercial hexylenes 1.5629 22 0.950 (Wtlantic) Dihexyl Prep. from commercial hexylenes 1.5506 34.5 0.936 25 375-385 296 (Atlantic) Prep. from commercial isohep- 1.5556 22.5 0.944 226 Heptyl . 308-322 tylene (Phillips) 324 Diheptyl Prep. from commercial isohep- 1.5426 22 386-398 42 0.929 tylene Prep. from 2-ethyl-1-hexanol 1.5727 18 0.930 240 Octyl . 346-358 Prep. from commercial diisobutyl- 1.5406 47 0.917 Dioctyl 24 368-373 352 ene Commercial (Sharples), Neolene 210 1,5545 18 0.942 320-350' Nonyl 254 Dinonyl Fractionally dist. from Sharples 1.5381 44 0.925 380 22 412-418 Neolene 220 Dodecyl Prep. from 1-dodecene 1.5343 31 0.887 380-412 296 Naphthalene (in decane solution) ... ... ... ... a Mixed with equal volume of heptane. Calculated from experimental boiling point a t reduced pressure on Lippincott's nomograph (6). Cryoscopic in benzene or ethylene dibromide. Based on experimental value for naphthalene. a Data from supplier (Sharples laboratory).
.
...
...
. .. .. ..
......
189 257 338 215
64.8 88.1 115.4 73.5
138.1 91.2 . . . . . . 114.3 7 2 . 7 90:50 90103
300
102.2
100.4 89.12 89.31
. . . . . .
9.50
9.85
10.88 10.86
221
75.2
77.3
90.10
9.80
10.08
323
109.4
109.6
88.82 89.07
11.18
10.92
23 1 352
81.8 120.5
81.9 89.94 89.98 118.9 88.56 88.20
10.06 11.43
9.92 11.62
253 377
86 1 86 5 120.'5 128:l
293
1 0 2 . 7 100.4 89.12 88.98 45.0 . . . . . . . . .
...
90.20
88.'35 88:47
ii:& ii:& 10.88 11.16 . .. . .. . ..
INDUSTRIAL A N D ENGINEERING CHEMISTRY
206
VoI 45, No. 1
points are experimental. The agreement between calculated and measured values indicates a series of homologs was prepared. The aniline points were determined by a control laboratory procedure with n-heptane (technical grade) as the diluent. Ten milliliters of sample were measured into a 25-nil. graduate. Ten milliliters of n-heptane were pipetted in and thoroughly mixed. Five milliliters of the solution were pipetted out, mixed with 5 ml. of reagent grade anilinc (from a IO-ml. graduate) in a 200 X 25 nim. test tube, and stirred with the thermometer while the test tube was dipped into a beaker of hot mater. The temperature was rcad when the mixture became clear on warming or cloudy on cooling. This temperature is the aniline
I
8
'
3;o
'
3;o
r
3;ow
Mole c u l a r W e i g h t
Figure 1. Rlolecular Refraction cs. MoIecular Weight for .ill\ylnaphthalenes
point usedinthepresentdiscussion. The procedure gave a precision of l o C. A plot of the aniline point against molecdar weight is shown in Figure 2. RESULTS
(CaHn)zCloH6is 352. Further physical data and anallsis are given in Table 111. Fraction I began t o crystallize in long needles after a few days. The needles were spread on a clay plate, then recrystallized from petroleum ether to a constant melting point, 135" t o 136" C.; it wm assumed t o be di-tert-butylnaphthalene. Attempts t o determine its structure by oxidation \?-ere unsuccessful. Refluxing with aqueous alkaline permanganate or with permangarlate in acetone had little effect on the substanc8e nor did heatlng with 5% nitric acid for 10 hours at 160" to 170" C. ( 4 ) . Analysis of the compound gave the following data: carbon, found 89.55% (two determinations), calculated for (C4He)2CloHk 89.940/0; hydrogen, found 10.00 and 10.34%, calculated for ( c , H ~ ) ~ c ~9.94%; ~ H ~ , molecular Tveight,found (cryoscopic) 238 axid 232, calculated for ( C ~ H ~ ) & I & 240. ,
The principal conclusion drawn from the screening tests presented in Table IV \\-as that higher dkylnaphthalenes, having 12 Or more alkyl carbon atoms, are the most promising source of starting m a t e r k h for wetting agents which will increase cord strength. A comparison of the controIs in columns 7 and 9 shows that the strength increase to be expected from dipping the cord in n-ater alone and dwing under tension waa 1.78 pounds or 2.47 pounds when the drying tension \\'as 3.76 pounds per cord. At low drying tensions (less than 0.5 pound per cord), indicaLions are t h a t M-ater alone has no effect. This inference a ~ a smade from a comparisofl Of the mean control values in columns 7 and 9. Addition t o the water of certain commercial wetting agents gave a slight increase or none to the breaking strength, while additions of the higher alkylnaphthalene sodium sulfonates resulted in an increase shown V a 5 0 t o be significant. The same sulfonates gave still c? -0greater increases when the cord was dried under ,3400 tension of 3.75 pounds per cord. It would appear w30that these increases were due t o the combined z effects of the sulfonates and of drying under tension. Tests oi a series of wetting agents in ply and w i xI cable trr-isting are in qualitative agreement with 200 220 240 260 280 300 320 340 360 certain conclusions from the screening test as MOLECULAR W E I G H T shown in Table V. Sodium sulfonates of polyamylnaphthalene and dodecylphenol along v, ith Figure 2. Mixed iniline Point z's. Molecular Weight for one commercial sulfonate are in a class above Alkylnaphthalenes the remaining wetting agents of various types. Use of a carefully prepared and controlled (as Physical constants and analvtical data on all alkylnaphthalen~s t o molecular M eight) series of sodium alkylnaphthalenesulfonates prepared are given in Table 111, along with physical corlstants in wet-t&ting tire cord of 10/4/2 construction shon-ed that the of commercial homologs also sulfonated. Figure 1 is a plot of maximum stlength rcmlted when the alkyl groups contained 14 mr,lecu~ar refraction, computed b y the Lorerite and Lorena to 18 carbon atoms. There i m s little difference in tensile effects f o r n ~ u l a against , moleculal %,eight. The llne is calculated; the among dialkylnaphthalenes containing 8 to 12 aliphatic carbon atoms, but a signifiicanth sharp rise in breaking strength waa observed when the alIq Iation \?-as increased from 12 to 14 aliphatic carbon atoms (molecular weight of hydrocarbon greater than 300). The data die presented in Table VI. In Figure 3, the breaking load of the cord is plotted against the molecular weight of the hydrocarbon base of the wetting agent. The size of the symbols was gaged to indicate significant differences on ( 7 water, control) the basis of the Student's t test (diameter was equal to t X standard deviation of the difference between means). Thus, failure of the 200 24 0 2 80 32 0 3 60 ordinates of two symbols to overlap shows that in 95 cases out MOLECULAR WE1 G H T OF H Y D R O C A R B O N of 100 there is a real difference between the mean breaking loads of cords prepared from these two sulfonates. Figure 3. Molecular Weight zs. Breaking Load of Cord It is a t once evident that the higher molecular weight sulfonates Sodium alkylnaphthalenesulfonateson 10/4/2 cotton tire cord
INDUSTRIAL AND E N G I N E E R I N G CHEMISTRY
January 1953
TABLE 117.
EFFECT OF HAND DIPPING IN SODIUAI .~LKARYLSULFONATE Sor,r;i~roljsO N TIRECORD
Hexylnaphthalene Heptylnaphthalene Octylnaphthalene Dibutylnaphthalene Di-tert-butylnaphthalene Nonylnaphthalene Decylnaphthalene Diamylnaphthalene
4
Dodecylnar~hthalene Dihexylriapht halene Dihrptylnaphthalene Polyam~'1nsphthalene Triainylnaphthalene Dioctylnar~lithalene Polynonylnaphthalene Dinonylnaphl halene (cornin.) Dinonylnaphthalene (coinin.,' Polyamylnaphthalene Octylated naphthalene Boilingpta (0.5 mm.) 125-175' C. 165-192' C. Over 192' C. Dinonylnaphthalene Dodecylated naphthalene Boiling pt. 228-395' C. Boiling pt. 395-472' C. Miscellaneous alkarylsulfonates Abietylphenol Amylbiphenyl C1*-Cle alkylbensene Cumene bottoms (Shell Oil) Diamylbi hen 1 Dodecvlp~eno~ Dutrek 20 (petrol. extr. Shell Oil) Dutrex 20 alba (petrol. extr. Shell Oil) Dutrex 21 (petrol. extr. Shell Oil) Retene oil Commercial sulfonates Aerosol OT Aresklene Meon Q
BREAKING STRENGTH OF COTTON
Mean Breaking Load, 8 Lh. ___ Increase in 7 Breaking Load, v WaterSulfonateSnlf onatetreated Treated Cord treated control over Watercord (oven- Treated Control, (ovendried) Lb. dried)
Sofid
No. of
Breaks
4 Const. of Cord
5 Drying Tension" Lb./Cord
1.5 1.5 1.5 1.5 1.5 1.5 1.5 2.25 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5 2.25 1.5 1.5 1 5 1.5
40 40 40 40 40 40 40 40 24 40 40 40 40 40 30 30 40 40 40 40 40 40 40 40 24 30
11/4/2 10/4/2 10/4/2 10/4/2 10/4/2 10/4/2 11/4/2 11/4/2 10/4/2 11/4/2 11/4/2 10/4/2 10/4/2 10/4/2 10/4/2 10/4/2 11/4/2 11/4/2 11/4/2 10/4/2 10/4/2 10/4/2 10/4/2 11/4/2 10/4/2 10/4/2
0.3 0.33 0.33 0.33 0.33 0.33 0.33 0.33 0.6 0.33 0.33 0.33 0.33 0.33 0.33 0.6 0.33 0.33 0.33 0.33 0.33 0.6 0.33 0.33 3.75 3.75
14.41 16.0 16.6 16.7 16.3 16.4 15.04 13.6 16.58 15.13 14.2 17.1 16.2 16.9 17.6 16.00 14.1 15.26 14.1 17.3 16.9 17.34 17.1 14.2 18.91 19.48
14.12 15.1 15.1 15.1 15.1 15.1 14.12 12.8
1.29 0.9 1.5 1.6 1.2 1.3 0.92 0.8
14: i 2 12.8 15.1 15.1 15.1 15.1
1.01 1.4 2.0 1.1 1.8 2.5
12: 8
14.12 12.8 15.1 15.1
1.3 1.14 1.3 2.1 1.8
15.1 12.8 16.45
2.0 1.4 2.46
1.6 1.5 1.5 1.5
24 24 24 24
10/4/2 10/4/2 10/4/2 10/4/2
3.76 3.75 3.75 3.75
18.87 19.58 19.58 19.79
16.78 16.78 16.78 16.45
1.5 1.5
24 24
10/4/2 10/4/2
3.75 3.75
18.78 19.39
2.25 2.25 2.25 2.25 2.25 2.25
40 40 24 24 40 40
11/4/2 10/4/2 11/4/2 11/4/2 10/4/2 10/4/2
0.15 0.6 0.5 0.5 0.6 0.6
16.31 16.34 14.67 15.69 16.20 16.37
2.25
24
11/4/2
0.5
16.35
2.25
40
11/4/2
0.15
16.04
2.25 2.25 2.25
40 24 40
11/4/2 11/4/2 11/4/2
0.15 0.5 0.15
16.21 16,77 16.61
0.3 2.25 3.0 2.0 3.0 3 .O 3.0
40 40 40 40 40 40 40
11/4/2 11/4/2 11/4/2 10/4/2 11/4/2 11/4/2 11/4/2
0.15 0.15 0.15 0.33 0.15 0.15 0.15
15.63 16.34 15.65 16.3 16.59 16.23 16.88
2 Concn., 1 Sodium Sulfonate of Alkylnaphthalenes Amylnaphthalene
THE
7
1.5
3
207
9 Untreated Cord Control, Mean Breaking Load, Lb.
10 Increase in Breaking Load, SulfonateTreated Cord over Untreated Control, Lb.
... ...
.,.
...
... ...
*..
... ,..
... ...
... ...
... ... ... ...
15: i 4
... ... ...
1.44
... ...
... ...
14:05
...
1.04
... ... ...
... ... ... ...
...
14: 49
1.85
,..
15:oo
... 4.'&
2.80 2.80 3.34
...
15.00 15.00 15.00 13.96
3.87 4.58 4.58
16.78 16.78
2.00 2.61
15.00 15.00
3.78
... ... ...
... , . . ... ... ...
14.88 14.87 15.14 15.14 15.49 14.58
1 43 1.47 0.53 0 55 0 71 1 79
15.41
1.21
14.87
1.17
14.88 15.07 14.88
1.33 1.70 1.73
14.88 14.87 14.88
0.75 1.47 0.77
14.88 14,88 14.88
1.69 1.35 1.97
...
...
...
...
... ... ... ...
... ... ... ... ...
15.1
...
...
...
...
...
1.2
... ...
Petrosol Sulphopet SV- 1959 Miscellaneous sulfates 24 11/4/2 0.5 15.67 3.0 Sodium abietene sulfate 0.5 24 11/4/2 16.03 3.0 Aquarex SMO ik'. i 2 -0.23 0.33 11/4/2 13.89 40 1.5 orvus a Skeins dried under 3.75 lb./cord tension were dipped and dried singly in a vertical oven: all others were dipped and dried b Identified in references (6, 1 9 ) .
... ...
...
gave not only significantly higher breaking strength but consistently replicable values which were close t o 20.7 pounds in all four cases. The breaking loads of cords twisted with the lower molecular weight sulfonates are not quite so consistent and are distributed about a value of 19.0 pounds. The controls, twisted with water alone, average 17.7 pounds. I n the alkylbenzene and alkylphenol series the molecular weights are not so evenly distributed, since there was less control of the molecular weights of the individual.members of the homologous series. When the alkytbenzenes had molecular weights below 220, the sulfonates produced cord with a breaking load close t o 18.4 pounds. B u t when the molecular weight was over 250, the breaking strength of the resulting cord increased t o 19.9 pounds. These conclusions are shown graphically in Figure 4, which is a plot of the data in Table VII. In the alkylphenolsulfonate series the difference between
... ...
... ...
..*
... ...
...
15.07 15.07
...
...
...
5.81 4.39
...
0.60
-0.04
...
on cord-conditioning racks.
levels was smaller. Sulfonates of alkylphenols below 190 in molecular weight apparently had no effect on cord strength. When the molecular weight was over 230, the sulfonate raised the breaking load t o about 19.4 pounds, 1.5 pounds higher than the control twisted with water alone. D a t a are listed in Tahle VI11 and plotted in Figure 5. The effect of wet stretching and drying tension on the elongation and breaking strength of cotton cord is well known (8). While the effect on tensile of the surface active material used in wet twisting is relatively simple t o demonstrate, the effect on elongation is probably indirect and related partially t o the behavior of the cord in the mechanical wet-stretching process. The relative variability of t h e elongation and breaking load mas discussed previously under experimental methods. For example, under twisting and stretching conditions favoring low elongation, the sodium salt of dinonylnaphthalene gave a cord with lower
208
INDUSTRIAL AND ENGINEERING CHEMISTRY
TABLEV. EFFECTOF VARIOGSWETTING AGENT^ ON TENSILESTRENGTHOF COTTONTIRE CORDAPPLIEDAT MILL IN A CORDTWISTER
Vol. 45, No. 1
THE THE
(1% solution in ply twisting, 2% solution in cable twisting, 10/4/2 construction) Breaking Loada, Lb Sulfonate-'' Increase Treated over Cord (Oven Controlb. Dried) Lb. Sulfonates c Sodium dodecylphenolsulfonate 20,33 1.81 Sodium polyamylnaphthalenesulfonate 19 83 1.65 Petrosol (petrol. fraction sodlum sulfonate) 19 43 1,56 Igepon A P (sodium sulfoxyethyl oleate) 19.21 0.74 S V-1959 (petrol. fraction sodium sulfonate) 18.65 0.18 Triton 720 (sulfonated ether) 0.13 18 22 Decerosol O T 17.03 -0.12 Nacconol N R (sodium alkarylsulfonate) 15 78 -0.32 Santomerse D (alkylated sulfonate) 0.12 16.58 Alkyl sulfates Duponol M E (fatty alcohol sulfate) 17.59 -0.50 Duponol WS (fatty alcohol sulfate) 18,47 0.38 Modinal D (fatty alcohol sulfate) 17.94 -0.15 Rosin soap with wetting agentc Rosin soap 2-3% (1/z% I epon A P added) 20.26 1.74 Rosin soap 3 (1-2%) {'/&Isepon A P added) 19.60 1,08 Rosin soap (2-3%) 1/z-l% Neomerpin SA added) 17.31 ... Nonionic8 Triton N E 17.60 -1.58 Tween 40 16.35 -0.08 a Average of 25 to 40 breaks. Control treated with Proprietary A, a sodium salt of a sulfonated petroleum fraction. The commercial products are identified as in (6, IS).
W E
IS0
m
I
220
260
300
-
M O L E C U L A R W E I G H T OF ALKYLPHENOL
Figure 5.
38 0
Alolecular Weight vs. Breaking Load
S o d i u m alkylphenolsulfonates as w e t t i n g a g e n t s in cable-twisting 10/4/2 cotton tire cord
study were made from the high molecular weight hydrocarbons. In the alkylnaphthalene series, these hydrocarbons had a mixed aniline point a t least 7.5" C. higher than the next lowest homolog. The relation is shown in Figure 7 , where the breaking load of the cord is plotted against the mixed aniline point of the hydrocarbon before sulfonation. This concurrence of properties suggests that the high molecular weight sulfonates fall into the class of "oil-soluble" sulfonate soaps. This classification was partly confirmed by the additional comparison in the following table:
Nonylnaphthalene Dinonylnaphthalene
Mixed Aniline Pt., C.
Breaking Load of Cord, Lb.
Solubility of Sodium Sulfonate in Hentane. ..~~., % Insoluble
18 44
18.86 20.28
97 5
.
Solubility of the sulfonate in heptane is associated with high cord strength and high aniline point of the parent hydrocarbon. The heptane solubility could not be determined throughout the series because some of the sulfonates tended t o form colloidal dispersions and pas3 through the extraction thimble along with the soluble fraction. As the dried sulfonates tend t o be resinous and sticky rather I than slippery, they could not be expected to act as lubricants. w 140 I80 220 260 360 400 I n this respect they resemble rosin soap, which gives a tacky a m M O L E C U L A R W E I G H T OF H Y D R O C A R B O N rather than a slippery film. The solubilities and physical characteristics of the higher alkarylsulfonates suggest that they may Figure 4. Molecular Weight vs. Breaking Load exert a binding action on the cotton fibers and thereby increase Sodium alkylbenzenesulfonates on 10/4/2 cotton t i r e cord the breaking strength of the cord. This theory also explains the increased breaking strength observed on hand dipping and drying under low tension even though the elongation ( a t a 10-pound elongation and higher breaking strength than sodium nonylload) of the cord is not reduced (Table I). This binding action naphthalenesulfonate (test 11, Table VI). Under conditions explanation was suggested by the commercial use of resinous sizes favoring higher elongations, the elongations of the two cords in processing filament yarns. On the other hand the mechanism were equal but the dinonrl derivative showed a still greater suggested by Buckwalter (3) for the action of rosin soap might advantage in breaking load (test I , Table VI). This observation was generalized in Figure 6, where breaking load is plotted against elongation for TABLE VI. CORDTWISTING TESTSON SODIUWALXYLNAPHTHALENESULFONATES. TESSILEDATA twisting tests reported in AKD STATISTICAL AK.4LYSIS Table VI. This shows a trend (Each figure represents a sample of 40 breaks of 10/4/2 cotton tire cord) toward an inverse relation of S, Standard S, Standard of Mean Deviation Deviation strength and elongation a t low of Mean Elongation Mean Mean Elongation Breaking 10-Lb. Breaking Breaking a t ranges of elongation-i.e., beBreaking a t 10-Cb. Load c, Loadb, Load", Loadn, Loada, Load , low 4.5% where the mechanical Lb. Lb. Lb. Lb. Sodium Sulfonate of % % Twisting Test I1 T'wisting Teat I p r o c e s s i n g presumably out... 0.177 18.77 5.1 Dibutylnaphthalene weighed the effects of the wet... 0.181 18.48 5.5 Amylnaphthalene 0.143 ting agent. At higher elonga19.22 5.0 Diamylnaphthalene o:i72 0.158 20.56 5.3 Triamylnaphthalene tions, over 4.7%, no correla0.156 0.178 18.91 5.1 Hexylnaphthalene 0.175 0.194 19.40 5.1 Dihexylnaphthalene tion between strength and 0.152 0.200 18,05 5 . 1 Heptylnaphthalene 0.177 elongation is discernible. It is 0.236 20.95 4.9 Diheptylnaphthaleni 0.179 0.215 18,44 4.9 Octylnaphthalene a t these greater elongations 0.148 0.172 21.10 4.7 Dioctylnaphthalene 0.148 0.160 18.86 5.1 Nonylnaphthalene that the use of higher sul0.184 0.141 20,28 5.1 Dinonylnaphthalene . . . fonates offers an advantage in 0.186 19.19 4.8 Dodecylnaphthalene o:i62 4.3 19,'95 0.166 19.22 5.1 A Proprietary cord strength without a con0.183 5.0 17.48 0.183 17.47 4.9 Water (control) 0.175 4.9 17,80 0.116 18.on comitant decrease in elongaa Oven-dried cord. tion. In t h e breaking load d a t a when S = 0.2, t h e t test shows a significant difference in means (40breaks of each) of 0.58 lb. (957' level) = t &,'where Sd = standard deviation of difference between means. ~IECHANISM OF ACTION OF I n t h e breakng load data, when S = 0.184,the I test shows a significant difference in means (40 breaks of each) of 0.53 lb. (95% levell = t S d . A L K A R Y L S U L F ONATES. The most effective sulfonates in this
TABLEVII. TENSILEPROPERTIES OF COTTON TIRE CORD (10/4/2) CABLETWISTED WITH SODIUM ALKYLBENZENE-
TABLEVIII.
TEXSILEPROPERTIES OF COTTONTIRE CORD (10/4/2) CABLETWISTED WITH SODIUM ALKYLPHENOLSULFONATES
SULFONATES
Moleo. Wt. of Elongation Hydro- at 10-Lb. Breaking carbon Loada, Loada, (Exptl.) % Lb.
Sodium Sulfonate of tert-Butvlbenzene (Phillius. m r e ) Amylbehzene (Sharples) . . Diisopropylbenzene (Dow) Diamylbenzene (Sharples) Dodecylbenzene (Oronite alkane) Kerylbenzene (Sharples) Dikerylbenzene (Sharples) Polydodecyltoluene (Sharples) Proprietary A Water (control) Dodecyltoluene (Sharples) Nonadecylbenzene (Oronite 51168R) Proprietary A Water (control) a
(1
,
209
INDUSTRIAL AND ENGINEERING CHEMISTRY
January 1953
134 148 157 217 250 26 1 272 360
... ... ... 386
... ...
4.65 4.6 4.4 4.2 4.1 4.2 4.2 4.0 4.1 4.8
17.82 18.26 18.66 20.19 19.80 19.49 20.14 19.71 18.62
4.7 5.2 4.7 5.05
17.85 19.67 17.65 17.27
18.91
Oven-dried cord. Calculated.
also explain the improved strength imparted by the higher alkarylsulfonates. The wetting properties of the conditioner permit it t o be dissolved or dispersed in water so that it can be applied t o the cord at the twister. The wetting properties also contribute to the action of water in the twisting and destretching operations since cotton is protected by natural waxes from rapid wetting by pure water. Thus, the speediest wetting agent, Decerosol OT (Table V),gave cord strength equal to the control which is, however, inferior to the best alkylnaphthalenesulfonates. The independence of the tensile effect from wetting efficiency is shown by a comparison of Figure 3 with Figure 8. I n the latter, the wetting (9) time of the sulfonate in0.15yOaqueous solution goes through a minimum when the molecular weight of the hydrocarbon residue increases from 257 through 352. On the other hand the maximum cord strength is obtained when the molecular weight of the hydrocarbon residue exceeds 320. The shapes of the two graphs are quite different. The cord-twisting tests were made with the sulfonates in 1.5% solution; a t that concentration the wetting in all cases would have been practically instantaneous if the sulfonates had any surface active characteristics a t all. SUMMARY
A series of alkylnaphthalenes was prepared of homologs containing from 6 t o 18 alkyl carbon atoms. A series of sodium sulfonates was prepared from amyl-, hexyl-, heptyl-, octyl-, dodecyl-, diamyl-, dihexyl-, diheptyl-, dioctyl-, dinonyl-, and triamylnaphthalenes. A screening test involving hand dipping of dry-twisted cotton tire cord was made on a wide range of sulfonates and other wetting agents, both laboratory preparations and commercial prod-
Sodium Eulfonate of tert-Amylphenol (Sharples) Diisopropylphenol Kop ers) tert-Hexvlohenol tS6arogs) NonylpheLol (Shbples) Diamylphenol (Sharples) Dodeoylphenol (Sharples) Dinonylphenol (Sharples) Water (control)
Molec. Wt. of Elongation Alkyla t 10-Lb. Breaking phenol Loada, Loada, (Exptl.) % Lb.
180 183 188 23 1 238 263
...
Nonylphenol (Sharples) Diamylphenol (Sharples) Dodeoylphenol (Sharples 28687) Tetradecyl henol Oronite 146069P) Octadeoylp%enol (iharples) Dinonylphenol (Jefferson) Water (oontrol) a Oven-dried.
4.9 4.5 4.3 4.8 4.0 4.5 4.1 5.0
17.5 17.9 18.2 18.2
4.55 4.4 4.4 4.8 4.4 5.6 5.0
19.7 19.3
19.3
18.1 19.4 17.3
420.0 ::; 18.8 17.7
ucts, which were possible wetting agents for use in wet twisting. The higher alkylnaphthalenesulfonates appeared outstanding as a class in t h a t they produced increased breaking strength even when the cord was dried under low tension. Use of the different types of wetting agents in experimental twisting tests confirmed this conclusion. A test of the more carefully prepared homologous series of sodium alkylnaphthalenesulfonates by addition t o the water in cable-twisting cotton tire cord showed that the higher members, diheptyl-, dioctyl-, dinonyl-, and triamylnaphthalenesulfonates, that is, those sulfonates derived from hydrocarbons over 320 in molecular weight, increased the breaking load by approximately 3 pounds. The lower homologs gave less uniform results but averaged a 1.3-pound increase. A shorter series of homologous sodium alkylbenzenesulfonates was similarly tested. Sodium sulfonates of hydrocarbons over A L K Y L C6-C12
BREAKING20
-
O F CORD 18
I
- L 89.
A L K Y L C,4-
C18
+
OVEN DRIED
2'
BREAKING 2 0 LOAD
19
'LBS.
18
-
-
0
Time of U
0.15 4: 4 0
-
I
Solution* 301
I 4.0 4.5 5.0 5.5 OVEN DRIED ELONOATION A T IO-LB L O A D O/o
3.5
I
-
Figure 6.
Elongation a t 10-Pound Load US. Breaking Load
Sodium alkylnaphthalenesulfonateeon l0/4/2 cotton tire cord
9
I
.
. . . . . -. . . .
I
*
.
240 260 280 300 3 2 0 340 360 M O L E C U L A R WEIGHT O F A L K Y L N A P H T H A L E N E
220
Figure 8.
-
Canvas Disk Wetting Time (9) us. iMolecular Weight of Alkylnaphthalene
Aqueous solutions of sodium alkylnaphthalenesulfonates
210
INDUSTRIAL AND ENGINEERING CHEMISTRY
250 in molecular weight gave breaking loads averaging 1.5 pounds over the control. Sodium sulfonates of the lower homologs had little effect. A short series of sodium alkylphenolsulfonates was similarly tested. Sodium sulfonates of alkylphenols above 230 in molecular weight gave a 1.5-pound increase in breaking load while the lower homologs were without effect, The increased cord strength attributable to alkarylsulfonates is realized at relatively high elongations without any significant trend toward lower elongation with higher breaking loads. Under is, conditions of processing favoring low elongations-that greater mechanical stretching in the wet condition-the increase in breaking load is additional to and may be overshadowed by the effects of the wet stretching.
Firestone Research Laboratories for carrying out the experimental twisting, for supplying the physical testing data, and for the discussion of the statistical handling of the latter. The authors' thanks are hereby expressed to W. James Lyons, D. E. Howe: and I. B. Prettyman. LITERATURE CITED (I)
(2) (3) (4) (5) (6)
(7) (8)
ACKNOWLEDGMENT
The interest and encouragement of F. W. Stavely, R. F. Dunbrook, and J. W. Liska in this investigation are gratefully acknowledged. The authors also wish to thank the management of The Firestone Tire and Rubber Co. for permission to publish this report. The authors are deeply indebted to the Textiles Group of the
Vol. 45, No. 1
(9) (10) (11) (12)
Adams and Myers, private communication to the Office of Rubber Reserve (Nov. 20, 1946). Andreev and Petrov, Zhur. Priklad. Khim.,21, 134 (1948). Buckwalter, U. S. Patent 2,297,536 (1942). Kitaigorodskii, Acta Physicochim. U.R.S.S., 21, 1047 (1946). Lippincott and Lyman, IND. ESG. C H m , 38, 320 (1946). hlcCutcheon, Chem. I n d s . , 61, 811 (1947). Petrov and Andreev, Zhur. Obshchet Khim., 12, 95 (1942). Philipp and Conrad, J. Applied PhzJs., 16, 32 (1945). Seyferth and Morgan, Am. Dyestuff R e p t r . , 27, 525 (1938). Snedeoor, "Statistical Methods," pp. 56-9, 71--3, Ames, Iowa, Iowa State College Press, 1940. Tilicheev, Khim. Tzerdogo Toplieu, 7, 181 (1938). Tsukervanik and Terent'eva, Zhur. ObshcheE Khim.. 7, 637 (1937).
(13)
I-oung and Coons, "Surface Active Agents," Brooklyn, Chemical Publishing Co., 1945.
RECEIVED for review May 20, 1952.
pp.
117-52,
ACCEPTED August 20, 1952.
Phase Behavior of the HydrogenPropane System W. L. BURRISS, N. T. HSU, H. H. REARIEK, AND B. H. SAGE California Institute of Technology, Pasadena, Calif.
L
I T T L E experimental information is available concerning the phase behavior a t elevated pressures of binary mixtures containing hydrogen. A study of the carbon dioxide-hydrogen system was reported by Verschaffelt (f7). This work indicated a rapid increase in the critical pressure with a decrease in temperature below t h a t corresponding t o the critical temperature of carbon dioxide. Information is available concerning the vaporliquid equilibrium of three binary hydrogen-paraffin hydrocarbon systems at temperatures between 100" and 300"F. and at pressures up t o 5000 pounds per square inch ( 5 ) . Kay (8) determined the bubble point and dew point pressures and temperatures for three mixtures of hydrogen in a petroleum naphtha and found a marked minimum solubility with respect t o changes in temperature. Frolich and coworkers (6) established the s o h hility of hydrogen in ten different hydrocarbon liquids including propane. This latter work represents the only information available at elevated pressures concerning the solubility of hydrogen in propane. Nelson and Bonnell (If) determined the composition of the liquid phase of mixtures of hydrogen and nbutane a t temperatures up t o 250' F. for pressures as high as 1500 pounds per square inch. Except for the measurements of Dean and Tooke ( 6 ) ,none of the data includes information concerning the composition of the coexisting gas phase. The volumetric behavior of hydrogen has been studied in detail by Wiebe and Gaddy ( 1 8 ) and by Bartlett and coworkers ( I ) in the temperature range coveied by this investigation. Johnston and White ( 7 ) recently summarized the compressibility data for hydrogen a t temperatures from its boiling point t o about 100 F. The vapor pressure of propane was studied by several investigators ( 2 , 3, I I ) , who also determined the volumetric behavior in the one- and two-phase regions with an accuracy adequate for present purposes. The volumetric and phase behavior of pro-
pane was reviewed in a recent study (19) and these data were employed here. MATERIALS
The hydrogen used in this study was obtained from the Matheson Chemical Co. and was prepared electrolytically. Akspectrographic analysis of the dried hydrogen as received indicated that it contained approximately 0.002 mole fraction of oxygen and negligible quantities of other materials. The hydrogen was passed over heated platinum at a pressure in excess of 1000 pounds per square inch and subsequently was dried over anhydrous calcium sulfate and activated charcoal. The purified gas contained less than 0.001 mole fraction of material other than hydrogen. The propane was obtained from the Phillips Petroleum Co. and it was reported to contain less than 0.001 mole fraction of material other than propane. This hydrocarbon was employed without further purification since such small quantities of inipurities would not alter significant,ly the results obtained. The vapor pressure of the propane employed did not change by more than 0.2 pound per square inch a t 130" F. upon a change in fraction vaporized from 0.2 to 0.9. METHODS
The apparatus used in this investigation TT-as described earlier (16). I n principle, it consisted of a stainless steel pressure vessel within which the sample was confined over mercury. Ports were provided a t two different points in the wall of the equilibrium vessel t o permit the withdrawal of gas and liquid phases after equilibrium was obtained. Equilibrium between the gas and liquid phases was attained by means of a mechanical spiral agitator located within the vessel. The stainless steel working
~
