I
R. M. BRICE
and W. M. BUDDE
Archer-Daniels-Midland Co., Minneapolis 2, Minn.
Epoxy Esters Relationship o f Structure to Plasticizer Performance
Internally positioned oxirane groups in long chains impart greater stabilizing and plasticizing properties to vinyl resin compounds than terminal oxirane groups in short chains. The presence of polymerizable unsaturation as in vinyl or acrylic esters diminishes compatibility following exposure to heat or light. Volatility properties are related to the molecular weight of the plasticizer; the lower the poorer. The trans isomer of a cis-trans epoxy pair is generally a poorer plasticizer than the cis isomer, especially in low temperature properties. Soapy water tends to extract the more polar plasticizer; gasoline and mineral oil behave in an opposite fashion
NINE
epoxidized esters were prepared to determine the effect on plasticizing properties of various functional groups and their placement in the fatty molecule (Tables I and 11). To maintain reasonable purity, the products were neither recrystallized nor distilled. Minimal fatty unsaturation was a primary objective. The performance of these epoxidized fatty acid and alcohol esters as poly(vinyl chloride) resin plasticizers was correlated with the number and relative
868
Table 1.
Preparation of Epoxy Esters
Epoxy Ester
Method of Preparation
+
Potassium oleate epichlorohydrin (quaternary ammonium salt catalyst) (4) Epoxidationa of oleyl acrylate Epoxidation" of oleyl acetate
Glycidyl oleate 9,10-Epoxystearyl acrylate 9,lO-Epoxystearyl acetate 9,lO-Epoxystearates Allyl Glycidyl
Alcoholysis of epoxidized triolein (KOH catalyst) Potassium 9,10-epoxystearateb epichlorohydrin (quaternary ammonium salt catalyst) (4) Epoxidationa of vinyl oleate Epoxidationa of ethyl oleate Epoxidation" of unsaturated butyl esters
+
Vinyl Ethyl Butyl (from oleate) ' Butyl (from elaidate"))
Polystyrene sulfonic acid catalyst, in situ procedure ( 3 ) . Prepared by saponifying butyl 9,lO-epoxystearate with theoretical amount of alcoholic KOH and isolating dry soap on vacuum hot roll dryer. C Prepared by esterification of elaidic acid, made by isomerization of oleic acid using selenium (6). 5
Table
Ester Glycidyl oleate 9,lO-Epoxystearyl acrylate 9,lO-Epoxystearyl acetate 9, IO-Epoxystearates Allyl Glycidyl Vinyl Ethyl Butyl (from oleate) Butyl (from elaidate)
INDUSTRIAL A N D ENGINEERING CHEMISTRY
Theoret. Mol. Wt.
It.
Properties of Epoxy Esters
Acid Oxirane Iodine Value", Oxygen, mrt. 75 Valuec, Mg. KOH/G. Theory Foundb G. Id100 G.
..
338
0.17
4.73
3.84
338
0.40
4.73
4.34
3.46
18.5
326
0.14
4.91
4.50
1.31
11.8
338 354 324 326
0.86 1.02 0.50 0.10
4.73 9.04 4.93 4.91
4.54 7.70 4.19 4.36
70.5 5.46 75.5 2.16
21.8
354
0.67
4.52
4.20
3.46
5.74
354
0.67
4.52
4.16
1.04
6.31
AOCS official method, Cd 4-40. Hydrogen bromide-acetic acid method ( 2 ) . TT'ijs. Cnpublished results from author's laboratory.
72.4
Hydroxyl Valued, Mg. KOH/G.
..
*.
11.9
Discussion of Results
position or spatial configuration of the oxirane groups and presence of carboncarbon double bonds (7). Fatty esters of this type which contain no oxirane groups have limited vinyl resin compatibility and cannot be tested at the high plasticizer level of 50 phr [parts of plasticizer per 100 parts of poly(viny1 chloride) 1.
CHI(CHz);CH-CH( CH2);COOCHzCH=CHz 'O\
CHI(Cn),CH=CH( CHZ)~COOCHZCH-CHZ
CHI(CHz)?CH-CH( CHZ);COOCH~CH-CHZ 'O\
The starting fatty materials were oleic acid (905 oleic acid, Swift and Co.) or oleyl alcohol (Ado1 85, Archer-Daniels-Midland Co.). Data are based on testing of plastic sheet made by milling plasticizer-resin blends on a two-roll rubber mill. A standard vinyl resin formulation was used in all evaluations.
Parts 100 50 '2 1
@
B. F. Goodrich Chemical Co. Advance Solvents & Chemical Corp.
The formulation was blended by first mixing the plasticizers and stabilizers thoroughly with a spatula in a stainless steel bowl, adding the vinyl resin, and blending on a Hobart mixer. This blend was worked on the mill for 10 minutes a t 310' F. before the sheets were rolled off. Stock used for tensile testing and for the Clash and Berg stiffness test was 0.075-inch molded sheet. The molding was done a t 320' F. for 5 minutes a t 1000 p.s.i. Because the number of carbon atoms in the molecule may appreciably affect performance, the compounds were compared in groups having the same number of carbon atoms.
Table 111. EPOXYstearyl Acrylate Flux Time, min. Temp., F. Mechanical properties Tensile strength', p.s.i. 100% modulus", p.8.i. yo elongation' Durometer hardnessb Clash and Berg Tf, C. Extraction, % ' loss White gasoline Mineral oil Soapy water Volatility, % loss Active carbon
7I/a 3 10 2400 930 387 87 -38.5
EPOXYstearyl Acetate
Glycidyl epoxystearate
0 ''
Glycidyl oleate was initially incompatible on milling when compounded a t 50 phr ; no further evaluation was carried out. Both glycidyl epoxystearate and allyl epoxystearate showed good initial compatibility. The terminal oxirane group in a fatty acid ester of this type contributes appreciably less to vinyl resin compatibility than an oxirane group internally positioned. Glycidyl epoxystearate showed slightly less compatibility than allyl epoxystearate in an accelerated sunlamp exposure test (modified ASTM D 620). In 3 months of exposure to north window light neither compound showed exudation. After 5 months of window exposure the allyl epoxystearate plasticized compound showed no exudation, whereas the glycidyl epoxystearate counterpart had a surface spew. Tensile strengths of the vinyl compounds were comparable (Table 111). Efficiency for allyl epoxystearate was somewhat higher, as indicated by its lower modulus. A modulus of 100% is the force in pounds per square inch required to stretch a specimen to twice its original length. The low temperature flexibility of the stock containing allyl epoxystearate was appreciably superior to that containing glycidyl epoxystearate, as indicated by the Clash-Berg torsion stiffness test (ASTM D 1043, 0.075-inch molded stock). T, (135,000 p.s.i.) for allyl
Standard Test Formulation Ingredient
Glycidyl oleate
0 ''
Experimental
Poly(viny1 chloride), Geon 101" Epoxy plasticizer Barium-cadmium stabilizer, BC-12* Stabilizer, CH-14b .
Allyl epoxystearate
epoxystearate was -43.5' C. and for glycidyl epoxystearate, - 29.4' C. Gasoline and oil extraction losses were appreciably higher from allyl epoxystearate plasticized stock than from the glycidyl epoxystearate compound (white gasoline, 24-hour immersion at 25' C., 0.030-inch stock). This is expected, because allyl epoxystearate contains roughly 50% less oxirane oxygen than glycidyl epoxystearate and hence is less polar and more soluble in hydrocarbon solvent. Soapy water extraction was slightly higher for glycidyl epoxystearate plasticized film compared to allyl epoxystearate, again reflecting its greater polarity (1% Ivory Snow, 24-hour immersion at 98' C.), using 0.030-inch stock. Volatilities were measured by the activated carbon method (24 hours a t 70' C., ASTM 1203-55), using 0.02inch stock. Glycidyl epoxystearate was considerably lower in volatility than allyl epoxystearate, probably partly because of its higher molecular weight. Specimens of the plasticized vinyl stock were placed in an oven a t 350" F. and samples were removed at 15-minute intervals over a 2-hour period. Color comparisons showed that both glycidyl epoxystearate and allyl epoxystearate stocks had excellent heat stability. The former was slightly superior, as might be anticipated, as its oxirane oxygen content is nearly 50% greater.
Evaluation of Poly(viny1 Chloride) Resin Sheets Allyl Epoxystearate
3 310
3 310
2373 800 433 83 -44.4
2410 860 423 84 -43.5
18.2 10.2 13.6
18.1 11.9 19.7
17.9 11.9 17.8
3.7
5.3
3.5
Glycidyl EPOXYstearate 31021/2 2480 997 410 87 -29.4 11.8 7.8 19.0 1.4'
Vinyl EPOXYstearate
Ethyl Epoxystearate
Epoxidized Butyl Oleate
Epoxidized Butyl Elaidate
3 310
2 3 10
2 3 10
2 310
2493 947 417 87 -38.4
2367 847 410 85 -44.1
2220 850 403 85 -46.2
2293 880 417 86 -37.8
17.3 12.1 17.0
17.7 11.9 18.7
20.2 11.3 10.4
24.2 13.2 8.9
7.1
6.3
2.5
2.2
" ASTM
D 412, 0.075-inch molded stock (Scott tester model L-6). ASTM D 676, 0.075-inch molded stock.
VOL. 5 0 , NO. 6
JUNE 1 9 5 8
869
CHa(CHz)?CH-CH( CHz)&OOCH&H=CH2
Allyl epoxystearate
‘d
CHs(CH~)7CH-CH(CH~)7CH200CCH=CH=CH~ Epoxystearyl acrylate O \/
The flux time for epoxystearyl acrylate was slower than for allyl epoxystearate (Table 111). This may indicate some polymerization of the easily polymerizable acrylic ester, because the polymer is expected to flux more slowly than the monomer. After 5 months of exposure to north window light these two products showed no tack. After the accelerated light exposure test the allyl epoxystearate compound had a slight spew, the epoxystearyl acrylate compound had developed a heavy spew and noticeably increased in stiffness. This may have been caused by further light-catalyzed polymerization of the reactive acrylate ester. Tensile strengths for the two compounds were comparable (Table 111). Efficiency and elongation were better for the compound containing allyl epoxystearate, and low temperature flexibility was somewhat better. This is probably a further indication of polymerization during milling of the epoxystearyl acrylate system. Gasoline extraction losses were comparable. Mineral oil extraction losses were slightly higher in the case of allyl epoxystearate; soapy water extraction losses were appreciably higher. If polymerization occurred during milling of epoxystearyl acrylate, one might expect the polymer to have better extraction properties than the monomer. A product made by externally polymerizing epoxystearyl acrylate using a vinyl polymerization catalyst showed very poor compatibility with poly(viny1 chloride). This high viscosity oil had nearly the same oxirane content as the corresponding monomer. Volatilities shown by the activated carbon test were comparable. The vinyl stock plasticized with allyl epoxystearate had excellent color stability in the oven heat test. Epoxystearyl acrylate produced a hazy film after 15 minutes of exposure a t this temperature. This difference is probably accounted for by the greater tendency of epoxystearyl acrylate to polymerize and lose compatibility.
All three samples were free from exudation after 3 months of exposure to north window light. After 5 months, vinyl epoxystearate showed a slight spew; the other two compounds showed no spew. I n the accelerated exposure test, compounds containing epoxystearyl acetate and ethyl epoxystearate remained free from surface spew; the vinyl epoxystearate compound developed a heavy exudation and the stock became stiff. Tensile strengths of epoxystearyl acetate and ethyl epoxystearate were comparable and a little lower than that of vinyl epoxystearate (Table 111). The efficiency of vinyl epoxystearate was inferior to those of ethyl epoxystearate or epoxystearyl acetate. The low temperature flexibilities of epoxystearyl acetate and ethyl epoxystearate were comparable and superior to that of vinyl epoxystearate. These differences would be expected if polymerization of vinyl epoxystearate had occurred. Gasoline and oil extraction losses were comparable. Soapy water extraction losses were high in all three cases. Volatilities of all three samples were relatively high, as anticipated from their lower molecular weight compared with materials described previously. The vinyl epoxystearate plasticized film possessed poor heat stability, as it became dark and cloudy after 15 minutes. Both ethyl epoxystearate and epoxystearyl acetate plasticized films had excellent heat stability. The deficiency of the vinyl ester may be due to polymerization of vinyl epoxystearate under test conditions. Epoxidized counterparts based on butyl oleate and butyl elaidate were compared. CHa(C\H2)7
>CHz)7COOBu
‘c-c’
\
’ 0 ‘ ”
cis H
\
(CHZ)~COOBU
/
c-c / \qH CH3(CHz)? 0
CHI(CHz),CH-CH( CH~)?COOCH=CHZ
trans
Vinyl epoxystearate
O ‘/
CH3(CHl)7CH-CH( CHz)?COOCH&H3
Ethyl epoxystearate
0 ‘’
CHs(CHZ)~CH-CH(CH~)?CH~OOCCH*Epoxystearyl acetate
870
INDUSTRIAL A N D ENGINEERING CHEMISTRY
Epoxidized butyl elaidate stock showed a slight waxy exudation after aging in the dark for a few days. Epoxidized butyl oleate stock showed no exudation after aging 5 months exposed to north window light. Tests were run on the epoxidized butyl elaidate stock in spite of this slight waxy exudation. Differences in tensile strength, elongation, and moduli between the elaidate and oleate counterparts were small (Table 111). Low temperature flexibility was appreciably poorer (Tf, -37.8’ C.) for epoxidized butyl elaidate than for epoxidized butyl-oleate (T,, - 46.2 ’ C.). The trans isomer is somewhat higher in melting point. Heat stabilities of the two products were comparable and very good. Gasoline and mineral, oil extraction losses were higher for the elaidic acidthan for the oleic acid-based product. These variations could be due to differences in compatibility. Literature Cited
Archer-Daniels-Midland Co., hlinneapolis, Minn., Tech. Paper 152. Durbetaki, A. J., Anal. Chem. 20, 2000 (1956). E. I. du Pont de Nemours & Co., Inc., Per-oxygen Products Bull. P61-454. Mueller, A. C. (to Shell Development Co.), U. S. Patent 2,772,296 (Nov. 11, 1956). Swern, D., Knight, H., Shreve, O., Heether. hl.. J . Am. Oil Chemists Soc. 27, i 7 (1950). RECEIVED for review February 13, 1958 ACCEPTEDMarch 29, 1958 Division of Paint, Plastics, and Printing Ink Chemistry, Epoxy Plasticizers-Stabilizers Symposium, 132nd Meeting, ACS, New York, N. Y., September 1957.
Recovering Fission ProductsCorrection I n the article on “Recovering Fission Products” [Barton, G. B., Hepworth, J. L., McClanahan, E. D., Jr., Moore, R. L., Van Tuyl, H. H., IKD.ENG. CHEY. 50, 21 2 (1958) 1, the following errors occurred. Table I, page 214. Footnote‘ refers to 2.5M Precipitant, and should read: nitric acid, 10-41M cesium. 0.1M urea present in ferrocyanide experiments. Table VI, first column, Rb, not Ru. Second column, NH4 concentration should have been given as 0.1. Sixth column, fourth numerical entry should have been given as 0.00005 (not 0.0005) and last entry as 0.0001. The heading of the seventh column should be Zn and Fe(CN)6-4M. I n the eighth column, the last entry should have been 14.
